Department of Radiation Oncology, Northwestern University, Chicago, Illinois.
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, Maryland.
Pediatr Blood Cancer. 2018 Dec;65(12):e27395. doi: 10.1002/pbc.27395. Epub 2018 Aug 12.
This pilot study was done to determine the feasibility and accuracy of University of Florida/National Cancer Institute (UF/NCI) phantoms and Monte Carlo (MC) retrospective dosimetry and had two aims: (1) to determine the anatomic accuracy of UF/NCI phantoms by comparing 3D organ doses in National Wilms Tumor Study (NWTS) patient-matched UF/NCI phantoms to organ doses in corresponding patient-matched CT scans and (2) to compare infield and out-of-field organ dosimetry using two dosimetry methods-standard radiation therapy (RT) treatment planning systems (TPS) and MC dosimetry in these two anatomic models.
Twenty NWTS patient-matched Digital Imaging and Communications in Medicine (DICOM) files of UF/NCI phantoms and CT scans were imported into the Pinnacle RT TPS. The NWTS RT fields (whole abdomen, flank, whole lung, or a combination) and RT doses (10-45 Gy) were reconstructed in both models. Both TPS and MC dose calculations were performed. For aim 1, the mean doses to the heart, kidney, thyroid gland, testes, and ovaries using TPS and MC in both models were statistically compared. For aim 2, the TPS and MC dosimetry for these organs in both models were statistically compared.
For aim 1, there was no significant difference between phantom and CT scan dosimetry for any of the organs using either TPS or MC dosimetry. For aim 2, there was a significant difference between TPS and MC dosimetry for both CT scan and phantoms for all organs. Although the doses for infield organs were similar for both TPS and MC, the doses for near-field and out-of-field organs were consistently higher for 90% to 100% of MC doses; however, the absolute dose difference was small (<1 Gy).
This pilot study has demonstrated that the patient-matched UF/NCI phantoms together with MC dosimetry is an accurate model for performing retrospective 3D dosimetry in large-scale epidemiology studies such as the NWTS.
本初步研究旨在确定佛罗里达大学/国家癌症研究所（UF/NCI）体模和蒙特卡罗（MC）回顾性剂量测定的可行性和准确性，并具有两个目的：（1）通过比较 UF/NCI 体模中 3D 器官剂量与相应患者匹配 CT 扫描中的器官剂量，确定 UF/NCI 体模的解剖准确性；（2）在这两种解剖模型中，使用两种剂量测定方法（标准放射治疗（RT）治疗计划系统（TPS）和 MC 剂量测定）比较场内和场外器官剂量。
将 20 例 NWTS 患者匹配的 UF/NCI 体模和 CT 扫描的数字成像和通信医学（DICOM）文件导入 Pinnacle RT TPS。在两种模型中重建 NWTS RT 场（全腹部、侧腹部、全肺或其组合）和 RT 剂量（10-45Gy）。同时进行 TPS 和 MC 剂量计算。对于目的 1，在两种模型中，使用 TPS 和 MC 分别比较体模和 CT 扫描剂量计算得到的心脏、肾脏、甲状腺、睾丸和卵巢的平均剂量。对于目的 2，比较两种模型中这些器官的 TPS 和 MC 剂量。
对于目的 1，使用 TPS 或 MC 剂量计算，对于任何器官，体模和 CT 扫描剂量均无显著差异。对于目的 2，对于所有器官，CT 扫描和体模的 TPS 和 MC 剂量均存在显著差异。尽管场内器官的 TPS 和 MC 剂量相似，但近场和场外器官的剂量对于 90%到 100%的 MC 剂量始终较高；然而，绝对剂量差异较小（<1Gy）。
本初步研究表明，患者匹配的 UF/NCI 体模与 MC 剂量测定相结合，是在大规模流行病学研究（如 NWTS）中进行回顾性 3D 剂量测定的准确模型。
