Estimation of Radiation Doses and Lifetime Attributable Risk of Radiation-induced Cancer from A Single Coronary Artery Bypass Graft Computed Tomography Angiography

Introduction: Despite worldwide consensus that coronary artery bypass graft computed tomography angiography (CABG CTA) confers benefit to patients when used for appropriate indications, the increased cancer risk due to radiation dose remains a concern. The aim of this study is the estimation of organ effective dose (ED) and lifetime attributable risk (LAR) of cancer incidence and mortality related to a single CABG CTA procedure. Methods and materials: This retrospective cross-sectional designed study included 102 CABG patients who, from January 2021 to June 2021, underwent a retrospective 64-slice ECG-gated CABG CTA covering the area of the grafts with optimal image quality. The estimation of ED was done using the imPACT CT Dosimetry spreadsheet. LAR of cancer incidence was estimated for CABG CTA using the website X-rayrisk.com. Results: The mean total ED of CABG procedure was 15.35 mSv. The highest organ doses were those to the lungs (5.04 mSv) and breast (4.49 mSv). The cancer risk is higher in female (1 in 1516) than in male patients (1 in 1762). The LAR of cancer is higher for the younger age group in both males and females. The total whole-body ED demonstrated that CABG CTA is equivalent to 154 chest radiographs or 37 screening mammography studies, which in turn correspond to approximately 4.3 or 5-years of natural background radiation, respectively. Conclusions: Despite many benefits of CABG CTA, it is associated with a non-negligible risk of malignancy, so a careful risk/benefit assessment is recommended in justifying CABG CTA procedures, especially for young female patients.