Monte Carlo simulations for assessment of organ radiation doses and cancer risk in patients undergoing abdominal stent-graft implantation.

Abstract

The aim of this work was to assess absorbed radiation doses in selected organs and to estimate cancer and mortality risks in patients undergoing abdominal stent-graft implantation, as a function of age, gender, and anatomical parameters of patients' aneurysms and arteries. 297 patients (266 males and 31 females) underwent endovascular aortic aneurysm repair (EVAR) with abdominal stent-graft implantation. Kerma-area products Gy-cm(2) for all implanted patients were collected retrospectively. Entrance surface air kerma (ESAK), doses absorbed by selected organs, and cancer/mortality risks were estimated using Monte Carlo simulation methods (CALDose_X software). The highest radiation doses were deposited in the skin, gallbladder wall, and colon wall. The highest average cancer risk was found for the youngest group of patients (<60 years old; 1:275) and the lowest for the oldest (>70 years old, 1:735). The radiation-induced risk of cancer mortality (mortality risk) was about 40% lower than radiation-induced cancer occurrence risk. Aneurysm neck angulations >45° had a significant impact on ESAK, as well as increasing cancer and mortality risks. The main factors increasing cancer risk are young age and aneurysm neck angulations >45°, which determines the difficulty of proper stent-graft placement. However, the radiation risk associated with the stent-graft implantation procedure is relatively low, and EVAR should not be avoided.