文章：

剂量约束是否可靠？前列腺癌放疗中膀胱与直肠的实际剂量暴露分析

Can the Dose Constraints Be Trusted? Actual Dose Exposure of Bladder and Rectum During Prostate Cancer Radiotherapy

原文发布日期：31 March 2025

DOI: 10.3390/cancers17071194

类型: Article

开放获取: 是

英文摘要：

Background/Objectives: The actual daily dose distribution during image-guided radiotherapy (IGRT) for prostate cancer (PCa) deviates from the planned due to positional and volumetric changes in the patient’s body and organs at risk (OAR). This study investigates the difference between planned and delivered dose, by calculating the actual daily dose to bladder and rectum for each radiotherapy fraction. The impact of OAR volumes on dose distribution and the correlation with treatment-related toxicities will be evaluated.Methods: A cone-beam computed tomography (CBCT) based daily dose calculation was performed for a total of 821 CBCT scans of 20 patients with localized PCa treated with IGRT. Each fraction’s dose-volume histogram was analyzed, and toxicities were correlated with OAR dose exposures.Results: Daily dosimetric evaluation showed a significant increase in bladderV65–V70 and rectumV50–V70 compared to planned values (p≤ 0.003 each). In contrast to bladderDmean, the rectumDmeanwas significantly increased (0.47 vs. 0.55;p< 0.001). For the bladder an exponential dose-volume relationship was demonstrated, while no dose-volume relationship was found for the rectum. On average, patients with increased genitourinary toxicities received significantly increased bladderDmean(0.44 vs. 0.63,p= 0.014).Conclusions: Conventional dose evaluation via a summation plan rather underestimates daily dosimetric parameters. For adaptive radiotherapy of PCa, volumetric parameters rather than mean doses should be used for daily treatment planning constraints. Because established dose constraints cannot be reduced to a single fraction, reasonable dose constraints should consider daily positional and volumetric changes, rather than relying on a single planning CT.

摘要翻译： 

背景/目的：前列腺癌图像引导放疗过程中，由于患者体位及危及器官的体积变化，实际日剂量分布与计划剂量存在偏差。本研究通过计算每次放疗分次中膀胱和直肠的实际日剂量，探究计划剂量与实施剂量的差异，并评估危及器官体积对剂量分布的影响及其与治疗相关毒性的关联性。方法：对20例接受图像引导放疗的局限性前列腺癌患者共计821次锥形束CT扫描进行基于锥形束CT的日剂量计算。分析每次分次的剂量体积直方图，并将毒性反应与危及器官受照剂量进行相关性分析。结果：日剂量学评估显示，膀胱V65–V70和直肠V50–V70较计划值显著增加（各项p≤0.003）。与膀胱平均剂量不同，直肠平均剂量显著增加（0.47对比0.55；p<0.001）。膀胱呈现指数型剂量-体积关系，而直肠未发现剂量-体积关系。平均而言，泌尿生殖系统毒性增加的患者膀胱平均剂量显著升高（0.44对比0.63，p=0.014）。结论：传统基于叠加计划的剂量评估方法可能低估日剂量学参数。在前列腺癌自适应放疗中，日治疗计划约束应采用体积参数而非平均剂量。由于既定剂量约束不能简化为单次分次，合理的剂量约束应考虑每日的体位和体积变化，而非依赖单次计划CT。

原文链接：

Can the Dose Constraints Be Trusted? Actual Dose Exposure of Bladder and Rectum During Prostate Cancer Radiotherapy