Department of Radiology & Radiologic Imaging, Medical University of South Carolina, Charleston, SC, USA.
Department of Bioengineering, Clemson University, Clemson-MUSC Bioengineering Program, Charleston, SC, USA.
Dentomaxillofac Radiol. 2021 Mar 1;50(3):20200225. doi: 10.1259/dmfr.20200225. Epub 2020 Nov 11.
The purpose of this study was to review the literature to examine the usage and magnitude of effective dose conversion factors (DC) for dental cone beam CT (CBCT) scanners.
A PubMed literature search for publications relating to radiation dosimetry in dental radiography was performed. Papers were included if they reported DC, or reported ICRP 103 effective dose and dose-area product. 71 papers relating to dental CBCT dosimetry were found, of which eight reported effective dose conversion factors or provided enough information to calculate dose conversion factors. Scanner model, effective dose, dose-area product, tube voltage, field of view size and DC were extracted from the papers for analysis.
DC values ranged from 0.035 to 0.31 µSv/mGy-cm with a mean of 0.129 µSv/mGy-cm (SD = 0.056). When categorized into small (<100 cm), medium (100-225 cm) and large (>225 cm) fields of view (FOV), linear fits to the effective dose and dose-area product yielded slopes of 0.129, 0.111 and 0.074 µSv/mGy-cm for small, medium and large FOVs respectively.
The range of reported DC values and spread with respect to field of view category suggests that DC values that depend on FOV would provide more accurate effective dose estimates. Tube voltage was found to be a smaller factor in determining DC. Reasonable values for DC taking into account FOV size were obtained. There is considerable room for more work to be done to examine the behaviour of DC with changes to patient age and dental CBCT imaging parameters.
本研究旨在回顾文献，以检查牙科锥形束 CT（CBCT）扫描仪有效剂量转换系数（DC）的使用和幅度。
对与牙科放射摄影辐射剂量学相关的出版物进行了 PubMed 文献检索。如果报告了 DC，或者报告了 ICRP 103 有效剂量和剂量面积乘积，则将论文包括在内。共发现 71 篇与牙科 CBCT 剂量学相关的论文，其中 8 篇报告了有效剂量转换系数或提供了足够的信息来计算剂量转换系数。从论文中提取了扫描仪型号、有效剂量、剂量面积乘积、管电压、视野大小和 DC 进行分析。
DC 值范围为 0.035 至 0.31 µSv/mGy-cm，平均值为 0.129 µSv/mGy-cm（SD = 0.056）。当按小（<100 cm）、中（100-225 cm）和大（>225 cm）视野（FOV）分类时，有效剂量和剂量面积乘积的线性拟合斜率分别为小、中、大 FOV 的 0.129、0.111 和 0.074 µSv/mGy-cm。
报告的 DC 值范围和相对于视野类别分布表明，取决于 FOV 的 DC 值将提供更准确的有效剂量估计。管电压对确定 DC 的影响较小。考虑到 FOV 大小，得出了合理的 DC 值。为了研究 DC 随患者年龄和牙科 CBCT 成像参数变化的行为，还需要做更多的工作。
