Brain and Lenses of the Eyes Doses from Head Computed Tomography: A Study of Selected Computed Tomography Centres in Enugu, Enugu State, Southeast and Nigeria

Exposure of the brain and/or eyes to excess radiation could have serious consequences. This study investigated the radiation doses received by the brain and the lenses of the eyes during diagnostic computed tomography (CT) examination of the head. Lithium Fluoride thermoluminescent dosimeter (TLD 100) chips were used to collect dose data from 32 patients(17males and 15females, age range 3-65years) attending for CT investigations of the head at the CT unit of Memfys Hospital for Neurosurgery, Enugu, Enugu State between July 2012 and January 2013. The absorbed dose to each subject was measured and converted to effective dose using appropriate tissue weighting factors. In adult patients the mean brain absorbed dose and effective dose were 2.940±1.120mSv and 0.147±0.056mSv respectively. For the eyes, the mean doses were: absorbed dose, 2.947±1.1.113mSv and effective dose, 0.884±0.334mSv. In children, the brain received a mean absorbed dose of 3.918±0.003mSv and a mean effective dose of 0.196±0.001mSv while the lens of the eyes received a mean absorbed dose of 5.600±0.001mSv and a mean effective dose of 1.680±0.001mSv. A weak negative non-significant correlation(r = - 0. 113; P = 0. 231) was noted between dose and age. A weak positive non-significant correlation (r = 0.124; P =0.136) occurred between dose and number of images. This study revealed that the radiation doses to the brain and the lenses of the eyes were quite low,