Evaluation of Effective Dose and Associated Radiation Risks in Common Computed Tomography Procedures

Abstract

Background:The radiation exposure associated with CT is known to be significantly higher compared to the conventional x-rays. The objective of this study was to estimate the radiation dose and related risks for five common CT procedures in clinical setting. Materials and Method:The study included 150 patients referred for CT brain, cerebral angiography, neck, thorax, abdomen & pelvis. The scan was performed using a 64 slice Philips Brilliance. "Dose length product" was used to estimate "effective dose" using specific "conversion factors". The lifetime attributable risk of cancer was determined using a formula adapted from the phase 2 BEIR VII report. Results:The results depicted that the mean effective dose varied substantially for various CT procedures. The "effective dose" ranged from 2.19 mSv for CT brain to 11mSv for CT abdomen and pelvis. An estimated incidence of cancer due to each procedurewas found to be 1 in 5618 for CT Brain, 1 in 4315 for CT Neck, 1 in 2.084 in CT Cerebral angiogram, 1 in 1773 patients for CT Chest and 1 in 1086 patients for CT Abdomen Conclusion: Radiation doses for certain CT procedures were found to be higher than generally quoted thereby increasing the risk. Therefore there is a need for optimizationof CT protocols.