Assessment of head CT protocol to reduce the radiation dose in eye lens in some selected hospital in Kaduna State, Nigeria

Abstract

The lens of the eye are very sensitive to radiation and mostly exposed to scattered radiation during the Computed Tomography (CT) procedure. The study measures the absorbed doses to the lens of the eye and proposed a diagnostic reference level for head examination by comparing the current research result with the international standard. The incurred doses of 62 patients who undergone head and neck CT procedure were measure using thermoluminescent dosimeters (TLD-100), the protocols adopted in the study were brain (sequential and spiral), sinus (sequential and spiral), and neck-brain (spiral). The scanning parameters were CT dose index (CTDI), dose length product (DLP), tube current-exposure time product (mAs), kilovoltage peak (kVp), pitch factor, for each patient were recorded. The patients were divided into two age groups (½ to 17) years for Pediatric and >18 years for adult patient, TLD chips were placed on the patient's skin surface at two different locations to measure the absorbed dose of the lens of the eye. The mean dose and standard deviation to left and right eye lens for Hospital A, for Paediatrics Patients were (left 5.29 ± 7.32 mGy, right 5.73 ± 8.9O mGy), Adult Patients (left 5.74 ± 9.23 mGy, right 4.78 ± 6.11 mGy), Hospital B Paediatrics (left 5.08 ± 9.06 mGy, right 2.82 ± 2.67 mGy) Adult (left 0.26 ± 0.07 mGy, right 0.48 ± 0.08 mGy), Hospital C Paediatrics (left 8.95 ± 15.20 mGy, right 7.32 ± 6.14 mGy) Adult (left 6.41 ± 4.15 mGy, right 7.24 ± 5.69 mGy). Threshold recommended by International Commission on Radiological Protection (ICRP) for lens of the eye damage, it appears to be clinically safe. While CT scan remains a crucial tool, further dose reduction can be achieved by controlling different factors affecting patient doses.

Keywords: Computed tomography; Dosimetry; Thermoluminescent and cataracts.