Saibishkumar Elantholi P, Borg Jette, Yeung Ivan, Cummins-Holder Cheryl, Landon Angela, Crook Juanita M
Department of Radiation Oncology, Princess Margaret Hospital, University Health Network, Toronto, ON, Canada.
Brachytherapy. 2008 Apr-Jun;7(2):200-5. doi: 10.1016/j.brachy.2007.12.005. Epub 2008 Mar 24.
To compare the critical organ dosimetry and toxicity of loose seeds (LS) with stranded seeds (SS) in (125)I permanent implant for low-risk prostate cancer.
Two cohorts of 20 patients each were treated in Institutional Review Board-approved protocols designed to assess prostate edema and seed stability using MR-CT fusion on Days 0, 7, and 30 after permanent implant. (125)I LS were used for one cohort and (125)I SS for the other. Rectal wall dosimetry was compared for the two cohorts using RV100 and RD1cc and urethral dosimetry using UD5, UD30, and UV150. Statistical comparisons were performed using unpaired Student's t test.
At each time point (Days 0, 7, and 30), both the mean RD1 cc (SS: 123.1, 139.7, and 156.1 Gy vs. LS: 90.2, 104, and 129.4 Gy, respectively) and the mean RV100 (SS: 0.63, 1.0, and 1.4 cc vs. LS: 0.2, 0.4, and 0.73 cc, respectively) were significantly higher for strands (all p-values<0.01). Only 1 patient developed radiotherapy oncology group (RTOG) Grade 1 acute rectal toxicity in the loose seed cohort, whereas 3 patients had Grade 1 and 1 patient had Grade 2 toxicity with strands. The mean percentage increase of UD5 (7.7% LS vs. 24.6% SS; p=0.004) and UD30 (5% LS vs. 15.9% SS; p=0.02) from preplan to Day 30 was higher for strands. The increase in UV150 from baseline to Day 30 was significantly higher for strands (0.2 vs. 0.06 cc; p=0.01). Urinary toxicity was similar in both cohorts.
SS resulted in higher dose to urethra and rectal wall compared with LS on postimplant dosimetry. A trend toward higher acute rectal toxicity rate was observed for SS.
比较低危前列腺癌¹²⁵I永久性植入治疗中，松散籽源（LS）与串珠籽源（SS）的关键器官剂量学及毒性。
两组各20例患者，按照机构审查委员会批准的方案进行治疗，该方案旨在通过永久性植入后第0、7和30天的MR-CT融合来评估前列腺水肿和籽源稳定性。一组使用¹²⁵I LS，另一组使用¹²⁵I SS。使用RV100和RD1cc比较两组的直肠壁剂量学，使用UD5、UD30和UV150比较尿道剂量学。采用非配对学生t检验进行统计学比较。
在每个时间点（第0、7和30天），串珠籽源的平均RD1cc（SS分别为123.1、139.7和156.1 Gy，LS分别为90.2、104和129.4 Gy）和平均RV100（SS分别为0.63、1.0和1.4 cc，LS分别为0.2、0.4和0.73 cc）均显著更高（所有p值<0.01）。松散籽源组仅1例患者发生放射肿瘤学组（RTOG）1级急性直肠毒性，而串珠籽源组有3例患者发生1级毒性，1例患者发生2级毒性。从预计划到第30天，串珠籽源的UD5（LS为7.7%，SS为24.6%；p = 0.004）和UD30（LS为5%，SS为15.9%；p = 0.02）的平均百分比增加更高。从基线到第30天，串珠籽源的UV150增加显著更高（0.2 vs. 0.06 cc；p = 0.01）。两组的泌尿毒性相似。
植入后剂量学显示，与松散籽源相比，串珠籽源导致尿道和直肠壁接受的剂量更高。观察到串珠籽源的急性直肠毒性率有升高趋势。
