研究前列腺种子丢失和迁移的剂量学和肿瘤控制后果。
Investigating the dosimetric and tumor control consequences of prostate seed loss and migration.
机构信息
Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
出版信息
Med Phys. 2012 Jun;39(6):3291-8. doi: 10.1118/1.4712227.
PURPOSE
Low dose-rate brachytherapy is commonly used to treat prostate cancer. However, once implanted, the seeds are vulnerable to loss and movement. The goal of this work is to investigate the dosimetric and radiobiological effects of the types of seed loss and migration commonly seen in prostate brachytherapy.
METHODS
Five patients were used in this study. For each patient three treatment plans were created using Iodine-125, Palladium-103, and Cesium-131 seeds. The three seeds that were closest to the urethra were identified and modeled as the seeds lost through the urethra. The three seeds closest to the exterior of prostatic capsule were identified and modeled as those lost from the prostate periphery. The seed locations and organ contours were exported from Prowess and used by in-house software to perform the dosimetric and radiobiological evaluation. Seed loss was simulated by simultaneously removing 1, 2, or 3 seeds near the urethra 0, 2, or 4 days after the implant or removing seeds near the exterior of the prostate 14, 21, or 28 days after the implant.
RESULTS
Loss of one, two or three seeds through the urethra results in a D(90) reduction of 2%, 5%, and 7% loss, respectively. Due to delayed loss of peripheral seeds, the dosimetric effects are less severe than for loss through the urethra. However, while the dose reduction is modest for multiple lost seeds, the reduction in tumor control probability was minimal.
CONCLUSIONS
The goal of this work was to investigate the dosimetric and radiobiological effects of the types of seed loss and migration commonly seen in prostate brachytherapy. The results presented show that loss of multiple seeds can cause a substantial reduction of D(90) coverage. However, for the patients in this study the dose reduction was not seen to reduce tumor control probability.
目的
低剂量率近距离放射治疗常用于治疗前列腺癌。然而，放射性粒子一旦植入，就容易发生丢失和移动。本研究旨在探讨前列腺近距离放射治疗中常见的放射性粒子丢失和迁移类型的剂量学和放射生物学效应。
方法
本研究纳入了 5 名患者。为每位患者分别创建了碘-125、钯-103 和铯-131 三种放射性粒子的治疗计划。确定并模拟最接近尿道的 3 个放射性粒子为经尿道丢失的粒子，最接近前列腺包膜外的 3 个放射性粒子为从前列腺周围丢失的粒子。从 Prowess 导出粒子位置和器官轮廓，并使用内部软件进行剂量学和放射生物学评估。在植入后 0、2 或 4 天，通过同时移除靠近尿道的 1、2 或 3 个放射性粒子（分别丢失 1、2 或 3 个），或在植入后 14、21 或 28 天移除靠近前列腺外部的放射性粒子，模拟放射性粒子丢失。
结果
经尿道丢失 1、2 或 3 个放射性粒子，D90 分别降低 2%、5%和 7%。由于外周放射性粒子的丢失时间延迟，其剂量学效应不如经尿道丢失严重。然而，尽管多个丢失的放射性粒子会导致剂量显著减少，但肿瘤控制概率的降低却微乎其微。
结论
本研究旨在探讨前列腺近距离放射治疗中常见的放射性粒子丢失和迁移类型的剂量学和放射生物学效应。研究结果表明，多个放射性粒子的丢失会导致 D90 覆盖范围的显著减少。然而，对于本研究中的患者，剂量减少并未导致肿瘤控制概率降低。
Zotero 插件