Department of Radiation Oncology, Centre Hospitalier de l'Université de Montréal, Montreal, Canada.
Int J Radiat Oncol Biol Phys. 2010 Nov 1;78(3):781-6. doi: 10.1016/j.ijrobp.2009.08.057. Epub 2010 Feb 19.
To compare low (mean 0.44, SD ± 0.0163 mCi) with high source activity (0.61 ± 0.0178 mCi) in I(125) permanent seed brachytherapy regarding seed loss, dosimetric outcome, and toxicity.
The study included 199 patients with prostate cancer treated by permanent seed brachytherapy alone: the first 105 with seeds of lower activity (first cohort), the following 94 with higher seed activity (second cohort). The V100, V150, V200, and D90 were analyzed on the CT scan 30 days after implantation (CTD30). The V100, V150, and D2 of the rectum were also calculated on CTD30. Seed loss was determined 30 days after implantation. Urinary toxicity was measured with the International Prostate Symptom Score (IPSS) questionnaire.
Lower seed activity was associated with lower V150 and V200 (p = 0.01 and p ≤ 0.001, respectively) on CTD30. More patients had a V100 <90% and D90 <140 Gy in the lower activity cohort (p = 0.098 for D90 and p = 0.029 for V100) on CTD30. There was no difference between cohorts in dose to the rectum (p = 0.325-0.516) or difference in patients' IPSS score from baseline (p = 0.0.117-0.618), although there was a trend toward more urinary toxicity at 4 and 8 months for high activity seeds. Seed loss as a percentage of implanted seeds was not different (p = 0.324).
Higher seed activity (I(125) ≥ 0.6 mCi) results in at least equal V100 and D90 on CTD30. However, dose inhomogeneity and a trend toward more urinary toxicity at 4 and 8 months after treatment may lead to a higher long-term urinary complications.
比较低源活性（平均 0.44，SD ± 0.0163 mCi）和高源活性（0.61 ± 0.0178 mCi）在 I（125）永久性种子近距离放射治疗中的种子丢失、剂量学结果和毒性。
本研究纳入了 199 例接受单纯永久性种子近距离放射治疗的前列腺癌患者：前 105 例患者使用低活性种子（第一队列），后 94 例患者使用高活性种子（第二队列）。在植入后 30 天（CTD30）进行 CT 扫描分析 V100、V150、V200 和 D90。还计算了直肠的 V100、V150 和 D2。在植入后 30 天确定种子丢失。使用国际前列腺症状评分（IPSS）问卷测量尿毒性。
低种子活性与 CTD30 时的 V150 和 V200 较低相关（p = 0.01 和 p ≤ 0.001）。在低活性队列中，更多患者的 V100<90%和 D90<140 Gy（D90 为 p = 0.098，V100 为 p = 0.029）。两个队列之间直肠剂量无差异（p = 0.325-0.516），或患者基线 IPSS 评分差异无统计学意义（p = 0.0.117-0.618），尽管高活性种子治疗后 4 个月和 8 个月时尿毒性趋势更为明显。种子丢失率（植入种子的百分比）无差异（p = 0.324）。
高种子活性（I（125）≥0.6 mCi）可导致 CTD30 时至少相等的 V100 和 D90。然而，剂量不均匀以及治疗后 4 个月和 8 个月时尿毒性趋势增加可能导致更高的长期尿并发症。
