J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, 32611-6131, USA.
Department of Medical Physics, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA.
Med Phys. 2017 Oct;44(10):5498-5508. doi: 10.1002/mp.12502. Epub 2017 Sep 1.
To quantify differences in computationally estimated computed tomography (CT) organ doses for patient-specific voxel phantoms to estimated organ doses in matched computational phantoms using different matching criteria.
Fifty-two patient-specific computational voxel phantoms were created through CT image segmentation. In addition, each patient-specific phantom was matched to six computational phantoms of the same gender based, respectively, on age and gender (reference phantoms), height and weight, effective diameter (both central slice and exam range average), and water equivalent diameter (both central slice and exam range average). Each patient-specific phantom and matched computational phantom were then used to simulate six different torso examinations using a previously validated Monte Carlo CT dosimetry methodology that accounts for tube current modulation. Organ doses for each patient-specific phantom were then compared with the organ dose estimates of each of the matched phantoms.
Relative to the corresponding patient-specific phantoms, the root mean square of the difference in organ dose was 39.1%, 20.3%, 22.7%, 21.6%, 20.5%, and 17.6%, for reference, height and weight, effective diameter (central slice and scan average), and water equivalent diameter (central slice and scan average), respectively. The average magnitude of difference in organ dose was 24%, 14%, 16.9%, 16.2%, 14%, and 11.9%, respectively.
Overall, these data suggest that matching a patient to a computational phantom in a library is superior to matching to a reference phantom. Water equivalent diameter is the superior matching metric, but it is less feasible to implement in a clinical and retrospective setting. For these reasons, height-and-weight matching is an acceptable and reliable method for matching a patient to a member of a computational phantom library with regard to CT dosimetry.
使用不同的匹配标准，定量计算特定于患者的体素体模中计算机体层摄影术 (CT) 器官剂量与匹配计算体模中估计器官剂量之间的差异。
通过 CT 图像分割创建了 52 个特定于患者的计算体素体模。此外，每个特定于患者的体模分别根据年龄和性别（参考体模）、身高和体重、有效直径（中央切片和检查范围平均值）以及水等效直径（中央切片和检查范围平均值）与六个相同性别的计算体模匹配。然后，使用以前验证的蒙特卡罗 CT 剂量学方法模拟每个特定于患者的体模和匹配的计算体模进行六次不同的躯干检查，该方法考虑了管电流调制。然后将每个特定于患者的体模的器官剂量与每个匹配体模的器官剂量估算值进行比较。
与相应的特定于患者的体模相比，器官剂量差异的均方根分别为 39.1%、20.3%、22.7%、21.6%、20.5%和 17.6%，分别为参考、身高和体重、有效直径（中央切片和扫描平均值）和水等效直径（中央切片和扫描平均值）。器官剂量差异的平均幅度分别为 24%、14%、16.9%、16.2%、14%和 11.9%。
总体而言，这些数据表明，将患者与库中的计算体模匹配优于与参考体模匹配。水等效直径是优越的匹配指标，但在临床和回顾性环境中实施起来不太可行。出于这些原因，对于 CT 剂量学而言，身高和体重匹配是将患者与计算体模库中的成员匹配的一种可接受且可靠的方法。
