Department of Physics and Astronomy, University of Calgary, Calgary, Canada; Department of Medical Physics, Tom Baker Cancer Centre, Calgary, Canada.
Department of Physics and Astronomy, University of Calgary, Calgary, Canada; Department of Medical Physics, Tom Baker Cancer Centre, Calgary, Canada; Department of Oncology, University of Calgary, Calgary, Canada.
Int J Radiat Oncol Biol Phys. 2020 Jun 1;107(2):243-252. doi: 10.1016/j.ijrobp.2020.02.026. Epub 2020 Feb 26.
This study quantified plan quality differences across the 4 cancer centers in Alberta, Canada for plans that followed the PROstate Fractionated Irradiation Trial protocol.
Prostate plans of 235 patients were retrospectively reviewed. Interinstitutional plan quality comparisons were made based on distributions of protocol-specified parameters using 1-way analysis of variance with Games-Howell post hoc analysis. Dosimetrically representative cases were selected from each center using k-medoid clustering, enabling side-by-side comparison of dose-volume histograms and dose distributions. Fourteen anatomic features were investigated to explore interinstitutional patient population differences. Anatomically representative cases were selected from each center to explore differences in planning practices. Tumor control probability (TCP), as well as rectal wall and bladder wall normal tissue complication probabilities (NTCPs), were calculated to quantify the clinical effect of the differences in plan quality.
Comparing the mean value of each center to the other 3, statistically significant differences were observed for bladder wall D30% and D50%, left and right femoral heads D5%, planning target volume D99% and D1cc, and clinical target volume D99%. Dosimetrically representative cases demonstrated consistent results. Although anatomic differences were observed between the center-specific populations, an analysis using anatomically similar cases demonstrated consistent trends in the dosimetric differences, suggesting the dosimetric variation is not exclusively due to anatomic differences. Minimal differences (<1%) among the 4 centers were noted for TCP and NTCPs, suggesting the reported differences in plan quality may not have any clinical significance.
Despite common guidelines, statistically significant differences in plan quality metrics occurred among the 4 investigated centers. The differences are due at least in part to variation in local planning practices. TCP and NTCP calculations suggest that the clinical significance of the differences is minimal. These results can serve as a reference for the degree of variation among centers that can be accepted when a common protocol is adopted.
本研究通过定量比较加拿大艾伯塔省 4 家癌症中心遵循 PROstate Fractionated Irradiation Trial 方案的前列腺分割放疗计划的质量差异。
回顾性分析了 235 例前列腺患者的计划。通过 1 路方差分析（Games-Howell 事后分析），基于协议规定参数的分布对机构间计划质量进行比较。使用 k-中值聚类从每个中心选择具有代表性的剂量学病例，以便对剂量体积直方图和剂量分布进行并排比较。研究了 14 个解剖特征，以探讨机构间患者人群差异。从每个中心选择具有代表性的解剖病例，以探讨计划实践中的差异。计算肿瘤控制概率（TCP）以及直肠壁和膀胱壁正常组织并发症概率（NTCP），以量化计划质量差异的临床影响。
将每个中心的平均值与其他 3 个中心进行比较，观察到膀胱壁 D30%和 D50%、左右股骨头 D5%、计划靶区体积 D99%和 D1cc、以及临床靶区体积 D99%存在统计学差异。具有代表性的剂量学病例证实了一致的结果。尽管中心特异性人群之间存在解剖差异，但使用解剖相似病例的分析表明剂量学差异存在一致趋势，表明剂量学变化不仅仅是由于解剖差异所致。4 个中心之间的 TCP 和 NTCP 差异极小（<1%），表明报告的计划质量差异可能没有任何临床意义。
尽管采用了共同的指南，但在调查的 4 个中心之间，计划质量指标存在统计学显著差异。这些差异至少部分归因于局部计划实践的差异。TCP 和 NTCP 计算表明，差异的临床意义很小。这些结果可作为采用通用方案时可以接受的中心间变异程度的参考。
