Department of Medical Physics, School of Medicine, University of Patras, 265 04 Patras, Greece.
Department of Medical Physics, University Hospital of Patras, 265 04 Patras, Greece.
Biomed Phys Eng Express. 2022 Jul 19;8(5). doi: 10.1088/2057-1976/ac7169.
To estimate organs' absorbed dose from the two-phase CT of parathyroid glands, effective dose (ED) based on three different methods, and compare the dose values with those reported by other published protocols.
Volumetric-computed-tomography-dose-index (CTDI), dose-length-product (DLP), and the corresponding scan length during each phase of a parathyroid protocol were recorded, for seventy-six patients. One k-factor, and two different k-factors for the neck and chest area were used to estimate the ED from DLP. A Monte Carlo software, VirtualDoseCT, was also used for the estimation of organs' absorbed dose and ED.
Two-phase parathyroid CT resulted in a mean ED of 3.93 mSv, 4.29 mSv and 4.21 mSv according to the one k-factor, two k-factors, and VirtualDoseCT methods, respectively. The two k-factors method resulted in a slight overestimation of 1.9% in total ED compared to VirtualDoseCT. No statistically significant difference was found in ED values between these methods (Wilcoxon test, p > 0.05), except for female patients in the pre-contrast phase. The organs inside the scanning field of view (SFOV) received the following doses: thymus 23.3 mGy, lungs 11.5 mGy, oesophagus 9.2 mGy, thyroid 6.9 mGy, and breast 6.3 mGy. The ED and organs' dose (OD) values were significantly lower in the pre-contrast than in the arterial phase (Wilcoxon test, p < 0.001). A statistically significant difference was observed between male and female patients for the pre-contrast phase (Mann-Whitney test, p < 0.05), regarding the ED values obtained with the two k-factors method and VirtualDoseCT software.
The two k-factors method could be applied for the ED estimation in clinical practice, if appropriate software is not available. An extensive range of ED values derived from the literature, mainly depending on the acquisition protocol parameters and the estimation method.
评估甲状旁腺双能 CT 扫描的器官吸收剂量、基于三种不同方法的有效剂量（ED），并与其他已发表方案的剂量值进行比较。
记录 76 例患者的容积 CT 剂量指数（CTDI）、剂量长度乘积（DLP）以及每个甲状旁腺协议阶段的相应扫描长度。使用一个 k 因子和颈部和胸部区域的两个不同 k 因子来估计来自 DLP 的 ED。还使用蒙特卡罗软件 VirtualDoseCT 来估计器官吸收剂量和 ED。
根据一个 k 因子、两个 k 因子和 VirtualDoseCT 方法，双能甲状旁腺 CT 分别导致平均 ED 为 3.93 mSv、4.29 mSv 和 4.21 mSv。与 VirtualDoseCT 相比，两种 k 因子方法导致总 ED 轻微高估 1.9%。除了女性患者的对比前阶段外，这些方法的 ED 值之间没有统计学上的显著差异（Wilcoxon 检验，p>0.05）。在 SFOV 内的器官接受以下剂量：胸腺 23.3 mGy、肺 11.5 mGy、食管 9.2 mGy、甲状腺 6.9 mGy 和乳房 6.3 mGy。与动脉期相比，对比前期的 ED 和器官剂量（OD）值明显较低（Wilcoxon 检验，p<0.001）。对于对比前阶段，男性和女性患者之间的 ED 值存在统计学上的显著差异（Mann-Whitney 检验，p<0.05），这是使用两种 k 因子方法和 VirtualDoseCT 软件获得的。
如果没有合适的软件，双 k 因子法可用于临床实践中的 ED 估计。从文献中得出的 ED 值范围广泛，主要取决于采集协议参数和估计方法。
