Analysis of lens absorbed dose in head CT scan using a male anthropomorphic phantom

This study aims to perform a dosimetric study on lens in head CT scan. A Ge CT scanner, model Discovery with 64 channels, was used for irradiated a male anthropomorphic phantom, model Alderson Rando and radiochromic film strips were used for dose measures. Two head scans were performed using the routine protocol used in the radiodiagnosis service, programming the appliance with a voltage of 120 kV, a current of 175 m A and a pitch of 0.984. Experiments were performed with the phantom in supine position and in supine with the head tilted. Radiochromic film strips were placed in the lenses and in nearby radiosensitive organs, such as: thyroid, pharynx, hypophysis, salivary glands, spinal cord and breasts for each scan. Recorded absorbed doses were among 1.80 and 19.23 mGy. Recorded absorbed doses were lower with the head tilted, mainly in the lenses. The analysis of noise indexes in the image of the head central slice presented acceptable values for soft tissues, less than 1%. (Author)