Department of Medical Physics, BC Cancer - Kelowna, Kelowna, British Columbia, Canada; Department of Computer Science, Mathematics, Physics and Statistics, The University of British Columbia Okanagan, Kelowna, British Columbia, Canada.
Department of Medical Physics, BC Cancer - Vancouver, Vancouver, British Columbia, Canada; Department of Physics & Astronomy, The University of British Columbia, Vancouver, British Columbia, Canada.
Brachytherapy. 2024 Jul-Aug;23(4):433-442. doi: 10.1016/j.brachy.2024.03.005. Epub 2024 May 9.
In this study we aim to quantitatively evaluate the stability of implanted seeds in permanent breast seed implant (PBSI) brachytherapy and assess any impact on treatment quality.
Sixty-seven consecutive patients who received PBSI treatment at BC Cancer Kelowna from 2013 to 2021 with post-implant CT images available were included in this study. For each patient, two sets of post-implant CT scans were retrospectively analyzed: Day0, obtained immediately after implant, and Day30, obtained approximately one month following implant. Seed distributions were quantified using the 90% isodose contour, outlier seed maximum spread, and number of seeds located in the seroma as well as seroma quadrants. These were then compared between Day0 and Day30. Post-implant dosimetry of target volumes as well as critical structures were compared.
The 90% isodose volume was found to decrease over time. All seeds remained in the breast region however the maximum spread of seeds increased in all directions from Day0 to Day30. All recorded target volume dosimetric parameters were, on average, lower on Day30 compared to Day0 but mean dosimetry levels still met clinical goals. Dose in critical structures was overall similar.
In this study, we quantitatively described the changes in seed distributions as well as dosimetry from Day0 to Day30 post PBSI procedure. We addressed concerns related to seed stability in breast tissue and provided clinical evidence on dosimetric efficacy of the PBSI technique.
本研究旨在定量评估永久性乳腺种子植入（PBSI）近距离放疗中植入种子的稳定性，并评估其对治疗质量的任何影响。
本研究纳入了 2013 年至 2021 年期间在 BC 癌症基洛纳接受 PBSI 治疗且有植入后 CT 图像的 67 例连续患者。对于每位患者，回顾性分析了两组植入后 CT 扫描：第 0 天，植入后立即获得；第 30 天，植入后大约一个月获得。使用 90%等剂量线轮廓、异常种子最大扩散和位于血清肿及血清肿象限中的种子数量来量化种子分布。然后比较第 0 天和第 30 天之间的差异。比较了目标体积和关键结构的植入后剂量学。
发现 90%等剂量体积随时间推移而减少。尽管所有种子仍留在乳房区域，但种子的最大扩散在第 0 天至第 30 天期间在各个方向上均增加。所有记录的目标体积剂量学参数在第 30 天均低于第 0 天，但平均剂量水平仍符合临床目标。关键结构中的剂量总体相似。
在本研究中，我们定量描述了 PBSI 手术后第 0 天至第 30 天种子分布和剂量学的变化。我们解决了与乳腺组织中种子稳定性相关的问题，并提供了 PBSI 技术剂量学效果的临床证据。
