Department of Radiation Oncology, Cancer Center, Peking University Third Hospital, Beijing, China.
Cancer Biother Radiopharm. 2009 Dec;24(6):701-5. doi: 10.1089/cbr.2009.0648.
As a well-established single-modality approach for early-stage prostate cancer, transperineal interstitial permanent prostate brachytherapy (TIPPB) has gained increasing popularity due to its favorable clinical results. Currently, three isotopes, namely Cs-131, I-125, and Pd-103, are commercially available for TIPPB. This is the first study to systematically explore the dosimetric difference of these three isotopes for TIPPB. In total, 25 patients with T1-T2c prostate cancer previously implanted with I-125 seeds were randomly selected and replanned with Cs-131, I-125, and Pd-103 seeds to the prescription doses of 115, 145, and 125 Gy, respectively. The planning goals attempted were prostate V(p)100 approximately 95%, D(p)90 >or= 100%, and prostatic urethra D(u)10 <or= 150%. The dosimetric parameters, as well as the number of seeds and needles required, were analyzed and compared. The mean homogeneity index (HI) was 0.59, 0.56, and 0.46 for Cs-131, I-125, and Pd-103 plans, respectively. The average D(u)10 was 124.6%, 125.7%, and 129.7%, respectively. The average rectum V(r)100 was 0.19, 0.22, and 0.31 cc, respectively. In addition, the average number of seeds was 57.9, 63.0, and 63.7, and the average number of needles required was 31.6, 32.9, and 33.6 for Cs-131, I-125, and Pd-103 seeds, respectively. This study demonstrates that TIPPB, utilizing Cs-131 seeds, allows for better dose homogeneity, while providing comparable prostate coverage and sparing of the urethra and rectum, with a comparable number of, or fewer, seeds and needles required, compared to I-125 or Pd-103 seeds. Further biological and clinical studies associated with Cs-131 are warranted.
作为一种成熟的早期前列腺癌单模态治疗方法，经会阴间隙内永久性前列腺近距离放射治疗（TIPPB）由于其良好的临床结果而越来越受欢迎。目前，有三种同位素，即 Cs-131、I-125 和 Pd-103，可用于 TIPPB。这是第一项系统研究这三种同位素用于 TIPPB 的剂量学差异的研究。总共随机选择了 25 名以前植入 I-125 种子的 T1-T2c 前列腺癌患者，并分别用 Cs-131、I-125 和 Pd-103 种子重新计划至 115、145 和 125 Gy 的处方剂量。尝试的计划目标是前列腺 V(p)100 约为 95%，D(p)90 >= 100%，前列腺尿道 D(u)10 <= 150%。分析并比较了剂量学参数以及所需的种子和针数。Cs-131、I-125 和 Pd-103 计划的平均均匀性指数（HI）分别为 0.59、0.56 和 0.46。平均 D(u)10 分别为 124.6%、125.7%和 129.7%。平均直肠 V(r)100 分别为 0.19、0.22 和 0.31 cc。此外，Cs-131、I-125 和 Pd-103 种子的平均种子数分别为 57.9、63.0 和 63.7，所需的平均针数分别为 31.6、32.9 和 33.6。这项研究表明，与 I-125 或 Pd-103 种子相比，使用 Cs-131 种子的 TIPPB 可实现更好的剂量均匀性，同时提供相似的前列腺覆盖范围，并保护尿道和直肠，所需的种子和针数相当或更少。需要进一步进行与 Cs-131 相关的生物学和临床研究。
