paediatric ct exposure practice in the federal republic of...

Paediatric CT Exposure Practicein theFederal Republic of Germany

M. Galanski, H.D. Nagel, G. Stamm

Results of a Nation-wide Survey in 2005/06

ii

Business Addresses of the Authors

Prof. Dr. med. Michael GalanskiZentrum Radiologie der MHHDiagnostische RadiologieCarl-Neuberg-Straße 1D-30625 Hannover

mail: [email protected]

Dr. rer. nat. Georg StammZentrum Radiologie der MHHExperimentelle RadiologieCarl-Neuberg-Str. 130625 Hannover


Dr. rer. nat. Hans Dieter NagelPhilips Medizin Systeme GmbHWissenschaftliche AbteilungRöntgenstr. 24D-22335 Hamburg


The survey was conducted on behalf of the Ministry of Environment, Conservation and Reactor Safety (project StSch 4470”Investigation of representative data on the patient’s exposure resulting from frequent paediatric CT examinations for establishingdiagnostic reference levels”).

The content of the report in its present form was co-ordinated with the working group ”Paediatric Radiology” of the GermanRoentgen Society.

The report represents the views and opinions of the authors and does not necessarily represent the opinion of the Ministry ofEnvironment, Conservation and Reactor Safety.

Layout: H. D. Nagel, Hamburg, typeset on Apple Macintosh with Adobe PageMakerDeadline: Nov. 30, 2006Translation: H. D. Nagel, P. C. Shrimpton (English), and J.-F. Valley (French)

iii

Summary ....................................................................................................................................... 1

Résumé........................................................................................................................................... 2

1. Introduction .............................................................................................................................. 3

2. Organisation of the Survey ...................................................................................................... 4

3. Dosimetry .................................................................................................................................. 5

3.1. Weighted CTDI .................................................................................................................. 5 3.2. Volume CTDI ..................................................................................................................... 6 3.3. Dose-Length Product ......................................................................................................... 6 3.4. Effective Dose .................................................................................................................... 6

4. Results ........................................................................................................................................ 9

4.1. General Results .................................................................................................................. 94.1.1 Phase I ....................................................................................................................................................... 94.1.2 Phase II ...................................................................................................................................................... 9

4.2. Dosimetric Results ........................................................................................................... 12 4.3. Detailed Results ............................................................................................................... 12

4.3.1 Manual settings vs. automatic dose control ............................................................................................ 124.3.2 Overranging effects ................................................................................................................................. 124.3.3 Age-specific dose adaptation................................................................................................................... 134.3.4 Use of reduced tube potential .................................................................................................................. 174.3.5 Comparison with other surveys ............................................................................................................... 18

5. Discussion ................................................................................................................................ 19

6. Reference Values, Feedback Action ...................................................................................... 23

6.1. Proposal for Diagnostic Reference Values ....................................................................... 23 6.2. Comparison with other Reference Values ........................................................................ 23 6.3. Feedback Action .............................................................................................................. 24

7. Recommendations ................................................................................................................... 25

References.................................................................................................................................... 27

Appendix .......................................................................................................................... I - XXIII

Table of Contents

1Summary

Summary

A nation-wide survey of exposure practice in paediatricCT was conducted in Germany during the period fromSeptember 2005 until May 2006 on behalf of the ministryfor environmental protection, conservation and nuclearsafety. The survey was based on questionnaires that werefirst sent to 1640 users of CT scanners installed in hospi-tals and private practices, asking for the frequencies offive types of examination, subdivided into five age groups.In a subsequent second survey, a selected number of 72users, responsible for about two thirds of the annual pae-diatric CT examinations reported in phase I, were askedfor detailed dose-relevant data (scanner data, scan proto-cols, examination-related data and examination frequen-cies). These data were used for individualised dose as-sessments, depending on the type of scanner and age ofthe patient.

With return rates of 40% in the first part and 58% in thesecond part of the survey, representative results could beobtained for the five most frequent types of paediatric CTexamination. The most essential findings are:

• The percentage of paediatric CT examinations was inthe order of only 1% of all CT and thus much smallerthan elsewhere (e.g. 6.5% for USA)

• The most frequent type of examination was brain(52%), followed by chest (17%) and entire abdomen(7%); other types of examination were quite rare (lessthan 5%).

• The age distribution for paediatric CT examinationswas almost uniform (0 to 5 years: 40%, 6 to 10 years:28%, 11 to 15 years: 32%).

• The majority of paediatric CT examinations were con-ducted in university institutions and with the latest CTtechnology (multi-slice spiral scanners with solid statedetectors and dose display, often also equipped withdevices for automatic dose control).

• Exposure settings were generally adapted to the age orweight of the patients.

• On average, the adaptation was made in a moderatefashion that is in accordance with specific studies onthe topic and tailored more with respect to radiologists’impression of subjective noise than to measured imagenoise.

• Devices for automatic dose control (ADC) were avail-able on roughly 50% of scanners, but were not regu-larly used; compared with manually adapted dose set-tings, dose values resulting from the use of ADC de-vices were slightly to significantly higher.

• Patient-size dependent adaptation of exposure settingsresulted in a significant dose reduction in terms ofCTDIvol; with respect to effective dose, however, dosewas reduced to a lesser extent or even not at all if theincreased risk for induction of malignant tumours inchildren and newborn was taken into account.

• In comparison with the UK CT survey for 2003, simi-lar results were found for brain examinations, whereasdoses for chest examinations were significantly lower.

Based on the results of this survey, proposals have beenmade for diagnostic reference levels that refer to the thirdquartiles of the observed dose distributions. In addition,feedback was given to all participants of the survey insuch a way that the doses resulting from their scan proto-col settings could be benchmarked against the proposedreference dose values.

2 Résumé

Résumé

Une enquête nationale concernant la pratique des examenstomodensitométriques chez les enfants a été effectuéedurant la période de septembre 2005 à octobre 2006 surmandat du Ministère fédéral pour l’environnement, laprotection de la nature et la sécurité des réacteursnucléaires. L’enquête a d’abord consisté en l’envoi d’unquestionnaire à 1640 exploitants d’installations detomodensitométrie dans les hôpitaux et les cabinets privés.Il y était demandé des indications concernant les fré-quences pour 5 types d’examens, ventilés en 5 groupesd’âge. Dans une deuxième étape on s’est adressé à 72institutions, représentant plus des deux tiers des examensannuels tomodensitométriques en pédiatrie, pour obtenirdes données dosimétriques détaillées (indication surl’installation, protocole d’examen, données liées auxexamens, fréquence de ceux-ci). A l’aide des indicationsde chaque protocole, on a calculé les valeurs individuel-les de dose en fonction du type de l’installation et du grouped’âge.

Les taux de réponse ont été de 40 % dans la première phaseet de 58 % dans la seconde, autorisant la détermination derésultats représentatifs pour les examens les plus courantsde pédiatrie. Les conclusions les plus importantes del’enquête sont les suivantes:

• La part des examens pédiatriques à l’ensemble desexamens tomodensitométriques s’est établie à 1%, cequi est sensiblement plus faible que le taux rencontrédans d’autres pays (par exemple de 6,5% aux USA).

• Le type d’examen le plus courant a été l’examen ducerveau (52%), suivi par le thorax (17%) et l’abdomencomplet (7%) ; les autres types d’examen ont été parcontre rare (moins de 5%).

• Les groupes d’âge de 0 à 5 ans, de 6 à 10 ans et de 11 à15 ans ont présenté des taux proches, de 40%, 28% et32%.

• Les examens pédiatriques de tomodensitométrie ont étéréalisés principalement sur des installations univer-sitaires et avec la technologie la plus récente (tomoden-sitomètres hélicoïdaux à barrettes multiples, à base desemi-conducteurs, et indication de dose, souvent avecégalement réglage automatique du courant).

• Les paramètres d’exposition ont été généralementadaptés à la classe d’âge et au poids du patient.

• L’adaptation en question a été en moyenne modérée,en accord avec les résultats des études dédicacées à cethème. Ainsi l’adaptation se base moins sur le bruitobjectif mesuré que sur l’impression subjective de bruitperçue par l’observateur.

• Le réglage automatique du courant, disponible sur àpeu près la moitié des installations, n’a été utilisé quepartiellement et a conduit en moyenne à des doseslégèrement, et dans certains cas significativement, plushautes que celles obtenues avec une adaptation manu-elle des paramètres d’exposition.

• L’adaptation des paramètres d’exposition au patient aconduit à une réduction significative de la dose appré-ciée par la CTDI

vol; les réductions, appréciées par la

dose efficace, ont été plus faibles et ont même disparu,si l’on tient compte de l’augmentation du risque d’in-duction de tumeurs malignes pour les jeunes années.

• Les résultats de l’enquête ont indiqué des valeurs pourles examens du cerveau de même niveau que celles del’enquête anglaise de 2003, mais des valeurs significa-tivement plus faibles pour le thorax.

Sur la base des résultats de la présente enquête, des valeursdosimétriques de référence ont été établies, basées sur le3ème quartile de la distribution des doses. En outre un re-tour d’information a été donné à tous les participants àl’enquête (« action de feedback») sur la base duquel lecentre est à même de comparer la hauteur des doses qu’ildélivre aux valeurs de référence proposées.

31. Introduction

1. Introduction

Notwithstanding its proven diagnostic benefits, computedtomography leads to an increased radiation exposure ofpatients. New and improved imaging techniques enabledby the introduction of multi-slice CT have further increasedthe attractiveness of CT, resulting in increased examina-tion frequencies. Consequently in a number of countries,such as Germany (BfS 2006), CT now contributes morethan 50% of the radiation exposure of the population thatresults from diagnostic medical procedures.

In February 2001, a series of articles was published in theAmerican Journal of Roentgenology (Rogers 2001, Bren-ner et al. 2001, Paterson et al. 2001), indicating that themajority of paediatric CT examinations were made withthe same exposure settings that are used for adults, de-spite the fact that the x-ray beam is attenuated less by in-fants and children. The radiation exposure thus resultingis not only unnecessarily high, but, due to the reduceddiameter of children, the mean absorbed doses are evenhigher than for adults.

Since then, numerous recommendations have been pub-lished on how to adapt exposure settings in accordancewith patient size, weight or age (e.g. Huda et al. 2000,Donelly et al 2001, Honnef et al. 2004). In addition, allmajor CT manufacturers now offer devices for automaticdose control (ADC) that automatically adapt the exposuresettings to match the attenuating properties of the patient(ImPACT 2005). However, both the dose recommenda-tions and the characteristics of the ADC devices varygreatly, making it difficult for the casual user to profit fromthese developments and innovations.

In Germany, a number of CT-related projects have beenundertaken since 1999 when the ‘Concerted Action DoseReduction in CT’ was founded. Among them were twonation-wide surveys of CT exposure practice in 1999 (sin-gle-slice CT, Galanski et al. 2000) and 2002 (multi-sliceCT, Brix et al. 2003). These have served as the basis fordose recommendations (e.g. diagnostic reference levels,BfS 2003) that have been established in the meantime.However, no dedicated data were collected with respectto the application CT in paediatrics. As a consequence, aproject was advertised for bids in 2005 by the FederalRadiation Protection Office to conduct a dedicated sur-vey of CT exposure practice in paediatric CT.

The aims of this study are manifold:

• obtain data on the distribution and frequency of paedi-atric CT examinations;

• document the current status of paediatric CT;• investigate whether and how exposure settings are

adapted to patient’s age;• generate specific diagnostic reference dose levels.

This report presents the results of this new survey. In thenext chapter, a description is given of how the survey wasorganised and conducted. Chapter 3 outlines how dosevalues were derived from the reported exposure param-eters. The results of this survey are presented in chapter 4and discussed in chapter 5. A proposal for diagnostic ref-erence values for paediatric CT examinations and the feed-back given to the participants of this survey are presentedin chapter 6. In chapter 7, a number of practical recom-mendations are given on how to optimise examinationtechnique. Finally, comprehensive statistical data are com-piled in the appendix.

4 2. Organisation of the survey

2. Organisation of the Survey

The survey was organised in two consecutive phases:

• In phase I, a total of 1640 radiologists working inuniversity, public and private hospitals, as well as inprivate radiological practices, were asked to providethe following data concerning annual frequencies ofCT examination: the total number of examinations forall patients; and for paediatric patients up to 10 years,subdivided into five age groups (premature infants,newborn, up to 1 year, up to 5 years, up to 10 years)and five types of examination (brain, chest, upperabdomen, pelvis, entire abdomen). The principal aimof this activity was to identify institutions with signifi-cant annual frequencies of paediatric CT in order toreduce efforts in the second, more detailed phase ofthe survey whilst nevertheless ensuring that the majorityof paediatric CT examinations conducted in Germanywere represented. Addresses were taken either from thehead physician register of the German Roentgen Societyor from the membership register of the professionalassociation of German radiologists. The questionnaireused for this phase is shown in the appendix (fig. A1).

• In phase II, a total of 72 institutions, collectively re-sponsible for 68% (i.e. two thirds) of the annual paed-iatric CT examinations reported in phase I, were askedto provide detailed protocol data for the paediatric CTexaminations carried out on their scanners. Only thoseinstitutions reporting at least 100 paediatric CT exam-inations per year in phase I of the survey were includedin phase II. In contrast to the first phase, the age groupfrom 11 to 15 years was included, while prematureinfants and newborn were combined into a single agegroup. As a consequence of the results obtained fromphase I, the range of examinations involved was alsosomewhat altered: spine and facial bone examinationswere added, whereas upper abdomen and pelvis werediscarded, since the relative frequencies of these lattertwo types of examination were too small. The quest-ionnaire with the parameters requested is shown in theappendix (fig. A2). Based on the experience from thepreceding surveys, a detailed instruction sheet was sentwith the questionnaire in order to minimise the rate ofincorrect data (fig. A3).

The data in the returned questionnaires were checked forcompleteness and consistency, thereby making use of someredundancies in the data collected (e.g. exposure settingsas well as dose values indicated at the scanner’s console).If necessary, additional requests were sent to the partici-pants, either to supplement incomplete data, correct in-consistent data or clarify ambiguous data.

53. Dosimetry

3. Dosimetry

Dose calculations were made in a manner similar to dataevaluation for the two preceding German CT surveys in1999 and 2002 (Galanski et al. 2001, Brix et al. 2003).The algorithms, dose relevant scanner data and conver-sion coefficients used were as described in the textbook‘Radiation Exposure in Computed Tomography’ (Nagelet al. 2002) and updated in the recent version of the CTdose calculation software CT-Expo (Stamm and Nagel2002). However, in order to meet the particular require-ments for multi-slice scanners and paediatric patients, afew major modifications were necessary:

• Firstly, with the advent of scanners capable of acquir-ing an increasingly large number of slices simultane-ously, overranging effects (i.e. the elongation of thescan range in spiral scan mode to enable data interpo-lation at the beginning and at the end of the scan) couldno longer be neglected. This applies in particular topaediatric examinations with relatively short scanranges, where the percentage increase in dose-lengthproduct (DLP) is relatively large. A correction formal-ism (Nagel 2005) as implemented in the CT-Expo soft-ware (version 1.4 and later) was used to account foroverranging effects.

• Secondly, in order to calculate CTDIvol values that giverealistic estimates of organ dose and allow comparisonof results with those from other surveys (Shrimpton etal. 2005), calculations for all age groups up to 10 years

were based on CTDI values relating to the smallerstandard CT dosimetry phantom (head phantom). TheseCTDI values account for the smaller patient diameter,but apply only if the scan was made in head scanningmode. Since paediatric CT examinations in the trunkregion are usually carried out in body scanning mode,specific dosimetry was needed for those scanners thatapply different beam filtration in head and body modein order to obtain CTDI data for the smaller 16 cm phan-tom in body scanning mode. Such data were establishedfor a Somatom Sensation 4 (representative for Siemensscanners) and a LightSpeed 16 (representative for GEscanners).

• Thirdly, since conversion coefficients for the calcula-tion of organ doses and effective doses were availableonly for a six week old infant (‘BABY’) and a sevenyear old child (‘CHILD’) (Zankl et al. 1993), furthereffort was required in order to allow the computationof effective dose for all age groups involved in thisstudy. This was achieved by careful analysis of thepublication by Khursheed et al. (2002). As a result, aset of correction factors was derived that could be ap-plied to the effective doses calculated for adults for thescan protocol parameters used for the respective pae-diatric age group.

Dose calculations were made for all relevant CT dosedescriptors in the following way:

3.1. Weighted CTDI

The ‘Weighted Computed Tomography Dose Index’(CTDI

w, unit: mGy) is calculated according to

CTDI CTDIU

UI t kw H B n w H B

refOB, / , /

.

( . )= ⋅

⋅ ⋅ ⋅

2 5

3 1

where nCTDI

w,H/B is the normalised weighted CTDI (unit:

mGy/mAs) for head and body scanning mode (H and B),respectively; U (in kV) is the tube potential applied; U

ref

(in kV) is the reference tube potential to which the dosedata for the particular scanner refer; I · t is the electricaltube load (mAs product) per rotation; and k

OB is the

overbeaming correction factor that accounts for the por-tion of the beam that is not used for imaging purposes.Overbeaming correction is achieved by

kN h N h dz

N h N h dzOBref col

col ref

( )

( ) ( . )=

⋅( ) ⋅ ⋅ +⋅ ⋅ ⋅( ) +

3 2

where (N·h)ref

is the reference beam width to which thedose data for the particular scanner refer; N·h

col is the ac-

tual beam width for the scan protocol; and dz is theoverbeaming parameter that describes the effective widthof the unused portion of the dose profile (typically 3 mm,dependent on the type of scanner).

In order to distinguish between CTDIw values in body scan-

ning mode that refer either to the smaller 16 cm or thelarger 32 cm phantom, CTDI values are labelled asCTDI

w16 and CTDI

w32, respectively.

6 3. Dosimetry

The ‘Volume Computed Tomography Dose Index’(CTDI

vol, unit: mGy) is defined as

CTDICTDI

pvolw ( . )= 3 3

i.e. CTDIvol

is the pitch-corrected weighted CTDI. CTDIvol

is equal to the average absorbed dose (the ’intensity’ ofthe irradiation) inside the scan range and provides a fairestimate of the dose to organs that are entirely locatedinside the scan range. CTDI

vol is displayed at the scan con-

sole of all newer scanners. Whether it refers to values ofhead or body CTDI depends solely on the selected scanmode (head or body), and not on the size of the patient.Therefore the dose to paediatric patients in examinationsof the trunk region, based on the CTDI

vol from the scan-

ner’s dose display, is under-estimated by a factor two tothree. Consequently, values were calculated for bothCTDI

vol16 and CTDI

vol32 in order not only to provide real-

3.2. Volume CTDI

istic dose estimates, but also to allow comparison withthe quantity shown at the dose display.

The pitch definition used here refers to the revised IECstandard 60601-2-44 ed. 2.0 (IEC 2001):

pTF

N hcol

( . )=⋅

3 4

where TF is the table feed per rotation and N·hcol

is theactual beam width for the scan protocol. This universalpitch definition, resulting in typical pitch factors ofbetween 0.5 and 2.0, is now used for most scanners,whereas older MSCT scanners often display pitch factors(‘volume pitch’ or ‘detector pitch’) that are N times larger(N = number of slices acquired simultaneously).

3.3. Dose-Length Product

The ‘Dose-Length Product’ (DLP, unit: mGy·cm) is obtain-ed from the CTDI

vol and the scan length via

DLP CTDI Lvol tot ( . )= ⋅ 3 5

where Ltot

is the total scan length (in cm!). The scan lengthinformation, given explicitly or implicitly in the imagesand on most scanner consoles, refers only to the positionof the first and the last slice. Therefore one half of a (re-constructed) slice width h

rec has to be added at each end of

the scan range to get at least the length of the range that isrepresented by the set of images obtained from the scan.If the examination is carried out in spiral scanning mode,overranging effects also imply an additional length ∆L.Therefore the total scan length L

tot is:

L first last slice position h L (3.6)tot rec= − + + ∆

∆L is calculated according to

∆L N h m p bcol OR OR ( . )= ⋅ ⋅ ⋅ +( ) 3 7

where mOR

and bOR

are the overranging parameters thatexpress the pitch dependence of overranging effects.

If the scan range for a given type of examination is scanned(entirely or in part) more than once, the dose length prod-uct for the entire examination DLP

exam is derived by mul-

tiplying the DLP per scan series by the number of scanseries n

Ser:

DLP DLP nexam Ser ( . )= ⋅ 3 8

In the context of this survey, nSer

can be a non-integernumber if one of the scan series for an examination cov-ers a portion only of the entire range or if multi-phaseexaminations are performed on a fraction only of the pa-tients.

3.4. Effective Dose

The ‘Effective Dose’ (E, unit: mSv) is calculated accord-ing to

E DLP

P f k f

k

kH/B

H/Bmean CT(H/B) age,region

CT,H

CT,B

x

= ⋅ ⋅ ⋅ ⋅

( . )3 9

where PH and P

B are the so-called phantom factors, i.e. the

ratio between the weighted CTDI (derived from CTDImeasurements inside the standard dosimetry phantoms)and the corresponding CTDI measured free-in-air, i.e.without phantom, either for head (H) or body (B) scan-ning mode. f

mean (unit: mSv/mGy·cm) is the average fac-

73. Dosimetry

tor for converting DLP (based on CTDI free-in-air) intoeffective dose. f

mean was calculated for the typical scan

ranges for standard CT examinations of adults (e.g. brain,chest etc.) from a set of tabulated organ dose conversionfactors for male and female adults (Zankl et al. 1991).The conversion factors used here apply to a specific scan-ner model (Somatom DRH) that was in common use atthe time when the GSF conversion factors were compiled.k

CT(H/B) is the scanner factor that allows these conversion

factors to be used also for other scanners, by matching thecharacteristics of the particular scanner model to those ofthe Somatom DRH. f

age,region is a correction factor, depend-

ent on the patient’s age and the scan region, derived fromthe publication by Khursheed et al., that accounts for thedifferences in patient size and organ location between adultand paediatric patients. The term (k

CT,H / k

CT,/B)x is also re-

quired for scanner matching in order to account for thesmaller size of paediatric patients. The exponent x in thisterm varies with age group between 1.5 (for newborn) and0 (for age group 11 – 15 years); in head scanning mode, xis equal to 0 for all age groups.

Following the same approach used for DLP, the effectivedose for the entire examination E

exam is derived from the

effective dose per scan series by multiplying by the numberof scan series n

Ser:

E E nexam Ser ( . )= ⋅ 3 10

The dose relevant data for the scanners involved in thissurvey, the conversion factors and correction factors usedfor the calculation of dose are tabulated in tables A1 to A3in the appendix. With the exception of the CTDI meas-urements described above to obtain CTDI values for the16 cm phantom in body scanning mode, no other dosemeasurements were made. Instead, the normalised CTDIvalues that form the basis for the CT-Expo software wereused. Dedicated comparisons, either with TLD measure-ments in an anthropomorphic phantom (Brix et al. 2004)or with other programs for CT dose calculation (Tack andGevenois 2006), have led to the conclusion that the un-certainties and variances involved in our dosimetry arealways framed by other uncertainties in surveys of thiskind. Therefore dedicated dose measurements for the scan-ners at each institution participating in this survey wouldnot have significantly reduced the overall uncertainties.

8 3. Dosimetry

94. Results

4. Results

4.1. General Results

4.1.1 Phase I

In phase I, 663 out of 1640 addressees replied (40% par-ticipation rate) and reported in total 3.2 million CT ex-aminations, including 20,900 paediatric CT examinationson patients aged up to 10 years. As a projection from pre-vious surveys (1999 and 2002), the total number of CTscanners installed in Germany is presently about 2500,and the annual total number of CT examinations is about8.2 million (i.e., ca. 100 CT exams per 1000 inhabitantsper year). By making reference to these figures, the insti-tutions that participated in phase I of the survey comprisedabout 30% of all scanners and about 40% of all CT ex-aminations.

The corrected number of paediatric CT examinations re-ported (including also the age group 11 to 15 years) wasabout 30,700. Projected to all CT examinations in Ger-many, the contribution from paediatric CT examinationsamounts to 0.95%. Bearing in mind the uncertainties inthis projection, it can thus be concluded that the relativeproportion of paediatric CT examinations is in the orderof 1%.

4.1.2 Phase II

72 institutions with 102 CT scanners reporting at least 100

paediatric CT examinations per year in phase I were askedto provide detailed protocol data for the paediatric CTexaminations carried out on their scanners. These institu-tions collectively included 21,600 (i.e. 70%) of the cor-rected annual number of paediatric CT examinations re-ported in phase I. In phase II, data were returned by 42institutions (return rate 58%) operating 63 scanners (62%of 102) and conducting 10,100 paediatric CT examina-tions (47% of 21600). The names of the institutions par-ticipating in this survey and the scanner models used bythem are listed in table A4 in the appendix.

Detailed protocol data were reported for a total of 54 scan-ners. Almost two thirds were provided by university hos-pitals and one third by general hospitals; only a few (4%)were contributed by private practices. The majority ofpaediatric CT examinations are therefore performed inuniversity hospitals (fig. 4.1). The vast majority of scan-ners were multi-slice in design, capable of acquiring si-multaneously 2 or more slices per rotation. Most were ei-ther 2-slice to 6-slice scanners (35%) or 8-slice to 16-slicescanners (39%); only 15% were single-slice scanners (fig.4.2). The distribution by manufacturer (fig. 4.3) was verysimilar to the patterns observed in previous surveys. Aboutone half of the scanners were less than 4 years old, whereasabout one third were between 4 and 7 years old; only 17%were more than 7 years old (fig. 4.4). The vast majority of

Fig. 4.1 Distribution of participating institutions. Fig. 4.2 Distribution of technology of participatingscanners (N = number of simultaneously acquirableslices).

Private practices4%

Generalhospitals

33%

Universityhospitals

63%

N=115%

N=2 to 635%

N=8 to1639%

N=20 to 6411%

10 4. Results

the scanners (91%) were equipped with a dose display(fig. 4.5). Devices for automatic dose control were avail-able on more than half of the scanners, but not used for alltypes of examinations (fig. 4.6).

The annual number of paediatric CT examinations perscanner varied from less than 100 to more than 600. Aboutone quarter of scanners each performed less than 100, from100 to 149, 150 to 249 and more than 250 examinations,respectively (fig. 4.7). On average, the institutions par-ticipating in phase II conducted 187 paediatric CT exami-nations per scanner and year. The fraction of paediatricCT examinations varied between less than 1% and morethan 10% of all CT. The two largest groupings of institu-tions (about one third each) were for the ranges 1 to 2%and 2 to 5% (fig. 4.8). Three of the participating institu-tions were dedicated children’s hospitals, where for eachmore than 50% of all CT examinations were performedon children aged up to 15 years. The average fraction of

GE17%

Philips(Elscint)

6%

Philips17%

Philips(Picker)

4%

Siemens49%

Toshiba7%

Fig. 4.3 Distribution of the manufacturers of the scan-ners participating in this survey.

Fig. 4.4 Age distribution of the participating scanners. Fig. 4.7 Annual number of paediatric CT examinationsper scanner.

Fig. 4.6 Frequency of use of automatic dose controldevices.

Fig. 4.5 Availability of dose displays.

paediatric CT examinations among the participating in-stitutions was 2.5% of all CT.

< 4 years50%

4 to 7 years33%

> 7 years17%

with dose display91%

without dose display9%

always used20%

partially used39%

never used41%

<10027%

100 to 14924%

150 to 24926%

250 to 39915%

400 to 5994%

≥6004%

114. Results

The age distribution of paediatric CT examinations (fig.4.9) was split almost equally into the age groups up to 5

years (40%), 6 to 10 years (28%) and 11 to 15 years (32%).Only very few exams were performed on the newborn(3%). Most of the examinations were standard brain scans(52%), followed by scans of the chest (17%) and abdo-men (incl. pelvis) (7%); spine and facial bone examina-tions were relatively rare. A larger fraction (17%) couldnot be attributed to any of these 5 types of examination(fig. 4.10a). A more detailed analysis (fig. 10b) shows thatthese percentages also hold true for each age group, ex-cept for the newborn where chest and abdomen examina-tions are performed more frequently than in other agegroups.

Fig. 4.8 Fraction of paediatric CT examinations per par-ticipating scanner.

Fig. 4.9 Age distribution for paediatric CT examinations. Fig. 4.10a Frequency distribution for types of paediatricCT examination.

Fig. 4.10bRelative fractions forthe types of exami-nation per age group(BRN = brain, FB/SIN = facial bone/si-nuses, CHE = chest,ABDPE = abdomen(incl. pelvis), LSP =lumbar spine).

<1%13%

1 to 2%33%

2 to 5%36%

5 to 10%11%

>10%7%

Newborn3% up to 1y

9%

2 to 5y28%

6 to 10y28%

11 to 15y32%

Brain52%

Facial bones/sinuses4%

Chest17%

AbdoPel7%

Spine3%

Misc.17%

0%

10%

20%

30%

40%

50%

60%

70%

newborn up to 1y 2 to 5y 6 to 10y 11 to 15y all

Age group

BRN

FB/SIN

CHE

ABDPE

LSP

Rel

ativ

e fr

acti

on

per

ag

e g

rou

p

12 4. Results

4.2. Dosimetric Results

The dosimetric results are compiled in tables A5 to A9 inthe appendix. Table A5 shows the average values, sortedwith respect to age group. For the purposes of compari-son, corresponding values are also shown from the twopreceding surveys in 1999 and 2002 that referred to adultpatients. For some age groups and types of examination,the number of participating institutions and patients in-cluded was quite small. Therefore these data (given in Ital-ics) should be treated with particular caution.

Table A6 presents the same data as in Table 5, but sortedwith respect to the type of examination. This allows a di-rect comparison of how the dose settings have been adaptedto patient’s age. In tables A7 and A8, corresponding dataare given for the first quartile and the median, respectively.In table 9, third quartile values are presented that may serveas a base for reference dose values. Comprehensive sta-tistical data relating to each type of examination are com-piled in tables A10 to A14.

4.3. Detailed Results

4.3.1 Manual settings vs. automatic dose control

As already mentioned above, devices for automatic dosecontrol were available on more than half of the scanners,although not used for all types of examination. Accord-ingly, it is of interest to see whether there are significantdifferences in the dose values between manual dose set-tings and those adjusted automatically.

In fig. 4.11, the fraction of users who employ automaticdose control is analysed by type of examination. Whereasabout 50% of users employ ADC devices for examina-tions of the trunk region, only about 25% do so for exami-nations of the head region.

Differences in the dose values applied in ADC mode com-pared with those for manual setting, averaged over all agegroups, are shown in fig. 4.12. In general, higher doseswere applied in ADC mode than with manual settings.Whereas only slight differences were found for examina-tions of the chest and the abdomen, significant differences

(25%) occur for examinations of the head region; for spineexaminations, doses applied in ADC mode are higher onaverage by 70%.

4.3.2 Overranging effects

With the advent of scanners capable of acquiring an in-creasingly large number of slices simultaneously, over-ranging effects (i.e. the elongation of the scan range inspiral scan mode to enable data interpolation at the begin-ning and at the end of the scan) make a significant contri-bution to the dose-length product. For most multi-slicescanners, the elongation ∆L of the scan range amountsroughly to 1.5 times the total beam width N·h

col (Nagel

2005). When compared with an examination of the samebody region performed in sequential scan mode, the in-crease in DLP resulting from this elongation also dependson the scan length. It must therefore be expected thatoverranging effects will become more pronounced withthe shorter scan ranges encountered in paediatric CT ex-aminations.

Fig. 4.11 Relative frequencies of use for devices forautomatic dose control (ADC).

Fig. 4.12 Percentage increase in dose (CTDIvol

) whenusing ADC devices compared with manual dose settingfor the types of examination covered by this survey(average for all age groups).

0%

10%

20%

30%

40%

50%

60%

70%

Brain Sinuses Chest AbdoPel Spine

Type of Exam

Fra

ctio

n m

akin

g u

se o

f A

DC

0%

10%

20%

30%

40%

50%

60%

70%

80%


Type of Exam

incr

ease

d C

TD

Ivo

l wit

h A

DC

vs.

w/o

AD

C

134. Results

As shown in fig. 4.13, all or most paediatric CT examina-tions are performed in spiral mode, with the exception ofbrain examinations, where 90% of the protocols are setup for sequential acquisition. Consequently, overrangingeffects are negligible for brain examinations. For all othertypes of examination investigated, overranging effects lead

on average to an increase in DLP in the order of 10 to20% (fig. 4.14). Even greater increases were found forspine examinations on newborn and infants owing to therelatively short scan ranges. This additional exposure isreduced with increasing age owing to the more extendedscan ranges found in these age groups (fig. 4.15). Underspecial circumstances, i.e. on scanners with a large numberof simultaneously acquired slices (e.g. 64-slice scanners),a significant increase in the DLP must be expected.

4.3.3 Age-specific dose adaptation

Since there is reduced x-ray beam attenuation for thesmaller size of paediatric patients relative to an adult, anadequate image quality can be achieved with a lower dose.Figs. 4.16a to 4.16e show how dose settings of CTDI

vol

were adapted on average to the body weight of the pa-tients. In the case of examinations in the trunk region,CTDI

vol32 is used for this analysis since, for a given scan-

ner with tube potential kept constant, this quantity is pro-portional to the mAs setting. The conversion from patient’sage to body weight as shown in fig. 4.17 is based on thetabulated anatomical data from Prader et al. (1989). Adultdata (to which the relative dose level of 100% at 80 kgbody weight refers) were taken from the 2002 Germanmulti-slice CT survey (Brix et al. 2003).

In addition, values corresponding to recommendations forexaminations of the trunk region (Rogalla, 2004) and ex-aminations of the head region (Morgan, 2003) have beenplotted for the purposes of comparison. Good agreementis found between the average results of this survey andthe recommendations made by these authors for the threemost frequent types of examination (brain, chest and ab-domen). For examinations of the facial bone/sinuses, doseadaptation is more pronounced than recommended. Forspine examinations, dose settings are also reduced in com-parison with adults, but without further adaptation to pa-

Fig. 4.15 Average net scan length for the types ofexamination and age groups covered by this survey.

Fig. 4.14 Percentage increase in DLP due to overrang-ing effects in spiral scanning mode for the types ofexamination and age groups covered by this survey.

Fig. 4.13 Relative fractions of scan protocols performedin spiral mode for the types of examination covered bythis survey (average for all age groups).

Fig. 4.17 Correlation between patient’s age andaverage body weight for male paediatric patients (fromPrader et al. 1989).

0%

20%

40%

60%

80%

100%


Type of Exam

0%

10%

20%

30%

40%

Newborn up to 1y 2 to 5y 6 to 10y 11 to 15y

Age Group

SpineChestSinusesAbdoPel Brain

Rel

ativ

e In

crea

se in

DL

P

0

10

20

30

40

50

Age Group

AbdoPelChestSpineBrainSinuses

Newborn up to 1y 2 to 5y 6 to 10y 11 to 15y Adults

Ave

rag

e N

et S

can

Len

gth

[cm

]

0

10

20

30

40

50

60

70

0 5 10 15 20

Patient’s Age [years]

Ave

rag

e B

od

y W

eig

ht

[kg

]

14 4. Results

tient’s weight; i.e. very similar settings are used for bothinfants as well as 15 year-old adolescents.

Contrary to circumstances for brain examinations, exami-nations of the facial bone/sinuses are characterised by highinherent contrast that allows reduced dose settings. Fig.

Fig. 4.16 Adaptation of dose settings to patient’s body weight for the types of examination covered by this survey:brain (a), facial bone/sinuses (b), chest (c), abdomen (incl. pelvis) (d), and lumbar spine (e). Relative dose values(mean values) in terms of CTDI

vol16 (a and b) and CTDI

vol32 (c to e) refer (as 100%) to the corresponding mean values

from the German MSCT survey 2002 for adults (80 kg) (Brix et al. 2003). For the purposes of comparison, the corre-sponding relative values resulting from the recommendations of Morgan (2003) and Rogalla (2004) are also given.

4.18a shows the ratio of the average settings of CTDIvol16

for these 2 types of examination, demonstrating that dosesettings for facial bone/sinuses examinations are lower bya factor 3. For chest examinations, both the reduced at-tenuation and the increased inherent contrast are in fa-

Fig. 4.18a Ratio of the dose settings (CTDIvol

) for exami-nations of the brain in comparison with those of the facialbone/sinuses .

Brain

0%

20%

40%

60%

80%

100%

0 20 40 60 80 100

Body weight (kg)

SurveyMorgan'Rogalla'

a.

Facial Bone/Sinuses

0%

20%

40%

60%

80%

100%

0 20 40 60 80 100

Body weight (kg)

SurveyMorgan'Rogalla'

b.

Chest

0%

20%

40%

60%

80%

100%

0 20 40 60 80 100

Body weight (kg)

SurveyRogalla

c.

Abdomen (incl. pelvis)

0%

20%

40%

60%

80%

100%

0 20 40 60 80 100

Body weight (kg)

SurveyRogalla

d.

Spine

0%

20%

40%

60%

80%

100%

0 20 40 60 80 100

Body weight (kg)

SurveyRogalla

e.

0

1

2

3

4

Newborn <1y 2-5y 6-10y 11-15y Adults

Age Group

154. Results

Chest

0

2

4

6

8


Age group c.

Fig. 4.19 Mean values of effective dose in relation to patient age for types of CT examination brain (a), facial bone/sinuses (b), chest (c), abdomen (incl. pelvis) (d) and lumbar spine (e). The corresponding mean values for adults weretaken from the German MSCT survey 2002 (Brix et al. 2003).

vour of reducing the dose compared with examinations ofthe abdomen. As shown in fig. 4.18b, however, theCTDI

vol32 settings for chest examinations, when compared

with those for the abdomen, are lower by a factor of about1.25 only.

Fig. 4.18b Ratio of the dose settings (CTDIvol

) for exami-nations of the abdomen (incl. pelvis) in comparison withthose of the chest.

0

0.25

0.5

0.75

1

1.25

1.5


Age Group

CT

DIv

ol A

bd

oP

el v

s. C

hes

t

Brain

0

1

2

3

4


Age group a.

Facial Bone/Sinuses

0.0

0.5

1.0


Age group b.

Spine

0

5

10

15


Age group e.


0

5

10

15

20


Age group d.

16 4. Results

Absolute values of effective dose per examination aregiven (in mSv) in figs. 4.19 a to 4.19e, with analysis bythe patient’s age. Once again the corresponding resultsfor adults from the 2002 MSCT survey are also includedand these serve as the bases for the relative effective doses

Fig. 4.20 Relative effective dose in relation to patient age for types of CT examination brain (a), facial bone/sinuses(b), chest (c), abdomen (incl. pelvis) (d) and lumbar spine (e). Relative dose values refer (as 100%) to the correspond-ing mean values from the German MSCT survey 2002 for adults (80 kg) (Brix et al. 2003) and these are given both withand without correction for differences in the risk for the induction of malignant tumours. The corresponding age-dependent risk factors were taken from ICRP publication 60 (ICRP 1991).

presented in figs. 4.20a to 4.20e. These relative values arepresented both with and without correction for the in-creased risk at lower patient age for the induction of ma-lignant tumours, utilising age-dependent risk factors fromICRP publication 60 (ICRP 1991). In comparison withadults aged 50 years, the relative risk is 3 times higher forthe age group 10 to 19 years and 5 times higher for theage group 0 to 9 years. Notwithstanding the fact that re-duced dose settings are applied in a reasonable mannerfor younger patients, the reduction in effective dose is lesspronounced, since, for the same exposure settings (i.e. kVand mAs), the absorbed dose to the patient increases withdecreasing patient size. When the higher risk for tumourinduction is taken into account (risk corrected effectivedose), the relative doses are generally higher than foradults. This holds true in particular for examinations ofthe brain and the spine.

Brain

0%

100%

200%

300%

400%


Age group

not correctedrisk corrected

a.

Facial Bone/Sinuses

0%

100%

200%

300%

400%


Age group


b.

Chest

0%

50%

100%

150%

200%

250%


Age group


c.


0%

50%

100%

150%

200%

250%


Age group


d.

Spine

0%

100%

200%

300%

400%


Age group


e.

174. Results

Brain - DLP16 per exam

0%

50%

100%

150%

200%


Age group

Brain - CTDIvol16

0%

50%

100%

150%

200%


Age group

Brain

0%

20%

40%

60%

80%

100%

0 20 40 60 80 100

Body weight (kg)

SurveyUK2003

Fig. 4.21 Percentage fraction of scan protocols applyingtube potentials below 110 kV, subdivided into the types ofexamination and age groups covered by this survey.

Fig. 4.22 Comparison of the results of this survey with those from the UK CT survey 2003 for brain examinations:adaptation of the dose settings to the patient’s weight (a), CTDI

vol16 (b), dose-length product (c) and effective dose

(d). The corresponding average German values for adults were taken from the German MSCT survey 2002.

4.3.4 Use of reduced tube potential

The use of reduced tube potentials are frequently advo-cated, i.e. 80 kV or 100 kV instead of 120 kV, which is thestandard tube potential setting for adult CT examinations.Accordingly, it is of interest to explore the extent to whichreduced kV settings are applied. In fig. 4.21, the fractionof protocols utilising tube potentials below 110 kV arepresented, with analysis by patient age group. In general,lower kV settings are applied to a greater extent for new-born and infants, and to a lesser extent for adolescents.Reduced tube potentials are used more frequently for chestexaminations (35% on average), followed by facial bone/sinuses (21%) and abdomen-pelvis (17%), whereas forbrain and spine examinations, standard kV settings (110to 130 kV) are mostly used (more than 90% on average).

0%

20%

40%

60%

80%

100%

Age Group

ChestSinusesAbdoPelSpineBrain

Newborn up to 1y 2 to 5y 6 to 10y 11 to 15y

a.

b.

c.

Brain - effective dose per exam

0%

50%

100%

150%

200%


Age group d.

18 4. Results

4.3.5 Comparison with other surveys

Up to now, there has been only one survey (the 2003 UKCT survey, Shrimpton et al. 2005) in which data on thedose settings used in paediatric CT examinations have beencollected, although this included fewer types of examina-tion (brain and chest) and age groups (up to 1 year, 2 to 5years and 6 to 10 years) compared with our survey. Forexaminations of the brain, CTDI

vol16 values and their age/

weight dependence are quite similar between surveys (figs.4.22a and 4.22b); DLP and effective dose values found in

Fig. 4.23 Comparison of the results of this survey with those from the UK CT survey 2003 for chest examinations:adaptation of the dose settings to the patient’s weight (a), CTDI

vol32 (b), dose-length product (c) and effective dose

(d). The corresponding average German values for adults were taken from the German MSCT survey 2002.

our survey, both expressed per exam, are somewhat higher(figs. 4.22c and 4.22d). For examinations of the chest,CTDI

vol32 values are lower in our survey (fig. 4.23a), and

the dose adaptation to body weight is more pronounced(fig. 4.23b); the same patterns hold true for DLP and ef-fective dose per exam (figs. 4.23c and 4.23d). However, itshould be noted that overranging effects were not takeninto account for DLP and effective dose in the UK 2003survey and that a different formalism was used for theassessment of effective dose.

Chest

0%

20%

40%

60%

80%

100%

0 20 40 60 80 100

Body weight(kg)

SurveyRogallaUK2003

a.

Chest - CTDIvol32

0%

50%

100%

150%


Age group b.

Chest - DLP32 per exam

0%

50%

100%

150%

200%


Age group c.

Chest - effective dose per exam

0%

50%

100%

150%

200%

250%


Age group d.

195. Discussion

5. Discussion

As the first survey of its kind worldwide, the German sur-vey on paediatric CT practice for 2005/2006 has revealeda number of interesting details not previously known. Al-though the study is based on a limited number of institu-tions, with most (75%) being university sites, the resultsof this survey can nevertheless be regarded as being na-tionally representative since the vast majority of paediat-ric CT examinations in Germany are carried out by theseparticular institutions.

In contrast to practice in other countries, where childrenup to 15 years account on average for 6% of all CT ex-aminations (UNSCEAR 2000), the fraction of paediatricCT examinations is relatively small in Germany (about1%). In absolute terms, with about 100 annual CT examsper 1000 inhabitants (Galanski et al. 2001), only 1 childaged up to 15 years among 1000 inhabitants undergoes apaediatric CT exam each year in Germany. In the U. S.,with about 160 annual CT examinations per 1000 inhabit-ants and where the fraction of CT exams on paediatricpatients is 6.5% (CRCPD 2006), the corresponding fig-ure is more than 10 times higher. This could be interpretedthat the justification for paediatric CT examinations isviewed somewhat more restrictively in Germany.

Dose relevant data were collected for examinations ofbrain, chest, abdomen (incl. pelvis), facial bone/sinusesand spine, which were identified in the first part of thissurvey as being the five most frequent types. Other typesof examination are quite rare and were therefore not takeninto account. Most paediatric CT examinations are re-stricted to the head region (roughly two thirds), whereasonly one third are carried out in the trunk region. In par-ticular, the fraction of abdomen examinations, which is arelatively frequent type of examination for adults (about25%) and associated with a relatively high effective dose(about 20 mSv), is quite rare in the paediatric domain (only7%). Therefore, not only is the number of paediatric CTexaminations relatively small in Germany, but so is theaverage dose per paediatric CT exam. The age distribu-tion is relatively flat, i.e. similar frequencies are noted forall age groups (up to 5 years, 6 to 10 years, and 11 to 15years).

The majority of the scanners used for paediatric CT ex-aminations are quite modern, i.e. spiral scanners with solidstate detectors. Most of these have multi-slice capabili-

ties, thus enabling significantly reduced total scan times.Practically all of them (more than 90%) are equipped witha dose display (indicating at least CTDI

vol). Most of these

scanners (about 60%) are also equipped to a greater orlesser extent with a sophisticated device for automatic dosecontrol (ADC), although only 20% of the users employADC devices regularly, i.e. for all of their paediatric CTprotocols. Whereas ADC is used for about 50% of bodyexaminations, it is employed for only 25% of head ex-ams.

Surprisingly, patient doses resulting from examinationsmade with ADC are somewhat higher than from those withmanual adaptation of the dose settings. This can be ex-plained in part by the present characteristics of some (butnot all) ADC devices, where exposure settings cannot bemade in terms of dose or mAs, but rather in terms of im-age quality, i.e. noise settings. In addition, these particu-lar devices are designed to maintain the selected noise levelwith changes in almost any exposure setting that has in-fluence on the noise in the resulting image (ImPACT 2005).Therefore, a reduced slice thickness or a sharper recon-struction filter inevitably forces these ADC devices tooperate at an increased dose level. However, since changesin these parameters often have a positive effect on otheraspects of image quality, e.g. detail contrast, the corre-sponding increase in noise need be compensated for onlyslightly or not at all.

In this context, the question arises how dose (or mAs)should be adapted appropriately to the size of the patient.In the past few years, a large number of papers have beenpublished on this subject with significantly differing rec-ommendations: slight adaptation (e.g. Donelly et al. 2001),intermediate adaptation (e.g. Rogalla 2004) and strongadaptation (e.g. Huda et al. 2000). In fig. 5.1a, the charac-teristics of these recommendations are shown in terms ofrelative dose settings as a function of body weight.

From theoretical considerations (i.e. from measurementsof the half value layer in body tissue, which amounts toabout 4 cm in the CT range), mAs should be adapted by afactor of 2 for each 4 cm difference in tissue-equivalentbody diameter, in order to achieve images with a constantnoise level. However, in a fundamental study (Wilting etal. 2001) in which the mAs settings were manually adaptedin this manner to patient size, it turned out that this method

20 5. Discussion

0%

25%

50%

75%

100%

0 20 40 60 80 100

Body weight (kg)

DonellyRogallaHuda

Rel

ativ

e m

As

did not yield the results desired. Whereas the resultingimages exhibited almost the same noise independent ofthe patient diameter (fig. 5.2a), CT images of patients ofsmaller size were subjectively rated inferior by the radi-ologists (fig. 5.2b). This finding was interpreted as beingmainly due to the fact that slim patients have less bodyfat, which serves as a kind of ’natural’ contrast agent.Therefore, it is not sufficient to maintain a constant noiselevel; instead, images of slim patients need to be less noisyin order to maintain a constant contrast-to-noise ratio. Asa consequence, dose adaptation should be made in a moregentle fashion, i.e. by a factor of 2 for each 8 cm differ-ence in tissue-equivalent body diameter.

Using the data collected at a large German children’s hos-pital, showing the relationship between lateral body di-ameter and body weight (fig. 5.1b) (Schneider 2003), itturns out that the moderate adaptation recommended byRogalla correlates almost perfectly with the ’factor 2 per8 cm’ philosophy. In practice, this recommendation is quiteeasy to apply, since it can be expressed fairly well by asimple formula (‘Rogalla formula’):

rel mAsbody weight in kg

. ( )

( . )= + 585

5 1

This formula can be used, for example, to set up a limitednumber of weight-adapted scan protocols (e.g. 0 – 5 kg, 6– 10 kg, 11 – 20 kg, 21 – 40 kg, 41 – 60 kg, 61 – 80 kg),utilising the (optimised) dose settings for an average maleadult of about 80 kg body weight as a starting point. Theseprotocols can then be applied simply on the basis of thepatient’s body weight. An almost identical relationship hasbeen recommended by another paediatric CT researchgroup from Aachen University (Honnef et al. 2004).

Fig. 5.1 The characteristics of three representative recommendations on how to adapt the dose settings to the patient’sbody weight (a) and the correlation between lateral diameter and body weight (b), based on patient data from a majorGerman children’s hospital (Schneider 2003). The bright lines inside the diagrams indicate that the ’factor 2 per 8 cmphilosophy’ is almost perfectly met by the moderate dose adaptation recommended by Rogalla (2004).

The most surprising result of this survey is the way inwhich dose is adapted to body weight: on average this isin quite good agreement with the Rogalla formula for chestand abdomen examinations (see figs. 4.16c and 4.16d).The same should also hold true for spine examinations,but with dose settings somewhat reduced, although in prac-tice almost the same dose (CTDIvol) is applied regardlessof patient’s age (fig. 4.16e). This might be due to the cir-cumstances of spine examinations being quite rare, so pre-sumably less attention has yet been paid to optimising theseprotocols.

In paediatric CT examinations of the head region, it wouldnot make much sense to adapt the dose settings accordingto body weight, since the size of the head is dispropor-tionately large for infants and children. Consequently, doseadaptation should best be made according to patient’s age.As an additional surprise, the age adaptation found in thissurvey for CT examinations of the brain (fig. 4.16a) al-most perfectly matches another recommendation that hasbeen developed in the Philips CT community (Morgan2003). Fig. 4.16a also reveals that even the ‘gentle’ doseadaptation given by the Rogalla formula would reduce thedose by an overly large extent. The dose adaptation foundfor CT examinations of the facial bone/sinuses, however,is more of the Rogalla formula type (fig. 4.16b), althougha pattern similar to that for brain examinations should beexpected. This might be explained by the circumstancesthat these examinations are also relatively rare and that -even for adults - there is still little agreement on the ap-propriate dose settings for this type of examination.

At present, ADC devices implemented in MSCT scannersfrom Philips and Siemens offer a more ‘gentle’ mAs ad-aptation (i.e. roughly by a factor of 2 per 8 cm), thus pro-viding an ‘adequate’ noise compensation, whereas ADC

a.

0

5

10

15

20

25

30

35

40

0 20 40 60 80 100

Body weight (kg)

PatientsFit

Lat

eral

dia

met

er (

cm)

b.

215. Discussion

Fig. 5.2 Measured image noise (a) and subjective assessment of noise, visibility of small structures and diagnosticconfidence (b) for scan protocols with mAs settings manually adapted to the lateral patient diameter (by a factor 2 per4 cm difference). Whereas the objective image noise was almost constant for different patient diameters between 24and 36 cm, the subjective rating of image quality became increasingly worse with decreasing patient diameter (from:Wilting et al. 2001).

a. b.

devices found in GE and Toshiba MSCT scanners attemptto ensure a constant noise level by using a strong mAsadaptation that follows theoretical considerations (i.e. bya factor of 2 per 4 cm).

In this context, it should be kept in mind that ADC de-vices do not reduce dose per se, but merely accomplishdose adaptation according to the size of the patient, i.e.they simply have an impact on the relative dose settings.Absolute dose settings, however, are still dependent onthe user’s preferences. These can either be made in termsof mAs for a ‘standard’ patient (‘reference mAs control’,as provided by Philips and Siemens) or in terms of imagenoise (‘standard deviation based control’, as provided byGE and Toshiba). Whereas a number of commonly agreedrecommendations on dose have been developed in the pastfew years (e.g. diagnostic reference levels) and these canbe translated without too much effort into mAs settings,things are much more complex for noise-based ADC de-vices. This is due to the fact that no agreement exists onadequate noise levels and also that contrast-to-noise ratio,rather image noise, is the more relevant descriptor of im-age quality that needs to be maintained. This becomesapparent on changes in slice thickness and patient size,whereby detail contrast is also altered. The results fromthis survey and the publications mentioned above that arein favour of a more gentle dose adaptation should be seenas suggestions to the relevant manufacturers to reflect ontheir present ADC philosophy (for both regulation mecha-nism and control).

Although the results of this survey revealed that dose set-tings concerning local dose (i.e. CTDI

vol) were reasonably

well adapted to the age or the body weight of the patients,it must be noted that effective doses for complete exami-nations were only slightly reduced when compared withadults (fig. 4.20 a to e). When also taking into account theincreased sensitivity of paediatric patients for the induc-

tion of malignant tumours, the risk-corrected effective doseis not reduced, but made even greater. Therefore the useof adequately adapted mAs settings is obligatory so as toimprove the situation, although it is by no means a com-plete solution and the necessity still exists to justify care-fully each paediatric CT examinations.

As far as absolute dose settings are concerned, examina-tions of the facial bone/sinuses are fully adjusted for theimproved inherent contrast, with dose reductions by a fac-tor of about 3 compared with brain examinations. For ex-aminations of the chest, however, dose is only slightlyreduced compared with abdominal examinations (by abouta factor of 1.25). In this case, a larger reduction of be-tween 1.5 and 2, as recommended by e.g. Rogalla (2004)and Honnef et al. (2004), can be justified owing to thereduced attenuation and the improved inherent contrast inthe chest region.

All of the scanners involved in this survey were spiralscanners, and almost all examinations were made in heli-cal scan mode, with the exception of brain examinationsthat were preferentially (about 90%) conducted in sequen-tial scan mode. Users of single-slice scanners regularlyconducted their helical examinations with increased pitchsettings (1.5 and higher). However, for the majority ofmulti-slice scanners, i.e. those making use of the so-called‘effective mAs concept’ (MSCT scanners made by Elscint,Philips and Siemens), dose no longer depends on pitchsetting and so the selected pitch factor is not relevant inthis context. For scanners not employing effective mAs(MSCT scanners from GE and Toshiba), increased pitchsettings result in reduced dose, but at the expense of anincreased noise if mAs settings are not adjusted manually.

As expected, overranging effects are most pronounced forexaminations that comprise a short scan range only (i.e.spine and facial bone/sinuses), and for newborn and in-

22 5. Discussion

fant patients in particular. Although the average increasesin dose-length product do not appear dramatic when com-pared with examinations made in sequential scan mode, itshould be kept in mind that overranging effects can bequite large for true 64-slice scanners (e.g. about 60% inthe case of spine examinations). Therefore it is worthwhileconsidering either to conduct these examinations in se-quential scan mode or to operate 64-slice scanners in 16-slice mode with reduced beam width.

In contrast to CTDIvol

, integral dose quantities such as ef-fective dose are subject to two additional factors (scanlength and number of scan series (i.e. phases)), which areheavily dependent on the user’s preferences. Whereasmulti-phase examinations are very rare in paediatric CT(see tab. A5), the average scan length was often some-what larger than expected (and in some cases even largerthan for adults). There is therefore some room for improve-ment by more careful adjustment of the length of the scanrange.

Only a minority of the users applied reduced settings oftube potential (i.e. kV). Contrary to mAs, changes in kVsetting alter not only the quantity, but also the quality ofthe radiation. There is a clear benefit from low kV set-tings in CT angiography, since the gain in contrast out-

weighs by far the increase in noise. However for non-en-hanced scans or non-vascular examinations with admin-istration of contrast agents, image contrast in areas of tis-sue free from contrast agent will remain almost constant.In practice, noise is not compensated for by improvedcontrast in these cases and, in addition, the softer beam isabsorbed more strongly by the patient. As a result, therelationship between dose and image quality is not in fa-vour of reduced tube potentials for non-CTA examinations.Recommendations for low kV settings are merely a relicof the past when mAs settings could not be reduced muchand a reduction in kV was the only solution. Modern scan-ners, however, allow the tube current-time product to bereduced down to values of about 10 mAs, which corre-sponds to a CTDI

vol32 of between 0.5 and 1 mGy (depend-

ent on the type of scanner). There is therefore rarely aneed to use kV settings other than 120 kV (except for CTA).

There are only limited possibilities for comparison withthe results from other surveys. Whereas dose values forbrain examinations are similar to those in the UK survey,dose values reported for chest examinations in the UK arehigher, and the dose adaptation to body weight is less pro-nounced. Therefore it seems that efforts towards doseoptimisation in paediatric CT are more advanced in Ger-many.

236. Reference Values, Feedback Action

6. Reference Values, Feedback Action

6.1. Proposal for Diagnostic Reference Values

Proposals for diagnostic reference values for volume CTDI(CTDI

vol) and dose-length product per examination

(DLPexam

) are compiled in table A15 in the appendix forthe age groups and types of examination covered by thissurvey. All values are based on the 3rd quartile results fromthis survey.

For a number of reasons, however, 3rd quartile values werenot used directly, but in a modified manner:

• For some types of examination and age groups (facialbone/sinuses and lumbar spine for newborn and in-fants), the sample size was very small and was thusassociated with relatively large uncertainties.

• Dose values for chest examinations differed onlyslightly from those for abdomen examinations, i.e. theywere unnecessarily high.

• Most users did not differentiate in their dose settingsbetween newborn and infants.

Modifications were made as follows:

• The 3rd quartile value of CTDIvol

for abdomen exami-nations (incl. pelvis) from the 2002 MSCT survey andthe present reference value of 60 mGy for brain ex-aminations were taken as starting points.

• For all other types of examination, the correspondingCTDI

vol values for adults were derived as follows: 1/3

of the brain value for facial bone/sinuses; 2/3 of theabdomen value for chest; and 2.5 times the abdomenvalue for lumbar spine.

• The adaptation of CTDIvol

values to the patient’s agewas made according to the recommendations of Morgan(head region) and Rogalla (trunk region), since bothapproaches already showed good correlation with theresults of this survey.

• The DLP per exam values were derived by multiply-ing the CTDI

vol values by each of the corresponding

average values for net scan length, overranging andnumber of scan series.

In general, the proposals that were modified in this wayare in good agreement with the 3rd quartile values fromthis survey. Larger discrepancies are found only in thosecases where modifications were necessary for the reasonsmentioned above. The values compiled in table A15 aregraduated in a meaningful (moderate adaptation to patient’sage and weight) and consistent manner, i.e. the correla-tion between the different types of examination is in ac-cordance with the results from other surveys and relevantpublications.

6.2. Comparison with other Reference Values

The first proposal for reference values with respect to pae-diatric CT examinations were published in 2000 byShrimpton et al. (2000), based on a European-wide sur-vey with 40 participating institutions. Cross-validation canbe made for three age-groups (up to 1 year, 2 to 5 years, 6to 10 years) and three types of examination (brain, chestand abdomen (incl. pelvis)). The values published byShrimpton et al. were given in terms of CTDI

w16 and DLP

16

per exam. For the purposes of comparison, these CTDIw16

values were converted into CTDIvol16

on the assumptionof a pitch of 1 for brain and a pitch of 1.5 for the othertypes of examination, since these latter were performedpredominantly in spiral scanning mode.

The results of comparing the data of Shrimpton et al.

(2000) with our proposals are given in table A16 in theappendix (see column ‘ratio’). For brain examinations,both values are almost identical, with our proposals beingsomewhat lower, except for the age group ‘up to 1 year’where our proposed DLP is somewhat higher. This is dueto the inclusion of a scan length of 7.5 cm in the Shrimptonet al. data, which appears relatively small. For chest andabdomen examinations, all our proposals are significantlylower (by a factor of between 1.5 and 4, depending on theage group and dose quantity).

Bearing in mind that our proposals are based on a moder-ate adaptation of dose settings to patient’s age or weightand that chest values were only slightly modified withrespect to abdomen values, the values proposed by Shrimp-

24 6. Reference Values, Feedback Action

6.3. Feedback Action

As with the two preceding surveys conducted by us, feed-back was given to all participants in this survey. This wasdone in terms of absolute and relative dose values, thelatter referring to the proposed reference values for thecorresponding age group, type of examination, and dosequantity.

For this purpose, the dose values that were calculated forthe particular scanner model from the reported exposuresettings were presented as shown in figs. A4 to A6 in theappendix. In sheet 1 (fig. A4), the reported scan protocolsettings are listed along with the resulting dose values.Local dose quantities, such as CTDI

w and CTDI

vol, de-

pend exclusively on the tube potential (U), the tube load(Q), the beam width (N·h

col) and the pitch, and they apply

per scan series. Integral dose quantities, such as dose-length product (DLP) and effective dose (E), depend ad-ditionally on the scan length (L) and the number of scanseries (n

Ser.), and they refer to the entire examination. Ef-

fective dose enables comparisons with other examinationtechniques using ionising radiation and with natural back-ground radiation (e.g. 2.1 mSv per year in Germany). Thecategory ‘relative values’ provides percentage values foreach dose quantity and type of examination, indicatingthe dose level for each participant in relation to the pro-posed reference value.

In sheet 2 (fig. A5), these same facts are presented ingraphical form for CTDI

vol and DLP

exam. Relative dose val-

ues above 100% indicate that the particular participantshould consider corrective actions, dependent on whetherthis breach relates to the local dose (CTDI

vol ), the integral

radiation exposure (DLPexam

) or both. In the case of thefirst dose quantity, the mAs setting should be reduced ac-cordingly; in the latter case, a multitude of factors shouldbe taken into account. Sheet 3 (figs. A6a to A6d) there-fore provides information that allows detailed analysis ofthe potential sources (act. = actual values of the particularparticipant; ref. = average values for this survey). Apartfrom the local dose, excessive values of DLP

exam can be

caused by an above-average scan length L, a below-aver-age pitch factor p, an above-average number of scan se-ries or an unfavourable combination of all these factors.Since thin slices are associated with increased image noiseand this may therefore tempt the user to increase mAssettings, a comparison of the slice thickness reveals if thisaspect could be of importance.

Finally, explanations on how to interpret the results andhow to make use of them were provided on a separatesheet.

ton et al. are much too high from our point of view. Apossible explanation might be that the underlying surveywas conducted before the majority of CT users becameaware of the need for appropriately adapted dose settingsfor paediatric purposes. For want of other values, the pro-posals of Shrimpton et al. were used in the present ver-

sion of the CT guidelines (Nagel and Vogel 2004) for gen-eral orientation purposes. With the proposals in table A15,however, more appropriate values are now available, whichmake use of the potential for dose reduction in the paedi-atric range. A revision of the CT guidelines is in prepara-tion.

257. Recommendations

7. Recommendations

In order to ensure that paediatric CT examinations arecarried out in a dose-optimised fashion, the following rec-ommendations should be observed:

A. Choice of equipment

If possible, paediatric CT examinations should be per-formed on modern, dose-efficient scanners (i.e. spiral scan-ners with solid-state detectors) only. Multi-slice (MSCT)scanners are advantageous insofar as these allow muchshorter scan times compared with single-slice scanners.

B. Choice of tube potential

Tube voltage settings below 110 kV should be used onlyif the range of mAs settings is not sufficient to achieve thereduced dose settings desired (e.g. chest examinations onnewborn and infants). Otherwise, the standard voltagesetting for the particular scanner (between 110 and 130kV) should be applied.

C. Beam collimation on MSCT scanners

For paediatric examinations and their associated short scanranges, a beam width (total collimation) of between 10and 24 mm is optimal. Narrower beam widths should beavoided, since the patient’s exposure will increase exces-sively due to overbeaming effects (i.e. the portion of thebeam not used for imaging). In spiral scanning mode, awider beam width should also be avoided since over-ranging effects (i.e. the consequence of extra rotations)will inevitably become more pronounced.

D. Pitch factor

For single-slice scanners, spiral scans should be made withan increased pitch of 1.5, resulting in a corresponding dosereduction. However, for multi-slice scanners that achievetheir mAs settings in terms of ‘effective mAs’ or ’mAsper slice’ (i.e. MSCT scanners from Elscint, Philips andSiemens), dose is no longer affected by the pitch setting,since any modification in the pitch factor is associatedwith a corresponding adjustment of the electrical mAsproduct. For these particular scanners, the pitch factor ismodified for other reasons (scan speed, reduction of arte-facts). In contrast, multi-slice scanners from GE andToshiba achieve their mAs settings in terms of ‘electricalmAs’ (similar to single-slice scanners); therefore increasedpitch settings will reduce the patient’s dose, but at the ex-pense of an increased image noise. Particular attentionshould be paid if pitch settings below 1 are used for thesetypes of scanner, since the overlapping scans will result inincreased dose unless the electrical mAs settings are manu-ally adapted (i.e. reduced). A look at the scanner’s dosedisplay (increasing CTDI

vol values at pitch settings < 1)

reveals whether this aspect is of importance.

E. Dose adaptation

The adaptation of dose settings according to age or bodyweight should be made in a moderate fashion (factor ±2for each 8 cm difference in effective body diameter forexaminations of the trunk region). The data given in tabs.7.1 and 7.2 can be used to create sets of age- or weight-adapted scan protocols.

Tab. 7.1 Age-adapted relative mAs values for paediatricCT examinations of the head region. Starting point(=100%) is the optimised mAs setting for brain examina-tions on adults, which corresponds to a CTDI

vol16 of not

more that 60 mGy.

Tab. 7.2 Weight-adapted relative mAs values for paediat-ric CT examinations of the trunk region. Starting point(=100%) is the optimised mAs setting for abdomen ex-aminations on adults, which corresponds to a CTDI

vol32 of

not more that 15 mGy.

Age groupRelative mAs setting

BrainFacial

bone/sinuses

Newborn 45% 15%

< 1 y 55% 18%

2 - 5 y 65% 22%

6 - 10 y 85% 28%

11 - 15 y 100% 33%

> 15 y 100% 33%

Body weight Age (appr.) Relative mAs setting

(kg)Abdomen(w. pelvis)

Chest Spine

0 - 5 0 - 3 m 10% 7% 25%

6 - 10 4 m - 1 y 17% 10% 50%

11 - 20 2 - 5 y 30% 20% 75%

21 - 40 6 - 12 y 50% 33% 125%

41 - 60 13 - 18 y 75% 50% 200%

61 - 80 >18 y 100% 65% 250%

26 7. Recommendations

F. Automatic dose control

Automatic dose control should be used only if these de-vices are designed to provide a moderate dose adaptation.The default dose setting (‘reference mAs’) for the par-ticular type of examination should be below the referencevalue for adults given in tab. A15. Purely noise-based ADCdevices are difficult to handle owing to both their regula-tion characteristic (mAs factor ±2 per 4 cm difference ineffective diameter) and their settings (pre-selection of im-age quality instead of dose). Therefore manual dose adap-tation as described above should be preferred.

G. Dose display

Up to now all scanners display the CTDIvol

that relates tothe larger body phantom (CTDI

vol32) if the scan is made in

body scanning mode, regardless of the body size. As aconsequence, reference values based on CTDI

vol32 must be

used for optimisation purposes. The CTDIvol16

values thatare additionally given in tab. A15 for the age groups up to10 years are only informative at present (e.g. for the as-sessment of realistic organ doses). This might change inthe future, however, if the dose display is made to referprimarily to the diameter of the scanned body region andnot to the scan mode.

27References

References

BfS (2003) Bundesamt für Strahlenschutz: Bekanntma-chung der diagnostischen Referenzwerte für radiologischeund nuklearmedizinische Untersuchungen vom 10. Juli2003. Bundesanzeiger Nummer 143 vom 5.8.2003, 17503– 17504

BfS (2006) Bundesamt für Strahlenschutz: Annual report2004 (in German)

Brenner DJ, Elliston CD, Hall EJ, Berdon WE (2001)Estimated risks of radiation-induced fatal cancer frompaediatric CT. AJR:176, 289-296

Brix G, Nagel HD, Stamm G et al. (2003) Radiation expo-sure in multi-slice versus single-slice spiral CT: results ofa nationwide survey. Eur Radiol 13:1979–1991

Brix G, Lechel U, Veit R, Truckenbrodt R, Stamm G,Coppenrath EM, Griebel J, Nagel HD (2004) Assessmentof a theoretical formalism for dose estimation in CT. EurRadiol 14: 1274–1285

CRCPD (2006) Nationwide evaluation of X-ray trends2000 computed tomography. CRCPD Publication#NEXT_2000CT-T (Download: http://www.crcpd.org/NEXT.asp#2000)

Donelly LF, Emery KH, Brody AS et al. (2001) Min-imizing radiation dose for pediatric body applications ofsingle-detector helical CT: strategies at a large children’shospital. AJR:176, 303-306

Galanski M, Nagel HD, Stamm G (2001) CT exposurepractice in the Federal Republic of Germany - results of anation-wide survey 1999. Fortschr Roentgenstr 173: R1 -R66 (in German)

Honnef D, Wildberger JE, Stargardt A et al. (2004) Multi-slice spiral CT (MSCT) in paediatric radiology: dose re-duction for chest and abdomen examinations. FortschrRoentgenstr 176: 1021–1030 (in German)

Huda W, Scalzetti EM, Levin G (2000) Technique factorsand image quality as functions of patient weight at ab-dominal CT. Radiology 217:430–435

ICRP (1991) 1990 Recommendations of the InternationalCommission on Radiological Protection. ICRP Publica-tion 60, p. 176. Pergamon Press, Oxford

IEC (2001) Medical Electrical Equipment - Part 2: Partic-ular requirements for the safety of X-ray equipment forcomputed tomography. IEC-Standard 60601-2-44 ed. 2.0.International Electrotechnical Commission, Geneva

ImPACT (2005) CT scanner automatic control systems.Report 05016. Medicines and Healthcare products Regu-latory Agency (MHRA), London

Khursheed A, Hillier MC, Shrimpton PC, Wall BF (2002)Influence of patient age on normalized effective dosescalculated for CT examinations. Br J Radiol 75: 819-830

Morgan H (2003) Image quality improvement and dosereduction in CT pediatric imaging. MedicaMundi 46,3:16-21

Nagel HD, Galanski M, Hidajat N, Maier W, Schmidt T(2002) Radiation exposure in computed tomography: Fun-damentals, influencing parameters, dose assessment,optimisation, scanner data, terminology. 4th revised andupdated edition. CTB Publications, Hamburg (contact: [email protected])

Nagel HD, Vogel H (2004) Guideline for the assessmentand optimisation of the radiation exposure caused by CTexaminations. Download: www.strahlungheute.de (inGerman)

Nagel HD (2005) Significance of overbeaming and over-ranging effects of single- and multi-slice CT scanners.Biomedizinische Technik 50, suppl. vol. 1, part 1: 395-396

Paterson A, Frush DP, Donelly LF (2001) Helical CT ofthe body: Are settings adjusted for pediatric patients?AJR:176, 297-301

Prader A, Largo RH, Molinari L, Issler C (1989) Physicalgrowth of Swiss children from birth to 20 years of age.Helv. Paediat. Acta Suppl. 52: 1-125

28 References

Rogalla P (2004) pers. communication

Rogers LF (2001) Taking care of children: Check out theparameters used for helical CT. AJR: 176, 287

Schneider K (2003) pers. communication

Shrimpton PC Wall B (2000) Reference doses for paedi-atric computed tomography. Radiation Protection Dosime-try 90: 249-252

Shrimpton PC, Hillier MC, Lewis M, Dunn M (2005)Doses from computed tomography (CT) examinations inthe UK – 2003 review. Report NRPB-W67. National Ra-diological Protection Board, Chilton

Stamm G, Nagel HD (2002) CT-Expo – a novel programfor dose evaluation in CT. Fortschr Roentgenstr 174: 1570–1576 (in German)

Tack D, Gevenois PA (2006) Calculation of effective dosedelivered by CT: Comparison of commercially availablesoftware tools (submitted for publication)

UNSCEAR (2000) Report of the United Nations Scien-tific Committee on the effects of atomic radiation to theGeneral Assembly. Annex D, p. 370. United Nations, NewYork

Wilting JE, Zwartkruis A, van Leeuwen MS et al. (2001)A rational approach to dose reduction on CT: individualscan protocols. Eur radiol 11: 2627-2632

Zankl M, Panzer W, Drexler G (1991) The calculation ofdose from external photon exposures using reference hu-man phantoms and Monte Carlo methods part VI: Organdoses from computed tomographic examinations. GSFreport 30/91. GSF research centre, Oberschleißheim

Zankl M, Panzer W, Drexler G 1993 Tomographic anthro-pomorphic models part II: Organ doses from computedtomographic examinations in paediatric radiology. GSFreport 30/93. GSF research centre, Oberschleißheim

I

Appendix

Tab.

A1

Dos

e-re

leva

nt d

ata

for

the

scan

ners

par

tici

pati

ng in

this

sur

vey

(N =

num

ber

of s

lice

s ac

quir

ed s

imul

tane

ousl

y an

d in

depe

nden

tly

per

r ota

tion

; Ure

fan

d (N

·h) re

f = r

efer

ence

tub

e po

tent

ial

and

beam

wid

th,

resp

., to

whi

ch a

ll o

ther

dat

a re

fer;

dz

= o

verb

eam

ing

para

met

er;

mO

R a

nd b

OR =

ove

rran

ging

para

met

ers;

nCT

DI w

,H =

nor

mal

ized

wei

ghte

d C

TD

I fo

r he

ad s

cann

ing

mod

e; nC

TD

I w,B

32 =

nor

mal

ized

wei

ghte

d C

TD

I fo

r bo

dy s

cann

ing

mod

e, r

efer

ring

toth

e 32

cm b

ody

phan

tom

; nCT

DI w

,B16

= n

orm

aliz

ed w

eigh

ted

CT

DI f

or b

ody

scan

ning

mod

e, r e

ferr

ing

to th

e 16

cm h

ead

phan

tom

; PH, P

B32

and

PB

16 =

pha

ntom

fact

ors

for

conv

ersi

on fr

om w

eigh

ted

CT

DI

to C

TD

I fr

ee-i

n-ai

r; k

CT =

sca

nner

fact

or)

Man

u-

fact

ure

rS

can

ner

Mis

cella

neo

us

Hea

dB

od

yB

od

y (

pa

ed

.)

NU

ref

(N·h

) ref

dz

mO

Rb

OR

nC

TD

I w,H

PH

kC

TnC

TD

I w,B

32P

B32

k CT

nC

TD

I w,B

16P

B16

kC

T(k

V)

(mm

)(m

m)

(mG

y/m

As)

(mG

y/m

As)

(mG

y/m

As)

Els

cint

CT

Tw

in2

120

200.

80.

730.

230.

105

0.59

0.70

0.04

30.

240,

500.

105

0.59

0.70

GE

Ligh

tSpe

ed Q

X/i,

-Plu

s4

120

203

0.53

0.90

0.18

20.

640.

800.

094

0.39

0,80

0.18

80.

780.

90

GE

Ligh

tSpe

ed V

FX

16

1612

020

30.

381.

020.

182

0.64

0.80

0.09

40.

390,

800.

188

0.78

0.90

GE

Ligh

tSpe

ed 1

6, -

Pro

1612

020

30.

381.

020.

182

0.64

0.80

0.09

40.

390,

800.

188

0.78

0.90

GE

Ligh

tSpe

ed V

CT

6412

040

30.

470.

740.

201

0.64

0.80

0.09

70.

390,

800.

201

0.64

0.80

Phi

lips

CT

Aur

a1

120

101.

41

2.00

-1.0

00.

250

0.57

0.70

0.12

00.

280,

500.

250

0.57

0.70

Phi

lips

Bril

lianc

e 6

612

024

1.5

0.58

0.95

0.13

00.

750.

900.

067

0.39

0,80

0.13

00.

750.

90

Phi

lips

Mx8

000

IDT

, B

rillia

nce

1616

120

243

0.57

1.02

0.13

00.

750.

900.

067

0.39

0,80

0.13

00.

750.

90

Phi

lips

Bril

lianc

e 40

/64

40/6

412

040

72

0.54

1.18

0.11

00.

750.

900.

057

0.39

0,80

0.11

00.

750.

90

Pic

ker

PQ

Ser

ies

(Filt

er 0

)1

130

100

1.50

-1.0

00.

168

0.44

0.60

0.11

20.

290,

500.

168

0.44

0.60

Sie

men

sS

omat

om P

lus

4 S

erie

s1

120

101

12.

00-1

.00

0,14

60.

821.

000.

083

0.47

1,00

0.14

60.

821.

00

Sie

men

sB

alan

ce,

Em

otio

n (p

re '0

0)1

130

100.

31

2.00

-1.0

00.

270

0.76

0.90

0.15

00.

420,

800.

270

0.76

0.90

Sie

men

sB

alan

ce, E

mot

ion

(pos

t '00

)1

130

100.

31

2.00

-1.0

00.

241

0.73

0.90

0.12

60.

380,

800.

241

0.73

0.90

Sie

men

sV

olum

e Z

oom

412

020

1.7

0.31

1.11

0.20

00.

760.

900.

083

0.49

1,00

0.14

30.

841.

00

Sie

men

sS

ensa

tion

44

120

201.

70.

311.

110.

190

0.76

0.90

0.07

70.

441,

000.

132

0.76

0.90

Sie

men

sS

ensa

tion

1010

120

182.

51.

011.

010.

177

0.75

0.90

0.07

40.

441,

000.

127

0.76

0.90

Sie

men

sS

ensa

tion

1616

120

243

1.01

1.01

0.18

40.

760.

900.

076

0.45

1,00

0.13

10.

770.

90

Sie

men

sS

ensa

tion

6432

120

2416

21.

55-0

.16

0.13

40.

740.

900.

065

0.36

0,80

0.13

40.

740.

90

Tos

hiba

Aqu

ilion

44

120

203

4.00

-0.7

00.

207

0.67

0.80

0.11

10.

290,

650.

207

0.67

0.80

Tos

hiba

Aqu

ilion

16

1612

032

32.

070.

050.

220

0.77

0.90

0.12

10.

330,

650.

220

0.77

0.90

Rem

arks

1 f

or 1

mm

slic

e co

llim

atio

n on

ly2fo

r ov

erbe

amin

g co

rrec

tion

purp

oses

onl

y

II

Tab. A2 Standard CT examinations and their corresponding anatomical landmarks, scan ranges, and mean conver-sion factors, based on the mathematical phantoms ‚ADAM’ and ‚EVA’ (Zankl et al. 1991)

Tab. A3 Correction factors to convert from effective dose values for adultsto those for particular age groups and body regions. The factors were takenfrom the publication by Khursheed et al. (2002) and adapted to the formal-ism for effective dose assessment used in this survey.

Standard examination Anatomical landmarks Scan range Length fmean

Name Abbr. cranial caudal (male) (female) (cm) (mSv/mGy*cm)

from-to from-to (m.) (f.) (m.) (f.)

Routine Brain BRN Vertex Skull base 94 82 89 77 12 12 0.0022 0.0024

Facial Bones /Sinuses

FB/SIN Superior marginof frontal sinus

Occlusial plane 89 78 85 74 11 11 0.0022 0.0024

Routine Chest CHE C7 / T1 Sinus 69 41 65 39 28 26 0.0068 0.0088

Routine Abdomen(tot.) ABDPE Diaphragm Pubic symphysis 43 0 41 0 43 41 0.0072 0.0104

Lumbar Spine LSP L2/3 L3/4 35 29 33 27 6 6 0.0096 0.0108

Age groupfage, region

xHead and

neckChest Abdomen

and pelvis

Newborn 3.53 3.90 4.47 1.5

up to 1 year 2.63 2.70 2.94 1.0

2 to 5 years 1.51 2.03 2.12 1.0

6 to 10 years 1.25 1.53 1.55 0.5

11 to 15 years 1.05 1.11 1.10 0

III

Tab. A4 Institutions providing examination protocols for phase II of the survey and their scanner models.

City Institution DepartmentScanner

Manufact. Type Slices

Aachen University Radiology Siemens Sensation 16 16

Aachen University Neuro Radiology Siemens Volume Zoom 4

Baden-Baden Hospital Radiology Siemens Emotion 1

Bonn University Radiology Siemens Plus 4 1

Bonn University Radiology Philips Mx8000 IDT 16

Bonn University Neuro Radiology Philips Brilliance 16 16

Dresden University Radiology Siemens Sensation 16 16

Düsseldorf University Radiology Siemens Sensation 64 32

Düsseldorf University Neuroradiologie Siemens Volume Zoom 4

Erfurt Hospital Radiology GE LightSpeed 16 16

Erfurt Hospital Radiology GE LightSpeed QX/i 4

Erlangen University Radiology Siemens Sensation 10 10

Frankfurt University Neuro Radiology Philips Brilliance 6 6

Frankfurt University Radiology Siemens Sensation 16 16

Freiburg University Neuroradiologie Siemens Sensation 16 16

Fulda Hospital Radiology GE LightSpeed Plus 4

Fulda Hospital Radiology GE LightSpeed 16 Pro 16

Giessen University Paed. Radiology Siemens Balance 1

Greifswald University Radiology Siemens Sensation 16 16

Gummersbach Hospital Radiology Siemens Sensation 4 4

Halle University Radiology Siemens Volume Zoom 4

Halle University Radiology Siemens Sensation 64 32

Hamburg-Heidberg Hospital Radiology Philips Mx8000 IDT 16

Hannover University Neuro Radiology GE LightSpeed VFX16 16

Hannover University Radiology GE LightSpeed VCT 64

Hannover Childrens hosp. Paed. Radiology Philips Brilliance 6 6

Heidelberg University Radiology Siemens Volume Zoom 4

Heidelberg University Radiology Siemens Sensation 16 16

Jena University Radiology GE LightSpeed 16 16

Jena University Radiology GE LightSpeed QX/i 4

Kassel Hospital Radiology Elscint CT Twin 2

Leipzig University Radiology Siemens Volume Zoom 4

Leipzig University Radiology Philips Mx8000 IDT 16

Lübeck University Radiology Toshiba Aquilion 4 4

Lübeck University Radiology Toshiba Aquilion 16 16

Magdeburg University Radiology Toshiba Aquilion 16 16

Mainz University Neuro Radiology Picker PQ5000 1

Mainz University Radiology Siemens Volume Zoom 4

Mainz University Radiology Philips Brilliance 64 64

Marburg University Radiology Siemens Volume Zoom 4

Mönchengladbach Hospital Radiology Siemens Emotion 1

München Heart centre Radiology Siemens Sensation 64 32

München University Paed. Radiology Philips Aura 1

München-Schwabing Hospital Radiology Siemens Sensation 16 16

München-Schwabing Hospital Radiology Siemens Sensation 16 16

Münster Hospital Radiology Toshiba Aquilion 64 64

Neubrandenburg Hospital Radiology Philips Brilliance 10 10

Oldenburg Hospital Radiology Siemens Plus 4 1

Stuttgart Hospital Radiology Picker PQ5000 1

Stuttgart Hospital Radiology GE LightSpeed Plus 4

Trier Hospital Radiology Siemens Plus 4 4

Ulm University Radiology Elscint CT Twin 2

Wiesbaden Private practice Radiology Elscint CT Twin 2

Würzburg University Radiology Siemens Sensation 16 16

IVG

erm

an S

urve

y on

Pae

diat

ric C

T 20

05/0

6Av

erag

e Va

lues

Exam

inat

ion

para

met

ers

Dos

e va

lues

per

sca

n se

ries

Dos

e va

lues

per

exa

min

atio

nSt

atis

tics

Age

gro

upTy

pe o

f exa

min

atio

nU

Qel

tRN

hcol

Pitc

hhr

ecW

indo

wLe

ngth

Ser

ies

CTD

Iw16

CTD

Ivol

16D

LP16

CTD

Iw32

CTD

Ivol

32D

LP32

E (m

.)E

(f.)

DLP

16D

LP32

E (m

.)E

(f.)

Par

tici-

Exa

ms

Frac

tion

[kV

][m

As]

[s]

[mm

][m

m]

CW

[cm

](P

hase

s)[m

Gy]

[mG

y][m

Gy*

cm]

[mG

y][m

Gy]

[mG

y*cm

][m

Sv]

[mS

v][m

Gy*

cm]

[mG

y*cm

][m

Sv]

[mS

v]pa

nts

Bra

in11

612

81.

26.

33.

31.

04.

536

859.

81.

021

.821

.922

7n.

a.n.

a.n.

a.2.

12.

423

3n.

a.2.

22.

427

112

1.1%

Faci

al b

one/

sinu

ses

108

810.

911

.41.

21.

42.

439

918

508.

31.

015

.110

.913

7n.

a.n.

a.n.

a.1.

31.

413

7n.

a.1.

31.

49

60.

1%

Che

st10

044

0.6

10.8

2.0

1.3

3.3

-88

746

10.1

1.0

4.5

3.6

462.

52.

025

1.6

2.1

4625

1.6

2.1

2164

0.6%

Ent

ire a

bdom

en10

845

0.6

8.6

2.3

1.2

3.8

5035

714

.21.

15.

24.

271

2.9

2.3

392.

94.

277

433.

14.

413

270.

3%S

pine

118

610.

812

.31.

51.

32.

557

520

008.

31.

09.

07.

590

5.2

4.3

524.

14.

690

524.

14.

64

10.

0%

Bra

in11

516

21.

26.

73.

51.

05.

436

8510

.71.

026

.426

.230

2n.

a.n.

a.n.

a.2.

12.

332

3n.

a.2.

32.

542

559

5.5%

Faci

al b

one/

sinu

ses

110

460.

811

.31.

11.

22.

252

322

737.

31.

07.

57.

768

n.a.

n.a.

n.a.

0.5

0.5

68n.

a.0.

50.

511

130.

1%

Che

st10

852

0.7

13.0

1.9

1.2

3.4

-127

812

12.3

1.0

6.0

5.4

773.

12.

840

1.9

2.4

8142

1.9

2.5

3114

31.

4%

Ent

ire a

bdom

en11

453

0.6

14.5

2.0

1.2

3.7

4334

919

.61.

27.

06.

214

83.

83.

379

3.9

5.6

177

944.

66.

722

610.

6%S

pine

116

118

0.9

11.7

1.4

1.1

2.1

434

1563

9.7

1.0

21.9

23.7

297

11.8

12.7

160

10.7

12.0

297

160

10.7

12.0

910

0.1%

Bra

in11

919

71.

29.

33.

41.

05.

746

117

11.9

1.1

35.4

35.7

452

n.a.

n.a.

n.a.

1.8

2.0

470

n.a.

1.9

2.1

4816

3416

.2%

Faci

al b

one/

sinu

ses

113

680.

89.

41.

21.

12.

142

820

239.

11.

011

.110

.811

6n.

a.n.

a.n.

a.0.

50.

511

6n.

a.0.

50.

518

710.

7%

Che

st11

155

0.7

14.6

2.1

1.2

3.7

-102

747

16.4

1.0

7.0

6.1

116

3.7

3.2

612.

22.

812

063

2.2

2.9

3639

73.

9%

Ent

ire a

bdom

en11

661

0.7

11.6

2.5

1.2

4.1

4633

925

.11.

19.

07.

921

94.

84.

111

54.

46.

426

013

65.

27.

527

140

1.4%

Spi

ne11

813

31.

19.

91.

61.

22.

043

717

4011

.11.

024

.821

.927

913

.611

.715

17.

58.

427

915

17.

58.

423

850.

8%

Bra

in12

123

11.

37.

03.

91.

05.

937

8812

.81.

042

.443

.758

2n.

a.n.

a.n.

a.1.

92.

160

4n.

a.2.

02.

244

1391

13.8

%

Faci

al b

one/

sinu

ses

114

780.

810

.31.

21.

22.

142

420

429.

81.

013

.113

.214

7n.

a.n.

a.n.

a.0.

50.

514

7n.

a.0.

50.

525

124

1.2%

Che

st11

469

0.7

13.2

2.5

1.2

4.2

-103

740

20.4

1.0

10.5

8.5

194

5.5

4.5

102

2.6

3.3

196

103

2.6

3.3

3954

35.

4%

Ent

ire a

bdom

en11

587

0.7

11.0

2.6

1.2

4.4

4334

029

.01.

212

.610

.734

26.

75.

618

04.

76.

840

721

45.

68.

132

213

2.1%

Spi

ne11

916

71.

08.

51.

51.

12.

248

218

0411

.71.

031

.528

.338

317

.215

.220

87.

18.

038

320

87.

18.

023

991.

0%

Bra

in12

228

41.

38.

73.

51.

05.

737

139

13.9

1.1

52.6

53.2

764

n.a.

n.a.

n.a.

2.1

2.3

809

n.a.

2.2

2.5

4414

3414

.2%

Faci

al b

one/

sinu

ses

118

860.

810

.01.

31.

22.

042

319

9511

.41.

015

.715

.420

1n.

a.n.

a.n.

a.0.

60.

620

1n.

a.0.

60.

628

231

2.3%

Che

st11

990

0.7

13.7

2.6

1.2

4.4

-100

741

26.0

1.0

n.a.

n.a.

n.a.

7.7

6.2

180

2.8

3.7

n.a.

186

2.9

3.8

4061

36.

1%

Ent

ire a

bdom

en11

912

50.

712

.92.

71.

24.

546

342

35.9

1.2

n.a.

n.a.

n.a.

10.1

8.3

328

5.4

7.9

n.a.

433

7.2

10.3

3325

42.

5%S

pine

121

149

0.9

11.8

1.4

1.0

1.8

386

1638

15.9

1.0

n.a.

n.a.

n.a.

15.4

16.7

294

6.4

7.3

n.a.

294

6.4

7.3

2614

91.

5%

Bra

in12

231

71.

42.

85.

71.

07.

313

.21.

358

.455

.688

1n.

a.n.

a.n.

a.2.

32.

610

99n.

a.2.

93.

110

4

Faci

al b

one/

sinu

ses

123

123

0.9

3.2

1.7

1.1

2.4

10.2

1.0

28.2

26.7

298

n.a.

n.a.

n.a.

0.8

0.9

311

n.a.

0.8

0.9

102

Che

st12

816

30.

73.

44.

01.

46.

331

.01.

0n.

a.n.

a.n.

a.14

.810

.936

85.

26.

8n.

a.38

15.

47.

010

8

Ent

ire a

bdom

en12

120

00.

73.

34.

31.

36.

641

.91.

5n.

a.n.

a.n.

a.15

.612

.656

88.

512

.3n.

a.84

812

.718

.410

6S

pine

130

285

1.2

3.1

2.3

1.0

2.8

13.5

1.0

n.a.

n.a.

n.a.

30.3

32.4

474

9.5

10.7

n.a.

474

9.5

10.7

107

Bra

in12

732

72.

21.

08.

41.

08.

412

.31.

557

.156

.367

6n.

a.n.

a.n.

a.1.

82.

098

0n.

a.2.

62.

981

0

Faci

al b

one/

sinu

ses

126

239

1.9

1.0

3.3

1.3

3.3

9.1

1.1

41.0

36.9

406

n.a.

n.a.

n.a.

1.1

1.2

448

n.a.

1.2

1.3

792

Che

st12

719

11.

41.

08.

41.

38.

429

.81.

2n.

a.n.

a.n.

a.18

.415

.441

75.

86.

9n.

a.51

47.

18.

679

8

Ent

ire a

bdom

en12

422

81.

51.

08.

91.

38.

940

.71.

6n.

a.n.

a.n.

a.20

.917

.975

110

.915

.0n.

a.12

3617

.924

.779

1S

pine

131

381

2.4

1.0

3.3

1.1

3.3

6.0

1.0

n.a.

n.a.

n.a.

39.2

38.4

230

4.4

4.9

n.a.

234

4.4

5.0

796

Tab.

A5

Ave

rage

val

ues f

rom

the

Ger

man

surv

ey o

n pa

edia

tric

CT,

arr

ange

d by

age

gro

up (f

or e

xpla

natio

ns o

f the

term

s and

abb

revi

atio

ns se

e ta

b. A

.7);

for t

he p

urpo

ses o

f com

pari

son,

t

he c

orre

spon

ding

val

ues f

or a

dults

from

the

prev

ious

surv

eys i

n 19

99 (S

SCT)

and

200

2 (M

SCT)

are

als

o sh

own.

Adults (SSCT survey

1999)Newborn up to 1 year 2 to 5 years 6 to 10 years 11 to 15 years

Adults (MSCT survey

2002)

Ger

man

Sur

vey

on P

aedi

atric

CT

2005

/06

Aver

age

Valu

es

Exam

inat

ion

para

met

ers

Dos

e va

lues

per

sca

n se

ries

Dos

e va

lues

per

exa

min

atio

nSt

atis

tics

Type

of

Age

gro

upU

Qel

tRN

hcol

Pitc

hhr

ecW

indo

wLe

ngth

Ser

ies

CTD

Iw16

CTD

Ivol

16D

LP16

CTD

Iw32

CTD

Ivol

32D

LP32

E (m

.)E

(f.)

DLP

16D

LP32

E (m

.)E

(f.)

Par

tici-

Exa

ms

Frac

tion

exam

inat

ion

[kV

][m

As]

[s]

[mm

][m

m]

CW

[cm

](P

hase

s)[m

Gy]

[mG

y][m

Gy*

cm]

[mG

y][m

Gy]

[mG

y*cm

][m

Sv]

[mS

v][m

Gy*

cm]

[mG

y*cm

][m

Sv]

[mS

v]pa

nts

New

born

116

128

1.2

6.3

3.3

1.0

4.5

3685

9.8

1.0

21.8

21.9

227

n.a.

n.a.

n.a.

2.1

2.4

233

n.a.

2.2

2.4

2711

21.

1%

up to

1 y

ear

115

162

1.2

6.7

3.5

1.0

5.4

3685

10.7

1.0

26.4

26.2

302

n.a.

n.a.

n.a.

2.1

2.3

323

n.a.

2.3

2.5

4255

95.

5%

1 to

5 y

ears

119

197

1.2

9.3

3.4

1.0

5.7

4611

711

.91.

135

.435

.745

2n.

a.n.

a.n.

a.1.

82.

047

0n.

a.1.

92.

148

1634

16.2

%

6 to

10

year

s12

123

11.

37.

03.

91.

05.

937

8812

.81.

042

.443

.758

2n.

a.n.

a.n.

a.1.

92.

160

4n.

a.2.

02.

244

1391

13.8

%

11 to

15

year

s12

228

41.

38.

73.

51.

05.

737

139

13.9

1.1

52.6

53.2

764

n.a.

n.a.

n.a.

2.1

2.3

809

n.a.

2.2

2.5

4414

3414

.2%

Adu

lts (M

SC

T 20

02)

122

317

1.4

2.8

5.7

1.0

7.3

13.2

1.3

58.9

61.1

881

n.a.

n.a.

n.a.

2.3

2.5

1099

n.a.

2.9

3.2

104

Adu

lts (S

SC

T 19

99)

127

327

2.2

1.0

8.4

1.0

8.4

12.3

1.5

57.1

56.3

676

n.a.

n.a.

n.a.

1.8

2.0

981

n.a.

2.6

2.9

810

New

born

108

810.

911

.41.

21.

42.

439

918

508.

31.

015

.110

.913

7n.

a.n.

a.n.

a.1.

31.

413

7n.

a.1.

31.

49

60.

1%

up to

1 y

ear

110

460.

811

.31.

11.

22.

252

322

737.

31.

07.

57.

768

n.a.

n.a.

n.a.

0.5

0.5

68n.

a.0.

50.

511

130.

1%

1 to

5 y

ears

113

680.

89.

41.

21.

12.

142

820

239.

11.

011

.110

.811

6n.

a.n.

a.n.

a.0.

50.

511

6n.

a.0.

50.

518

710.

7%

6 to

10

year

s11

478

0.8

10.3

1.2

1.2

2.1

424

2042

9.8

1.0

13.1

13.2

147

n.a.

n.a.

n.a.

0.5

0.5

147

n.a.

0.5

0.5

2512

41.

2%

11 to

15

year

s11

886

0.8

10.0

1.3

1.2

2.0

423

1995

11.4

1.0

15.7

15.4

201

n.a.

n.a.

n.a.

0.6

0.6

201

n.a.

0.6

0.6

2823

12.

3%

Adu

lts (M

SC

T 20

02)

123

123

0.9

3.2

1.7

1.1

2.5

10.2

1.0

28.5

26.9

298

n.a.

n.a.

n.a.

0.8

0.9

311

n.a.

0.8

0.9

102

Adu

lts (S

SC

T 19

99)

126

239

1.9

1.0

3.3

1.3

3.3

9.1

1.1

41.0

36.9

406

n.a.

n.a.

n.a.

1.1

1.2

448

n.a.

1.2

1.3

792

New

born

100

440.

610

.82.

01.

33.

3-8

874

610

.11.

04.

53.

646

2.5

2.0

251.

62.

146

251.

62.

121

640.

6%

up to

1 y

ear

108

520.

713

.01.

91.

23.

4-1

2781

212

.31.

06.

05.

477

3.1

2.8

401.

92.

481

421.

92.

531

143

1.4%

1 to

5 y

ears

111

550.

714

.62.

11.

23.

7-1

0274

716

.41.

07.

06.

111

63.

73.

261

2.2

2.8

120

632.

22.

936

397

3.9%

6 to

10

year

s11

469

0.7

13.2

2.5

1.2

4.2

-103

740

20.4

1.0

10.5

8.5

194

5.5

4.5

102

2.6

3.3

196

103

2.6

3.3

3954

35.

4%

11 to

15

year

s11

990

0.7

13.7

2.6

1.2

4.4

-100

741

26.0

1.0

n.a.

n.a.

n.a.

7.7

6.2

180

2.8

3.7

n.a.

186

2.9

3.8

4061

36.

1%

Adu

lts (M

SC

T 20

02)

128

163

0.7

3.4

4.0

1.4

6.3

31.0

1.0

n.a.

n.a.

n.a.

14.9

11.0

368

5.2

6.8

n.a.

381

5.4

7.0

108

Adu

lts (S

SC

T 19

99)

127

191

1.4

1.0

8.4

1.3

8.4

29.8

1.2

n.a.

n.a.

n.a.

18.4

15.4

416

5.8

6.9

n.a.

514

7.1

8.6

798

New

born

108

450.

68.

62.

31.

23.

850

357

14.2

1.1

5.2

4.2

712.

92.

339

2.9

4.2

7743

3.1

4.4

1327

0.3%

up to

1 y

ear

114

530.

614

.52.

01.

23.

743

349

19.6

1.2

7.0

6.2

148

3.8

3.3

793.

95.

617

794

4.6

6.7

2261

0.6%

1 to

5 y

ears

116

610.

711

.62.

51.

24.

146

339

25.1

1.1

9.0

7.9

219

4.8

4.1

115

4.4

6.4

260

136

5.2

7.5

2714

01.

4%

6 to

10

year

s11

587

0.7

11.0

2.6

1.2

4.4

4334

029

.01.

212

.610

.734

26.

75.

618

04.

76.

840

721

45.

68.

132

213

2.1%

11 to

15

year

s11

912

50.

712

.92.

71.

24.

546

342

35.9

1.2

n.a.

n.a.

n.a.

10.1

8.3

328

5.4

7.9

n.a.

433

7.2

10.3

3325

42.

5%

Adu

lts (M

SC

T 20

02)

121

200

0.7

3.3

4.3

1.3

6.6

41.9

1.5

n.a.

n.a.

n.a.

15.6

12.7

568

8.5

12.3

n.a.

848

12.7

18.4

106

Adu

lts (S

SC

T 19

99)

124

228

1.5

1.0

8.9

1.3

8.9

40.7

1.6

n.a.

n.a.

n.a.

20.9

17.9

751

10.9

15.0

n.a.

1236

17.9

24.7

791

New

born

118

610.

812

.31.

51.

32.

557

520

008.

31.

09.

07.

590

5.2

4.3

524.

14.

690

524.

14.

64

10.

0%

up to

1 y

ear

116

118

0.9

11.7

1.4

1.1

2.1

434

1563

9.7

1.0

21.9

23.7

297

11.8

12.7

160

10.7

12.0

297

160

10.7

12.0

910

0.1%

1 to

5 y

ears

118

133

1.1

9.9

1.6

1.2

2.0

437

1740

11.1

1.0

24.8

21.9

279

13.6

11.7

151

7.5

8.4

279

151

7.5

8.4

2385

0.8%

6 to

10

year

s11

916

71.

08.

51.

51.

12.

248

218

0411

.71.

031

.528

.338

317

.215

.220

87.

18.

038

320

87.

18.

023

991.

0%

11 to

15

year

s12

114

90.

911

.81.

41.

01.

838

616

3815

.91.

0n.

a.n.

a.n.

a.15

.416

.729

46.

47.

3n.

a.29

46.

47.

326

149

1.5%

Adu

lts (M

SC

T 20

02)

130

285

1.2

3.1

2.3

1.0

2.9

13.5

1.0

n.a.

n.a.

n.a.

30.5

32.6

474

9.5

10.7

n.a.

474

9.5

10.7

107

Adu

lts (S

SC

T 19

99)

131

381

2.4

1.0

3.3

1.1

3.3

6.0

1.0

n.a.

n.a.

n.a.

39.2

38.4

230

4.4

4.9

n.a.

234

4.4

5.0

796

Tab.

A6

Ave

rage

val

ues f

rom

the

Ger

man

surv

ey o

n pa

edia

tric

CT,

arr

ange

d by

type

of e

xam

inat

ion

(for e

xpla

natio

n of

the

term

s and

abb

revi

atio

ns se

e ta

b. A

.7);

for t

he p

urpo

ses o

f

c

ompa

riso

n, th

e co

rres

pond

ing

valu

es fo

r adu

lts fr

om th

e pr

evio

us su

rvey

s in

1999

(SSC

T) a

nd 2

002

(MSC

T) a

re a

lso

show

n.

VBrain SpineEntire abdomenChestFacial bone/sinuses

VIG

erm

an S

urve

y on

Pae

diat

ric C

T 20

05/0

61s

t Qua

rtile

Exam

inat

ion

para

met

ers

Dos

e va

lues

per

sca

n se

ries

Dos

e va

lues

per

exa

min

atio

nSt

atis

tics

Age

gro

upTy

pe o

f exa

min

atio

nU

Qel

tRN

hcol

Pitc

hhr

ecW

indo

wLe

ngth

Ser

ies

CTD

Iw16

CTD

Ivol

16D

LP16

CTD

Iw32

CTD

Ivol

32D

LP32

E (m

.)E

(f.)

DLP

16D

LP32

E (m

.)E

(f.)

Par

tici-

Exa

ms

Frac

tion

[kV

][m

As]

[s]

[mm

][m

m]

CW

[cm

](P

hase

s)[m

Gy]

[mG

y][m

Gy*

cm]

[mG

y][m

Gy]

[mG

y*cm

][m

Sv]

[mS

v][m

Gy*

cm]

[mG

y*cm

][m

Sv]

[mS

v]pa

nts

Bra

in12

080

0.8

1.0

1.5

1.0

3.5

3576

8.7

1.0

14.1

16.1

162

n.a.

n.a.

n.a.

1.5

1.6

170

n.a.

1.6

1.7

2711

21.

1%

Faci

al b

one/

sinu

ses

8023

0.5

1.0

0.8

0.8

2.0

400

1500

5.0

1.0

3.3

4.3

40n.

a.n.

a.n.

a.0.

40.

440

n.a.

0.4

0.4

96

0.1%

Che

st80

230.

51.

00.

81.

03.

0-2

5035

08.

81.

02.

12.

025

1.1

1.0

140.

91.

125

140.

91.

121

640.

6%

Ent

ire a

bdom

en90

300.

51.

01.

51.

03.

040

350

13.0

1.0

4.3

3.1

492.

21.

828

1.9

2.7

4928

1.9

2.7

1327

0.3%

Spi

ne11

859

0.8

12.3

0.8

1.3

2.0

300

1500

7.0

1.0

8.7

5.8

595.

13.

435

2.5

2.8

5935

2.5

2.8

41

0.0%

Bra

in12

010

00.

82.

01.

51.

04.

535

7610

.01.

015

.616

.917

9n.

a.n.

a.n.

a.1.

21.

318

3n.

a.1.

31.

442

559

5.5%

Faci

al b

one/

sinu

ses

105

300.

53.

00.

80.

81.

340

018

006.

01.

03.

54.

537

n.a.

n.a.

n.a.

0.3

0.3

37n.

a.0.

30.

311

130.

1%

Che

st10

028

0.5

4.0

0.8

1.0

2.9

-400

350

10.0

1.0

3.4

2.6

361.

81.

419

1.0

1.3

3619

1.0

1.3

3114

31.

4%

Ent

ire a

bdom

en12

034

0.5

4.0

0.9

1.0

3.0

4032

817

.31.

04.

74.

087

2.5

2.3

471.

92.

810

052

2.4

3.4

2261

0.6%

Spi

ne12

060

0.8

4.0

1.0

0.8

1.3

300

1500

9.0

1.0

8.7

6.3

715.

13.

441

2.6

2.9

7141

2.6

2.9

910

0.1%

Bra

in12

012

60.

82.

01.

51.

04.

535

8011

.01.

019

.321

.627

1n.

a.n.

a.n.

a.1.

11.

227

8n.

a.1.

11.

248

1634

16.2

%

Faci

al b

one/

sinu

ses

120

360.

82.

50.

80.

71.

332

515

257.

11.

04.

86.

151

n.a.

n.a.

n.a.

0.2

0.2

51n.

a.0.

20.

218

710.

7%

Che

st10

030

0.5

4.0

0.9

1.0

3.0

-400

350

15.0

1.0

3.7

3.0

602.

01.

630

1.1

1.4

6030

1.2

1.5

3639

73.

9%

Ent

ire a

bdom

en12

036

0.5

2.0

1.4

1.0

3.0

4031

022

.01.

05.

04.

210

32.

72.

558

1.8

2.6

105

581.

92.

827

140

1.4%

Spi

ne12

074

0.8

1.5

1.0

0.8

1.3

325

1500

10.0

1.0

9.3

8.7

105

5.3

5.1

542.

63.

010

554

2.6

3.0

2385

0.8%

Bra

in12

017

30.

92.

01.

51.

04.

535

8012

.01.

022

.929

.339

4n.

a.n.

a.n.

a.1.

31.

439

4n.

a.1.

31.

444

1391

13.8

%

Faci

al b

one/

sinu

ses

120

380.

82.

00.

80.

71.

330

015

008.

11.

05.

75.

568

n.a.

n.a.

n.a.

0.2

0.2

68n.

a.0.

20.

225

124

1.2%

Che

st10

539

0.5

3.0

0.9

1.0

3.0

-400

350

18.1

1.0

4.7

3.7

982.

42.

055

1.2

1.5

100

581.

21.

639

543

5.4%

Ent

ire a

bdom

en12

056

0.5

3.5

1.2

1.0

3.0

4032

026

.81.

07.

86.

022

04.

53.

211

73.

04.

322

712

43.

14.

532

213

2.1%

Spi

ne12

097

0.8

1.5

0.9

0.8

1.3

400

1500

10.0

1.0

12.9

11.7

147

6.9

6.4

802.

83.

214

780

2.8

3.2

2399

1.0%

Bra

in12

023

01.

02.

01.

51.

04.

535

8013

.01.

041

.344

.458

8n.

a.n.

a.n.

a.1.

61.

858

8n.

a.1.

61.

844

1434

14.2

%

Faci

al b

one/

sinu

ses

120

450.

82.

00.

80.

71.

324

015

009.

31.

07.

17.

894

n.a.

n.a.

n.a.

0.3

0.3

94n.

a.0.

30.

328

231

2.3%

Che

st12

056

0.5

3.5

1.3

1.0

3.0

-400

350

24.1

1.0

n.a.

n.a.

n.a.

4.3

4.0

112

1.8

2.3

112

112

1.8

2.3

4061

36.

1%

Ent

ire a

bdom

en12

088

0.5

2.0

1.3

1.0

3.0

4032

030

.01.

0n.

a.n.

a.n.

a.6.

76.

520

43.

65.

221

521

53.

85.

533

254

2.5%

Spi

ne12

090

0.8

2.5

0.8

0.7

1.1

213

1500

12.3

1.0

n.a.

n.a.

n.a.

7.3

7.4

120

2.6

3.0

120

120

2.6

3.0

2614

91.

5%

Expl

anat

ion

of te

rms

and

abbr

evia

tions

Utu

be p

oten

tial (

in k

V)

Leng

thle

ngth

of t

he im

aged

bod

y se

ctio

n (=

net s

can

leng

th) (

in c

m)

E (m

.)ef

fect

ive

dose

for m

ales

(in

mS

v)

Qel

elec

trica

l tub

e-cu

rren

t-tim

e pr

oduc

t (in

mA

s)S

erie

snu

mbe

r of s

can

serie

s (=

phas

es)

E (f

.)ef

fect

ive

dose

for f

emal

es (i

n m

Sv)

tRro

tatio

n tim

e (in

s)

CTD

Iw16

wei

ghte

d C

TDI f

or th

e 16

cm

hea

d ph

anto

m (i

n m

Gy)

Par

ticip

ants

num

ber o

f sca

nner

s ap

plyi

ng th

at p

artic

ular

Nnu

mbe

r of s

lices

acq

uire

d si

mul

tane

ousl

y pe

r rot

atio

nC

TDIv

ol16

volu

me

CTD

I for

the

16 c

m h

ead

phan

tom

(in

mG

y)ty

pe o

f exa

min

atio

n in

that

age

gro

up

hcol

slic

e co

llim

atio

n (in

mm

)D

LP16

dose

-leng

th p

rodu

ct fo

r the

16

cm h

ead

phan

tom

(in

mG

y x

cm)

Exa

ms

num

ber o

f ann

ual e

xam

inat

ions

per

form

ed fo

r tha

t

Pitc

hpi

tch

fact

orC

TDIw

32w

eigh

ted

CTD

I for

the

32 c

m b

ody

phan

tom

(in

mG

y)ty

pe o

f exa

min

atio

n an

d ag

e gr

oup

hrec

reco

nstru

cted

slic

e th

ickn

ess

(in m

m)

CTD

Ivol

32vo

lum

e C

TDI f

or th

e 32

cm

bod

y ph

anto

m (i

n m

Gy)

Frac

tion

fract

ion

of th

at p

artic

ular

type

of e

xam

inat

ion

and

Win

dow

win

dow

set

tings

(C=c

entre

, W=w

idth

)D

LP32

dose

-leng

th p

rodu

ct fo

r the

32

cm b

ody

phan

tom

(in

mG

y x

cm)

age

grou

p w

ith a

ll pa

edia

tric

CT

exam

inat

ions

= 1

00%

Tab.

A7

Fir

st q

uart

ile v

alue

s fro

m th

e G

erm

an su

rvey

on

paed

iatr

ic C

T, a

rran

ged

by a

ge g

roup

.

11 to 15 yearsNewborn up to 1 year 2 to 5 years 6 to 10 years

Ger

man

Sur

vey

on P

aedi

atric

CT

2005

/06

Med

ian

Exam

inat

ion

para

met

ers

Dos

e va

lues

per

sca

n se

ries

Dos

e va

lues

per

exa

min

atio

nSt

atis

tics

Age

gro

upTy

pe o

f exa

min

atio

nU

Qel

tRN

hcol

Pitc

hhr

ecW

indo

wLe

ngth

Ser

ies

CTD

Iw16

CTD

Ivol

16D

LP16

CTD

Iw32

CTD

Ivol

32D

LP32

E (m

.)E

(f.)

DLP

16D

LP32

E (m

.)E

(f.)

Par

tici-

Exa

ms

Frac

tion

[kV

][m

As]

[s]

[mm

][m

m]

CW

[cm

](P

hase

s)[m

Gy]

[mG

y][m

Gy*

cm]

[mG

y][m

Gy]

[mG

y*cm

][m

Sv]

[mS

v][m

Gy*

cm]

[mG

y*cm

][m

Sv]

[mS

v]pa

nts

Bra

in12

011

01.

04.

02.

51.

05.

035

8010

.01.

017

.518

.018

1n.

a.n.

a.n.

a.1.

71.

819

0n.

a.1.

71.

927

112

1.1%

Faci

al b

one/

sinu

ses

120

450.

816

.00.

80.

93.

045

017

009.

01.

04.

64.

551

n.a.

n.a.

n.a.

0.5

0.5

51n.

a.0.

50.

59

60.

1%

Che

st10

030

0.5

10.0

1.5

1.2

3.0

4040

010

.01.

04.

03.

135

2.0

1.6

181.

21.

635

181.

21.

621

640.

6%

Ent

ire a

bdom

en12

034

0.5

10.0

1.5

1.1

3.0

5035

014

.01.

04.

74.

464

2.7

2.3

362.

53.

664

362.

94.

213

270.

3%S

pine

120

600.

816

.01.

11.

52.

550

017

508.

01.

08.

86.

262

5.1

3.5

353.

23.

662

353.

23.

64

10.

0%

Bra

in12

015

01.

04.

02.

81.

05.

035

8010

.81.

021

.921

.925

2n.

a.n.

a.n.

a.1.

82.

026

4n.

a.1.

82.

042

559

5.5%

Faci

al b

one/

sinu

ses

120

400.

816

.00.

80.

83.

050

020

007.

01.

05.

57.

172

n.a.

n.a.

n.a.

0.5

0.5

72n.

a.0.

50.

511

130.

1%

Che

st12

039

0.5

16.0

1.5

1.1

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4040

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52.

031

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Ent

ire a

bdom

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047

0.5

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4035

020

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05.

74.

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pine

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816

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92.

050

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811

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811

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86.

519

511

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Bra

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020

01.

04.

02.

51.

05.

035

8012

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028

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%

Faci

al b

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ses

120

490.

811

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00.

82.

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51.

010

.110

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st12

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015

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51.

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023

51.

04.

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05.

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Faci

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ses

120

700.

86.

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92.

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011

.710

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Che

st12

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0.5

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1.5

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020

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081

0.5

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1.5

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04.

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02.

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020

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031

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36.

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35.

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023

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Bra

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030

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05.

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8314

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9n.

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%

Faci

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sinu

ses

120

770.

85.

01.

00.

92.

050

020

0010

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013

.112

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4n.

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516

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st12

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0.5

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1.5

1.2

5.0

4040

026

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0n.

a.n.

a.n.

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916

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63.

416

616

62.

63.

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613

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ire a

bdom

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011

40.

510

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51.

45.

050

350

36.6

1.0

n.a.

n.a.

n.a.

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5.5

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339

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8.1

3325

42.

5%S

pine

120

140

0.9

11.0

1.0

0.8

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425

2000

16.0

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n.a.

n.a.

n.a.

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207

207

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Expl

anat

ion

of te

rms

and

abbr

evia

tions

Utu

be p

oten

tial (

in k

V)

Leng

thle

ngth

of t

he im

aged

bod

y se

ctio

n (=

net s

can

leng

th) (

in c

m)

E (m

.)ef

fect

ive

dose

for m

ales

(in

mS

v)

Qel

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trica

l tub

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rren

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oduc

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s)S

erie

snu

mbe

r of s

can

serie

s (=

phas

es)

E (f

.)ef

fect

ive

dose

for f

emal

es (i

n m

Sv)

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tatio

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e (in

s)

CTD

Iw16

wei

ghte

d C

TDI f

or th

e 16

cm

hea

d ph

anto

m (i

n m

Gy)

Par

ticip

ants

num

ber o

f sca

nner

s ap

plyi

ng th

at p

artic

ular

Nnu

mbe

r of s

lices

acq

uire

d si

mul

tane

ousl

y pe

r rot

atio

nC

TDIv

ol16

volu

me

CTD

I for

the

16 c

m h

ead

phan

tom

(in

mG

y)ty

pe o

f exa

min

atio

n in

that

age

gro

up

hcol

slic

e co

llim

atio

n (in

mm

)D

LP16

dose

-leng

th p

rodu

ct fo

r the

16

cm h

ead

phan

tom

(in

mG

y x

cm)

Exa

ms

num

ber o

f ann

ual e

xam

inat

ions

per

form

ed fo

r tha

t

Pitc

hpi

tch

fact

orC

TDIw

32w

eigh

ted

CTD

I for

the

32 c

m b

ody

phan

tom

(in

mG

y)ty

pe o

f exa

min

atio

n an

d ag

e gr

oup

hrec

reco

nstru

cted

slic

e th

ickn

ess

(in m

m)

CTD

Ivol

32vo

lum

e C

TDI f

or th

e 32

cm

bod

y ph

anto

m (i

n m

Gy)

Frac

tion

fract

ion

of th

at p

artic

ular

type

of e

xam

inat

ion

and

Win

dow

win

dow

set

tings

(C=c

entre

, W=w

idth

)D

LP32

dose

-leng

th p

rodu

ct fo

r the

32

cm b

ody

phan

tom

(in

mG

y x

cm)

age

grou

p w

ith a

ll pa

edia

tric

CT

exam

inat

ions

= 1

00%

Tab.

A8

Med

ian

valu

es fr

om th

e G

erm

an su

rvey

on

paed

iatr

ic C

T, a

rran

ged

by a

ge g

roup

.

VII11 to 15 yearsNewborn up to 1 year 2 to 5 years 6 to 10 years

VIIIG

erm

an S

urve

y on

Pae

diat

ric C

T 20

05/0

63r

d Q

uart

ile

Exam

inat

ion

para

met

ers

Dos

e va

lues

per

sca

n se

ries

Dos

e va

lues

per

exa

min

atio

nSt

atis

tics

Age

gro

upTy

pe o

f exa

min

atio

nU

Qel

tRN

hcol

Pitc

hhr

ecW

indo

wLe

ngth

Ser

ies

CTD

Iw16

CTD

Ivol

16D

LP16

CTD

Iw32

CTD

Ivol

32D

LP32

E (m

.)E

(f.)

DLP

16D

LP32

E (m

.)E

(f.)

Par

tici-

Exa

ms

Frac

tion

[kV

][m

As]

[s]

[mm

][m

m]

CW

[cm

](P

hase

s)[m

Gy]

[mG

y][m

Gy*

cm]

[mG

y][m

Gy]

[mG

y*cm

][m

Sv]

[mS

v][m

Gy*

cm]

[mG

y*cm

][m

Sv]

[mS

v]pa

nts

Bra

in12

015

81.

58.

05.

01.

05.

040

8810

.81.

026

.926

.127

5n.

a.n.

a.n.

a.2.

52.

827

5n.

a.2.

52.

827

112

1.1%

Faci

al b

one/

sinu

ses

120

601.

016

.01.

01.

53.

050

020

0010

.01.

010

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158

n.a.

n.a.

n.a.

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0.6

58n.

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69

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1%

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st12

064

0.8

16.0

3.0

1.5

4.0

5012

5010

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05.

64.

247

3.2

2.1

261.

82.

347

261.

82.

321

640.

6%

Ent

ire a

bdom

en12

065

0.8

16.0

3.0

1.5

5.0

5038

015

.01.

05.

54.

681

3.1

2.5

453.

75.

410

550

3.7

5.4

1327

0.3%

Spi

ne12

062

0.8

16.0

1.9

1.5

3.0

775

2250

9.3

1.0

9.1

7.8

925.

24.

452

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5.4

9252

4.8

5.4

41

0.0%

Bra

in12

020

01.

58.

05.

01.

07.

540

8411

.01.

038

.533

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3n.

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a.n.

a.2.

72.

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3n.

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Faci

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ses

120

531.

016

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30.

93.

070

031

008.

51.

09.

410

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84n.

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st12

060

0.8

16.0

2.5

1.5

5.0

5014

5013

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07.

16.

993

3.8

3.8

492.

22.

995

552.

43.

131

143

1.4%

Ent

ire a

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en12

066

0.8

16.0

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1.5

5.0

5036

520

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48.

66.

816

44.

93.

982

4.0

5.8

191

111

4.3

6.2

2261

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Spi

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015

01.

016

.01.

51.

53.

050

020

0010

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039

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419

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220

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428

220

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100.

1%

Bra

in12

026

61.

513

.05.

01.

07.

640

9512

.51.

051

.449

.061

1n.

a.n.

a.n.

a.2.

52.

764

0n.

a.2.

52.

748

1634

16.2

%

Faci

al b

one/

sinu

ses

120

791.

016

.01.

31.

33.

060

030

0010

.81.

014

.212

.313

2n.

a.n.

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50.

613

2n.

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50.

618

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st12

067

0.8

16.0

2.5

1.5

5.0

5013

2517

.21.

08.

78.

413

74.

54.

473

2.8

3.6

137

762.

83.

636

397

3.9%

Ent

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bdom

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082

0.8

16.0

3.8

1.5

5.0

5035

028

.11.

010

.78.

326

16.

14.

714

74.

66.

627

415

54.

86.

927

140

1.4%

Spi

ne12

020

01.

316

.02.

01.

53.

050

020

0012

.51.

038

.633

.448

321

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812

.614

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327

812

.614

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850.

8%

Bra

in12

030

01.

512

.05.

01.

08.

040

9513

.51.

055

.558

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1n.

a.n.

a.n.

a.2.

32.

678

4n.

a.2.

52.

844

1391

13.8

%

Faci

al b

one/

sinu

ses

120

100

1.0

16.0

1.5

1.5

3.0

600

3000

10.0

1.0

18.1

16.2

162

n.a.

n.a.

n.a.

0.5

0.6

162

n.a.

0.5

0.6

2512

41.

2%

Che

st12

089

0.8

16.0

5.0

1.5

5.0

5013

5022

.71.

013

.611

.925

77.

26.

012

83.

44.

425

712

83.

44.

439

543

5.4%

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ire a

bdom

en12

011

10.

816

.05.

01.

55.

050

350

31.6

1.0

16.3

13.7

477

8.8

7.4

227

5.9

8.5

489

227

7.5

10.8

3221

32.

1%S

pine

120

200

1.0

16.0

2.3

1.5

3.0

550

2000

12.0

1.0

47.3

37.3

524

26.2

22.6

306

10.6

11.9

524

306

10.6

11.9

2399

1.0%

Bra

in12

035

01.

516

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01.

07.

540

9614

.61.

065

.264

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0n.

a.n.

a.n.

a.2.

52.

810

07n.

a.2.

93.

244

1434

14.2

%

Faci

al b

one/

sinu

ses

120

100

1.0

16.0

1.5

1.5

3.0

600

3000

13.6

1.0

22.5

18.8

243

n.a.

n.a.

n.a.

0.7

0.7

243

n.a.

0.7

0.7

2823

12.

3%

Che

st12

011

00.

816

.05.

01.

55.

550

1325

30.0

1.0

n.a.

n.a.

n.a.

11.1

8.0

244

3.8

4.9

259

259

3.8

5.0

4061

36.

1%

Ent

ire a

bdom

en12

014

90.

816

.05.

01.

55.

050

350

40.0

1.5

n.a.

n.a.

n.a.

12.0

10.1

402

6.5

9.4

546

546

8.5

12.3

3325

42.

5%S

pine

120

200

1.0

16.0

1.9

1.4

2.0

500

2000

16.8

1.0

n.a.

n.a.

n.a.

20.4

17.9

294

6.8

7.7

294

294

6.8

7.7

2614

91.

5%

Expl

anat

ion

of te

rms

and

abbr

evia

tions

Utu

be p

oten

tial (

in k

V)

Leng

thle

ngth

of t

he im

aged

bod

y se

ctio

n (=

net s

can

leng

th) (

in c

m)

E (m

.)ef

fect

ive

dose

for m

ales

(in

mS

v)

Qel

elec

trica

l tub

e-cu

rren

t-tim

e pr

oduc

t (in

mA

s)S

erie

snu

mbe

r of s

can

serie

s (=

phas

es)

E (f

.)ef

fect

ive

dose

for f

emal

es (i

n m

Sv)

tRro

tatio

n tim

e (in

s)

CTD

Iw16

wei

ghte

d C

TDI f

or th

e 16

cm

hea

d ph

anto

m (i

n m

Gy)

Par

ticip

ants

num

ber o

f sca

nner

s ap

plyi

ng th

at p

artic

ular

Nnu

mbe

r of s

lices

acq

uire

d si

mul

tane

ousl

y pe

r rot

atio

nC

TDIv

ol16

volu

me

CTD

I for

the

16 c

m h

ead

phan

tom

(in

mG

y)ty

pe o

f exa

min

atio

n in

that

age

gro

up

hcol

slic

e co

llim

atio

n (in

mm

)D

LP16

dose

-leng

th p

rodu

ct fo

r the

16

cm h

ead

phan

tom

(in

mG

y x

cm)

Exa

ms

num

ber o

f ann

ual e

xam

inat

ions

per

form

ed fo

r tha

t

Pitc

hpi

tch

fact

orC

TDIw

32w

eigh

ted

CTD

I for

the

32 c

m b

ody

phan

tom

(in

mG

y)ty

pe o

f exa

min

atio

n an

d ag

e gr

oup

hrec

reco

nstru

cted

slic

e th

ickn

ess

(in m

m)

CTD

Ivol

32vo

lum

e C

TDI f

or th

e 32

cm

bod

y ph

anto

m (i

n m

Gy)

Frac

tion

fract

ion

of th

at p

artic

ular

type

of e

xam

inat

ion

and

Win

dow

win

dow

set

tings

(C=c

entre

, W=w

idth

)D

LP32

dose

-leng

th p

rodu

ct fo

r the

32

cm b

ody

phan

tom

(in

mG

y x

cm)

age

grou

p w

ith a

ll pa

edia

tric

CT

exam

inat

ions

= 1

00%

Tab.

A9

Thi

rd q

uart

ile v

alue

s fro

m th

e G

erm

an su

rvey

on

paed

iatr

ic C

T, a

rran

ged

by a

ge g

roup

.

11 to 15 yearsNewborn up to 1 year 2 to 5 years 6 to 10 years

Ger

man

Sur

vey

on P

aedi

atric

CT

2005

/06

Type

of E

xam

inat

ion:

Bra

in

Exam

inat

ion

para

met

ers

Dos

e va

lues

per

sca

n se

ries

Dos

e va

lues

per

exa

min

atio

nSt

atis

tics

Age

gro

upSt

atis

tical

qua

ntity

UQ

eltR

Nhc

olP

itch

hrec

Win

dow

Leng

thS

erie

sC

TDIw

16C

TDIv

ol16

DLP

16C

TDIw

32C

TDIv

ol32

DLP

32E

(m.)

E (f

.)D

LP16

DLP

32E

(m.)

E (f

.)P

artic

i-E

xam

sFr

actio

n[k

V]

[mA

s][s

][m

m]

[mm

]C

W[c

m]

(Pha

ses)

[mG

y][m

Gy]

[mG

y*cm

][m

Gy]

[mG

y][m

Gy*

cm]

[mS

v][m

Sv]

[mG

y*cm

][m

Gy*

cm]

[mS

v][m

Sv]

pant

s

Aver

age

116

128

1.2

6.3

3.3

1.0

4.5

3685

9.8

1.0

21.8

21.9

227

n.a.

n.a.

n.a.

2.1

2.4

233

n.a.

2.2

2.4

2711

21.

1%

Sta

ndar

d de

viat

ion

9%52

%46

%11

3%63

%15

%31

%12

%16

%14

%13

%58

%55

%58

%n.

a.n.

a.n.

a.61

%61

%56

%n.

a.58

%58

%

Min

imum

9040

0.8

1.0

0.5

0.5

2.5

2870

7.2

1.0

3.9

3.9

34n.

a.n.

a.n.

a.0.

30.

334

n.a.

0.3

0.3

Max

imum

140

300

3.0

32.0

8.0

1.5

8.0

4312

012

.01.

554

.454

.463

2n.

a.n.

a.n.

a.5.

86.

363

2n.

a.5.

86.

3

1st q

uarti

le12

080

0.8

1.0

1.5

1.0

3.5

3576

8.7

1.0

14.1

16.1

162

n.a.

n.a.

n.a.

1.5

1.6

170

n.a.

1.6

1.7

Med

ian

120

110

1.0

4.0

2.5

1.0

5.0

3580

10.0

1.0

17.5

18.0

181

n.a.

n.a.

n.a.

1.7

1.8

190

n.a.

1.7

1.9

3rd

quar

tile

120

158

1.5

8.0

5.0

1.0

5.0

4088

10.8

1.0

26.9

26.1

275

n.a.

n.a.

n.a.

2.5

2.8

275

n.a.

2.5

2.8

Aver

age

115

162

1.2

6.7

3.5

1.0

5.4

3685

10.7

1.0

26.4

26.2

302

n.a.

n.a.

n.a.

2.1

2.3

323

n.a.

2.3

2.5

4255

95.

5%

Sta

ndar

d de

viat

ion

12%

51%

44%

112%

66%

16%

38%

12%

19%

13%

18%

62%

62%

66%

n.a.

n.a.

n.a.

66%

66%

78%

n.a.

78%

78%

Min

imum

8025

0.8

1.0

0.5

0.5

2.5

2860

7.2

1.0

4.8

4.8

48n.

a.n.

a.n.

a.0.

30.

448

n.a.

0.3

0.4

Max

imum

140

320

3.0

32.0

10.0

1.5

10.0

4315

015

.02.

083

.083

.089

6n.

a.n.

a.n.

a.6.

06.

613

80n.

a.9.

610

.6

1st q

uarti

le12

010

00.

82.

01.

51.

04.

535

7610

.01.

015

.616

.917

9n.

a.n.

a.n.

a.1.

21.

318

3n.

a.1.

31.

4

Med

ian

120

150

1.0

4.0

2.8

1.0

5.0

3580

10.8

1.0

21.9

21.9

252

n.a.

n.a.

n.a.

1.8

2.0

264

n.a.

1.8

2.0

3rd

quar

tile

120

200

1.5

8.0

5.0

1.0

7.5

4084

11.0

1.0

38.5

33.6

393

n.a.

n.a.

n.a.

2.7

2.9

393

n.a.

2.7

2.9

Aver

age

119

197

1.2

9.3

3.4

1.0

5.7

4611

711

.91.

135

.435

.745

2n.

a.n.

a.n.

a.1.

82.

047

0n.

a.1.

92.

148

1634

16.2

%

Sta

ndar

d de

viat

ion

8%44

%48

%12

5%75

%13

%38

%14

6%17

5%11

%18

%56

%53

%55

%n.

a.n.

a.n.

a.56

%56

%54

%n.

a.55

%55

%

Min

imum

9025

0.8

1.0

0.5

0.5

2.5

2860

7.2

1.0

4.8

4.8

60n.

a.n.

a.n.

a.0.

20.

360

n.a.

0.2

0.3

Max

imum

140

360

3.0

64.0

10.0

1.5

10.0

500

1500

15.0

2.0

83.0

83.0

1186

n.a.

n.a.

n.a.

4.6

5.0

1186

n.a.

4.6

5.0

1st q

uarti

le12

012

60.

82.

01.

51.

04.

535

8011

.01.

019

.321

.627

1n.

a.n.

a.n.

a.1.

11.

227

8n.

a.1.

11.

2

Med

ian

120

200

1.0

4.0

2.5

1.0

5.0

3580

12.0

1.0

28.6

28.6

374

n.a.

n.a.

n.a.

1.5

1.6

411

n.a.

1.6

1.8

3rd

quar

tile

120

266

1.5

13.0

5.0

1.0

7.6

4095

12.5

1.0

51.4

49.0

611

n.a.

n.a.

n.a.

2.5

2.7

640

n.a.

2.5

2.7

Aver

age

121

231

1.3

7.0

3.9

1.0

5.9

3788

12.8

1.0

42.4

43.7

582

n.a.

n.a.

n.a.

1.9

2.1

604

n.a.

2.0

2.2

4413

9113

.8%

Sta

ndar

d de

viat

ion

7%39

%45

%10

2%71

%11

%36

%10

%18

%14

%12

%53

%51

%49

%n.

a.n.

a.n.

a.50

%50

%51

%n.

a.51

%51

%

Min

imum

9050

0.5

1.0

0.5

0.5

2.5

2860

7.2

1.0

10.9

10.9

132

n.a.

n.a.

n.a.

0.4

0.5

132

n.a.

0.4

0.5

Max

imum

140

400

3.0

32.0

10.0

1.1

10.0

4515

020

.01.

511

3.0

113.

014

24n.

a.n.

a.n.

a.4.

85.

314

24n.

a.4.

85.

3

1st q

uarti

le12

017

30.

92.

01.

51.

04.

535

8012

.01.

022

.929

.339

4n.

a.n.

a.n.

a.1.

31.

439

4n.

a.1.

31.

4

Med

ian

120

235

1.0

4.0

3.1

1.0

5.0

3580

13.0

1.0

40.5

41.3

536

n.a.

n.a.

n.a.

1.8

1.9

539

n.a.

1.8

2.0

3rd

quar

tile

120

300

1.5

12.0

5.0

1.0

8.0

4095

13.5

1.0

55.5

58.0

711

n.a.

n.a.

n.a.

2.3

2.6

784

n.a.

2.5

2.8

Aver

age

122

284

1.3

8.7

3.5

1.0

5.7

3713

913

.91.

152

.653

.276

4n.

a.n.

a.n.

a.2.

12.

380

9n.

a.2.

22.

544

1434

14.2

%

Sta

ndar

d de

viat

ion

5%29

%44

%10

0%74

%12

%33

%16

%17

6%15

%18

%37

%35

%36

%n.

a.n.

a.n.

a.37

%37

%40

%n.

a.40

%40

%

Min

imum

110

500.

81.

00.

50.

62.

520

607.

21.

010

.910

.917

8n.

a.n.

a.n.

a.0.

50.

517

8n.

a.0.

50.

5

Max

imum

140

413

3.0

32.0

10.0

1.5

10.0

6415

0020

.02.

011

3.0

113.

016

38n.

a.n.

a.n.

a.4.

75.

216

38n.

a.4.

75.

2

1st q

uarti

le12

023

01.

02.

01.

51.

04.

535

8013

.01.

041

.344

.458

8n.

a.n.

a.n.

a.1.

61.

858

8n.

a.1.

61.

8

Med

ian

120

300

1.0

4.0

2.5

1.0

5.0

3683

14.0

1.0

51.6

54.6

763

n.a.

n.a.

n.a.

2.1

2.3

789

n.a.

2.2

2.4

3rd

quar

tile

120

350

1.5

16.0

5.0

1.0

7.5

4096

14.6

1.0

65.2

64.5

920

n.a.

n.a.

n.a.

2.5

2.8

1007

n.a.

2.9

3.2

Tab.

A10

Res

ults

from

the

Ger

man

surv

ey o

n pa

edia

tric

CT

for b

rain

exa

min

atio

ns (f

or e

xpla

natio

ns o

f the

term

s and

abb

revi

atio

ns se

e ta

b. A

.7).

IXNewborn 11 to 15 years6 to 10 years2 to 5 yearsUp to 1 year

XG

erm

an S

urve

y on

Pae

diat

ric C

T 20

05/0

6Ty

pe o

f Exa

min

atio

n: F

acia

l Bon

e/Si

nuse

s

Exam

inat

ion

para

met

ers

Dos

e va

lues

per

sca

n se

ries

Dos

e va

lues

per

exa

min

atio

nSt

atis

tics

Age

gro

upSt

atis

tical

qua

ntity

UQ

eltR

Nhc

olP

itch

hrec

Win

dow

Leng

thS

erie

sC

TDIw

16C

TDIv

ol16

DLP

16C

TDIw

32C

TDIv

ol32

DLP

32E

(m.)

E (f

.)D

LP16

DLP

32E

(m.)

E (f

.)P

artic

i-E

xam

sFr

actio

n[k

V]

[mA

s][s

][m

m]

[mm

]C

W[c

m]

(Pha

ses)

[mG

y][m

Gy]

[mG

y*cm

][m

Gy]

[mG

y][m

Gy*

cm]

[mS

v][m

Sv]

[mG

y*cm

][m

Gy*

cm]

[mS

v][m

Sv]

pant

s

Aver

age

108

810.

911

.41.

21.

42.

439

918

508.

31.

015

.110

.913

7n.

a.n.

a.n.

a.1.

31.

413

7n.

a.1.

31.

49

60.

1%

Sta

ndar

d de

viat

ion

21%

143%

48%

92%

68%

100%

41%

83%

48%

54%

0%17

2%15

3%20

2%n.

a.n.

a.n.

a.20

4%20

4%20

2%n.

a.20

4%20

4%

Min

imum

8020

0.5

1.0

0.6

0.5

1.0

-250

150

3.0

1.0

2.9

3.2

20n.

a.n.

a.n.

a.0.

20.

220

n.a.

0.2

0.2

Max

imum

140

385

1.5

32.0

3.0

5.0

4.0

850

3200

15.0

1.0

82.6

55.1

875

n.a.

n.a.

n.a.

8.3

9.0

875

n.a.

8.3

9.0

1st q

uarti

le80

230.

51.

00.

80.

82.

040

015

005.

01.

03.

34.

340

n.a.

n.a.

n.a.

0.4

0.4

40n.

a.0.

40.

4

Med

ian

120

450.

816

.00.

80.

93.

045

017

009.

01.

04.

64.

551

n.a.

n.a.

n.a.

0.5

0.5

51n.

a.0.

50.

53r

d qu

artil

e12

060

1.0

16.0

1.0

1.5

3.0

500

2000

10.0

1.0

10.7

7.1

58n.

a.n.

a.n.

a.0.

50.

658

n.a.

0.5

0.6

Aver

age

110

460.

811

.31.

11.

22.

252

322

737.

31.

07.

57.

768

n.a.

n.a.

n.a.

0.5

0.5

68n.

a.0.

50.

511

130.

1%

Sta

ndar

d de

viat

ion

15%

53%

39%

86%

54%

110%

42%

42%

39%

36%

0%68

%45

%50

%n.

a.n.

a.n.

a.50

%50

%50

%n.

a.50

%50

%

Min

imum

8023

0.5

1.0

0.6

0.5

1.0

5050

03.

51.

03.

34.

023

n.a.

n.a.

n.a.

0.2

0.2

23n.

a.0.

20.

2

Max

imum

120

100

1.5

32.0

2.5

5.0

3.2

850

3200

12.5

1.0

19.9

12.3

126

n.a.

n.a.

n.a.

0.9

0.9

126

n.a.

0.9

0.9

1st q

uarti

le10

530

0.5

3.0

0.8

0.8

1.3

400

1800

6.0

1.0

3.5

4.5

37n.

a.n.

a.n.

a.0.

30.

337

n.a.

0.3

0.3

Med

ian

120

400.

816

.00.

80.

83.

050

020

007.

01.

05.

57.

172

n.a.

n.a.

n.a.

0.5

0.5

72n.

a.0.

50.

53r

d qu

artil

e12

053

1.0

16.0

1.3

0.9

3.0

700

3100

8.5

1.0

9.4

10.8

84n.

a.n.

a.n.

a.0.

60.

784

n.a.

0.6

0.7

Aver

age

113

680.

89.

41.

21.

12.

142

820

239.

11.

011

.110

.811

6n.

a.n.

a.n.

a.0.

50.

511

6n.

a.0.

50.

518

710.

7%

Sta

ndar

d de

viat

ion

12%

84%

35%

74%

55%

92%

45%

58%

53%

32%

0%77

%66

%67

%n.

a.n.

a.n.

a.66

%66

%67

%n.

a.66

%66

%

Min

imum

809

0.5

1.0

0.8

0.3

1.0

4035

04.

91.

01.

74.

032

n.a.

n.a.

n.a.

0.1

0.1

32n.

a.0.

10.

1

Max

imum

120

250

1.5

16.0

3.0

5.0

3.2

850

3200

15.0

1.0

35.3

35.3

365

n.a.

n.a.

n.a.

1.4

1.6

365

n.a.

1.4

1.6

1st q

uarti

le12

036

0.8

2.5

0.8

0.7

1.3

325

1525

7.1

1.0

4.8

6.1

51n.

a.n.

a.n.

a.0.

20.

251

n.a.

0.2

0.2

Med

ian

120

490.

811

.01.

00.

82.

042

520

008.

51.

010

.110

.411

4n.

a.n.

a.n.

a.0.

50.

511

4n.

a.0.

50.

53r

d qu

artil

e12

079

1.0

16.0

1.3

1.3

3.0

600

3000

10.8

1.0

14.2

12.3

132

n.a.

n.a.

n.a.

0.5

0.6

132

n.a.

0.5

0.6

Aver

age

114

780.

810

.31.

21.

22.

142

420

429.

81.

013

.113

.214

7n.

a.n.

a.n.

a.0.

50.

514

7n.

a.0.

50.

525

124

1.2%

Sta

ndar

d de

viat

ion

11%

72%

32%

91%

59%

82%

48%

59%

50%

27%

0%72

%77

%83

%n.

a.n.

a.n.

a.83

%83

%83

%n.

a.83

%83

%

Min

imum

809

0.5

1.0

0.5

0.3

0.5

3027

06.

01.

01.

73.

635

n.a.

n.a.

n.a.

0.1

0.1

35n.

a.0.

10.

1

Max

imum

130

250

1.5

32.0

3.0

5.0

4.0

850

3200

17.5

1.0

35.3

43.9

541

n.a.

n.a.

n.a.

1.8

1.9

541

n.a.

1.8

1.9

1st q

uarti

le12

038

0.8

2.0

0.8

0.7

1.3

300

1500

8.1

1.0

5.7

5.5

68n.

a.n.

a.n.

a.0.

20.

268

n.a.

0.2

0.2

Med

ian

120

700.

86.

01.

00.

92.

050

020

009.

01.

011

.710

.711

4n.

a.n.

a.n.

a.0.

40.

411

4n.

a.0.

40.

43r

d qu

artil

e12

010

01.

016

.01.

51.

53.

060

030

0010

.01.

018

.116

.216

2n.

a.n.

a.n.

a.0.

50.

616

2n.

a.0.

50.

6

Aver

age

118

860.

810

.01.

31.

22.

042

319

9511

.41.

015

.715

.420

1n.

a.n.

a.n.

a.0.

60.

620

1n.

a.0.

60.

628

231

2.3%

Sta

ndar

d de

viat

ion

7%73

%29

%90

%56

%76

%51

%60

%54

%27

%0%

76%

69%

80%

n.a.

n.a.

n.a.

80%

80%

80%

n.a.

80%

80%

Min

imum

100

150.

51.

00.

50.

50.

540

807.

51.

02.

83.

635

n.a.

n.a.

n.a.

0.1

0.1

35n.

a.0.

10.

1

Max

imum

140

282

1.5

32.0

3.0

5.0

4.0

850

3200

20.0

1.0

60.5

43.9

731

n.a.

n.a.

n.a.

2.0

2.2

731

n.a.

2.0

2.2

1st q

uarti

le12

045

0.8

2.0

0.8

0.7

1.3

240

1500

9.3

1.0

7.1

7.8

94n.

a.n.

a.n.

a.0.

30.

394

n.a.

0.3

0.3

Med

ian

120

770.

85.

01.

00.

92.

050

020

0010

.01.

013

.112

.916

4n.

a.n.

a.n.

a.0.

40.

516

4n.

a.0.

40.

53r

d qu

artil

e12

010

01.

016

.01.

51.

53.

060

030

0013

.61.

022

.518

.824

3n.

a.n.

a.n.

a.0.

70.

724

3n.

a.0.

70.

7

Tab.

A11

Res

ults

from

the

Ger

man

surv

ey o

n pa

edia

tric

CT

for f

acia

l bon

e/si

nuse

s exa

min

atio

ns (f

or e

xpla

natio

ns o

f the

term

s and

abb

revi

atio

ns se

e ta

b. A

.7).

Newborn 11 to 15 years6 to 10 years2 to 5 yearsUp to 1 year

Ger

man

Sur

vey

on P

aedi

atric

CT

2005

/06

Type

of E

xam

inat

ion:

Che

st

Exam

inat

ion

para

met

ers

Dos

e va

lues

per

sca

n se

ries

Dos

e va

lues

per

exa

min

atio

nSt

atis

tics

Age

gro

upSt

atis

tical

qua

ntity

UQ

eltR

Nhc

olP

itch

hrec

Win

dow

Leng

thS

erie

sC

TDIw

16C

TDIv

ol16

DLP

16C

TDIw

32C

TDIv

ol32

DLP

32E

(m.)

E (f

.)D

LP16

DLP

32E

(m.)

E (f

.)P

artic

i-E

xam

sFr

actio

n[k

V]

[mA

s][s

][m

m]

[mm

]C

W[c

m]

(Pha

ses)

[mG

y][m

Gy]

[mG

y*cm

][m

Gy]

[mG

y][m

Gy*

cm]

[mS

v][m

Sv]

[mG

y*cm

][m

Gy*

cm]

[mS

v][m

Sv]

pant

s

Aver

age

100

440.

610

.82.

01.

33.

3-8

874

610

.11.

04.

53.

646

2.5

2.0

251.

62.

146

251.

62.

121

640.

6%

Sta

ndar

d de

viat

ion

16%

64%

32%

90%

66%

28%

36%

-334

%79

%19

%0%

71%

61%

71%

74%

62%

75%

75%

75%

71%

75%

75%

75%

Min

imum

8015

0.3

1.0

0.5

0.8

1.0

-600

275

7.6

1.0

1.2

1.2

160.

70.

79

0.5

0.6

169

0.5

0.6

Max

imum

120

105

1.0

32.0

5.0

2.0

6.0

500

2000

15.0

1.0

15.3

7.8

146

8.7

4.5

855.

36.

914

685

5.3

6.9

1st q

uarti

le80

230.

51.

00.

81.

03.

0-2

5035

08.

81.

02.

12.

025

1.1

1.0

140.

91.

125

140.

91.

1

Med

ian

100

300.

510

.01.

51.

23.

040

400

10.0

1.0

4.0

3.1

352.

01.

618

1.2

1.6

3518

1.2

1.6

3rd

quar

tile

120

640.

816

.03.

01.

54.

050

1250

10.6

1.0

5.6

4.2

473.

22.

126

1.8

2.3

4726

1.8

2.3

Aver

age

108

520.

713

.01.

91.

23.

4-1

2781

212

.31.

06.

05.

477

3.1

2.8

401.

92.

481

421.

92.

531

143

1.4%

Sta

ndar

d de

viat

ion

15%

73%

31%

75%

76%

24%

47%

-227

%73

%29

%19

%69

%78

%81

%63

%73

%77

%84

%84

%79

%76

%82

%82

%

Min

imum

8010

0.3

1.0

0.5

0.7

0.6

-600

275

7.0

1.0

1.2

1.2

200.

70.

712

0.4

0.5

2012

0.4

0.5

Max

imum

140

160

1.0

32.0

5.0

2.0

6.5

500

2000

25.0

2.0

17.6

21.1

360

8.7

10.6

180

8.6

11.1

360

180

8.6

11.1

1st q

uarti

le10

028

0.5

4.0

0.8

1.0

2.9

-400

350

10.0

1.0

3.4

2.6

361.

81.

419

1.0

1.3

3619

1.0

1.3

Med

ian

120

390.

516

.01.

51.

13.

040

400

12.0

1.0

4.7

3.9

682.

72.

338

1.5

1.9

7038

1.5

2.0

3rd

quar

tile

120

600.

816

.02.

51.

55.

050

1450

13.0

1.0

7.1

6.9

933.

83.

849

2.2

2.9

9555

2.4

3.1

Aver

age

111

550.

714

.62.

11.

23.

7-1

0274

716

.41.

07.

06.

111

63.

73.

261

2.2

2.8

120

632.

22.

936

397

3.9%

Sta

ndar

d de

viat

ion

14%

60%

30%

101%

76%

22%

40%

-268

%76

%19

%18

%65

%72

%69

%69

%70

%67

%73

%73

%68

%66

%72

%72

%

Min

imum

8020

0.5

1.0

0.5

0.7

0.6

-600

275

10.0

1.0

1.7

1.7

301.

00.

712

0.5

0.7

3012

0.5

0.7

Max

imum

140

158

1.0

64.0

5.0

1.8

6.5

500

2000

25.0

2.0

24.2

22.5

407

14.1

11.3

203

7.3

9.4

407

203

7.3

9.4

1st q

uarti

le10

030

0.5

4.0

0.9

1.0

3.0

-400

350

15.0

1.0

3.7

3.0

602.

01.

630

1.1

1.4

6030

1.2

1.5

Med

ian

120

490.

516

.01.

51.

14.

040

400

15.8

1.0

5.7

4.6

953.

12.

352

1.4

1.9

9854

1.5

1.9

3rd

quar

tile

120

670.

816

.02.

51.

55.

050

1325

17.2

1.0

8.7

8.4

137

4.5

4.4

732.

83.

613

776

2.8

3.6

Aver

age

114

690.

713

.22.

51.

24.

2-1

0374

020

.41.

010

.58.

519

45.

54.

510

22.

63.

319

610

32.

63.

339

543

5.4%

Sta

ndar

d de

viat

ion

13%

55%

28%

110%

78%

22%

38%

-264

%77

%17

%16

%75

%71

%67

%75

%71

%67

%70

%70

%66

%66

%69

%69

%

Min

imum

8023

0.5

1.0

0.5

0.7

1.0

-600

200

15.0

1.0

2.0

2.0

491.

01.

025

0.6

0.8

4925

0.6

0.8

Max

imum

140

203

1.0

64.0

8.0

1.8

8.0

500

2000

30.0

2.0

31.0

25.5

603

16.5

14.0

332

8.7

11.2

603

332

8.7

11.2

1st q

uarti

le10

539

0.5

3.0

0.9

1.0

3.0

-400

350

18.1

1.0

4.7

3.7

982.

42.

055

1.2

1.5

100

581.

21.

6

Med

ian

120

580.

516

.01.

51.

35.

040

400

20.0

1.0

8.1

6.5

148

4.2

3.2

832.

02.

614

883

2.0

2.6

3rd

quar

tile

120

890.

816

.05.

01.

55.

050

1350

22.7

1.0

13.6

11.9

257

7.2

6.0

128

3.4

4.4

257

128

3.4

4.4

Aver

age

119

900.

713

.72.

61.

24.

4-1

0074

126

.01.

0n.

a.n.

a.n.

a.7.

76.

218

02.

83.

7n.

a.18

62.

93.

840

613

6.1%

Sta

ndar

d de

viat

ion

11%

46%

34%

107%

76%

25%

44%

-271

%76

%19

%15

%n.

a.n.

a.n.

a.57

%47

%48

%47

%47

%n.

a.53

%53

%53

%

Min

imum

8026

0.5

1.0

0.5

0.6

1.0

-600

275

14.0

1.0

n.a.

n.a.

n.a.

1.9

1.6

530.

91.

2n.

a.53

0.9

1.2

Max

imum

140

203

1.5

64.0

8.0

2.0

8.0

500

2000

37.0

2.0

n.a.

n.a.

n.a.

17.2

14.0

416

6.2

8.0

n.a.

475

8.0

10.3

1st q

uarti

le12

056

0.5

3.5

1.3

1.0

3.0

-400

350

24.1

1.0

n.a.

n.a.

n.a.

4.3

4.0

112

1.8

2.3

n.a.

112

1.8

2.3

Med

ian

120

870.

516

.01.

51.

25.

040

400

26.0

1.0

n.a.

n.a.

n.a.

6.4

5.9

166

2.6

3.4

n.a.

166

2.6

3.4

3rd

quar

tile

120

110

0.8

16.0

5.0

1.5

5.5

5013

2530

.01.

0n.

a.n.

a.n.

a.11

.18.

024

43.

84.

9n.

a.25

93.

85.

0

Tab.

A12

Res

ults

from

the

Ger

man

surv

ey o

n pa

edia

tric

CT

for c

hest

exa

min

atio

ns (f

or e

xpla

natio

ns o

f the

term

s and

abb

revi

atio

ns se

e ta

b. A

.7).

XINewborn 11 to 15 years6 to 10 years2 to 5 yearsUp to 1 year

XIIG

erm

an S

urve

y on

Pae

diat

ric C

T 20

05/0

6Ty

pe o

f Exa

min

atio

n: E

ntire

Abd

omen

(inc

l. Pe

lvis

)

Exam

inat

ion

para

met

ers

Dos

e va

lues

per

sca

n se

ries

Dos

e va

lues

per

exa

min

atio

nSt

atis

tics

Age

gro

upSt

atis

tical

qua

ntity

UQ

eltR

Nhc

olP

itch

hrec

Win

dow

Leng

thS

erie

sC

TDIw

16C

TDIv

ol16

DLP

16C

TDIw

32C

TDIv

ol32

DLP

32E

(m.)

E (f

.)D

LP16

DLP

32E

(m.)

E (f

.)P

artic

i-E

xam

sFr

actio

n[k

V]

[mA

s][s

][m

m]

[mm

]C

W[c

m]

(Pha

ses)

[mG

y][m

Gy]

[mG

y*cm

][m

Gy]

[mG

y][m

Gy*

cm]

[mS

v][m

Sv]

[mG

y*cm

][m

Gy*

cm]

[mS

v][m

Sv]

pant

s

Aver

age

108

450.

68.

62.

31.

23.

850

357

14.2

1.1

5.2

4.2

712.

92.

339

2.9

4.2

7743

3.1

4.4

1327

0.3%

Sta

ndar

d de

viat

ion

17%

55%

32%

79%

61%

22%

35%

46%

13%

18%

17%

41%

38%

48%

41%

38%

49%

57%

57%

50%

52%

54%

54%

Min

imum

8025

0.5

1.0

0.8

0.8

2.0

3030

010

.01.

01.

21.

631

0.7

0.9

181.

01.

431

181.

01.

4

Max

imum

120

110

1.0

16.0

5.0

1.5

6.0

122

458

20.0

1.5

8.8

7.8

162

5.1

4.5

946.

89.

916

294

6.8

9.9

1st q

uarti

le90

300.

51.

01.

51.

03.

040

350

13.0

1.0

4.3

3.1

492.

21.

828

1.9

2.7

4928

1.9

2.7

Med

ian

120

340.

510

.01.

51.

13.

050

350

14.0

1.0

4.7

4.4

642.

72.

336

2.5

3.6

6436

2.9

4.2

3rd

quar

tile

120

650.

816

.03.

01.

55.

050

380

15.0

1.0

5.5

4.6

813.

12.

545

3.7

5.4

105

503.

75.

4

Aver

age

114

530.

614

.52.

01.

23.

743

349

19.6

1.2

7.0

6.2

148

3.8

3.3

793.

95.

617

794

4.6

6.7

2261

0.6%

Sta

ndar

d de

viat

ion

12%

53%

41%

99%

71%

21%

37%

16%

10%

18%

30%

53%

75%

95%

49%

68%

87%

104%

104%

93%

86%

101%

101%

Min

imum

8014

0.3

1.0

0.6

0.8

0.6

3030

013

.01.

01.

81.

339

0.9

0.6

191.

11.

639

191.

11.

6

Max

imum

120

126

1.5

64.0

5.0

1.6

5.0

5040

028

.02.

018

.523

.170

59.

011

.234

220

.429

.570

534

220

.429

.5

1st q

uarti

le12

034

0.5

4.0

0.9

1.0

3.0

4032

817

.31.

04.

74.

087

2.5

2.3

471.

92.

810

052

2.4

3.4

Med

ian

120

470.

516

.01.

51.

23.

740

350

20.0

1.0

5.7

4.8

104

3.3

2.5

572.

84.

011

862

3.1

4.5

3rd

quar

tile

120

660.

816

.02.

51.

55.

050

365

20.0

1.4

8.6

6.8

164

4.9

3.9

824.

05.

819

111

14.

36.

2

Aver

age

116

610.

711

.62.

51.

24.

146

339

25.1

1.1

9.0

7.9

219

4.8

4.1

115

4.4

6.4

260

136

5.2

7.5

2714

01.

4%

Sta

ndar

d de

viat

ion

8%64

%37

%11

4%77

%21

%40

%18

%13

%19

%23

%70

%77

%79

%67

%71

%73

%89

%89

%11

2%10

6%11

6%11

6%

Min

imum

901

0.4

1.0

0.6

0.8

1.0

3020

015

.01.

00.

10.

01

0.0

0.0

00.

00.

01

00.

00.

0

Max

imum

130

200

1.5

64.0

8.0

1.5

8.0

6040

035

.02.

024

.827

.277

713

.313

.638

815

.822

.815

5377

730

.744

.4

1st q

uarti

le12

036

0.5

2.0

1.4

1.0

3.0

4031

022

.01.

05.

04.

210

32.

72.

558

1.8

2.6

105

581.

92.

8

Med

ian

120

540.

510

.01.

51.

15.

050

350

25.0

1.0

7.5

6.5

181

4.0

3.4

893.

85.

518

495

4.1

5.9

3rd

quar

tile

120

820.

816

.03.

81.

55.

050

350

28.1

1.0

10.7

8.3

261

6.1

4.7

147

4.6

6.6

274

155

4.8

6.9

Aver

age

115

870.

711

.02.

61.

24.

443

340

29.0

1.2

12.6

10.7

342

6.7

5.6

180

4.7

6.8

407

214

5.6

8.1

3221

32.

1%

Sta

ndar

d de

viat

ion

11%

45%

29%

107%

76%

22%

35%

21%

13%

18%

30%

50%

52%

55%

49%

50%

52%

55%

55%

78%

75%

77%

77%

Min

imum

8015

0.5

1.0

0.6

0.7

1.0

3020

015

.01.

03.

12.

249

1.5

1.1

250.

71.

099

491.

31.

9

Max

imum

130

200

1.0

64.0

8.0

1.5

8.0

6040

040

.02.

029

.722

.275

616

.512

.241

010

.815

.615

1275

620

.629

.7

1st q

uarti

le12

056

0.5

3.5

1.2

1.0

3.0

4032

026

.81.

07.

86.

022

04.

53.

211

73.

04.

322

712

43.

14.

5

Med

ian

120

810.

510

.01.

51.

35.

040

350

30.0

1.0

12.4

9.1

301

6.5

5.0

157

4.3

6.2

309

164

4.3

6.2

3rd

quar

tile

120

111

0.8

16.0

5.0

1.5

5.0

5035

031

.61.

016

.313

.747

78.

87.

422

75.

98.

548

922

77.

510

.8

Aver

age

119

125

0.7

12.9

2.7

1.2

4.5

4634

235

.91.

2n.

a.n.

a.n.

a.10

.18.

332

85.

47.

9n.

a.43

37.

210

.333

254

2.5%

Sta

ndar

d de

viat

ion

5%42

%35

%11

8%81

%22

%43

%20

%12

%18

%33

%n.

a.n.

a.n.

a.43

%38

%44

%44

%44

%n.

a.71

%70

%70

%

Min

imum

9050

0.5

1.0

0.6

0.7

1.0

3022

018

.01.

0n.

a.n.

a.n.

a.3.

12.

910

11.

62.

4n.

a.10

11.

62.

4

Max

imum

130

249

1.5

64.0

8.0

1.5

8.0

6040

050

.02.

4n.

a.n.

a.n.

a.18

.817

.569

411

.716

.9n.

a.13

8822

.532

.5

1st q

uarti

le12

088

0.5

2.0

1.3

1.0

3.0

4032

030

.01.

0n.

a.n.

a.n.

a.6.

76.

520

43.

65.

2n.

a.21

53.

85.

5

Med

ian

120

114

0.5

10.0

1.5

1.4

5.0

5035

036

.61.

0n.

a.n.

a.n.

a.9.

48.

033

65.

57.

9n.

a.33

95.

68.

13r

d qu

artil

e12

014

90.

816

.05.

01.

55.

050

350

40.0

1.5

n.a.

n.a.

n.a.

12.0

10.1

402

6.5

9.4

n.a.

546

8.5

12.3

Tab.

A13

Res

ults

from

the

Ger

man

surv

ey o

n pa

edia

tric

CT

for a

bdom

en (i

ncl.

pelv

is) e

xam

inat

ions

(for

exp

lana

tions

of t

he te

rms a

nd a

bbre

viat

ions

see

tab.

A.7

).

Newborn 11 to 15 years6 to 10 years2 to 5 yearsUp to 1 year

Ger

man

Sur

vey

on P

aedi

atric

CT

2005

/06

Type

of E

xam

inat

ion:

Lum

bar S

pine

Exam

inat

ion

para

met

ers

Dos

e va

lues

per

sca

n se

ries

Dos

e va

lues

per

exa

min

atio

nSt

atis

tics

Age

gro

upSt

atis

tical

qua

ntity

UQ

eltR

Nhc

olP

itch

hrec

Win

dow

Leng

thS

erie

sC

TDIw

16C

TDIv

ol16

DLP

16C

TDIw

32C

TDIv

ol32

DLP

32E

(m.)

E (f

.)D

LP16

DLP

32E

(m.)

E (f

.)P

artic

i-E

xam

sFr

actio

n[k

V]

[mA

s][s

][m

m]

[mm

]C

W[c

m]

(Pha

ses)

[mG

y][m

Gy]

[mG

y*cm

][m

Gy]

[mG

y][m

Gy*

cm]

[mS

v][m

Sv]

[mG

y*cm

][m

Gy*

cm]

[mS

v][m

Sv]

pant

s

Aver

age

118

610.

812

.31.

51.

32.

557

520

008.

31.

09.

07.

590

5.2

4.3

524.

14.

690

524.

14.

64

10.

0%

Sta

ndar

d de

viat

ion

4%9%

15%

61%

71%

29%

23%

59%

35%

19%

0%6%

39%

63%

3%39

%64

%56

%56

%63

%64

%56

%56

%

Min

imum

110

550.

81.

00.

80.

82.

030

015

007.

01.

08.

75.

859

5.1

3.4

352.

52.

859

352.

52.

8

Max

imum

120

681.

016

.03.

01.

53.

010

0030

0010

.31.

09.

811

.817

55.

46.

810

27.

48.

417

510

27.

48.

4

1st q

uarti

le11

859

0.8

12.3

0.8

1.3

2.0

300

1500

7.0

1.0

8.7

5.8

595.

13.

435

2.5

2.8

5935

2.5

2.8

Med

ian

120

600.

816

.01.

11.

52.

550

017

508.

01.

08.

86.

262

5.1

3.5

353.

23.

662

353.

23.

63r

d qu

artil

e12

062

0.8

16.0

1.9

1.5

3.0

775

2250

9.3

1.0

9.1

7.8

925.

24.

452

4.8

5.4

9252

4.8

5.4

Aver

age

116

118

0.9

11.7

1.4

1.1

2.1

434

1563

9.7

1.0

21.9

23.7

297

11.8

12.7

160

10.7

12.0

297

160

10.7

12.0

910

0.1%

Sta

ndar

d de

viat

ion

9%56

%15

%56

%49

%34

%39

%69

%55

%14

%0%

77%

86%

82%

74%

83%

80%

87%

87%

82%

80%

87%

87%

Min

imum

9055

0.8

1.0

0.8

0.8

1.0

5027

06.

91.

05.

75.

868

2.9

3.3

352.

12.

468

352.

12.

4

Max

imum

120

225

1.0

16.0

3.0

1.5

3.0

1000

3000

12.0

1.0

47.8

52.3

570

26.3

26.2

332

22.7

25.5

570

332

22.7

25.5

1st q

uarti

le12

060

0.8

4.0

1.0

0.8

1.3

300

1500

9.0

1.0

8.7

6.3

715.

13.

441

2.6

2.9

7141

2.6

2.9

Med

ian

120

900.

816

.01.

30.

92.

050

015

0010

.01.

09.

811

.819

55.

46.

811

35.

86.

519

511

35.

86.

53r

d qu

artil

e12

015

01.

016

.01.

51.

53.

050

020

0010

.01.

039

.239

.256

419

.622

.828

220

.723

.256

428

220

.723

.2

Aver

age

118

133

1.1

9.9

1.6

1.2

2.0

437

1740

11.1

1.0

24.8

21.9

279

13.6

11.7

151

7.5

8.4

279

151

7.5

8.4

2385

0.8%

Sta

ndar

d de

viat

ion

9%70

%34

%97

%53

%32

%44

%59

%51

%31

%0%

88%

91%

88%

94%

90%

87%

90%

90%

88%

87%

90%

90%

Min

imum

9026

0.5

1.0

0.6

0.5

0.6

4027

05.

01.

03.

44.

652

2.0

2.7

271.

51.

652

271.

51.

6

Max

imum

140

400

2.0

32.0

3.0

2.0

3.2

1000

4000

20.0

1.0

70.5

69.8

821

44.8

34.9

411

21.7

24.4

821

411

21.7

24.4

1st q

uarti

le12

074

0.8

1.5

1.0

0.8

1.3

325

1500

10.0

1.0

9.3

8.7

105

5.3

5.1

542.

63.

010

554

2.6

3.0

Med

ian

120

100

1.0

4.0

1.3

1.1

2.0

475

1600

11.0

1.0

14.9

11.8

160

7.6

6.1

764.

04.

516

076

4.0

4.5

3rd

quar

tile

120

200

1.3

16.0

2.0

1.5

3.0

500

2000

12.5

1.0

38.6

33.4

483

21.6

20.3

278

12.6

14.2

483

278

12.6

14.2

Aver

age

119

167

1.0

8.5

1.5

1.1

2.2

482

1804

11.7

1.0

31.5

28.3

383

17.2

15.2

208

7.1

8.0

383

208

7.1

8.0

2399

1.0%

Sta

ndar

d de

viat

ion

10%

53%

36%

98%

59%

35%

49%

66%

54%

31%

0%65

%65

%72

%70

%64

%73

%70

%70

%72

%73

%70

%70

%

Min

imum

9053

0.5

1.0

0.5

0.7

0.5

4027

06.

01.

07.

36.

584

3.8

3.6

471.

61.

884

471.

61.

8

Max

imum

140

400

2.0

32.0

3.0

2.0

5.0

1500

4000

20.0

1.0

71.5

69.8

969

44.8

34.9

563

17.1

19.2

969

563

17.1

19.2

1st q

uarti

le12

097

0.8

1.5

0.9

0.8

1.3

400

1500

10.0

1.0

12.9

11.7

147

6.9

6.4

802.

83.

214

780

2.8

3.2

Med

ian

120

167

1.0

4.0

1.3

1.0

2.0

500

2000

12.0

1.0

31.3

23.8

259

17.1

13.5

143

5.3

6.0

259

143

5.3

6.0

3rd

quar

tile

120

200

1.0

16.0

2.3

1.5

3.0

550

2000

12.0

1.0

47.3

37.3

524

26.2

22.6

306

10.6

11.9

524

306

10.6

11.9

Aver

age

121

149

0.9

11.8

1.4

1.0

1.8

386

1638

15.9

1.0

n.a.

n.a.

n.a.

15.4

16.7

294

6.4

7.3

n.a.

294

6.4

7.3

2614

91.

5%

Sta

ndar

d de

viat

ion

5%66

%27

%11

3%61

%40

%47

%63

%54

%51

%0%

n.a.

n.a.

n.a.

90%

114%

127%

125%

125%

n.a.

127%

125%

125%

Min

imum

110

170.

51.

00.

50.

50.

540

270

6.0

1.0

n.a.

n.a.

n.a.

1.8

3.2

240.

50.

6n.

a.24

0.5

0.6

Max

imum

140

500

1.5

64.0

3.0

2.0

3.2

1000

4000

49.0

1.0

n.a.

n.a.

n.a.

69.1

100.

519

7942

.748

.1n.

a.19

7942

.748

.1

1st q

uarti

le12

090

0.8

2.5

0.8

0.7

1.1

213

1500

12.3

1.0

n.a.

n.a.

n.a.

7.3

7.4

120

2.6

3.0

n.a.

120

2.6

3.0

Med

ian

120

140

0.9

11.0

1.0

0.8

2.0

425

2000

16.0

1.0

n.a.

n.a.

n.a.

11.1

10.8

207

4.3

4.9

n.a.

207

4.3

4.9

3rd

quar

tile

120

200

1.0

16.0

1.9

1.4

2.0

500

2000

16.8

1.0

n.a.

n.a.

n.a.

20.4

17.9

294

6.8

7.7

n.a.

294

6.8

7.7

Tab.

A14

Res

ults

from

the

Ger

man

surv

ey o

n pa

edia

tric

CT

for l

umba

r spi

ne e

xam

inat

ions

(for

exp

lana

tions

of t

he te

rms a

nd a

bbre

viat

ions

see

tab.

A.7

).

XIIINewborn 11 to 15 years6 to 10 years2 to 5 yearsUp to 1 year

XIV

Type of Age group CTDIvol16 DLP16 CTDIvol32 DLP32examination (mGy) (mGy x cm) (mGy) (mGy x cm)

Newborn 27 290 n.a. n.a.Up to 1 year 33 390 n.a. n.a.1 to 5 years 40 520 n.a. n.a.6 to 10 years 50 710 n.a. n.a.11 to 15 years 60 920 n.a. n.a.Above 15 years 60 1100 n.a. n.a.

Newborn 9 70 n.a. n.a.Up to 1 year 11 95 n.a. n.a.1 to 5 years 13 125 n.a. n.a.6 to 10 years 17 180 n.a. n.a.11 to 15 years 20 230 n.a. n.a.Above 15 years 20 230 n.a. n.a.

Newborn 2 25 1 12Up to 1 year 3.5 55 1.7 281 to 5 years 5.5 110 2.7 556 to 10 years 8.5 210 4.3 10511 to 15 years n.a. n.a. 6.8 205Above 15 years n.a. n.a. 10 345

Newborn 3 55 1.5 27Up to 1 year 5 145 2.5 701 to 5 years 8 255 4 1256 to 10 years 13 475 6.5 24011 to 15 years n.a. n.a. 10 500Above 15 years n.a. n.a. 15 980

Newborn 7.5 85 3.7 42Up to 1 year 13 165 6.5 851 to 5 years 20 270 10 1356 to 10 years 32 430 16 21511 to 15 years n.a. n.a. 26 380Above 15 years n.a. n.a. 37 530

Tab. A15 Proposal for diagnostic reference values for paediatric CT examinations; DLP values apply to complete examinations.

Lum

bar s

pine

Bra

inFa

cial

bon

e/

sinu

ses

Che

stEn

tire

abdo

men

(in

cl. P

elvi

s)

XV

Tab. A16 Comparison of the reference values proposed by us (survey D2005/06) with those given in the publication byShrimpton et al. (Shrimpton2000). ‘Ratio’ shows the D2005/06 values relative to the Shrimpton2000 data.

CTDIw16

CTDIvol16

* CTDIvol16

Ratio DLP16

DLP16

Ratio

Type ofexamination

Age groupShrimpton

2000Shrimpton

2000Survey

D2005/06Shrimpton

2000Survey

D2005/06

(mGy) (mGy) (mGy) (mGy x cm) (mGy x cm)

Brain Up to 1y 40 40 33 0.83 300 390 1.30

(BRN) 2 to 5y 60 60 40 0.67 600 520 0.87

6 to 10y 70 70 50 0.71 750 710 0.95

Chest Up to 1y 20 13 3,5 0.27 200 55 0.28

(CHE) 2 to 5y 30 20 5,5 0.28 400 110 0.28

6 to 10y 30 20 8,5 0,43 600 210 0.35

Entire abdomen ** Up to 1y 20 13 5 0.38 500 145 0.29

(ABDPE) 2 to 5y 25 17 8 0.47 610 255 0.42

6 to 10y 30 20 13 0.65 1300 475 0.37

* Assumption: Pitch 1 with BRN and 1.5 with CHE and ABDPE ** DLP values for entire abdomen Shrimpton2000 = sum of abdomen and pelvis

XVI

Inst

itutio

n: a

ddre

ssEx

ampl

e: R

emar

ksM

HH

Dia

gn. R

adio

logi

e30

625

Han

nove

rC

onta

ct p

erso

n fo

r que

ries?

Nam

e:D

r. G

. Sta

mm

Tel.

or e

-mai

l:(1

)st

amm

.geo

rg@

mh-

hann

over

.de

CT

scan

ner:

man

ufac

ture

rG

E

CT

scan

ner:

type

Ligh

tspe

ed V

CT

Set

-up

Mon

th/y

ear

0820

05

CT

exam

inat

ions

per

yea

r (2

)25

00(to

tal n

umbe

r)P

aedi

atric

CT

exam

inat

ions

per

yea

r(3

)30

0(to

tal n

umbe

r for

pat

ient

s up

to 1

2 ye

ars)

Exam

inat

ion

rang

eN

umbe

r of e

xam

inat

ions

per

yea

r in

age

grou

pPr

emat

ure

New

born

10 m

onth

s5

year

s10

yea

rs

Hea

d0

25

6013

0

Che

st0

03

1520

Upp

er a

bdom

en0

00

1020

Ent

ire a

bdom

en (i

ncl.

pelv

is)

00

05

10

Pel

vis

00

05

10

Oth

ers

(4)

(ple

ase

spec

ify)

Pre

mat

ure

=N

ewbo

rn =

10 m

onth

s =

5 ye

ars

=10

yea

rs =

appr

. 100

0 g

appr

. 300

0 g

>3 m

onth

s >

2 ye

ars

> 7

year

s to

3 m

onth

sto

2 y

ears

to 7

yea

rsto

12

year

s

Plea

se re

turn

this

que

stio

nnai

re a

t alle

vent

s (e

ven

if yo

u do

n't o

pera

te a

CT

scan

ner o

r if

you

don'

t per

form

pae

diat

ric C

T ex

amin

atio

ns).

If yo

u sh

ould

dis

pose

pae

diat

ric C

T ex

amin

atio

ns a

t ano

ther

inst

itutio

n: p

leas

e te

ll us

the

corr

espo

ndin

g na

me

and

addr

ess.

Fig.

A1

Que

stio

nnai

re u

sed

in p

hase

I of

the

surv

ey fo

r the

regi

stra

tion

of e

xam

inat

ion

frequ

enci

es (t

rans

late

d).!

(4) P

leas

e sp

ecify

all

othe

r pa

edia

tric

CT

exam

inat

ions

freq

uent

ly p

erfo

rmed

in y

our i

nstit

utio

n (c

ompr

isin

g m

ore

than

5%

of a

ll pa

edia

tric

CT

exam

inat

ions

)

(3) T

otal

num

ber o

f pae

diat

ric C

T ex

amin

atio

ns p

er

year

for c

hild

ren

up t

o 12

yea

rs(a

ppro

xim

ate

valu

e or

ave

rage

of p

revi

ous

year

))

(2) T

otal

num

ber o

f CT

exam

inat

ions

per

yea

r(a

ppro

xim

ate

valu

e or

ave

rage

of p

revi

ous

year

))

(1) P

leas

e sp

ecify

a c

onta

ct p

erso

n fo

r que

ries

(

man

dato

ry)!

Plea

se re

turn

to:

Pro

f. D

r. M

. Gal

ansk

iD

iagn

ostis

che

Rad

iolo

gie

Med

izin

isch

e H

ochs

chul

e H

anno

ver

Car

l-Neu

berg

-Str.

130

625

Han

nove

rFa

x: 0

511/

532-

3885

Inst

itutio

nC

T sc

anne

rM

anuf

actu

rer

Sca

nner

type

Set-u

pEx

ams

per y

ear

Mon

th:

(2)

Year

:C

onta

ct p

erso

n fo

r qu

erie

s?Te

l. or

e-m

ail (

1)

Age

gro

upTy

pe o

f exa

min

atio

nA

ppr.

leng

thM

ode

UI o

r QA

DC

tR

Nhc

olTV

Pitc

hhr

ecR

IR

econ

.-W

indo

wN

o. o

fD

ose

disp

laye

d (1

4)A

ppr.

[cm

][S

eq/S

pi]

[kV

][m

A/m

As]

[Not

atio

n][s

][m

m]

[mm

][m

m]

[mm

]Fi

lter

C/W

serie

sC

TDIv

olD

LPfra

ctio

n(3

)(4

)(5

)(5

)(6

)(7

)(8

)(9

)(9

)(1

0)(1

0)(1

1)(1

2)(1

3)[m

Gy]

[mG

y*cm

][%

] (2

)

Bra

in

Che

st

Ent

ire a

bdom

en

Spi

ne

Faci

al b

one

/ sin

uses

Oth

ers:

(3)

Age

gro

upTy

pe o

f exa

min

atio

nA

ppr.

leng

thM

ode

UI o

r QA

DC

tR

Nhc

olTV

Pitc

hhr

ecR

IR

econ

.-W

indo

wN

o. o

fD

ose

disp

laye

d (1

4)A

ppr.

[cm

][S

eq/S

pi]

[kV

][m

A/m

As]

[Not

atio

n][s

][m

m]

[mm

][m

m]

[mm

]Fi

lter

C/W

serie

sC

TDIv

olD

LPfra

ctio

n(3

)(4

)0

(5)

(5)

(6)

(7)

(8)

(9)

(9)

(10)

(10)

(11)

(12)

(13)

[mG

y][m

Gy*

cm]

[%]

(2)

Bra

in

Che

st

Ent

ire a

bdom

en

Spi

ne

NN

H

Oth

ers:

(3)

Age

gro

upTy

pe o

f exa

min

atio

nA

ppr.

leng

thM

ode

UI o

r QA

DC

tR

Nhc

olTV

Pitc

hhr

ecR

IR

econ

.-W

indo

wN

o. o

fD

ose

disp

laye

d (1

4)A

ppr.

[cm

][S

eq/S

pi]

[kV

][m

A/m

As]

[Not

atio

n][s

][m

m]

[mm

][m

m]

[mm

]Fi

lter

C/W

serie

sC

TDIv

olD

LPfra

ctio

n(3

)(4

)(5

)(5

)(6

)(7

)(8

)(9

)(9

)(1

0)(1

0)(1

1)(1

2)(1

3)[m

Gy]

[mG

y*cm

][%

] (2

)

Bra

in

Che

st

Ent

ire a

bdom

en

Spi

ne

NN

H

Oth

ers:

(3)

Fig.

A2a

Pag

e 1

of th

e qu

estio

nnai

re fo

r the

regi

stra

tion

of sc

an p

roto

cols

and

exa

min

atio

n fre

quen

cies

in p

hase

II o

f the

surv

ey (t

rans

late

d).

XVII

Page 1

Newborn Up to 1 year 2 to 5 years

XVIIIIn

stitu

tion

Age

gro

upTy

pe o

f exa

min

atio

nA

ppr.

leng

thM

ode

UI o

r QA

DC

tR

Nhc

olTV

Pitc

hhr

ecR

IR

econ

.-W

indo

wN

o. o

fD

ose

disp

laye

d (1

4)A

ppr.

[cm

][S

eq/S

pi]

[kV

][m

A/m

As]

[Not

atio

n][s

][m

m]

[mm

][m

m]

[mm

]Fi

lter

C/W

serie

sC

TDIv

olD

LPfra

ctio

n(3

)(4

)(5

)(5

)(6

)(7

)(8

)(9

)(9

)(1

0)(1

0)(1

1)(1

2)(1

3)[m

Gy]

[mG

y*cm

][%

] (2

)

Bra

in

Che

st

Ent

ire a

bdom

en

Spi

ne

Faci

al b

one

/ sin

uses

Oth

ers:

(3)

Age

gro

upTy

pe o

f exa

min

atio

nA

ppr.

leng

thM

ode

UI o

r QA

DC

tR

Nhc

olTV

Pitc

hhr

ecR

IR

econ

.-W

indo

wN

o. o

fD

ose

disp

laye

d (1

4)A

ppr.

[cm

][S

eq/S

pi]

[kV

][m

A/m

As]

[Not

atio

n][s

][m

m]

[mm

][m

m]

[mm

]Fi

lter

C/W

serie

sC

TDIv

olD

LPfra

ctio

n(3

)(4

)0

(5)

(5)

(6)

(7)

(8)

(9)

(9)

(10)

(10)

(11)

(12)

(13)

[mG

y][m

Gy*

cm]

[%]

(2)

Bra

in

Che

st

Ent

ire a

bdom

en

Spi

ne

NN

H

Oth

ers:

(3)

Fig.

A2b

Pag

e 2

of th

e qu

estio

nnai

re fo

r the

regi

stra

tion

of sc

an p

roto

cols

and

exa

min

atio

n fre

quen

cies

in p

hase

II o

f the

surv

ey (t

rans

late

d).

11 to 15 years

Page

2

Page 2

6 to 10 years

FILENAME 1

___________________________________________________________________________ XIX

Instructions for Use of the Questionnaire ’Paediatric CT’

General remarks:

- Please fill in separate questionnaires for each scanner if you should operatemore than one scanner.

- Please specify data to the category ’Others’ only for those types of examina-tions that comprise at least 10 % of all paediatric CT examinations performed at yourinstitution.

Typical anatomical landmarks of scan ranges:

Region Upper limit Lower limitBrain Vertex Scull baseChest C7/T1 SinusEntire abdomen Diaphragm Pubic symphysis

In order to ensure a high quality of the submitted data and to minimize the number of querieswe kindly ask you to carefully read the following explanations and to observe them when fill-ing in the questionnaires.

1) Please specify a contact person to whom queries can be addressed.

2) Please make reliable specifications of the number of paediatric CT examinations per year(example: 350) and of the percentage fraction of the corresponding types of examinationand age groups (referring to the total number of all paediatric CT examinations).

3) In field ’Appr. length’ the approximate typical length of the scan range (not that of thescan projection radiograph (topogram etc.)) in [cm] must be stated. Below ’Others’ onlythose examinations that comprise at least 10% of all paediatric CT examinations should betaken into account. Please specify separately for each type of examination and age group.Example: 17 (cm).

4) Please specify in field ‘Mode’ whether the examination is carried out in sequential (’Seq.’)or in spiral scanning mode (’Spi.’). Example: Spi.

5) In field ’I or Q [mA/mAs]’ please take carea) that either tube current (mA) or tube current-time product values are stated as dis-

played on your scanner. Example: 125 (mAs).b) The conversion from mA to mAs and to electrical or effective mAs will be mode by us.c) If your scanner is equipped with an automatic dose control device (e.g. ‘DoseRight‘ etc.),

the dose-saving feature applied by you should be specified in the field ’ADC [notation]’.Example: DoseRight DOM.

d) Warning: When using ADC devices, typical mA or mAs values must be stated thatresult on average for the pertaining age group and type of examination!

Fig. A3a Instructions for use of the questionnaire in phase II of the survey (p.1, translated)

FILENAME 1

XX ____________________________________________________________________________

6) Field ’tR’ requires the applied rotation time, not the total can time. Example: 0,75s.

7) Please specify in field ’N’ the number of slices that are simultaneously acquired perrotation. Example: 16.

8) For the slice collimation ’hcol’ the thickness of the smallest single collimation used forscanning must be entered (e.g. 2.5 mm for a scan made with a 4 x 2.5 mm beam width). Ex-ample: 2,5 (mm).

9) Please enter to fields ’TF’ or ’Pitch’ – depending on which parameter is displayed at thescanner’s console – either the table feed (or increment) in [mm] per rotation (not the tablespeed (in [mm/sec])) or the pitch factor. Example: 7 (mm) or 1.5.

10) Please specify in field ’hrec’ the thickness of the slices that are reconstructed from theacquired data (i.e. whether data acquired with a beam width setting of 4 x 1.25 mm are usedas 1.25 mm thick slices or are reconstructed as 2.5 mm thick slices). Reconstruction in-crement (field ’RI’) denotes the spacing between the reconstructed slices (which can besmaller than the slice thickness). Example: 5 (mm) and 2.5 (mm).

11) Field ’Recon.-Filter’ requires the notation of the reconstruction filter (= reconstructionalgorithm, filter kernel etc.) that is used for image reconstruction from the raw data. Exam-ple: AH40.

12) Please specify in field ’Window’ the settings for window centre (C) and window width(W) that are routinely used for diagnosis. Example: 40/100.

13) The number of ’Series’ refers to the number of times a scan region (or a part of it) isscanned more than once (e.g. liver without and with administration of contrast = 2 series). Anexamination that is performed in several consecutive steps (e.g. entire trunk = chest + upperabdomen + pelvis) is counted as 1 series only. A series that covers only a portion of the scanregion contributes a fraction only (e.g. entire abdomen with 1st series = entire abdomen, 2ndseries = upper abdomen results in a total of 1.5 series).

14) All modern scanners should be equipped with a dose display (indicating at least volumeCTDI (CTDIvol = weighted CTDI / pitch), occasionally also dose-length product (DLP)). Pleasespecify in field ’Dose display’ the values indicated at your scanner in terms of the units re-quired in the questionnaire for a complete scan series. Example: 10.5 (mGy) und 211(mGy*cm).

Please don’t hesitate to contact either Dr. Stamm (phone: 0511/532-2690) or Dr. Nagel(phone: 040/ 5078-2742) if there should be any questions left.

Fig. A3b Instructions for use of the questionnaire in phase II of the survey (p. 2, translated)

Ger

man

Sur

vey

on P

aedi

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CT

2005

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6

Inst

itutio

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Man

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Inst

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Dis

play

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Exa

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p.a.

tot.:

9000

City

:B

BB

Type

:D

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Mon

th:

12A

DC

:O

CC

Exa

ms

p.a.

pae

d.:

149

Age

Exam

inat

ion

Para

met

ers

Dos

e Va

lues

per

Sca

n Se

ries

Dos

e Va

lues

per

Exa

min

atio

nR

elat

ive

Valu

esgr

oup

Type

of E

xam

inat

ion

UQ

eff

Nhc

olP

itch

hrec

LS

erie

sC

TDIv

ol16

DLP

16C

TDIv

ol32

DLP

32E

(m.)

E (f

.)D

LP16

DLP

32E

(m.)

E (f

.)C

TDIv

olD

LPE

[kV

][m

As]

[mm

][m

m]

[cm

](P

hase

s)[m

Gy]

[mG

y*cm

][m

Gy]

[mG

y*cm

][m

Sv]

[mS

v][m

Gy*

cm]

[mG

y*cm

][m

Sv]

[mS

v][m

Gy]

[mG

y*cm

][m

Sv]

Bra

inB

RN

012

014

04

4.5

1.0

4.5

9.0

1.0

18.9

178

n.a.

n.a.

1.7

1.8

178

n.a.

1.7

1.8

70%

62%

63%

Fac.

Bon

e/S

in.

FBS

012

030

160.

80.

81.

03.

01.

04.

321

n.a.

n.a.

0.2

0.2

21n.

a.0.

20.

248

%30

%31

%C

hest

CH

E0

120

1716

1.5

1.2

1.0

10.0

1.0

2.2

311.

116

1.2

1.5

3116

1.2

1.5

111%

126%

142%

ent.

Abd

omen

AB

D0

120

3516

1.5

1.0

2.0

14.0

1.0

4.6

822.

342

3.8

5.4

8242

3.8

5.4

152%

148%

188%

Lum

bar S

pine

LSP

0

Bra

inB

RN

112

014

04

4.5

1.0

4.5

9.0

1.0

18.9

178

n.a.

n.a.

1.2

1.4

178

n.a.

1.2

1.4

57%

46%

47%

Fac.

Bon

e/S

in.

FBS

112

030

160.

80.

81.

03.

51.

04.

323

n.a.

n.a.

0.2

0.2

23n.

a.0.

20.

239

%24

%24

%C

hest

CH

E1

120

1716

1.5

1.2

1.0

12.0

1.0

2.2

361.

119

0.9

1.2

3619

0.9

1.2

63%

65%

73%

ent.

Abd

omen

AB

D1

120

3516

1.5

1.0

2.0

20.0

1.0

4.6

109

2.3

563.

14.

510

956

3.1

4.5

91%

75%

112%

Lum

bar S

pine

LSP

1

Bra

inB

RN

512

021

04

4.5

1.0

4.5

10.8

1.0

28.3

319

n.a.

n.a.

1.3

1.4

319

n.a.

1.3

1.4

71%

61%

62%

Fac.

Bon

e/S

in.

FBS

512

040

160.

80.

81.

06.

01.

05.

845

n.a.

n.a.

0.2

0.2

45n.

a.0.

20.

244

%36

%35

%C

hest

CH

E5

120

2316

1.5

0.9

1.0

14.0

1.0

3.0

531.

527

1.0

1.3

5327

1.0

1.3

54%

48%

49%

ent.

Abd

omen

AB

D5

120

5016

1.5

1.0

2.0

21.0

1.0

6.5

162

3.4

843.

34.

816

284

3.3

4.8

81%

64%

85%

Lum

bar S

pine

LSP

5

Bra

inB

RN

1012

028

04

4.5

1.0

4.5

12.6

1.0

37.7

493

n.a.

n.a.

1.6

1.8

493

n.a.

1.6

1.8

75%

69%

70%

Fac.

Bon

e/S

in.

FBS

1012

050

160.

80.

81.

07.

61.

07.

268

n.a.

n.a.

0.2

0.2

68n.

a.0.

20.

242

%38

%39

%C

hest

CH

E10

120

3816

1.5

0.9

1.0

19.0

1.0

4.9

113

2.5

581.

51.

911

358

1.5

1.9

58%

54%

55%

ent.

Abd

omen

AB

D10

120

8016

1.5

1.0

2.0

27.0

1.0

10.4

322

5.4

166

4.6

6.6

322

166

4.6

6.6

80%

68%

58%

Lum

bar S

pine

LSP

10

Bra

inB

RN

1512

033

04

4.5

1.0

4.5

14.4

1.0

44.5

661

n.a.

n.a.

1.8

2.0

661

n.a.

1.8

2.0

74%

72%

69%

Fac.

Bon

e/S

in.

FBS

1512

060

160.

80.

81.

09.

01.

08.

794

n.a.

n.a.

0.3

0.3

94n.

a.0.

30.

343

%41

%41

%C

hest

CH

E15

120

5516

1.5

0.9

1.0

21.0

1.0

n.a.

n.a.

3.7

911.

41.

8n.

a.91

1.4

1.8

54%

45%

46%

ent.

Abd

omen

AB

D15

120

120

161.

51.

02.

030

.01.

0n.

a.n.

a.8.

027

34.

46.

4n.

a.27

34.

46.

480

%55

%57

%Lu

mba

r Spi

neLS

P15

Rem

arks

: R

elat

ive

valu

es (i

n %

) ref

er to

the

refe

renc

e va

lues

for t

he c

orre

spon

ding

type

of e

xam

inat

ion,

age

gro

up a

nd d

ose

quan

tity

as p

ropo

sed

by u

s;th

e la

bels

"16"

und

"32"

add

ed to

CTD

Ivol

and

DLP

spe

cify

the

diam

eter

(in

cm) o

f the

und

erly

ing

dosi

met

ry p

hant

om.

Fig.

A4

Exa

mpl

e of

feed

back

giv

en to

a p

artic

ipan

t in

the

surv

ey, c

ompr

isin

g ex

amin

atio

n pa

ram

eter

s, an

d ab

solu

te a

nd re

lativ

e do

se v

alue

s (fo

r ter

ms a

nd a

bbre

viat

ions

see

tab.

A7)

.

XXI

11 to 15 yearsNewborn Up to 1 year 2 to 5 years 6 to 10 years

XXII

0%20%

40%

60%

80%

100%

120%

140%

160%

BRN0

FBS0

CHE0

ABD0

LSP0

BRN1

FBS1

CHE1

ABD1

LSP1

BRN5

FBS5

CHE5

ABD5

LSP5

BRN10

FBS10

CHE10

ABD10

LSP10

BRN15

FBS15

CHE15

ABD15

LSP15

Typ

e o

f ex

amin

atio

n /

age

gro

up

Relative dose

CT

DIv

ol

DLP

Fig

. A5

Rel

ativ

e do

se v

alue

s in

term

s of

vol

ume

CT

DI

(CT

DI vo

l) an

d do

se-l

engt

h pr

oduc

t exa

min

atio

n (D

LP

) fo

r th

e ex

ampl

e pr

esen

ted

in fi

g. A

4. F

or e

ach

type

of

exam

inat

ion

and

age

grou

p, th

e100

% le

vel r

efer

s to

the

corr

espo

ndin

g re

fere

nce

valu

es fo

r pa

edia

tric

CT

exam

inat

ions

pro

pose

d by

us.

XXIII

01234567

Typ

e o

f ex

amin

atio

n /

age

gro

up

act.

ref. (d)

BRN0

BRN1

BRN5

BRN10

BRN15

SIN0

SIN1

SIN5

SIN10

SIN15

CHE0

CHE1

CHE5

CHE10

CHE15

ABD0

ABD1

ABD5

ABD10

ABD15

LSP0

LSP1

LSP5

LSP10

LSP15

Reconstructed slice thickness [mm]0

0.51

1.52

Typ

e o

f ex

amin

atio

n /

age

gro

up

act.

ref. (c)

BRN0

BRN1

BRN5

BRN10

BRN15

SIN0

SIN1

SIN5

SIN10

SIN15

CHE0

CHE1

CHE5

CHE10

CHE15

ABD0

ABD1

ABD5

ABD10

ABD15

LSP0

LSP1

LSP5

LSP10

LSP15

Number of scan series

0

0.2

0.4

0.6

0.81

1.2

1.4

1.6

Typ

e o

f ex

amin

atio

n /

age

gro

up

act.

ref.

(b)

BRN0

BRN1

BRN5

BRN10

BRN15

SIN0

SIN1

SIN5

SIN10

SIN15

CHE0

CHE1

CHE5

CHE10

CHE15

ABD0

ABD1

ABD5

ABD10

ABD15

LSP0

LSP1

LSP5

LSP10

LSP15

Pitch factor

0510152025303540

Typ

e o

f ex

amin

atio

n /

age

gro

up

act.

ref.

Scan length [cm]

BRN0

BRN1

BRN5

BRN10

BRN15

SIN0

SIN1

SIN5

SIN10

SIN15

CHE0

CHE1

CHE5

CHE10

CHE15

ABD0

ABD1

ABD5

ABD10

ABD15

LSP0

LSP1

LSP5

LSP10

LSP15

(a)

Fig

. A6

Com

pari

son

of th

e pa

ram

eter

s ap

plie

d by

the

part

icul

ar p

arti

cipa

nt fr

om fi

g. A

4 an

d th

e co

rres

pond

ing

aver

age

valu

es fr

om th

e su

rvey

for

scan

leng

th (

a), p

itch

fact

or(b

), n

umbe

r of

sca

n se

ries

(c)

and

rec

onst

ruct

ed s

lice

thic

knes

s (d

). I

f nec

essa

ry, t

hese

dat

a ca

n he

lp to

iden

tify

the

orig

in o

f abo

ve-a

vera

ge d

ose

valu

es.

paediatric ct exposure practice in the federal republic of...

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