Evaluation in the Use of Bismuth Shielding on Cervical CT Scan Using a Female Phantom

Abstract

Computed Tomography (CT) has become an important tool to diagnose cancer and to obtain additional information for different clinical questions. Today, it is a very fast, painless and noninvasive test that can be performed high quality images. However, CT scans usually require a higher radiation exposure than a conventional radiography examination. The aim of this study is to determine the dose variation deposited in thyroid and in nearby radiosensitive organs, such as: lenses, pharynx, hypophysis, salivary gland, spinal cord and breasts with and without the use of bismuth shielding. A cervical CT scan was performed on anthropomorphic female phantom model Alderson Rando, from the occipital to the first thoracic vertebra, using a GE CT scanner, Discovery model with 64 channels. Dose measurements have been performed by using radiochromic film strips to recorder the individual doses in the organs of interest. After the phantom cervical CT scan, the radiochromic film strips were processed for obtaining digital images. Digital images were worked to obtain the dose variation profiles for each film. With the data obtained, it was found the organ dose variation. The results show us that the thyroid received the highest dose, 24.59 mGy, in the phantom, according to the incidence of the primary X-ray beam.