Analysis of the relationship between prescribed dose and dosimetric advantage of real-time intraoperatively built custom
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RESEARCH
Open Access
Analysis of the relationship between prescribed dose and dosimetric advantage of real-time intraoperatively built custom-linked seeds in iodine-125 prostate brachytherapy Katsumi Hirose1,3, Masahiko Aoki1*, Mariko Sato1, Hiroyoshi Akimoto1, Yasuhiro Hashimoto2, Atsushi Imai2, Noritaka Kamimura2, Hideo Kawaguchi1, Yoshiomi Hatayama1, Ichitaro Fujioka1, Mitsuki Tanaka1, Chikara Ohyama2 and Yoshihiro Takai1,3
Abstract Background: The purpose of this study was to investigate the differences in the dosimetric advantage of using intraoperatively built custom-linked (IBCL) seeds between permanent iodine-125 (I-125) seed implantation (PI) alone and PI followed by external-beam radiation therapy (EBRT) for prostate cancer. Methods: We reviewed the records of 62 patients with localized prostate cancer who received transperineal interstitial brachytherapy with I-125 using free seeds or IBCL seeds. Twenty-four low- and intermediate-risk patients underwent PI alone with the prescribed dose of 160 Gy, and 39 high-risk patients underwent PI with 110 Gy, followed by EBRT with 45 Gy (PI + EBRT). Intraoperative and post-implant dosimetric parameters 1 month after implantation were collected and analyzed. Results: The numbers of patients implanted with free seeds and IBCL seeds were 14 (58.3%) and 10 (41.7%), respectively, in the PI group and 25 (65.8%) and 13 (34.2%), respectively, in the PI + EBRT group. In the PI group, although there were significant differences in prostate V100 (p = 0.003) and D90 (p = 0.009) and rectum V100 (p = 0.026) on intraoperative dosimetry, these differences were not found on post-implant dosimetry. In the PI + EBRT group, the dosimetric parameters of IBCL seeds, such as prostate V200 (p = 0.013) and V250 (p = 0.010) and urethra D30 (p = 0.038), were better than those of free seeds on intraoperative dosimetry. Furthermore, even on post-implant dosimetry, prostate D90 (p = 0.004), V150 (p = 0.001), and homogeneity index (HI, p = 0.001), as well as V200 (p = 0.001) and V250 (p = 0.020), and urethra D5 (p = 0.008) as well as D30 (p = 0.003) had a better dosimetric quality in IBCL seeds than in free seeds. There was no significant difference in the operation time between free seeds and IBCL seeds in each PI and PI + EBRT group. Conclusions: Our results reveal that greater dosimetric benefits could be obtained using IBCL seeds in the case of permanent implantation with a lower prescribed dose, such as PI + EBRT, rather than PI alone. Keywords: Prostate cancer, Brachytherapy, IBCL seed, Seed migration
* Correspondence: [email protected] 1 Department of Radiology and Radiation Oncology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan Full list of author information is available at the end of the article © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
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