Patient-Specific Radiation Dose and Cancer Risk in Computed Tomography Examinations in Ondo, Nigeria

Introduction: The dose in computed tomography (CT) often approach or exceed the optimum levels, thereby increasing the probability of cancer induction. With wide application of this diagnostic test, it is expedient to determine the effective dose (ED) for each patient to estimate their cancer risk. This study was conducted to investigate the patient-specific dose (PSD) and cancer risk in CT examinations in Ondo, Nigeria. Material and Methods: The study was conducted on ۱۶۰ patients undergoing eight most common types of CT examinations performed at the center, from December ۵, ۲۰۱۵ to February ۲۸, ۲۰۱۶. Body mass index (BMI) was calculated for each patient using demographic data, PSD was determined and estimation of the lifetime attributable risk (LAR) of cancer was accomplished using the Biologic Effects of Ionizing Radiation VII (۲۰۰۶) report phase ۲ models. Results: From the results, radiation doses varied significantly within and between the types of CT examinations. The mean ED was ۵.۸۸±۳.۷۵ mSv in a range of ۰.۷۸-۱۹.۰۰ mSv. The mean PSD was ۰.۲۷۴±۰.۲۲۹ mSv/kgm-۲ in a range of ۰.۰۲۴-۱.۵۵۵ mSv/kgm-۲ and the mean LAR of cancer incidence was ۰.۰۴۸۶۱±۰.۰۳۹۹۶ Sv-۱ in a range of ۰.۰۰۰۰۴-۰.۲۱۹۴۲ Sv-۱. Conclusion: ED and PSD varied within and across the CT examinations. In this regard, the coefficients of variation of ED for abdominal, cranial, craniocervical, abdomen/pelvis, thoracic, thoracoabdominal, cervical spine, and pelvis were ۵.۷%, ۶.۶%, ۳.۹%, ۸.۹%,۳.۷%, ۶.۰%, ۴۴.۷%, and ۱۹.۲%, respectively. Accordingly, the coefficients of variation of PSD were ۹.۰%, ۷.۹%, ۷.۰%, ۱۰.۱%,۵.۶%,۲۳.۸%, ۴۷.۷%, and ۱۴.۲%.