READING, UK. A team of medical doctors from several hospitals in the UK has performed a survey of their peers to gauge their knowledge of the amount of radiation exposure their patients receive when subjected to various types of x-ray examinations. One hundred and thirty practicing medical doctors were involved in the survey. The results were, to put if mildly, disappointing. Not one of the respondents know the approximate dose a patient is exposed to during a chest x-ray let alone the unit of measurement used to quantify x-ray exposure. A chest x-ray exposes the patient to approximately 0.02 mSv of radiation. The doctors were also asked to provide an estimate of the radiation exposure in other procedures in terms of the equivalent number of chest x-rays. Only 1.5% of the doctors knew that one abdominal x-ray is equivalent to 75 chest x- rays and only 6% were aware that a CT scan of the abdomen is equivalent to 400 chest x-rays. None of the doctors knew that a leg arteriogram exposes the patient to a radiation dosage equivalent to that of 400 chest x-rays. The researchers conclude that most doctors have no idea as to the amount of radiation received by patients undergoing common x-ray examinations. They estimate 100 to 250 deaths occur each year in the UK as a result of cancers caused by medical radiation exposure.
Shiralkar, S, et al. Doctors' knowledge of radiation exposure: questionnaire study. British Medical Journal, Vol. 327, August 16, 2003, pp. 371-72
Editor's comments: I think perhaps the investigators in this study are being a little harsh on their fellow physicians. From what I can glean from the literature estimates of the radiation exposure from a chest x-ray varies between 0.02 milliSievert (2 millirem) and 0.08 mSv (8 millirem). Similarly, estimates of exposure from a CT scan vary between 1.1 mSv and 8 mSv. It is interesting that very few medical sites on the Internet actually give values for exposure. Most couch the exposure risk in very vague terms like "don't worry, be happy!" The Canadian Centre for Radiation Safety limits maximum annual exposure from medical x-rays to 1.0 mSv. So having more than one CT scans in a year could be problematical down the road. I think the problem of doctors not knowing how much radiation they are causing their patients to be exposed to goes much deeper. Do the radiation experts really know and, perhaps more important, do they really know the associated long-term cancer risks?