Beydoun Nadine, Bucci Joseph A, Chin Yaw S, Malouf David
Department of Radiation Oncology, St George Hospital, Kogarah, New South Wales, Australia.
J Med Imaging Radiat Oncol. 2014 Feb;58(1):109-16. doi: 10.1111/1754-9485.12102. Epub 2013 Jul 19.
Prostate swelling following seed implantation is a well-recognised phenomenon. The purpose of this intervention was to assess whether using thinner seeds reduces post-implant swelling with permanent prostate brachytherapy.
Eighteen consecutive patients eligible for prostate seed brachytherapy underwent seed implantation using iodine-125 (I-125) thin seeds. Operative time, dosimetry, prostate swelling and toxicity were assessed and compared with standard I-125 stranded seed controls, sourced from the department's brachytherapy database.
A learning curve was noted with the thin seeds in terms of greater bending and deviation of needles from their intended path. This translated into significantly longer total operative time (88 vs 103 minutes; P = 0.009, 95% confidence interval (CI) 4.1-24.3) and time per needle insertion (2.6 vs 3.7 minutes; P < 0.001, 95% CI 0.5-1.3) for the thin seeds. Day 30 prostate volumes were significantly smaller in the thin seed group compared with standard seeds (40.9 cc vs 46.8 cc; P = 0.001, 95% CI 1.5-5.6). The ratio of preoperative transrectal ultrasound to day 30 post-implant CT volume was also smaller in the thin seed group (1.2 ± 0.1 for standard seeds vs 1.1 ± 0.1 for thin seeds). Post-implant dosimetric parameters were comparable for both groups. No significant differences were seen in acute urinary morbidity or quality of life between the two groups.
I-125 thin seeds are associated with an initial learning curve, with longer operative time, even for experienced brachytherapists. The significant reduction in day 30 prostate volumes with the thin seeds has useful implications in terms of optimising dose coverage to the prostate in the early period post-implantation, as well as improving the accuracy of post-implant dosimetric assessments.
种子植入后前列腺肿胀是一种公认的现象。本干预措施的目的是评估使用更细的种子进行永久性前列腺近距离放射治疗是否能减少植入后的肿胀。
连续18例符合前列腺种子近距离放射治疗条件的患者接受了使用碘-125（I-125）细种子的植入治疗。评估了手术时间、剂量测定、前列腺肿胀和毒性，并与来自该科室近距离放射治疗数据库的标准I-125串状种子对照组进行了比较。
细种子在针的弯曲和偏离预期路径方面存在学习曲线。这导致细种子的总手术时间显著延长（88分钟对103分钟；P = 0.009，95%置信区间（CI）4.1 - 24.3）以及每次针插入时间延长（2.6分钟对3.7分钟；P < 0.001，95%CI 0.5 - 1.3）。与标准种子相比，细种子组在第30天的前列腺体积显著更小（40.9立方厘米对46.8立方厘米；P = 0.001，95%CI 1.5 - 5.6）。细种子组术前经直肠超声与植入后第30天CT体积的比值也更小（标准种子为1.2±0.1，细种子为1.1±0.1）。两组植入后的剂量测定参数相当。两组在急性泌尿发病率或生活质量方面未观察到显著差异。
I-125细种子与初始学习曲线相关，即使对于经验丰富的近距离放射治疗师，手术时间也更长。细种子使第30天前列腺体积显著减小，这对于优化植入后早期前列腺的剂量覆盖以及提高植入后剂量测定评估的准确性具有重要意义。
