Department of Radiation Oncology, Sir Charles Gairdner Hospital, Western Australia 6009, Australia.
Med Phys. 2011 Sep;38(9):5167-75. doi: 10.1118/1.3626484.
To assess dose delivery accuracy to clinically significant points in a realistic patient geometry for two separate pelvic radiotherapy scenarios.
An inhomogeneous pelvic phantom was transported to 36 radiotherapy centers in Australia and New Zealand. The phantom was treated according to Phase III rectal and prostate trial protocols. Point dose measurements were made with thermoluminescent dosimeters (TLDs) and an ionisation chamber. Comprehensive site-demographic, treatment planning, and physical data were collected for correlation with measurement outcomes.
Dose delivery to the prescription point for the rectal treatment was consistent with planned dose (mean difference between planned and measured dose - 0.1 ± 0.3% std err). Dose delivery in the region of the sacral hollow was consistently higher than planned (+1.2 ± 0.2%). For the prostate treatment, dose delivery to the prostate volume was consistent with planned doses (-0.49 ± 0.2%) and planned dose uniformity, though with a tendency to underdose the PTV at the prostate-rectal border. Measured out-of-field doses were significantly higher than planned.
A phantom based on realistic anatomy and heterogeneity can be used to comprehensively assess the influence of multiple aspects of the radiotherapy treatment process on dose delivery. The ability to verify dose delivery for two trials with a single phantom was advantageous.
在真实患者几何形状中，评估两种不同盆腔放疗情况下临床相关点的剂量传递准确性。
将不均匀盆腔模型运送到澳大利亚和新西兰的 36 个放疗中心。根据 III 期直肠和前列腺试验方案对模型进行治疗。使用热释光剂量计（TLD）和电离室进行点剂量测量。收集全面的站点人口统计学、治疗计划和物理数据，以与测量结果相关联。
直肠治疗的处方点的剂量传递与计划剂量一致（计划剂量与测量剂量之间的平均差异为-0.1 ± 0.3%标准差误差）。骶骨空洞区域的剂量传递始终高于计划剂量（+1.2 ± 0.2%）。对于前列腺治疗，前列腺体积的剂量传递与计划剂量一致（-0.49 ± 0.2%）和计划剂量均匀性一致，尽管在前列腺直肠交界处有倾向于低估 PTV 的趋势。测量的场外剂量明显高于计划剂量。
可以使用基于真实解剖结构和异质性的模型来全面评估放疗治疗过程的多个方面对剂量传递的影响。使用单个模型验证两项试验的剂量传递的能力是有利的。
