Abstract
The number of computed tomography (CT) examinations and new indications for CT are increasing in frequency worldwide. While CT makes up only 4% of medical examinations, it might contribute as much as 40% of the total collective radiation dose to the population. Radiologists and referring clinicians should make sure that the CT examination is indicated. Doses can often approach or exceed levels known to increase the probability of cancer. This is especially relevant in children where dose reductions of up to 80% can be obtained by adjusting the exposure factors. The most important factors are decreased milliampere seconds (mAs) and increased pitch.
Highlights
Part of the work of a radiologist is to advise on the appropriate investigation for specific clinical problems
While clinicians are obligated to minimise doses administered to patients, strictly speaking there are no dose limits for patients.' While large radiation doses can result from fluoroscopic studies and interventional procedures, this article concentrates on computed tomography (CT) examinations as CT might contribute as much as 40% of the total collective dose to the population, while representing only 4% of the total number of medical examinations." In addition, newer CT indications and examinations, e.g. triplephase liver studies, have increased the radiation doses when compared with standard CT.[6,7]
What about doses received from CT? The United Kingdom National Radiological Protection Board (NRPB) has stated that the effective dose will underestimate the detrimental effect of paediatric exposure by about a factor of two.' In addition, a study using abdominal CT showed that the effective dose was 50% higher in children compared with adults," Asofearly2001 there are no published reference figures available for children on the effective dose received from CT examinations,'
Summary
Part of the work of a radiologist is to advise on the appropriate investigation for specific clinical problems. As radiation workers we are entrusted with the task of assessing whether the benefit from an investigation outweighs the radiation risk involved. Most radiologists in clinical practice are not sufficiently aware of the relative risks of the various examinations that they routinely perform. This is understandable given the numerous confusing methods used and quoted in radiation physics. There is increasing awareness among clinical colleagues and the public that we should know and adjust our practice . The dangers of radiation have been known since the early days of its usage in clinical medicine. While clinicians are obligated to minimise doses administered to patients, strictly speaking there are no dose limits for patients.' While large radiation doses can result from fluoroscopic studies and interventional procedures, this article concentrates on computed tomography (CT) examinations as CT might contribute as much as 40% of the total collective dose to the population, while representing only 4% of the total number of medical examinations." In addition, newer CT indications and examinations, e.g. triplephase liver studies, have increased the radiation doses when compared with standard CT.[6,7]
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