2024-03-29T14:57:18Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/839372022-11-17T02:08:08Zhdl_2115_20040hdl_2115_121A treatment planning study of urethra-sparing intensity-modulated proton therapy for localized prostate cancer1000070807742Yoshimura, Takaaki1000080463743Nishioka, Kentaro1000060400678Hashimoto, TakayukiSeki, KazuyaKogame, Shouki1000000826092Tanaka, SodaiKanehira, Takahiro1000040504775Tamura, Masaya1000010614216Takao, Seishin1000090590266Matsuura, TaekoKobashi, Keiji1000080399865Kato, Fumi1000080360915Aoyama, Hidefumi1000050463724Shimizu, Shinichimetadata only accessUrethra-sparing radiotherapyProstate cancerIntensity-modulated proton therapyTumor control probabilityNormal tissue complication probability490Background and Purpose: Urethra-sparing radiation therapy for localized prostate cancer can reduce the risk of radiation-induced genitourinary toxicity by intentionally underdosing the periurethral transitional zone. We aimed to compare the clinical impact of a urethra-sparing intensity-modulated proton therapy (US-IMPT) plan with that of conventional clinical plans without urethral dose reduction. Materials and Methods: This study included 13 patients who had undergone proton beam therapy. The prescribed dose was 63 GyE in 21 fractions for 99% of the clinical target volume. To compare the clinical impact of the US-IMPT plan with that of the conventional clinical plan, tumor control probability (TCP) and normal tissue complication probability (NTCP) were calculated with a generalized equivalent uniform dose-based Lyman-Kutcher model using dose volume histograms. The endpoints of these model parameters for the rectum, bladder, and urethra were fistula, contraction, and urethral stricture, respectively. Results: The mean NTCP value for the urethra in US-IMPT was significantly lower than that in the conventional clinical plan (0.6% vs. 1.2%, p < 0.05). There were no statistically significant differences between the conventional and US-IMPT plans regarding the mean minimum dose for the urethra with a 3-mm margin, TCP value, and NTCP value for the rectum and bladder. Additionally, the target dose coverage of all plans in the robustness analysis was within the clinically acceptable range. Conclusions: Compared with the conventional clinically applied plans, US-IMPT plans have potential clinical advantages and may reduce the risk of genitourinary toxicities, while maintaining the same TCP and NTCP in the rectum and bladder.Elsevier2021-10engjournal articleNAhttp://hdl.handle.net/2115/83937https://doi.org/10.1016/j.phro.2021.09.006Physics and Imaging in Radiation Oncology202329