acr phantom phantom images. overview session 2 ct20 patient dose15 equipment purchase/ acceptance...

ACR Phantom Phantom Images

Overview Session 2

CT 20

Patient dose 15

Equipment Purchase/ Acceptance Testing 15

Questions 10

Personnel qualifications 20

Education and training 10

Questions 20

Patient Dose (A 3.0)

It is recommended that Diagnostic Reference Levels (DRLs) be used as guidance in the optimization of patient dose

DRLs are values related to patient dose using Dose Indicators which can be easily measured

dose-linear product (DLP) for CT or dose-are product (DAP) for radiography/radioscopy.

Conversion factors are available to convert from Dose Indicator values to Effective Dose (E)

Diagnostic Reference Levels

It is very difficult to ‘optimize’ patient dose However, it is relatively easy to decide those doses

which are clearly too high and unacceptable DRLs are derived from large surveys of

examinations in a region or country; usually the DRL is set at the 75% level of the distribution

BC CT Dose Survey 2004

Hospitals around BC were asked to provide data on routine head, chest, abdomen, pelvis CT

Data collected from 18 hospitals

BC Patient Dose - Head

0

500

1000

1500

2000

2500

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Hospital #

DL

P (

mG

y.c

m) DRL

BC Patient Dose - Chest

0

200

400

600

800

1000

1200

1400

1600

1800

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Hospital #

DL

P (

mG

y.c

m)

BC Patient Dose – Abdomen

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Hospital #

DL

P (

mG

y.c

m)

Reference Doses BC

* 75 percentile

Exam ReferenceDLP

Reference Dose mSv

mGy.cm

Head 1300 3

Chest 600 10.2

Abdomen 900 13.8

Pelvis 650 12.3

Abdomen-Pelvis 1100 18.7

Reference Doses

For other imaging systems the dose-area product (DAP) is the most convenient to use to evaluate patient dose

Should be a requirement on all new radiographic and radioscopic systems

Dose Area Product Meter

Dose Area Product detector Dose Area Product detector after collimator intercepts after collimator intercepts all radiation used both for all radiation used both for radiography and radioscopyradiography and radioscopy

X-ray X-ray TubeTube

CollimatorCollimator

X-ray X-ray fieldfield

5.2 Gy.cm2

DAP meterPACS

Patient Dose MonitoringIt is now technically possible to estimate patient dose

from most x-ray systems

Equipment Dose Indicator Status

CT Dose-length product DLP

Available on all CTs

Radiographic/

Fluoroscopic/

Angiographic

Dose-area product DAP

Available on all new units- can be retrofitted

CR Exposure Index (EI) of detector

All CR

Both DLP and DAP values are directly related to patient dose

CT Patient Dose Monitoring

Patient ID: Exam No:

Exam Description: CABD2PCT Date:

Dose Report

Series Type Scan Range

(mm)

CTDIvol

(mGy)

DLP

(mGy.cm)

Phantom

cm

1 Scout - - - -

2 Helical S111-I319 12.77 577.08 Body 32

1/1


Radiographic Exam View DRL

Generalized Conversion Coefficients DAP to Effective Dose

Gy.cm2 mSv per Gy.cm2

Skull PA 2 0.03

Lat 1.3 0.03

Chest PA 0.15 0.12

Lat 0.6 0.1

T Spine Lat 7 0.1

AP 4 0.2

L Spine Lat 11 0.1

AP 5 0.2

Abdomen PA 4 0.1

AP 4 0.2

Pelvis AP 4 0.3

Diagnostic Reference LevelsComplete Exams DRL DAP to E

FluoroscopyTime

Gy.cm2 mSv per Gy.cm2 minutes

Barium Swallow 9 0.26 2.3

Barium Meal 14 0.26 2.7

Ba follow thru 12 0.26 2.2

Barium enema 24 0.26 2.8

IVP 14 0.2

MCU 12 0.2 1.9

Nephrostography 12 0.2 4.8

Retro Pyelogram 13 0.2 3

T tube cholangiogram 8 0.26 1.9

Sinography 9 2.1

Small bowel enema 40 9.2

Venography leg 7 2.2

Coronary angiography 29 0.2 4.5


Complete Exam DRL DAP to EFluoroscopy

Time

Gy.cm2 mSv per Gy.cm2 minutes

Biliary Drainage 50 0.26 15

Facet joint injection 5 0.2 1.8

Hickman line 3 0.1 1.4

Nephrostomy 14 0.16 5.1

Esophageal stent 25 0.1 5.9

Esophageal dilation 11 0.1 2.8

Pacemaker 11 0.1 8.2

PTCA single stent 50 0.2 26


Exam

EU DRL

Dose Area Product

Gy cm2

VGH DR

Ave Dose Area Product

Gy cm2

DAP to E Conversion

Factor

mSv/Gy cm2

Skull AP 4 0.2 0.03

Chest PA 0.2 0.15 0.12

Abdomen AP 7 2.3 0.2

Pelvis AP 5 1.4 0.2

Barium enema 30 0.2

IVP 14 0.1

Coronary Angiography

35-75 120* 0.15

*diagnostic + angioplasty

Overview Session 2

CT 20

Patient dose 15


Questions 10



Questions 20

Acceptance Testing (C 1.0)

“The following steps must be included for the establishment of QC procedures Clear performance specifications Baseline performance Reference images QC Action Levels”

Quality Control

Baseline value determination

Device use period

Next constancy testing

Data evaluation

Within the

established criteria

Remedy

Acceptance testing

FAIL

PASS

Acceptance testing New equipment Conformance to

manufacturer’s specifications/RFP

Baseline performance

Acceptance testing

Items for Acceptance Testing Film CR DR Radioscopic CT

1.0 Identification

1.1 Initial Inspection and Inventory X X X X X

1.2 Inspection of Documentation X X X X X

2.0 Visual and Functional Tests

2.1 Mechanical Properties X X X X X

2.2 Safety Systems X X X X X

Acceptance testing


3.0 Performance Evaluation (X-ray Generator)

3.1 X-ray Tube Voltage X X X X X

3.2 Current Time Product X X X

3.3 Loading Time X X X

3.4 Radioscopic Timer and Chronometer X

3.5 Beam Limitation and Indication X X X X X

3.6 X-ray Beam Filtration X X X X

3.7 Automatic Exposure Control X X X

3.8 Automatic Intensity Control X X

3.9 Radiation Output X X X X X

3.10 Maximum Air Kerma Rate X

3.11 Phantom (Entrance) Dose (Rate) X X X X X

Acceptance testing


4.0 Performance Evaluation (Image Receptor)

4.1 Exposure Index X X

4.2 Dynamic Range X X X

4.3 Spatial Resolution X X X X X

4.4 Contrast Detectability X X X X X

4.5 Uniformity X X X

4.6 Artifacts X X X X X

4.7 Digital Detector Residual Image X X

4.8 Noise X X X

4.9 Modulation Transfer Function X X

4.10 Mean CT Numbers (calibration and linearity) X

4.11 Tomographic Section Thickness X

4.12 Axial Patient Positioning Accuracy X

4.13 Positioning of Patient Support X

Equipment Purchase

This new Code has implications for new equipment

Code 20A was usually a condition for RFPs With Code 35 much more is involved

Performance of the x-ray system At acceptance In routine operation

Performance of the image receptor At acceptance In routine operation

Ability to determine patient dose indicators At control For transfer to PACS

Equipment Purchase

Will service contracts cover the increased testing? For new units For existing equipment

At the moment radiation doses such as CTDI are not measured by any of the companies as part of QC

What about equipment not on service contract?

Overview Session 2

CT 20

Patient dose 15


Questions 20



Questions 20

Personnel Qualifications

Responsible User

X-ray equipment Operator

RSO

Responsible User

Possess qualifications required by applicable province or statute eg RCPSC, CAMRT

Acquire refresher training according to similar standard

Ensure equipment functions correctly Ensure equipment is used correctly Establish safe operating procedures Promulgate radiation safety for staff Ensure radiation levels are within regulatory limits

X-ray Equipment Operator

Possess qualifications required by applicable province or statute eg RCPSC, CAMRT

Acquire refresher training according to similar standard

Have documented training Ensure equipment is used correctly Establish safe operating procedures Promulgate radiation safety for staff Ensure radiation levels are within regulatory limits

Overview Session 2

CT 20


Patient dose 15

Questions 20



Questions 20

Education and Training - Standards

Collation of Standards/Action Levels Although frequency of tests is well covered

in SC 35 not all Action Levels are defined.

Education and Training - QC

PACS and image display systems QC Visual Measurements

Image receptor quality tests and calibration CR DR DF CT

Education and Training - Dose

Patient dose measurement Dose- area product (DAP) in radiography

and radioscopy. Calibration of meters. CTDI in computed tomography

The Future

The only perfect science is hindsight

acr phantom phantom images. overview session 2 ct20 patient dose15 equipment purchase/ acceptance...

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