Diagnostic investigations using radiation have become a critical feature of medical practice in recent times. However, the possibility of doctors’ underestimation of risks of over-exposure of patients to diagnostic radiation still warrants further evaluation.
To investigate doctors’ awareness of diagnostic radiation exposure at Dr George Mukhari Academic Hospital, South Africa.
This was a cross-sectional, analytical investigation of the awareness of doctors about radiation exposure in diagnostic radiology investigations. A cluster sampling technique was employed to recruit 217 participants. Consent and approval of the participants were sought and obtained before questionnaire administration during departmental meetings between October 2017 and March 2018.
Of the participants, 80% had no formal training on radiation exposure and 33.8% of them correctly estimated natural background radiation. Correct estimates of the effective dose from a single-view abdominal X-ray (AXR) were expressed by 7.5%, quantity of radiation of a single-phase computed tomography (CT) abdomen by 30.3% and dosage from a two-view unilateral mammogram by 29.1% of the participants. More than 75% of participants agreed that children are more sensitive to radiation, but only 10.5% suggested medical termination of pregnancy for a woman who had CT abdomen and pelvis with contrast. Dosage and risk of inducing fatal cancer from common but more complex imaging procedures were poorly understood. Only the doctors of the radiology department showed a statistically significant (
Because of the high rate of poor awareness of radiation risks observed in this study, it is important to initiate, early in the medical curriculum for medical students, the need for a rotation in the Department of Radiology, similar to such rotations in other medical specialties.
Medical diagnostic radiation has been the fastest growing source of human exposure to ionising radiation, with the collective radiation increased by a factor of six in the last two to three decades.
This unbridled exposure to ionising radiation has been scientifically proven to cause damage to healthy tissues, such as skin burns and radiation sickness, at high exposures (deterministic effects) and also raises the risks of cancers and genetic damages (stochastic effects) at low exposures.
According to the 2007 International Commission on Radiological Protection recommendations,
The importance of these findings lies in the fact that when doctors have poor awareness of radiation risks, inherent in diagnostic radiology examinations, they will not be able to counsel their patients and request for appropriate examinations based on the principle of benefits outweighing the risks. This is much more important especially in paediatric patients in whom radiation must be kept to the barest minimum if not possible to avoid altogether. This is because their tissues are highly radiosensitive. In addition, children will also live longer and are more likely than adults to develop radiation-induced cancer. Also, as future parents, they are at risk of passing on radiation-induced genetic defects to the next generation.
Education of medical professionals in radiation protection issues and radiation safety has been a continuous problem even in well-developed countries.
A cross-sectional analytical method was used to explore the awareness of practising doctors employed by DGMAH about radiation exposure in diagnostic radiology. A cluster sampling technique was applied to recruit 217 volunteer participants in this study, after assuring them of the confidentiality of information supplied. The consent and approval of the heads of each department in the hospital were sought and obtained before questionnaire administration, which was carried out during departmental meetings from October 2017 to March 2018. Each department represented a cluster and being a single-stage cluster sampling, questionnaires were distributed at the same time to all doctors, including consultants, registrars, medical officers and interns present in each cluster meeting.
The inclusion criteria entailed that respondents were practising doctors, accredited as medical practitioners by the Health Professions Council of South Africa (HPCSA) and were employed by DGMAH. Professionals who were not clinicians or doctors employed by DGMAH, but present at each meeting, were excluded from this study.
The assessment tool was a self-reported questionnaire which was developed from three previously published studies.
A total of 217 doctors were enrolled in the study. The questionnaires were individually handed over to the doctors and collected by the researcher. Respondents who had been interviewed earlier were exempted from the subsequent data collection. For awareness scoring, one positive point was awarded for each correct answer. In addition, according to the total number of items, 0 was regarded as minimum score and the maximum overall score was 26. Scores less than 50% were considered as poor, those between 50% and 75% were considered as fair, while greater than 75% was considered as good awareness. Mann–Whitney and Kruskal–Wallis tests were used to compare the responses among groups. The characteristics of the participants were obtained through descriptive analysis using frequencies and percentages, while Fisher’s exact test was used to find out the association between doctors’ demographic characteristics and their awareness of diagnostic radiation exposure. A
A potential information bias may involve over-reporting of diagnostic X-ray procedures. This could possibly arise from the participants who may be more conscious of this type of exposure and therefore may have put more individual effort into recalling their diagnostic X-ray procedures when filling out the questionnaire. Selection of participants from different departments within the hospitals using cluster sampling was expected to significantly minimise this bias.
Ethical approval was obtained from Sefako Makgatho Health Sciences University Research Ethics Committee (SMUREC) before the commencement of this study (SMUREC/M/203/2017:PG). Approval was also obtained from the chief executive officer (CEO) of Dr George Mukhari Academic Hospital. Confidentiality of the participants was maintained as the names and other identifications were not required during the data collection process.
The investigations into medical doctors’ awareness of exposure to diagnostic radiation showed that more than 80% had not had any formal training on radiation exposure. Only 33.8% of doctors correctly estimated the average natural background radiation. Furthermore, the comparison of the radiation dose from a chest X-ray (CXR) to the annual dose a person receives from background radiation (1/10) was only correctly estimated by 20.6%, while the quantity of radiation a patient absorbs during a CXR (0.02 mSv) was only correctly estimated by 14.7% of respondents. The effective dose received by a patient in a two-view CXR was correctly estimated by the majority of doctors (54.6%) as twice the single-view CXR dose (
Doctors’ awareness of exposure to diagnostic radiation.
Parameters | Frequency | % |
---|---|---|
Yes | 36 | 18 |
No | 164 | 82 |
20–30 mSv | 39 | 26.9 |
2–3 mSv |
49 | 33.8 |
0.2–0.3 mSv | 46 | 31.7 |
200–300 mSv | 11 | 7.59 |
1/100 | 47 | 28.5 |
1/10 |
34 | 20.6 |
Equal | 24 | 14.6 |
10 times | 39 | 23.6 |
100 times | 21 | 12.73 |
0.02 mSv |
23 | 14.7 |
0.2 mSv | 54 | 34.6 |
2 mSv | 35 | 22.4 |
20 mSv | 37 | 23.7 |
200 mSv | 7 | 4.5 |
Almost equal to single-view chest X-ray | 27 | 17.5 |
Twice the single-view chest X-ray |
84 | 54.6 |
Five times the single-view chest X-ray | 21 | 13.6 |
10 times the single-view chest X-ray | 22 | 14.3 |
mSv, millisieverts.
, Correct responses.
Almost half of the doctors in this study showed that effective dose from a single-view abdominal X-ray (AXR) is equivalent to 1–10 CXR and that computed tomography (CT) abdomen single phase gives a dose of 100 mSv. Dosage from a two-view unilateral mammogram was stated to be almost equal to a single-view CXR by 38.8% doctors (
Doctors’ awareness of diagnostic radiation doses.
Parameters | Frequency | % |
---|---|---|
0–1 CXR | 39 | 24.4 |
1–10 CXR | 74 | 46.3 |
10–50 CXR | 35 | 21.9 |
50–100 CXR |
12 | 7.5 |
10 mSv |
49 | 30.3 |
100 mSv | 76 | 46.9 |
1 mSv | 19 | 11.7 |
None | 18 | 11.1 |
Almost equal to single-view chest X-ray | 64 | 38.8 |
Twice the single-view chest X-ray |
48 | 29.1 |
10–20 times the single-view chest X-ray | 41 | 24.9 |
50–100 times the single-view chest X-ray | 12 | 7.3 |
CT, computed tomography; CXR, chest X-ray; mSv, millisieverts.
, Correct responses.
More than 75% of doctors considered children as the most sensitive to radiation, while less than 20% perceived that the elderly were the best suited for this category (
Respondents’ perceptions of the category of people most sensitive to radiation (
In line with the American College of Radiology (ACR) guidelines, actions mostly recommended by the respondents in a situation where a pregnant woman had already undergone CT abdomen and pelvis with contrast without the radiologist’s knowledge of her pregnancy were to conduct a genetic analysis by amniocentesis or chorionic villous biopsy (36.6%) or to reassure the mother that the risk to the foetus is negligible (30.2%) (
Action to be taken according to American College of Radiology guidelines in a case of a pregnant woman that underwent computed tomography abdomen and pelvis with contrast, as her pregnancy status was not enquired into by the computed tomography technologist before performing computed tomography (
The most absorbed X-ray units as quantified by the respondents were between 1 and 10 units for AXR (39.8%), intravenous urography (IVU) (39.4%), barium enema (30.9%) and ventilation/perfusion scan (V/Q) (31.8%). Ultrasound (US) of the abdomen (64.2%), magnetic resonance imaging (MRI) of the brain (non-contrast) (48.5%) and MRI of the brain with intravenous (IV) contrast (35.5%) were considered to absorb between 0 and 1 units of X-ray. CT abdomen (with IV contrast) was mostly stated to absorb 50–100 units (26.9%) of X-ray (
The numbers of doctors who knew the doses of common but more complex imaging procedures.
Type of investigations | 0–1 u |
1–10 u> |
10–50 u |
50–100 u |
100–500 u |
Total |
||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
% | % | % | % | % | % | |||||||
Abdominal X-ray | 65 | 36.9 | 70 | 39.8 | 37 | 21.0 |
3 | 1.7 | 1 | 0.6 | 176 | 100 |
IVU | 31 | 18.8 | 65 | 39.4 | 53 | 32.1 | 15 | 9.1 | 1 | 0.6 |
165 | 100 |
Barium enema | 46 | 27.4 | 52 | 30.9 | 49 | 29.2 | 17 | 10.1 | 4 | 2.4 |
168 | 100 |
Abdominal ultrasound | 104 | 64.2 |
29 | 17.9 | 19 | 11.7 | 10 | 6.2 | 0 | 0 | 162 | 100 |
Brain MRI (non-contrast) | 83 | 48.5 |
31 | 18.1 | 21 | 12.3 | 23 | 13.5 | 13 | 7.6 | 171 | 100 |
Brain MRI with IV contrast | 61 | 35.5 |
47 | 27.3 | 24 | 13.9 | 23 | 13.4 | 17 | 9.9 | 172 | 100 |
V/Q scan | 31 | 18.2 | 54 | 31.8 | 41 | 24.1 | 33 | 19.4 |
11 | 6.5 | 170 | 100 |
CT abdomen (with IV contrast) | 15 | 8.8 | 40 | 23.4 | 40 | 23.4 | 46 | 26.9 | 30 | 17.5 |
171 | 100 |
CT, computed tomography; IV, intravenous; IVU, intravenous urography; US, ultrasound; MRI, magnetic resonance imaging; V/Q scan, ventilation/perfusion scan.
Note: Take a chest X-ray count as 1 unit (u).
, Correct responses.
The risk of inducing a fatal cancer from the radiation absorbed during diagnostic investigations was, in most instances, quantified as less than 1 in a million for AXR (55.8%), IVU (42.7%), barium enema (48.2%), abdominal ultrasound (75.3%), brain MRI (non-contrast) (60.5%), brain MRI with IV contrast (42.8%) and V/Q scan (32.5%). The risk associated with CT abdomen (with IV contrast) was assessed as 1 in 300 000–1 in 10 000 (32.3%) (
The number of doctors who knew the risk of inducing fatal cancer from common but more complex imaging procedures.
Type of investigations | Less than 1 in a million |
1 in a million to 1 in 300 000 |
1 in 300 000 to 1 in 10 000 |
1 in 10 000 to 1 in 5000 |
1 in 5000 to 1 in 1000 |
Total |
||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
% | % | % | % | % | % | |||||||
Abdominal X-ray | 96 | 55.8 | 36 | 20.9 | 25 | 14.5 |
11 | 6.4 | 4 | 2.3 | 172 | 100 |
IVU | 70 | 42.7 | 54 | 32.9 | 29 | 17.7 | 8 | 4.9 |
3 | 1.8 | 164 | 100 |
Barium enema | 80 | 48.2 | 47 | 28.3 | 28 | 16.7 | 9 | 5.4 | 2 | 1.2 |
166 | 100 |
Abdominal ultrasound | 122 | 75.3 |
24 | 14.8 | 8 | 4.9 | 4 | 2.5 | 4 | 2.5 | 162 | 100 |
Brain MRI (non-contrast) | 98 | 60.5 |
28 | 17.3 | 23 | 14.2 | 9 | 5.6 | 4 | 2.5 | 162 | 100 |
Brain MRI with IV contrast | 68 | 42.8 |
47 | 29.6 | 25 | 15.7 | 11 | 6.9 | 8 | 5.0 | 159 | 100 |
V/Q scan | 53 | 32.5 | 45 | 27.6 | 38 | 23.2 |
17 | 10.4 | 10 | 6.1 | 163 | 100 |
CT abdomen (with IV contrast) | 27 | 16.5 | 39 | 23.8 | 53 | 32.3 | 22 | 13.4 | 23 | 14.0 |
164 | 100 |
CT, computed tomography; IV, intravenous; MRI, magnetic resonance imaging; IVU, intravenous urography; V/Q scan, ventilation/perfusion scan.
, Correct responses.
Nearly all the medical doctors in this study (98.10%) demonstrated poor awareness of radiation risks, and only 1.40% expressed fair awareness, while none showed good awareness (
Respondents’ awareness of risk in diagnostic radiation.
Distribution of respondents based on their awareness of exposure to radiation (
The association between respondents’ awareness of exposure to diagnostic radiation and socio-demographic variables was not significant for most of the variables except the respondents’ departments which showed a statistically significant effect (
Association between respondents’ socio-demographic characteristics and their awareness of exposure to diagnostic radiation.
Parameters | Variables | Awareness | Test of significance | |||||||
---|---|---|---|---|---|---|---|---|---|---|
Poor |
Fair |
Total |
Fisher’s exact test | |||||||
<50% | 50% – 75% | % | ||||||||
Gender | Male | 133 | 99.3 | 1 | 0.8 | 134 | 100 | 3.71 | 2 | 0.563 |
Female | 78 | 97.5 | 2 | 2.5 | 80 | 100 | ||||
Age (years) | ≤ 30 | 47 | 100 | 0 | 0 | 47 | 100 | 2.97 | 4 | 0.429 |
31–40 | 97 | 99 | 1 | 1.0 | 98 | 100 | ||||
41–50 | 52 | 96.3 | 2 | 3.7 | 54 | 100 | ||||
51–60 | 7 | 100 | 0 | 0 | 7 | 100 | ||||
> 60 | 5 | 100 | 0 | 0 | 5 | 100 | ||||
Years of clinical practice | < 5 | 58 | 98.3 | 1 | 1.7 | 59 | 100 | 0.976 | 3 | 1.00 |
5–10 | 80 | 98.8 | 1 | 1.2 | 81 | 100 | ||||
11–20 | 48 | 98 | 1 | 2.0 | 49 | 100 | ||||
>20 | 17 | 100 | 0 | 0 | 17 | 100 | ||||
Employment level | Interns | 43 | 100 | 0 | 0 | 43 | 100 | 4.139 | 4 | 0.691 |
Medical officers | 36 | 97.3 | 1 | 2.7 | 37 | 100 | ||||
Resident doctors | 83 | 97.7 | 2 | 2.4 | 85 | 100 | ||||
Consultants | 38 | 100 | 0 | 0 | 38 | 100 | ||||
Department of the participants | Anaesthesiology | 50 | 100 | 0 | 0 | 50 | 100 | 20.4 | 10 | 0.0001 |
Gynaecology and Obstetrics | 34 | 100 | 0 | 0 | 34 | 100 | ||||
Internal Medicine | 31 | 100 | 0 | 0 | 31 | 100 | ||||
Orthopaedics | 6 | 100 | 0 | 0 | 6 | 100 | ||||
Surgery | 5 | 100 | 0 | 0 | 5 | 100 | ||||
Emergency Unit | 5 | 100 | 0 | 0 | 5 | 100 | ||||
Paediatrics | 12 | 100 | 0 | 0 | 12 | 100 | ||||
Radiology | 6 | 66.7 | 3 | 33.3 | 9 | 100 | ||||
Family Medicine | 31 | 100 | 0 | 0 | 31 | 100 | ||||
Urology | 5 | 100 | 0 | 0 | 5 | 100 | ||||
Ophthalmology | 7 | 100 | 0 | 0 | 7 | 100 | ||||
Investigations into the awareness of doctors about diagnostic radiation exposure revealed that over 80% of them have never had any formal training about ionising radiation. This possibly explains the poor awareness of most of the physicians about routine radiology examinations, as observed in the report of Azmoonfar et al.
An estimated exposure range of approximately 10–20 mSv per procedure, depending on the type of imaging test, and multiple tests have been reported to result in cumulative exposures of more than 100 mSv.
Generally, dosage from a two-view unilateral mammogram was said to be almost equal (38.8%), twice (29.1%), 10–20 times (24.9%) or 50–100 times (7.3%) to single-view chest X-ray, respectively. However, the record of children being the category of people most sensitive to radiation as indicated by more than 75% participants in this study is in line with the findings of Ramanathan and Ryan.
Except in abdominal ultrasound investigations where more than 64% respondents displayed good awareness of the recommended doses of imaging procedure, only a small percentage of the doctors demonstrated good awareness of radiation doses in other investigations such as AXR (21.02%), V/Q scan (19.41%), IVU (0.61%), barium enema (2.3%), CT abdomen (17.54%), brain MRI (non-contrast) (48.54%) and brain MRI with IV contrast (35.47%). This is in contrast to a survey conducted in Northern Ireland, where an improved awareness of the doctors in comparison with the result of the present study was attributed to the formal training about ionising radiation.
Generally, the results of 98.10% of doctors who displayed poor awareness of radiation exposure in diagnostic radiology investigations corroborated the findings of some earlier investigations.
Despite the higher number of male doctors compared to female doctors who participated in this study, female doctors displayed a higher level of awareness than the male doctors. Although the difference was not significant, this gender distribution was found to be in line with the finding from a study by Kamble et al.
Only participants from the radiology department demonstrated fair awareness of radiation exposure in diagnostic imaging, and this could be associated with the earlier training and ethics of their job.
The present study has some limitations. Firstly, it was conducted as a single-centre study at DGMAH, which prevented the researcher from making comparisons and eventually finding out any differences among doctors from different academic institutions. While this could be an interesting extension of the present work that might warrant further investigation, it was noted that the teaching curricula for doctors in the whole of South Africa are harmonised by the Department of Higher Education and Training (DHET) and the Colleges of Medicine of South Africa (CMSA). This harmonisation should contribute to mitigating potential inter-institutional discrepancies. Secondly, the sample size was not large compared with other studies,
Based on the findings of this study, the authors would recommend the following:
The management of DGMAH needs to conduct regular refresher programmes for its doctors on radiology investigations, with the aim of ensuring their adequate knowledge and awareness of radiation exposure in diagnostic radiology investigations.
The management of DGMAH and the Department of Health (DoH) must ensure that appropriate radiological examination guidelines are drafted, vigorously circulated, put into practice and enforced at all levels of healthcare services.
It is advisable for the DHET, DoH and CMSA to put more emphasis on the diagnostic radiation courses and education at graduate and postgraduate levels, as well as justification of referral for imaging among clinicians of all specialities. Medical students should be exposed to the Department of Radiology as much as they rotate in other medical specialities such as internal medicine and surgery.
Internship rotations should be made to include compulsory rotations in the Department of Diagnostic Radiology.
These will be achieved by doing the following: Efforts will be made to give the recommendations to the management of DGMAH and seek an audience to discuss the findings, implications and recommendations. Secondly, with the permission of the DGMAH’s management, the authors will write a memorandum relating to the findings of this research and recommendations to the DoH, DHET, CMSA and HPCSA.
The value of radiation and various technologies that utilise radiation are undisputed. However, the enormous growth in their use has not been paralleled by adequate education about the associated doses and risks of diagnostic ionising radiation. The results of this survey confirm that awareness of diagnostic radiation and its associated cancer-causing risks are inadequate across the medical professions. In certain clinical settings, doctors with inadequate awareness of these issues may be unable to perform required risk–benefit analyses and, therefore, will be incapable of fully informing their patients about these issues.
Injudicious use of diagnostic radiation is a small but concerning feature of modern medicine, and such practices may result in unnecessary exposure, avoidable stochastic effects, medico-legal uncertainty and, in some cases, an abandonment of evidence-based medicine. Improved education about radiation doses and potential risks from imaging is necessary across all levels of medical professions to ensure optimal use of these important diagnostic tools and the preservation of best medical practices. The educational programme for residents needs to focus not only on image interpretation but also on radiation awareness. Focussing on these aspects will be an important move towards minimising wastage of resources, reducing unnecessary radiation exposure and improving patient safety.
This article could never have been completed without the help and advice of many. Their help came in many forms. The authors would like to say thank you to the following people: to my head of department Prof. M. E. Kisansa for creating a conducive environment that enabled the conduct of this study; to the heads of departments and the doctors at Dr George Mukhari Academic Hospital who responded to the study questionnaires and finally, to the management of Dr George Mukhari Academic Hospital Gauteng Province, South Africa, for allowing the authors to conduct the research.
The authors declare that they have no financial or personal relationships which may have inappropriately influenced them in writing this article.
All authors contributed equally to this work.