Radiation Safety: Radiation Dosimetry and CT Dose Reduction Techniques

Abstract

The ability of modern multidetector CT scanners with submillimeter resolution, subsecond rotation time, and large volume imaging has resulted in widespread utilization of cardiovascular computed tomographic angiography (CCTA) [1]. However, the widespread use of CCTA has also raised concerns about the radiation dose to the patients. The National Council on Radiation Protection, NCRP Report No. 160, reported that the radiation exposure to the United States population due to medical sources increased more than 7 times in the 20 years between 1986 and 2006 [2]. Although in 2006 CT constituted about 10% of the diagnostic examinations that utilize X-rays, it contributed to nearly 50% of the population dose [2–4]. Based on our current knowledge of radiation biology, the deleterious effects of radiation are cumulative and medical radiation is increasingly a significant contributor to the amount of radiation accumulated in a person’s lifetime [1, 2, 5]. The risk of cancer from radiation exposure is especially worrisome in children and young women who received multiple CT examinations early in their lives. For example, studies found that one CT examination of the female chest gives as much radiation as 10 mammograms to each breast [6]. Therefore, the practitioners of CT must be constantly aware of the risks of radiation and strive toward applying the lowest dose to the patient consistent with the clinical study.