Does Radiation Exposure from Abdominal Computed Tomography Increase Cancer Risk in Patients with Inflammatory Bowel Disease and Behçet Disease?

Although high dose ionizing radiation (>100 mSv) harms humans, particularly (but not exclusively) concerning cancer, the effect of lower radiation doses is less clear. Low dose radiation exposure is of societal importance in relation to screening tests for cancer and occupational radiation exposure, as two examples. Inflammatory bowel disease (IBD) patients and cancer survivors undergo multiple radiological evaluations. Epidemiological data has implicated protracted exposure to a dose of 50 to 100 mSv with increased cancer risk. An X-ray irradiation from disease-related diagnostic procedures has recently been questioned because of the potential cancer risk associated with the increasing use of computed tomography (CT). The effective dose from plain abdominal X-ray, for example, is around 0.7 mSV, and the effective dose from abdominal CT is equivalent to the effective dose of approximately 14 to 15 abdominal X-rays. The effective radiation dose for abdominal CT is estimated to be 10 mSv and the dose for multidetector abdominal CT is 16.1 mSv. The number of CT scans performed has been increasing recently. Concerns arise when CT is used without a proven clinical rationale, when alternative modalities like ultrasound and magnetic resonance imaging (MRI) could be used with equal efficacy, or when CT is repeated unnecessarily. Another important issue is the increasing use of CT scans as a screening procedure in asymptomatic patients. The benefit/risk balance for CT should be considered. Chronic inflammation of the gastrointestinal (GI) tract in Crohn’s disease and ulcerative colitis increases the risk of cancer and medications including azathiopurine, mercaptopurine, and