Pinkawa Michael, Asadpour Branka, Gagel Bernd, Piroth Marc D, Borchers Holger, Jakse Gerhard, Eble Michael J
Department of Radiation Oncology, RWTH Aachen University, Aachen, Germany.
Radiother Oncol. 2007 Aug;84(2):190-6. doi: 10.1016/j.radonc.2007.07.014. Epub 2007 Aug 13.
The aim of the study was to analyze source displacements and dose-volume changes in the first month after a permanent implant.
In 51 consecutive patients, CT scans were performed at the postoperative day (day 1) and one month (day 30) after an (125)I implant with stranded seeds. Seed positions were determined relative to pelvic bones for five seeds at the base and five seeds at the apex for each patient (n=510) and compared. To verify these results, treatment margins (TM=distance of prescription isodose to prostate) and displacements of the prostate surface (anterior/posterior/right/left/superior/inferior) relative to pelvic bones were measured.
Seed positions have moved significantly between day 1 and 30 in the posterior (mean 1.0mm; p<0.001) and inferior (mean 3.8mm; p<0.001) directions. TM increased particularly at the posterior (mean 2.2mm; p<0.001) and apical (median 3.0mm; p<0.001) prostate contour with decreasing oedema. With a stable apex position and a mean inward posterior surface displacement of 1.1mm (p<0.001) relative to pelvic bones, seed displacements could be well correlated with prescription isodose displacements (Pearson correlation coefficients >or=0.81; p<0.001).
Both changes of prostate volume and seed displacements need to be considered to explain dosimetric changes after permanent prostate brachytherapy.
本研究旨在分析永久性植入术后第一个月内的源移位和剂量体积变化。
对51例连续患者在（125）I粒子植入术后第1天（术后日）和第1个月（第30天）进行CT扫描。对于每位患者（n = 510），确定相对于骨盆骨的位于底部的5颗粒子和位于顶端的5颗粒子的位置并进行比较。为验证这些结果，测量治疗边界（TM = 处方等剂量线到前列腺的距离）以及前列腺表面相对于骨盆骨的移位（前后/左右/上下）。
在第1天到第30天之间，粒子位置在后方（平均1.0mm；p < 0.001）和下方（平均3.8mm；p < 0.001）方向有显著移动。随着水肿减轻，TM尤其在前列腺后方轮廓（平均2.2mm；p < 0.001）和顶端轮廓（中位数3.0mm；p < 0.001）处增加。由于顶端位置稳定且前列腺后表面相对于骨盆骨平均向内移位1.1mm（p < 0.001），粒子移位与处方等剂量线移位具有良好的相关性（Pearson相关系数≥0.81；p < 0.001）。
解释永久性前列腺近距离治疗后的剂量学变化时，需要同时考虑前列腺体积变化和粒子移位。
