Estimation of radiation-induced cataract and cancer risks during routine CT head procedures

Abstract

Eye lenses lie within the radiation field during computed tomography (CT) procedures of the brain. Therefore, patients are at risk of forming eye lens opacity when exposures exceed the threshold for such onset. The purpose of this study was to estimate the eye lens equivalent and radiation effective doses during CT procedures of the brain, facial bones, and paranasal sinuses. A total of 85 patients were examined using a 16-detector CT machine. The organ and surface dose received by specific radiosensitive organs was carried out using software from the National Radiological Protection Board (NRPB). The overall mean patient doses were as follows: CTDIvol, 45.7 ± 15.6 mGy for brain; and 7.6 mSv for the eye lens. The mean eye lens equivalent dose per CT procedure was 11.5 mSv, 4.5 mSv, and 6.7 mSv for the brain, paranasal sinuses, and facial bones, respectively. The radiation risk per procedure equates to 1 cancer case per 11 × 10−3 procedures. The study shows there to be great need for improving the imaging protocol and for continuous training of staff. Dose reduction techniques in brain CT are required, eye lens irradiations potentially generating lens opacities.