Thyroid shield during brain CT scan: Dose reduction and image quality evaluation

Introduction: The aim of this study was to investigate the dose reduction to the thyroid gland during routine brain CT examinations. Also, the study compares the quality of the images before and after applying the thyroid shields. Material and methods: An experimental study utilizing head attenuation phantom and multi-slice 16 CT scanner. Dose measurement conducted by thermoluminescent dosimeter (TLD). A circumferential thyroid shielding was used during pre and post scan, images from scan qualitatively assessed for quality parameters such as grayscale, noise, soft tissue, bone details and overall image quality. Results: An average of 45% reduction in the entrance skin dose to the thyroid area was reported. 40-60% dose reduction was achieved at different points along thyroid region. The results of the image quality comparisons between scans done with and without shielding showed that quality of the images was not affected. Significant reduction in the scatter radiation dose to the thyroid during CT head scan when shielding applied. The study proved that application of thyroid shielding would not affect the quality of the images. Therefore, it is highly recommended to be used during brain scan whenever it is possible.