[Dosimetry of cone-beam computed tomography and multi-slice computed tomography scanning for temporal bone].

ABSTRACT

Objective: To compare the effective radiation dose levels of cone-beam computed tomography (CBCT) with those of multi-slice computed tomography (MSCT) when scanning for the temporal bone. Methods: The absorbed doses of CBCT and MSCT scanners were detected using thermoluminescent dosimeters (TLDs) that were placed in a head and neck phantom and a RGD-3D dose reader.Then the effective doses were calculated and expressed according to the International Commission on Radiation Protection (ICRP) 2007 guidelines. Results: Three-dimensional images about temporal bone can obtained by both CBCT and MSCT scanners in this study.The effective dose value of CBCT scanning for bilateral and unilateral temporal bone was 164.1 µSv (bone marrow 32.1 µSv; thyroid gland 10.6 µSv; salivary glands 31.0 µSv), and 98.1 µSv (bone marrow 17.4 µSv; thyroid gland 6.2 µSv; salivary glands 16.1 µSv), respectively.The dose of MSCT scanning for bilateral temporal bone was 714.6 µSv (bone marrow 95.1 µSv; thyroid gland 127.8 µSv; salivary glands 135.7 µSv). Conclusions: When scanning for the temporal regions, the dose levels for CBCT are lower than those for MSCT.Dose levels reduction for CBCT could be obtained when smaller regions were scanned.