Reduction in Lens Dose in Temporal Bone Computed Tomography by Modification of Scanning Plane

Abstract

Objectives: To evaluate the radiation dose reduction to the lens by modifying the scanning plane to exclude the orbit in temporal bone computed tomography (CT). The effect on diagnostic image quality was also evaluated. Methods: Radiation dose reduction was evaluated using a phantom head and calibrated thermoluminescent dosimeters. Image quality was assessed in 34 patients. Two radiology fellows independently reviewed the image and assessed the image quality of 20 temporal bone structures. The image quality was scored on a 4-point scale and analysed with Mann Whitney U test. Results: We demonstrated a 31.4% to 46.1% dose reduction to the lens by excluding the orbit in the scan field. The dose-length products before and after the modification were comparable (p = 0.267). None of the assessed temporal bone structures demonstrated any significant difference in image quality (p > 0.05). Conclusion: Modification of the scanning plane in temporal bone CT can reduce radiation dose exposure to the lens and preserve the diagnostic image quality. This protocol should be considered to minimise the radiation exposure to patients.