Measurement of Effective Dose to Head and Neck Critical Organs in Computed Tomography

One of the most effective methods to report organ dose in CT scan (Computed Tomography scan) is to report effective dose. This study aimed to investigate the actual dose during head and neck CT scans using an anthropomorphic head phantom. In this study, an anthropomorphic phantom was constructed with natural bone and paraffin wax. Then, we considered several sites in the phantom to investigate the dose. These sites include the Brain, Thyroid, Parotid, and Lens, which were filled by Gafchromic films. Finally, we irradiated the phantom using several CT protocols. Our findings indicate that the dose of the considered organs was in the different ranges according to the protocol used. The highest dose range was related to the ten-slice spiral, ranging from 0.75 to 15.8 mGy (Mean). We showed the lowest dose range in SPECT-CT which was in the range of 0.55 to 0.1 mGy (Mean). The absorbed dose of the eyes was much higher in most protocols compared to the other organs. There is also the most significant difference between the lens and the other organs in the ten-slice spiral CT. Comparing the 10 and 256 slice scanners; we showed that the organ dose in the 256 slice is less than ten slices. The lowest mean organ dose (mGy) and SD (Standard Deviation)  are related to the SPECT CT, which are 0.76±0.03, 0.95±0.02, 0.78±0.02, and 0.71±0.02 for the brain, parotid, lens, and thyroid, respectively.