Eye Lens Radiation Exposure and Diagnostic Image Quality in Pediatric Brain CT: Comparison of Different Dose Optimization Techniques

Introduction and objective: Computed tomography (CT) of the brain is associated with radiation exposure to the lens of the eyes. Therefore, it is necessary to optimize scan settings to keep radiation exposure as low as reasonably achievable without compromising diagnostic image information. The aim of this study was to comparative effectiveness of the five practical techniques for lowering eye radiation exposure and their effects on image quality in pediatric brain CT.Methods: The following scans were performed: reference scan, ۰.۰۶-mm Pbeq bismuth shield, ۳۰% globally lowering tube current (GLTC), lowering tube voltage (LTV) from ۱۲۰-to-۹۰ kVp, gantry tilting and combination of gantry tilting with bismuth shielding. Radiation measurements were performed using thermoluminescence dosimeters. Objective and subjective image quality were evaluated.Results: All strategies significantly reduced eye dose, and increased the posterior fossa artifact index (PFAI) and the temporal lobe artifact index (TLAI), relative to the reference setting. GLTC and LTV increased image noise, leading to lower signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Except for bismuth shielding, subjective image quality was relatively the same as the reference setting.Conclusions: Exclusion of the eyes’ lens from the scan field by using either gantry tilting or a patient chin down position may be the most effective strategy to reduce the eye dose in pediatric brain CT. For those having difficulty holding their chin down during the scan, GLTC setting might be an alternative .

کلیدواژه ها:

Radiation Exposure ، Image Quality ، Eye ، Lens ، brain CT