Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstraße 27, 91054 Erlangen, Germany; Comprehensive Cancer Center Erlangen-EMN (CCC ER-EMN), Erlangen, Germany.
Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstraße 27, 91054 Erlangen, Germany; Comprehensive Cancer Center Erlangen-EMN (CCC ER-EMN), Erlangen, Germany.
Radiother Oncol. 2023 Jun;183:109590. doi: 10.1016/j.radonc.2023.109590. Epub 2023 Feb 28.
To investigate differences in seed-displacements between the immediate post-implant phase (day 0-1) and the time to post-plan computed tomography (CT) (day 1-30) in seed prostate brachytherapy.
Seed positions were identified on the intra-operatively created ultrasound-based treatment plan (day 0) and CT scans of day 1 and 30 for 33 patients. The day 1 (30) seed arrangement was registered onto the day 0 (1) arrangement using a seed-only approach. Based on a 1:1 assignment of seeds via the Kuhn-Munkres algorithm, seed-displacements were analyzed. Displacements were evaluated depending on strand-length and anatomical implant location. Resulting dosimetric effects were calculated.
Seed-displacements in the immediate post-implant phase (median displacements: 3.8 ± 3.6 mm) were stronger than in the time to post-plan CT (2.1 ± 2.6 mm) and enhanced along the superior-inferior direction. From day 0 to 1, strands containing one (7.3 ± 5.4 mm) or two (8.1 ± 5.8 mm) seeds showed larger displacements than strands of higher lengths (up to 4.2 ± 7.0 mm), whereas no length-dependency was found to day 30. Seeds implanted in base and apex tended to move towards the prostate midzone during both time periods. D (dose that 90% of prostate receives) was with variations of 2 ± 15 Gy more stable from day 1 to 30 than in the immediate post-implant phase (-18 ± 11 Gy).
Seed-displacements in the immediate post-implant phase was enhanced compared to day 1-30. This may result from uncertainties in the gold-standard ultrasound-based treatment planning and implantation. Adaptive implantation workflows appear useful for ensuring high implant stability from the beginning.
研究前列腺近距离放射治疗中种子在植入后即刻（第 0-1 天）与计划后 CT（第 1-30 天）之间的位移差异。
对 33 名患者的术中超声治疗计划（第 0 天）和第 1 天和第 30 天的 CT 扫描中的种子位置进行了识别。通过仅使用种子的方法，将第 1 天（30 天）的种子排列注册到第 0 天（1 天）的排列上。通过 Kuhn-Munkres 算法进行一对一种子分配，分析种子位移。根据链长和解剖植入位置评估位移。计算了由此产生的剂量学效应。
植入后即刻（中位数位移：3.8±3.6mm）的种子位移强于计划后 CT 时（2.1±2.6mm），并且沿上下方向增强。从第 0 天到第 1 天，包含一个（7.3±5.4mm）或两个（8.1±5.8mm）种子的链比更长的链（最多 4.2±7.0mm）显示出更大的位移，而在第 30 天没有发现长度依赖性。在两个时期，植入基底和顶点的种子都有向前列腺中部区移动的趋势。与植入后即刻（-18±11Gy）相比，第 1 天到第 30 天的 D（90%前列腺接受的剂量）变化更稳定，波动范围为 2±15Gy。
与第 1-30 天相比，植入后即刻的种子位移增强。这可能是由于基于超声的金标准治疗计划和植入的不确定性所致。自适应植入工作流程似乎有助于从一开始就确保高植入稳定性。
