PURPOSE To perform bladder dose-surface map (DSM) analysis for (1) identifying symptom-related sub-surfaces (Ssurf) and evaluating their prediction capability of urinary toxicity, (2) comparing DSM with dose-volume map (DVM) (method effect), and (3) assessing the reproducibility of DSM (cohort effect). METHODS AND MATERIALS Urinary toxicities were prospectively analyzed for 254 prostate cancer patients treated with IMRT/IGRT at 78/80 Gy. DSMs were generated by unfolding bladder surfaces in a 2D plane. Pixel-by-pixel analysis was performed to identify symptom-related Ssurf. Likewise, voxel-by-voxel DVM analysis was performed to identify sub-volumes (Svol). The prediction capability of Ssurf and Svol DVHs was assessed by logistic/Cox regression using the area under the ROC curve (AUC). The Ssurf localization and prediction capability were compared to (1) the Svol obtained by DVM analysis in the same cohort and (2) the Ssurf obtained from other DSM studies. RESULTS Three Ssurf were identified in the bladder: posterior for acute retention (AUC = 0.64), posterior-superior for late retention (AUC = 0.68), and inferior-anterior-lateral for late dysuria (AUC = 0.73). Five Svol were identified: one in the urethra for acute incontinence and four in the posterior bladder part for acute and late retention, late dysuria, and hematuria. The overlap between Ssurf and Svol was moderate for acute retention, good for late retention, and bad for late dysuria, and AUCs ranged from 0.62 to 0.81. The prediction capabilities of Ssurf and Svol models were not significantly different. Among five symptoms comparable between cohorts, common Ssurf was found only for late dysuria, with a good spatial agreement. CONCLUSION Spatial agreement between methods is relatively good although DVM identified more sub-regions. Reproducibility of identified Ssurf between cohorts is low.

中文翻译：

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预测前列腺癌放疗后急性和晚期泌尿系统毒性的局部剂量分析：队列和方法效应的评估

目的 进行膀胱剂量表面图 (DSM) 分析，以 (1) 识别症状相关次表面 (Ssurf) 并评估其对尿毒性的预测能力，(2) 将 DSM 与剂量体积图 (DVM) 进行比较（方法效应），以及（3）评估 DSM 的可重复性（队列效应）。方法和材料 前瞻性分析了 254 名接受 78/80 Gy IMRT/IGRT 治疗的前列腺癌患者的泌尿毒性。DSM 是通过在 2D 平面中展开膀胱表面生成的。进行逐像素分析以识别与症状相关的 Ssurf。同样，进行逐体素 DVM 分析以识别子体积 (Svol)。Ssurf 和 Svol DVH 的预测能力通过 Logistic/Cox 回归使用 ROC 曲线下面积 (AUC) 进行评估。将 Ssurf 定位和预测能力与 (1) 在同一队列中通过 DVM 分析获得的 Svol 和 (2) 从其他 DSM 研究中获得的 Ssurf 进行比较。结果 在膀胱中确定了三种 Ssurf：急性潴留后部 (AUC = 0.64)、晚期潴留后上型 (AUC = 0.68) 和晚期排尿困难下前外侧 (AUC = 0.73)。确定了五个 Svol：一个在尿道中用于急性失禁，四个在膀胱后部用于急性和晚期潴留、晚期排尿困难和血尿。Ssurf 和 Svol 之间的重叠对于急性潴留是中等的，对于晚期潴留有益，对于晚期排尿困难不利，AUC 范围为 0.62 至 0.81。Ssurf 和 Svol 模型的预测能力没有显着差异。在队列之间具有可比性的五种症状中，常见的 Ssurf 仅用于晚期排尿困难，具有良好的空间一致性。结论 尽管 DVM 识别了更多的子区域，但方法之间的空间一致性相对较好。组间已识别 Ssurf 的重现性较低。