Variability of treatment planning of seed implantation: A Japanese multicenter simulation study

Publication date: Available online 13 June 2017
Source:Brachytherapy
Author(s): Hiromichi Ishiyama, Masahiro Nakano, Kazuhito Toya, Ryuichi Kota, Koyo Kikuchi, Takahiro Yamaguchi, Naoaki Kono, Shogo Kawakami, Yuki Tsutsumi, Tomoki Tanaka, Takahisa Eriguchi, Saiji Ohga, Toshihiro Yamaguchi, Yoshiaki Takakawa, Masashi Morita, Norihisa Katayama, Toshio Ohashi, Manabu Aoki, Atsunori Yorozu, Siro Saito
PurposeThis multicenter study was conducted to evaluate the current variability of treatment planning of seed implantation in Japanese centers and the feasibility of two virtual trials.Methods and MaterialsTwo types of contour data were sent to 12 radiation oncologists with a request letter that asked them to make treatment plans on the data in the same manner as in their own practice. Five of the 12 radiation oncologists were asked to participate in the two virtual trials in which the D90 (dose to the hottest 90% of prostate volume) was 1) required to be set at just 180 Gy and 2) increased as much as possible without violating other limitations.ResultsA relatively high dose with a small deviation was irradiated to the prostate in Japanese centers (mean D90 = 188 Gy; SD = 10 Gy). In the virtual trials, all five physicians could achieve 180 Gy for the D90 with a very small deviation, although the urethral dose showed relatively large deviations. Dose escalation without increase of urethral dose or V150 was difficult, although the rectum could be spared by most of the physicians.ConclusionOur study showed a relatively high dose with a small deviation was prescribed to the prostate in Japanese centers. Consolidated protocols such as D90 = 180 Gy could be available for future trials. Meanwhile, our study suggested that some cautions might be needed for urethral dose and the V150, even when a relatively low D90 was requested.



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