Evaluation of patient radiation dose and risk of cancer from CT examinations

Abstract

Computed Tomography (CT) examinations have been increasingly requested and become the major sources of patient exposure. The cancer risk from CT scans is contingent upon the amount of organ absorbed dose. This study aims to evaluate the cumulative effective doses (CED) and risk of cancer incidence and mortality from recurrent CT examinations in a single day. The patient data at aged 15 to 75 years old performed CT examinations during the period of five years from January 2018 to December 2022 were collected from two academic centers. The CED and organ doses were evaluated using Radimetrics™ Enterprise Platform from Monte Carlo simulations. Lifetime attributable risk (LAR) was determined following Biological Effects of Ionizing Radiation (BEIR) VII Phase 2 report based on the organ dose, gender, age at exposure, attained age, and demographic statistics of the Thai population (baseline rate of cancer and survival probability data). The number of patients who underwent CT examinations receiving CED 100 mSv and above in a single day was 27, accounting for 0.009 percent of 285,286 CT examinations. The highest LAR for breast cancer incidence in young female was 82 per 100,000 exposed patients with the breast dose of 148 mGy from CT whole abdomen. The highest LAR for liver cancer incidence in male patient was 72 per 100,000 with liver dose of 133 mGy from multiple CT scans. At low dose, the highest LAR for breast cancer incidence in young female was 23 per 100,000 while for liver cancer incidence in male patients was 22 per 100,000 from CTA whole aorta. Even though the LAR of cancer incidence and mortality was less than 100 per 100,000, they should not be neglected, particularly in young patients. The risk of cancer incidence could be increased in later life. The patient age at exposure has a strong negative correlation with LAR for cancer incidence and the statistically significant, p < 0.05.