Original Investigations

Radiation Safety Knowledge andPerceptions among Residents:

A Potential Improvement Opportunity for Graduate Medical Education in

the United States

Gelareh Sadigh, MD, Ramsha Khan, Michael T. Kassin, MD, Kimberly E. Applegate, MD, MS, FACR

Ac

Fr13De(Kco

ªht

Rationale and Objectives: To investigate residents’ knowledge of adverse effects of ionizing radiation, frequency of their education on

radiation safety, and their use of radioprotective equipment.

Materials and Methods: Residents from 15/16 residency programs at Emory University were asked to complete a resident radiation

safety survey through SurveyMonkey�. The associations between the residents’ knowledge and use of radioprotective equipment with

residents’ specialty and year of training were investigated.

Results: Response rate was 32.5% (173/532 residents). Thirty-nine percent residents reported radiation safety is discussed in their res-

idency curriculum at least every 6 months. Ninety-five percent believed in a link between radiation exposure and development of cancer.

Overall and Radiology residents’ knowledge about specific estimated dose effects (correct responses) was limited: radiation dose asso-

ciated with fetus brain malformation in pregnancy (10% vs. 26%), risk of developing cataract in interventional personnel (27% vs. 47%),lifetime risk of cancer mortality from a single abdominal computed tomography (CT) in children (22% vs. 29%), greater radiosensitivity of

children compared to adults (35% vs. 50%), and relative radiation dose from an abdominal CT compared to a chest x-ray (51% vs. 48%).

Radiology residents had modestly higher knowledge. There was no significant difference in residents’ knowledge across their

postgraduate training years. Use of lead thyroid shields was reported by 86% (97% radiology vs. 80% nonradiology; P = .03) andradiation-monitoring badges in 39% (68% radiology vs. 15% nonradiology; P < .001) of the residents.

Conclusions: Although radiology residents scored higher, knowledge of radiation safety for patients and healthcare workers is limited

among residents regardless of medical specialty. These findings emphasize the need for educational initiatives.

Key Words: Knowledge; medical education; radiation safety; resident; radioprotective equipment.

ªAUR, 2014

The National Council for Radiation Protection and

Measurement (NCRP) (1) performs periodic surveys

of radiation exposure from all sources to the American

population. Their most recent survey reported that there is a

rapid increase in average exposure to the American population

from medical imaging, particularly computed tomography

(CT) and cardiac nuclear medicine testing, from 15% in the

early 1980s to 48% in 2006 (2). Effective dose is a risk estimate

for a patient population from radiation exposure and is

expressed in Sieverts (Sv) (3,4). The risk that a radiation

dose will induce a cancer in a specific organ changes with

age, gender, and individual patients’ variations of intrinsic

radiation sensitivity. The population baseline lifetime cancer

risk is 25%. For every 100 mSv of radiation dose to an

ad Radiol 2014; -:1–10

om the Department of Radiology, Emory University School of Medicine,64 Clifton Rd NE, Atlanta, GA, 30322 (G.S., R.K., M.T.K., K.E.A.) andpartment of Radiology, Children’s Hospital of Atlanta, Atlanta, GA.E.A.). Received November 16, 2013; accepted January 15, 2014. Addressrrespondence to: G.S. e-mail: gsadigh@emory.edu

AUR, 2014tp://dx.doi.org/10.1016/j.acra.2014.01.016

average population, lifetime cancer mortality risk increases

from 25% to 25.5% (5,6). The relationship between

radiation dose and cancer risk is highly controversial;

however, the scientific community generally assumes that

there is no safe threshold at low dose (the linear no-

threshold model) (7). There is growing public concern that

low-dose (<100 mSv) ionizing radiation from diagnostic im-

aging may be associated with increased cancer risk (8–11)

depending on radiation dose and duration of exposure.

Extrapolating from data of the Life Span Study of Japanese

atomic bomb survivors, Brenner and Hall (4) estimated that

up to 2% of future cancers may be attributable to CT scanning.

The potential for cancer induction associated with medical

radiation is even more important in children and pregnant

women. The younger a patient, the more radiosensitive

they are for certain tumors (12). They also have a greater post-

radiation exposure life expectancy compared to adults in

which to manifest radiation-induced tumors (13,14).

Over the past several years, surveys have documented a lack

of knowledge and awareness of radiation doses and safety—

underestimating both dose and potential effects—among

referring physicians regardless of field of expertise (15–21).

1

SADIGH ET AL Academic Radiology, Vol -, No -, - 2014

The purpose of the current study was to determine: (1) the

frequency of discussion about radiation safety in residency

curricula; (2) the level of awareness of residents on radiation

doses of imaging tests and radiation safety principles; and (3)

perceived level of importance and the self-reported behavior

regarding wearing radiation-monitoring badges and thyroid

lead shields in a sample of medical and surgical residents at

Emory University.

METHODS

Study Population

The Resident Radiation Safety Survey (RRSS) included

detailed information about resident level of knowledge and

perception regarding potential adverse effects associated

with ionizing radiation exposure from diagnostic imaging

procedures and safety strategies. Institutional review board

approval was waived for this study.

Program directors of 16 residency programs at Emory

University were contacted in September 2012 and asked to

e-mail theRRSS link to the participating residents in their pro-

gram. All residency programs except for pediatrics (citing too

many e-mailed surveys as the reason) agreed to participate in

this survey. Participants of the survey were Emory University

residents in Emergency medicine, family medicine, internal

medicine, transitional year, obstetric/gynecology (OB/

GYN), general surgery, neurosurgery, orthopedics surgery,

vascular surgery, thoracic surgery, plastic surgery, urology, radi-

ology, radiation oncology, and nuclear medicine residency pro-

grams. These residency programs were selected, as their

residents either constitute the majority of referring/ordering

physicians or have occupational exposure to ionizing radiation.

Survey

The RRSS consisted of four sections: (1) participants’ gender,

specialty, and postgraduate year (PGY); (2) frequency of dis-

cussion about radiation safety in general, and specific to pedi-

atric and pregnant patients in their residency curriculum, the

resources they use to increase their knowledge about radiation

safety; (3) participants’ knowledge about potential adverse

effects from exposure to ionizing radiation including cancer,

skin burns, and cataract formation, knowledge about radiation

dose from an abdominal CT scan and its resulting estimated

risk of lifetime fatal cancer induction in children (stochastic

effect), the relative radiosensitivity of children compared to

adults, and finally the radiation dose associated with fetal brain

malformation during pregnancy (deterministic effect); and (4)

their perception of importance in wearing radiation-

monitoring badges and lead thyroid shields when working

in ionizing radiation exposed areas as well as the self-

reported frequency of wearing them.

The survey was made available through SurveyMonkey�

(www.surveymonkey.com), an online survey software and

questionnaire tool. An invitation to access and complete the

2

questionnaire was e-mailed with an embedded link to Emory

University residents on three occasions, over three consecu-

tive weeks. The online survey remained accessible for a total

of a 3-week period (September 2012). A pilot study of the sur-

vey questions was performed among 10 residents before e-

mailing the invitation to assess for any confusion about the

questions and solicit comments for improvement. No change

was made.

Data Analyses

Survey responses were downloaded from SurveyMonkey and

were analyzed using STATA 10 (Stata Corp., College Sta-

tion, TX). Study outcomes were frequency of discussion of

radiation safety in residency curriculums, residents’ knowl-

edge about radiation doses and radiation safety, residents’

perception of importance of using radiation-monitoring

badges and lead thyroid shields, and the frequency of

their use.

Frequency of discussion of radiation safety in residency cur-

riculum was collapsed into a dichotomous variable where sur-

vey responses ‘‘at least once a month’’ and ‘‘at least once every

6 months’’ were categorized as ‘‘at least every 6 months’’ and

survey response ‘‘at least once a year’’, ‘‘less than once a year’’,

and ‘‘never’’ were categorized as ‘‘less than every 6 months’’.

The response choices for questions assessing residents’ knowl-

edge about radiation doses and its adverse effects were pur-

posely widely categorized to allow the respondent to

estimate the answer without necessarily knowing the correct

response. Therefore, the responses were initially collapsed as

dichotomous variables (correct answer vs. incorrect answer)

for analyses. We further evaluated the rate of overestimation

or underestimation of the radiation adverse effects for each in-

dividual question. Finally, wearing radiation safety equipment

was categorized to ‘‘frequent’’ when survey responses were

‘‘everyday’’ and ‘‘most of the time’’ versus ‘‘infrequent’’

when survey responses were ‘‘sometime’’ and ‘‘rarely’’. Cate-

gorical variables were reported as frequency and percentage,

and quantitative variables were reported as mean and standard

deviation (SD).

Participants’ specialty was further categorized into four

groups: (1) medicine which included family medicine, inter-

nal medicine, emergency medicine, and transitional year; (2)

surgery which included general surgery, neurosurgery, plastic

surgery, vascular surgery, thoracic surgery, orthopedics sur-

gery, and urology; (3) obstetrics and gynecology; and (4) radi-

ology, which included diagnostic radiology, radiation

oncology, and nuclear medicine. Responses were compared

among specialty, PGY, and gender.

Chi-squared tests for categorical variables determined sig-

nificant differences between groups and were used to assess

the association between frequency of discussion about

ionizing radiation and residents’ specialty, residents’ percep-

tion and knowledge about radiation safety and their specialty,

PGY training, or gender. Resident’s perception of the impor-

tance of wearing radiation safety equipment was compared

TABLE 1. Demographic Characteristics of Respondents

All Respondents, n (%)

Response

Rate, n (%)

Gender

Male 104/173 (60) —

Female 69/173 (40) —

Specialty 173/532 (33)

Emergency medicine 22/162 (14) 22/59 (37)

Family medicine 1/162 (1) 1/21 (5)

General surgery 16/162 (10) 16/58 (28)

Internal medicine 41/162 (25) 41/173 (24)

Neurosurgery 2/162 (1) 2/18 (11)

Nuclear medicine 3/162 (2) 3/4 (75)

Obstetric/Gynecology 10/162 (6) 10/36 (28)

Orthopedic surgery 6/162 (4) 6/25 (24)

Plastic surgery 0/162 (0) 0/9 (0)

Diagnostic radiology 36/162 (22) 36/61 (59)

Radiation oncology 9/162 (6) 9/19 (47)

Thoracic surgery 4/162 (3) 4/10 (40)

Transitional year 9/162 (6) 9/22 (41)

Urology 3/162 (2) 3/15 (20)

Postgraduate year

1 50/174 (29) —

2 38/174 (22) —

3 46/174 (26) —

4 26/174 (15) —

5 or more 14/174 (8) —

Academic Radiology, Vol -, No -, - 2014 RESIDENT RADIATION SAFETY KNOWLEDGE

between radiology specialties versus the remaining specialties

using the t test. Statistical significance was set at P < .05.

RESULTS

Study Population

Five hundred thirty-two residents received the invitation e-

mail to complete the survey. Of them, 173 residents

completed the survey before the cutoff date (response rate

of 32.5%). Demographics of the respondents and response

rate in each of the specialties are demonstrated in Table 1.

Sixty percent (104/173) of respondents were male. The per-

centage of participating specialties ranged from 0% (in plastic

surgery) to 25% (41/162) from internal medicine with the

highest response rate among all specialties from radiology res-

idents (59%; 36/61).

Ninety-five percent (151/159) of residents, regardless of

their specialty, believed there was a link between ionizing ra-

diation and later cancer. This link was reported by 98% (41/

42) of residents in radiology specialties. There was a marginal

difference in more male residents reporting this cancer link

than female residents (98% vs. 92%, P = .06).

Radiation Safety as Part of the Residency Curriculum

Thirty-nine percent (64/164) of respondents reported that

radiation safety in general was discussed in their residency

curriculum at least once or more every 6 months (Table 2).

Furthermore, 46% (66/145) and 47% (56/120) of respondents

reported radiation safety in pregnancy and children, respec-

tively, were discussed in their residency curriculum, at least

once every 6 months. However, only 61% (87/143) and

75% (79/106) of respondents reported feeling comfortable

in making decisions for imaging in pregnancy and children,

respectively. Residents’ confidence in decision making for

appropriate imaging in pregnancy increased significantly

with higher postgraduate training level; 37% of PGY1, 65%

of PGY2, 66% of PGY 3, 79% of PGY4, and 71% of PGY5

residents reported feeling comfortable making such a decision

(P = .008). However, for decision regarding imaging in chil-

dren, residents’ confidence did not change over years of

training (P = .13). There was no difference between male

and female residents in their confidence for ordering imaging

tests in pregnant women and children (Table 3).

Faculty members (64%; 101/158), upper level residents or

fellows (56%; 88/158), and textbooks (43%; 68/158) were the

most common resources residents reported that they use to

learn more about radiation safety. Other less-common re-

sources were searching in Google (39%; 61/158), consulting

radiology department residents, fellows, or faculty (34%;

53/158), searching in UpToDate (28%; 44/158), Ovid or

Pubmed (17%; 27/158), and Image Gently Web site (7%;

11/158). Most residents (43%; 68/157) believed that diag-

nostic radiology faculty have provided them the most infor-

mation about radiation safety; whereas 41% (64/157) and

8% (12/157) reported that they have received their informa-

tion mostly from nonradiologist physicians and medical phys-

icists, respectively. Only 19 residents (of 161; 12%) reported

that they have visited ‘‘Image Gently’’ or ‘‘Image Wisely’’

Web sites with most residents (13/19, 68%) in diagnostic

radiology.

Subgroup analyses of resident’s specialty demonstrated that

residents in radiology specialties had significantly higher fre-

quency of education regarding radiation safety (Table 2).

However, the frequency of discussion over radiation safety

in pregnancy was also higher in OB/GYN (60%; 6/10)

compared to medicine (25%; 13/51) and surgery (25%;

7/28) specialties. Medicine specialties reported significantly

less comfort level in making decisions for imaging pregnant

women and children. Furthermore, residents in specialties

other than radiology ones report gaining the most of their

information about radiation safety from nonradiologist

physicians.

Residents’ Knowledge about Radiation Safety

Table 4 displays residents’ knowledge about radiation doses

and radiation safety. Where residents’ correct responses are

<50%, the percentage of underestimation and overestimation

of ionizing radiation adverse effects are shown in Figure 1a for

all residents and Figure 1b for diagnostic radiology residents.

Most of the residents correctly reported the estimated risk be-

tween ionizing radiation exposure and future development of

3

TABLE 2. Discussion Frequency and Comfort Level with Radiation Safety in Residency Programs

All Specialties, n (%)

Specialties, n (%)

P Value{Medicine* Surgeryy Obstetric/Gynecology Radiologyz

Discussion over radiation

safety at least once in

6 months in residency.

64/164 (39) 13/68 (19) 5/30 (17) 3/10 (30) 38/45 (84) <.001

Discussion over radiation

safety in pregnant

women at least once in

6 months in residencyx

66/145 (46) 13/51 (25) 7/28 (25) 6/10 (60) 37/45 (82) <.001

Discussion over radiation

safety in children at

least once in 6months in

residency k

56/120 (47) 11/35 (31) 8/28 (28) 1/4 (25) 34/44 (77) <.001

Feeling comfortable

making decisions for

imaging in pregnancyx

87/143 (61) 17/50 (34) 18/28 (64) 8/10 (80) 38/44 (86) <.001

Feeling comfortable

making decisions for

imaging in childrenk

79/106 (75) 17/28 (61) 19/26 (73) 2/3 (67) 37/41 (90) .04

*Medicine includes family medicine, internal medicine, emergency medicine, and transitional year.ySurgery includes general surgery, neurosurgery, thoracic surgery, orthopedics surgery, and urology.zRadiology includes diagnostic radiology, nuclear medicine, and radiation oncology specialties.xParticipants who responded that they do not treat pregnant women were excluded from analysis.kParticipants who responded that they do not treat children were excluded from analysis.{P values are based on Chi-squared test comparisons between residents’ specialties and discussion over radiation safety. Statistical signif-

icance was set at P < .05.

SADIGH ET AL Academic Radiology, Vol -, No -, - 2014

cancer. Sixty percent (96/160) of the residents correctly noted

that fluoroscopy may result in patient skin burns and 97%

(30/31) of diagnostic radiology residents. Only 27%

(43/158) residents correctly estimated five times more risk

of developing cataract in interventional personnel and 58%

(18/31) of diagnostic radiology residents. Fifty-one percent

(79/154) of residents (48% [14/29] of diagnostic radiology

residents) correctly estimated the radiation dose from abdom-

inal CT scan is approximately equivalent to 100 chest x-rays.

Only 35% of residents (54/155) responded that children are

approximately five times more sensitive to radiation compared

to adults. Ten percent (16/160) of the residents reported the

correct threshold radiation dose associated with fetal brain

malformation.

Male residents showed significantly higher level of knowl-

edge about adverse effects of ionizing radiation including skin

burn and cataract compared to female residents (P < .001).

There was no significant difference in residents’ knowledge

among different PGYs (Table 3).

Radiology Specialty Residents

As expected, Radiology residents (diagnostic radiology, radi-

ation oncology, and nuclear medicine) had generally greater

correct responses to the estimated risks of the potential adverse

effects associated with radiation exposure. Eighty-six percent

(36/42) and 47% (20/42) of Radiology residents correctly

estimated the risk of developing skin burns in patients (dose

4

dependently) and cataract in interventional personnel

compared to 45% (30/66) and 11% (7/66) of medicine resi-

dents and 62% (18/29) and 41% (12/29) of surgery residents,

respectively (P < .001). Specifically, among residents in spe-

cialties other than radiology who practice long fluoroscopic

procedures (general surgery, neurosurgery, and thoracic sur-

gery), only 52% (11/21) understood the link between fluoros-

copy and patient skin burns. Twenty-eight percent (6/21)

reported there is no risk, and 19% (4/21) reported the risk

is not dose dependent. Only 33% (7/21) of residents in general

surgery, neurosurgery, and thoracic surgery understood the

higher risk of cataract among interventional personnel,

respectively. Forty-seven percent (10/21) were not aware of

such a risk and 19% (4/21) underestimated the risk. In addi-

tion, 26% (11/42) of Radiology residents correctly estimated

radiation dose associated with fetal brain malformation

compared to 5% (3/66) and 0% correct response rate from

medicine and surgery specialties, respectively (P = .04). How-

ever, 20% (2/10) of OB/GYN residents correctly estimated

the dose. Forty percent (4/10) of OB/GYN residents under-

estimated the dose, and the remaining 40% (4/10) did not

know the correct dose. Subgroup analyses of resident’s spe-

cialties are listed in Table 4.

Table 5 specifically displays the performance of diagnostic

radiology residents versus nuclear medicine and radiation

oncology residents and all the other remaining specialties.

Diagnostic radiology residents had significantly greater per-

centage of correct response to questions assessing potential

TABLE 3. Residents’ Perceptions and Knowledge about Radiation Safety across Postgraduate Year and by Gender

Postgraduate Year, n (%) Gender, n (%)

1 2 3 4 5 P Valuez Male Female P Valuex

Feeling comfortable making

decisions for imaging in

pregnancy*

14/38 (37) 21/32 (65) 23/35 (66) 19/24 (79) 10/14 (71) .008 51/85 (60) 35/57 (61) .87

Feeling comfortable making

decisions for imaging in

childreny

11/21 (52) 22/27 (81) 22/27 (81) 15/20 (75) 9/11 (82) .13 48/68 (70) 30/37 (81) .24

Knowledge

There is a link between ionizing

radiation and future

development of cancer

40/42 (95) 35/36 (97) 39/41 (95) 23/25 (92) 13/13 (100) .81 95/97 (98) 54/59 (92) .06

Ionizing radiation > 200 mGy is

associated with fetal brain

malformation.

2/42 (5) 2/36 (6) 6/41 (15) 4/25 (16) 2/13 (15) .36 9/97 (9) 6/59 (10) .85

There is a risk of developing

cancer in patients or

interventional personnel who

are frequently exposed to

ionizing radiation, but is

uncommon

30/42 (71) 24/36 (67) 32/41 (78) 16/25 (64) 9/13 (69) .75 69/97 (71) 41/59 (69) .83

Patients undergoing

fluoroscopy are at risk of

developing skin burns

depending on the dose of

radiation they are exposed to

23/42 (55) 20/36 (56) 24/41 (59) 17/25 (68) 10/13 (77) .55 71/97 (73) 22/59 (37) <.001

Interventional personnel are

five times more at risk of

developing cataract

8/42 (19) 10/34 (29) 9/41 (22) 10/25 (40) 6/13 (46) .17 40/97 (41) 3/57 (5) <.001

Radiation dose from

abdominal computed

tomography (CT) scan is

equivalent to 100 chest x-rays

17/40 (43) 18/33 (54) 27/40 (68) 10/25 (40) 6/13 (46) .14 52/96 (54) 26/55 (47) .41

Children are five times more

radiosensitive compared to

adults

12/41 (29) 10/33 (30) 17/40 (43) 9/25 (36) 5/13 (39) .74 36/96 (38) 17/56 (30) .37

Estimated risk of lifetime fatal

cancer from a single

abdominal CT is 1:1500 in

children

4/41 (10) 11/33 (33) 12/41 (29) 2/25 (8) 6/13 (46) .007 22/96 (23) 13/57 (23) .99

Risk of lifetime fetal cancer is

20% in the American

population.

7/41 (17) 6/33 (46) 13/39 (33) 6/25 (24) 5/13 (39) .29 26/96 (27) 11/55 (20) .33

*Participants who responded they do not treat pregnant women were excluded from analysis.yParticipants who responded they do not treat children were excluded from analysis.zP values are based on the Chi-squared test comparison of the posttraining years.xP values are based on the Chi-squared test comparison of the gender. Statistical significance was set at P < .05.

Academic Radiology, Vol -, No -, - 2014 RESIDENT RADIATION SAFETY KNOWLEDGE

radiation risks such as skin burn and cataract compared

to nuclear medicine and radiation oncology residents

(P < .001).

Among diagnostic radiology residents, male residents

showed significantly higher level of knowledge about

increased risk of cataract among interventional personnel

compared to female residents (72% vs. 25%; P = .03). How-

ever, there was no gender difference about residents’ level of

knowledge regarding radiation-associated skin burn or other

questions in Table 5.

Use of Radiation-monitoring Badges and Lead ThyroidShields

On a scale from 0 to 5, the importance of wearing radiation-

monitoring badges and lead thyroid shields were reported as

5

TABLE 4. Resident Knowledge and Perceptions about Radiation Safety across Specialties

All Specialties, n (%)

Specialties, n (%)

P ValuexMedicine* Surgeryy Obstetric/Gynecology Radiologyz

There is a link between ionizing radiation

and future development of cancer

151/159 (95) 60/66 (91) 28/29 (96) 10/10 (100) 41/42 (98) .36

Ionizing radiation > 200 mGy is

associated with fetal brain

malformation

16/160 (10) 3/66 (5) 0/29 (0) 2/10 (20) 11/42 (26) .04

There is a risk of developing cancer in

patients or interventional personnel

who are frequently exposed to ionizing

radiation, but is uncommon

112/160 (70) 43/66 (65) 19/29 (65) 8/10 (80) 33/42 (79) .06

Patients undergoing fluoroscopy are at

risk of developing skin burns

depending on the dose of radiation

they are exposed to

96/160 (60) 30/66 (45) 18/29 (62) 2/10 (20) 36/42 (86) <.001

Interventional personnel are five times

more at risk of developing cataract

43/158 (27) 7/66 (11) 12/29 (41) 1/9 (11) 20/42 (47) <.001

Radiation dose from abdominal

computed tomography (CT) scan is

equivalent to 100 chest x-rays

79/154 (51) 36/62 (58) 16/29 (55) 4/10 (40) 19/40 (48) .09

Children are five times more

radiosensitive compared to adults

54/155 (35) 18/63 (28) 9/29 (31) 3/10 (30) 20/40 (50) .09

Risk of lifetime fetal cancer from

abdominal CT (performed based on

adult protocol) is 1:1500

35/156 (22) 10/63 (16) 10/29 (34) 1/10 (10) 12/41 (29) .51

Risk of lifetime fatal cancer is 20% in the

American population

38/154 (25) 14/63 (22) 5/29 (17) 0/9 (0) 16/40 (40) .03

*Medicine includes family medicine, internal medicine, emergency medicine, and transitional year.ySurgery includes general surgery, neurosurgery, thoracic surgery, orthopedics surgery, and urology.zRadiology includes diagnostic radiology, nuclear medicine, and radiation oncology specialties.xP values are based on the Chi-squared test comparison of the specialties. Statistical significance was set at P < .05.

SADIGH ET AL Academic Radiology, Vol -, No -, - 2014

4.3 � 0.9 and 4.8 � 0.5 among residents who are exposed to

ionizing radiation, respectively. However, only 39% (30/78)

of residents who are exposed to ionizing radiation and issued

a radiation-monitoring badge reported wearing themwhereas

86% (67/78) of residents reported wearing lead thyroid shields

while being exposed to ionizing radiation. A two-piece lead

apron was more preferable by residents compared to one-

piece lead apron (66% vs. 34%); however, the reported avail-

ability of both types of aprons was similar at our institution

(49% for one-piece vs. 51% for two-piece apron). There

was no difference by resident gender in their preference for

two-piece lead apron or one-piece apron (P = .18, Table 6).

Subgroup analyses of resident’s specialty demonstrated that

frequency of wearing both radiation-monitoring badges and

lead thyroid shields were significantly higher among residents

of Radiology compared to other specialties (68% vs. 15% for

badges; P < .001 and 97% vs. 80% for thyroid shields; P = .03;

Table 5). There was no difference between Radiology

residents’ versus all other residents’ reported importance for

wearing thyroid shields. However, Radiology residents re-

ported lower importance for wearing monitoring badges

compared to other residents (4.2 vs. 4.5), but this did not

reach significance (P = .12).

6

DISCUSSION

Knowledge about radiation doses from imaging that uses

ionizing radiation, and more importantly, the potential for

adverse effects such as cancer from these imaging tests is

limited (15). Radiology residents—particularly diagnostic

radiology residents—showed moderately higher knowledge

than their clinical resident colleagues when estimating radia-

tion dose and deterministic and stochastic risks from radiation

exposure. Granted, 95% (151/159) of residents, regardless of

their specialty, believe there is a potential cancer risk from

ionizing radiation.

The risk from low doses at which imaging exposes both pa-

tients and healthcare workers is under debate. For example,

there is controversial evidence from large cohort studies of

children who were exposed to CT scanning that show small

but statistically significant later cancer risks (9,10). Although

the absolute risk to an individual might be small, repeated

exposure to individual patients may lead to a significant

increase in the number of later cancer cases (22).

In our survey, only 51% of residents could estimate the ra-

diation dose from abdominal CT scan in adults in terms of

number of chest radiographs, and this rate was similar among

Figure 1. Residents’ knowledge about

radiation safety stratified by their re-

sponses for (a) all the residents and (b)diagnostic radiology residents. The verti-

cal axis demonstrates the percentage of

residents’ responses.

Academic Radiology, Vol -, No -, - 2014 RESIDENT RADIATION SAFETY KNOWLEDGE

different specialties. Surprisingly, diagnostic radiology resi-

dents performed no better (48% correct responses). Although

these responses show improvement over past-published

surveys of medicine, surgery, OB/GYN, pediatric, and radi-

ology physicians (both trainees and faculty) for the same ques-

tion (15%–22% correct responses), there is room for

further improvement (23,24). In the present study, 33%

of the residents either underestimated or did not know

the radiation dose associated with abdominal CT.

Underestimations of radiation exposure and potential

for harm from imaging tests may lead to inappropriate

imaging (25–27).

Although since 2006 began to decline, over the past 15 years

there has been a linear increase of pediatric CTexaminations

in the United States, likely the result of technologic advances

in fast multidetector CT (19,28,29). Higher radiosensitivity at

least for certain tumors in children and their longer lifetime

result in a greater lifetime cancer mortality risk attributable

7

TABLE 5. Relative Knowledge of Radiation Safety and Use of Radioprotective Equipment among Diagnostic Radiology ResidentsCompared to Other Specialties (Percent Correct Responses)

Diagnostic

Radiology, n (%)

Nuclear Medicine and

Radiation Oncology, n (%)

All Other

Specialties, n (%) P Valuey

Ionizing radiation > 200 mGy is associated with fetal

brain malformation.

11/31 (35) 0/11 (0) 5/105 (5) .001

Patients undergoing fluoroscopy are at risk of

developing skin burns depending on the dose of

radiation they are exposed to.

30/31 (97) 6/11 (54) 50/105 (48) <.001

Interventional personnel are five times more at risk of

developing cataract.

18/31 (58) 2/11 (18) 20/104 (19) <.001

Radiation dose from abdominal computed

tomography (CT) scan is equivalent to 100 chest

x-rays.

14/29 (48) 5/11 (45) 56/101 (55) .26

Children are five timesmore radiosensitive compared

to adults.

14/29 (48) 6/11 (54) 30/102 (30) .09

Risk of lifetime fatal cancer from abdominal CT

(performed based on adult protocol) is 1:1500.

8/30 (27) 4/11 (36) 21/102 (20) .96

Reported frequency of wearing radiation-monitoring

badges everyday or most of the time*

18/28 (64) 3/3 (100) 6/40 (15) <.001

Reported frequency of wearing lead thyroid shield* 28/28 (100) 2/3 (67) 32/40 (80) .03

Image Gently/Image Wisely use 13/33 (39) 1/12 (8) 3/105 (3) <.001

*Only residents who are exposed to ionizing radiation were queried.yP values are based on Chi square test for comparison of specialties. Statistical significance was set at P < .05.

TABLE 6. Importance of Wearing Radiation Safety Badges and Lead Apron across Specialties

All Specialties Radiology* Nonradiologyy P Value

Importance of wearing radiation-monitoring badges, mean � standard

deviation (SD)

4.3 � 0.9 4.2 � 0.2 4.5 � 0.1 .12z

Reported frequency of wearing radiation-monitoring badges everyday

or most of the time, n (%)

30/78 (39) 21/31 (68) 6/40 (15) <.001x

Importance of wearing lead thyroid shield, mean � SD 4.8 � 0.5 4.8 � 0.07 4.8 � 0.1 .52z

Reported frequency of wearing lead thyroid shield, N (%) 67/78 (86) 30/31 (97) 32/40 (80) .03x

Reported preference of two-piece lead aprons, n (%) 52/79 (66) 25/31 (80) 23/40 (57) .04x

Reported availability of two-piece lead aprons, n (%) 40/79 (51) 19/31 (61) 17/40 (42) .12x

Only residents who are exposed to ionizing radiation were queried.

*Radiology includes diagnostic radiology, nuclear medicine, and radiation oncology specialties.yNonradiology specialties included all specialties except for diagnostic radiology, nuclear medicine, and radiation oncology.zRating scale from the lowest, zero, to the highest, five. P value was based on the t test comparison of specialties.xP value was based on Chi-squared test comparison of specialties. Statistical significance was set at P < .05.

SADIGH ET AL Academic Radiology, Vol -, No -, - 2014

to radiation exposure from CT compared to adults. In the

present study, only 22% of residents overall, and 27% of

diagnostic radiology residents, accurately estimated this risk

at 1 in 1000. Furthermore, only 35% of residents, including

48% of diagnostic radiology residents, noted that children

are more radiosensitive than adults. More residents (37%)

reported that they did not know the correct response than

those who responded correctly.

Nonradiology resident knowledge regarding other adverse

effects of ionizing radiation was also limited. Specifically, po-

tential heavy fluoroscopic users (vascular surgery, thoracic sur-

gery, and neurosurgery) had significantly lower level of

knowledge compared to Radiology residents (52% vs. 86%

[P = .005] for skin burn and 33% vs. 47% for risk of cataract

8

[P = .002], respectively). This knowledge gap may be

explained by less radiation safety education and use of fluoros-

copy as compared to Radiology residents. The International

Commission on Radiological Protection (30), NCRP (1),

and American College of Radiology recommend formal

training and/or credentialing programs for any operator of

fluoroscopy equipment (31). These knowledge gaps about ra-

diation dose and safety may have several potential unintended

consequences on patient care, employee exposures, and physi-

cian practice behavior and may result in added healthcare cost

when these same residents consider appropriate diagnostic

imaging use for their patients, without understanding the risks

and benefits of the imaging test they order (32). Some health

policy leaders believe that up to one-third of all requested

Academic Radiology, Vol -, No -, - 2014 RESIDENT RADIATION SAFETY KNOWLEDGE

radiologic studies are unnecessary, do not help the patient, or

may harm the patient (29).

Interestingly, there was no difference in response accuracy

by year of training across specialties. For Radiology specialties,

this result may be explained by the early introduction of phys-

ics and radiation biology in PGY1 of residency. Radiology

specialty residents reported high levels of comfort with discus-

sing radiation safety and imaging appropriateness issues

compared to their nonradiology residents. This result is

both reassuring and may reflect the day-to-day teaching by

radiology faculty in the clinical work setting.

Residents participated in the present study believed that

wearing personal protective equipment was important; how-

ever, only 39% of residents being exposed to ionizing radia-

tion reported wearing radiation-monitoring badges and 86%

thyroid lead shields. Residents from Radiology specialties

were significantly more likely to use the personal protective

equipment (68% vs. 15% for badges and 97% vs. 80% for thy-

roid shields). At least part of this discrepancy may be explained

by lack of requirement for badges and lack of access to thyroid

shields (33). In a recent study, it has been reported that 85% of

the trauma team did not wear a lead apron in the trauma bay as

opposed to only 3% who failed to wear it in fluoroscopy (33).

Their reported rate for thyroid lead shield use was 40% for

trauma team members (33), which is similar to another article

reporting 52% use for internal medicine subspecialists (34).

Radiation safety knowledge and culture may not be

disseminated from the radiology community to other physi-

cian specialties (23). The radiology community has long advo-

cated for a required medical school curriculum in radiation

safety and appropriate use of imaging that includes education

on radiation exposure in medical imaging through initiatives

with the Liaison Committee onMedical Education, the Asso-

ciation of American Medical Colleges, and the American

Medical Association (35). Standard basic radiation safety and

protection curriculum for of all residents, particularly non-

radiology residents, may decrease this knowledge gap. Cre-

dentialing programs for all physicians using fluoroscopy

would improve interventional physician knowledge and safety

behavior for all personnel involved in these interventional

fluoroscopy programs (36,37). The American College of

Radiologists Appropriateness Criteria are open-source evi-

dence-based guidelines to assist ordering physicians in deter-

mining the most appropriate imaging for their patient and

informing them about relative radiation dose estimates associ-

ated with each modality (38). These materials are available

electronically as a clinical decision support tool for computer-

ized physician order entry (36–38). Moreover, there are open-

source educational tools on the Image Gently and Image

WiselyWeb sites (39) that help all stakeholders—from patients

to referring physicians, to technologists and radiologists to

minimize radiation dose in pediatric and adult populations,

respectively. However, the faculty, especially radiologists,

served as the most common radiation safety knowledge

resource for residents. Therefore, the presence of a radiology

consulting service may also be helpful, which could provide

information about the best available imaging test for a patient’s

condition, the associated risks of ionizing radiation, and the

alternative imaging tests especially in patients at high risk for

radiation adverse effects, such as children and pregnant

woman. Furthermore, these interactions might provide

educational opportunities on general radiation safety culture,

imaging dose estimates, and the appropriate use of radiopro-

tective equipment. Finally, using a paired physicist–radiology

physician team to teach medical physics and radiation safety to

radiology residents has been promoted to ensure learning safe

and appropriate use of complex medical technologies (40).

LIMITATIONS

Limitations of this study include the single sample from one

albeit large academic teaching system. The overall response

rate was reasonable for an e-mailed survey at 33%, but varied

widely by specialty. Several specialties had such low response

rates that the study results from these specialties are unlikely

to be representative. The single site survey results may not

be generalizable, as residents’ knowledge may differ between

residency programs in different geographic regions or univer-

sity versus community hospital settings. This survey did not

include responses from pediatric residents. Therefore, findings

regarding residents’ knowledge about radiation safety in chil-

dren are lower than expected if pediatric residents were

included. Furthermore, our study does not explore in detail

residents’ knowledge about different modalities and all aspects

of radiation safety.

CONCLUSIONS

Residents—our future physicians—will make decisions about

appropriate use of imaging tests for their patients, with a sug-

gested limited knowledge about imaging dose estimates,

ionizing radiation potential adverse effects and radiation safety.

Gaps in this knowledge may be addressed throughmultiple in-

terventions that include increased interactions and teaching

with radiology faculty (diagnostic and oncology, medical

physics, and nuclear medicine) from the early medical school

years through residency and fellowship, the use of required

credentialing programs in fluoroscopy, and the implementa-

tion of electronic clinical decision support systems.

REFERENCES

1. National Council for Radiation Protection and Measurement. Available at:

http://www.ncrponline.org. Accessed May 20, 2013.

2. NCRP Report No. 160, Ionizing radiation exposure of the population of the

United States. Recommendation of National Council on Radiation Protec-

tion and Measurement. 2009. Avaialble at: http://www.ncrponline.org/

Publications/Press_Releases/160press.html.

3. International Atomic Energy Agency. Radiation protection of patients.

Available at: https://rpop.iaea.org/RPOP/RPoP/Content/InformationFor/

HealthProfessionals/1_Radiology/QuantitiesUnits.htm. Accessed May

30, 2013.

4. Brenner DJ, Hall EJ. Computed tomography—an increasing source of

radiation exposure. N Engl J Med 2007; 357(22):2277–2284.

9

SADIGH ET AL Academic Radiology, Vol -, No -, - 2014

5. Balter S, Zanzonico P, Reiss GR, et al. Radiation is not the only risk. AJR

Am J Roentgenol 2011; 196(4):762–767.

6. Understanding radiation. United Kingdom: Health Protection Agency.

Updated 10 December 2008. Health Protection Agency. Available at:

http://www.hpa.org.uk/. Accessed May 20, 2013.

7. LittleMP,Wakeford R, Tawn EJ, et al. Risks associatedwith low doses and

low dose rates of ionizing radiation: why linearity may be (almost) the best

we can do. Radiology 2009; 251(1):6–12.

8. BogdanichW. ‘‘Radiation Boom’’ series. The NewYork Times. 2010–2011.

Available at: http://topics.nytimes.com/top/news/us/series/radiation_

boom/index.html. Accessed May 20, 2013.

9. Mathews JD, Forsythe AV, Brady Z, et al. Cancer risk in 680 000 people

exposed to computed tomography scans in childhood or adolescence:

data linkage study of 11 million Australians. BMJ 2013; 346:f2360.

10. Pearce MS, Salotti JA, Little MP, et al. Radiation exposure from CT scans

in childhood and subsequent risk of leukaemia and brain tumours: a retro-

spective cohort study. Lancet 2012; 380(9840):499–505.

11. Berrington deGonzalez A,MaheshM, KimKP, et al. Projected cancer risks

from computed tomographic scans performed in the United States in

2007. Arch Intern Med 2009; 169(22):2071–2077.

12. United Nations Scientific Committee on the Effect of Atomic Radiation

(UNSCEAR). No immediate health risks from Fukushima nuclear

accident says UN Expert Science Panel. Press Release, 2013. Available

at: http://www.unis.unvienna.org/unis/en/pressrels/2013/unisinf475.html.

Accessed June 12, 2013.

13. Lee C, Lee C, Staton RJ, et al. Organ and effective doses in pediatric

patients undergoing helical multislice computed tomography examination.

Med Phys 2007; 34(5):1858–1873.

14. Brenner DJ. Estimating cancer risks from pediatric CT: going from the

qualitative to the quantitative. Pediatr Radiol 2002; 32(4). 228–3; discus-

sion 42–4.

15. Wong CS, Huang B, Sin HK, et al. A questionnaire study assessing local

physicians, radiologists and interns’ knowledge and practice pertaining

to radiation exposure related to radiological imaging. Eur J Radiol 2012;

81(3):e264–e268.

16. Zhou GZ, Wong DD, Nguyen LK, et al. Student and intern awareness of

ionising radiation exposure from common diagnostic imaging procedures.

J Med Imaging Radiat Oncol 2010; 54(1):17–23.

17. Thomas KE, Parnell-Parmley JE, Haidar S, et al. Assessment of radiation

dose awareness among pediatricians. Pediatr Radiol 2006; 36(8):823–832.

18. Huda W. Effective doses to adult and pediatric patients. Pediatr Radiol

2002; 32(4):272–279.

19. Merzenich H, Krille L, Hammer G, et al. Paediatric CT scan usage and

referrals of children to computed tomography in Germany—a cross-

sectional survey of medical practice and awareness of radiation related

health risks among physicians. BMC Health Serv Res 2012; 12:47.

20. Krille L, Hammer GP, Merzenich H, et al. Systematic review on physician’s

knowledge about radiation doses and radiation risks of computed tomog-

raphy. Eur J Radiol 2010; 76(1):36–41.

21. Rice HE, Frush DP, Harker MJ, et al. Peer assessment of pediatric

surgeons for potential risks of radiation exposure from computed tomog-

raphy scans. J Pediatr Surg 2007; 42(7):1157–1164.

10

22. Berrington de Gonzalez A, Darby S. Risk of cancer from diagnostic X-rays:

estimates for the UK and 14 other countries. Lancet 2004; 363(9406):

345–351.

23. Lee CI, Haims AH, Monico EP, et al. Diagnostic CT scans: assessment of

patient, physician, and radiologist awareness of radiation dose and

possible risks. Radiology 2004; 231(2):393–398.

24. McBride JF, Wardrop RM, 3rd, Paxton BE, et al. Effect on examination

ordering by physician attitude, common knowledge, and practice

behavior regarding CT radiation exposure. Clin Imaging 2012; 36(5):

455–461 e1.

25. Brink JA, Amis ES, Jr. Image Wisely: a campaign to increase aware-

ness about adult radiation protection. Radiology 2010; 257(3):

601–602.

26. Yucel A, Alyesil C, Sim S. Physicians’ knowledge about ionizing radiation

and radiological imaging techniques: a cross-sectional survey. Acta Radiol

2011; 52(5):537–539.

27. Strauss KJ, Goske MJ, Kaste SC, et al. Image gently: ten steps you can

take to optimize image quality and lower CT dose for pediatric patients.

AJR Am J Roentgenol 2010; 194(4):868–873.

28. Brenner D, Elliston C, Hall E, et al. Estimated risks of radiation-induced

fatal cancer from pediatric CT. AJR Am J roentgenol 2001; 176(2):

289–296.

29. Picano E. Sustainability of medical imaging. BMJ 2004; 328(7439):

578–580.

30. The International Commission on Radiological Protection. Available at

http://www.icrp.info. Accessed May 31, 2013.

31. American College of Radiology. ACR technical standard for management

of the use of radiation in fluoroscopic procedures. 2008. Available at:

http://www.acr.org/�/media/F22C9D1FF46F43AAB001F9ED0466B7E9.

pdf. Accessed May 31, 2013.

32. Goergen S. They don’t know what they don’t know. J Med Imaging Radiat

Oncol 2010; 54(1):1–2.

33. HassanM, Patil A, Channel J, et al. Dowe glow? Evaluation of trauma team

work habits and radiation exposure. J Trauma Acute Care Surg 2012;

73(3):605–611.

34. Son BK, Lee KT, Kim JS, et al. Lack of radiation protection for endoscop-

ists performing endoscopic retrograde cholangiopancreatography.

Korean J Gastroenterol 2011; 58(2):93–99.

35. Amis ES, Jr, Butler PF, Applegate KE, et al. American College of Radiology

white paper on radiation dose in medicine. J Am Coll Radiol 2007; 4(5):

272–284.

36. Miller DL, Society for Interventional Radiology. Interventional fluoroscopy:

reducing radiation risks for patients and staff. J Vasc Interv Radiol 2009;

20(7 Suppl):S274.

37. Balter S, Miller DL. The new Joint Commission sentinel event pertaining to

prolonged fluoroscopy. J Am Coll Radiol 2007; 4(7):497–500.

38. American College of Radiology. ACR appropriateness criteria. Reston, VA:

American College of Radiology, 2010.

39. Image Gently. Available at http://www.imagegently.com. Accessed

December 25, 2012.

40. Hendee WR. Teaching physics to radiology residents. AJR Am J

Roentgenol 2009; 192(4):855–858.