用 CT 剂量指数（CTDIvol）来校正不同扫描仪之间的差异，评估 MDCT 扫描中从器官剂量的一种与扫描仪无关的技术的可行性。
The feasibility of a scanner-independent technique to estimate organ dose from MDCT scans: using CTDIvol to account for differences between scanners.
机构信息
Department of Biomedical Physics, David Geffen School of Medicine, University of California, Los Angeles, California 90024, USA.
出版信息
Med Phys. 2010 Apr;37(4):1816-25. doi: 10.1118/1.3368596.
PURPOSE
Monte Carlo radiation transport techniques have made it possible to accurately estimate the radiation dose to radiosensitive organs in patient models from scans performed with modern multidetector row computed tomography (MDCT) scanners. However, there is considerable variation in organ doses across scanners, even when similar acquisition conditions are used. The purpose of this study was to investigate the feasibility of a technique to estimate organ doses that would be scanner independent. This was accomplished by assessing the ability of CTDIvol measurements to account for differences in MDCT scanners that lead to organ dose differences.
METHODS
Monte Carlo simulations of 64-slice MDCT scanners from each of the four major manufacturers were performed. An adult female patient model from the GSF family of voxelized phantoms was used in which all ICRP Publication 103 radiosensitive organs were identified. A 120 kVp, full-body helical scan with a pitch of 1 was simulated for each scanner using similar scan protocols across scanners. From each simulated scan, the radiation dose to each organ was obtained on a per mA s basis (mGy/mA s). In addition, CTDIvol values were obtained from each scanner for the selected scan parameters. Then, to demonstrate the feasibility of generating organ dose estimates from scanner-independent coefficients, the simulated organ dose values resulting from each scanner were normalized by the CTDIvol value for those acquisition conditions.
RESULTS
CTDIvol values across scanners showed considerable variation as the coefficient of variation (CoV) across scanners was 34.1%. The simulated patient scans also demonstrated considerable differences in organ dose values, which varied by up to a factor of approximately 2 between some of the scanners. The CoV across scanners for the simulated organ doses ranged from 26.7% (for the adrenals) to 37.7% (for the thyroid), with a mean CoV of 31.5% across all organs. However, when organ doses are normalized by CTDIvoI values, the differences across scanners become very small. For the CTDIvol, normalized dose values the CoVs across scanners for different organs ranged from a minimum of 2.4% (for skin tissue) to a maximum of 8.5% (for the adrenals) with a mean of 5.2%.
CONCLUSIONS
This work has revealed that there is considerable variation among modern MDCT scanners in both CTDIvol and organ dose values. Because these variations are similar, CTDIvol can be used as a normalization factor with excellent results. This demonstrates the feasibility of establishing scanner-independent organ dose estimates by using CTDIvol to account for the differences between scanners.
目的
蒙特卡罗辐射传输技术使得能够从使用现代多排螺旋 CT（MDCT）扫描仪进行的扫描中准确估计患者模型中对辐射敏感器官的辐射剂量。然而，即使使用相似的采集条件，器官剂量在扫描仪之间也存在相当大的差异。本研究的目的是研究一种估计器官剂量的技术的可行性，这种技术将与扫描仪无关。这是通过评估 CTDIvol 测量值来实现的，这些测量值可以解释导致器官剂量差异的 MDCT 扫描仪的差异。
方法
对来自四个主要制造商的 64 层 MDCT 扫描仪进行了蒙特卡罗模拟。使用来自 GSF 体素化体模家族的成年女性患者模型，其中确定了所有 ICRP 出版物 103 个对辐射敏感的器官。使用类似的跨扫描仪扫描方案，对每个扫描仪模拟了 120 kVp 全身体螺旋扫描，螺距为 1。从每个模拟扫描中，根据每个毫安秒（mGy/mA s）获得每个器官的辐射剂量。此外，为选定的扫描参数从每个扫描仪获得 CTDIvol 值。然后，为了证明从与扫描仪无关的系数生成器官剂量估计的可行性，将模拟的器官剂量值根据这些采集条件的 CTDIvol 值进行归一化。
结果
跨扫描仪的 CTDIvol 值差异很大，扫描仪之间的变异系数（CV）为 34.1%。模拟患者扫描也显示出器官剂量值的显著差异，其中一些扫描仪之间的差异高达约 2 倍。模拟器官剂量的扫描仪间 CV 范围从 26.7%（肾上腺）到 37.7%（甲状腺），所有器官的平均 CV 为 31.5%。然而，当器官剂量通过 CTDIvolI 值归一化时，扫描仪之间的差异变得非常小。对于 CTDIvol，归一化剂量值，不同器官的扫描仪间 CV 范围从最小值 2.4%（皮肤组织）到最大值 8.5%（肾上腺），平均值为 5.2%。
结论
这项工作表明，现代 MDCT 扫描仪在 CTDIvol 和器官剂量值方面存在相当大的差异。由于这些变化相似，因此可以使用 CTDIvol 作为归一化因子，效果非常好。这证明了通过使用 CTDIvol 来解释扫描仪之间的差异，建立与扫描仪无关的器官剂量估计是可行的。
Zotero 插件