Effect of hydrogel rectal spacer on seminal vesicle inter-fraction motion during prostate stereotactic body radiotherapy

Abstract The study aimed to assess the effect of a rectal spacer on the inter-fraction motion of the seminal vesicles (SV) during prostate stereotactic body radiotherapy (SBRT). Clinical data from 60 consecutive patients (300 fractions) with localized prostate cancer treated with definitive SBRT alo...

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Main Authors: Hiroaki Kunogi, Nana Shimoyachi, Itsuko Serizawa, Tatsuya Kamima, Noboru Numao, Junji Yonese, Yasuo Yoshioka
Format: Article
Language:English
Published: Nature Portfolio 2025-06-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-04475-6
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author Hiroaki Kunogi
Nana Shimoyachi
Itsuko Serizawa
Tatsuya Kamima
Noboru Numao
Junji Yonese
Yasuo Yoshioka
author_facet Hiroaki Kunogi
Nana Shimoyachi
Itsuko Serizawa
Tatsuya Kamima
Noboru Numao
Junji Yonese
Yasuo Yoshioka
author_sort Hiroaki Kunogi
collection DOAJ
description Abstract The study aimed to assess the effect of a rectal spacer on the inter-fraction motion of the seminal vesicles (SV) during prostate stereotactic body radiotherapy (SBRT). Clinical data from 60 consecutive patients (300 fractions) with localized prostate cancer treated with definitive SBRT alone (five fractions), between June 2022 and January 2024 were retrospectively reviewed. Of the 60 patients, 44 had a spacer implanted. The residual displacement of SVs in the cone-beam CT relative to those in the planning CT was compared between with and without spacer. The maximum displacement of the proximal SV in 90% of the patients was also evaluated. Additionally, the relationship between the gel/prostate volume ratio and SV displacement was analyzed. The gel/prostate volume ratio was 30 ± 15%. Proximal SV displacement significantly differed with and without the spacer (2.0 vs. 3.8 mm, P < 0.001). Maximum proximal SV displacement also significantly differed with and without the spacer (3.0 vs. 5.1 mm, P < 0.001). In 90% of patients with the spacer, the maximum proximal SV displacement was within 4 mm. SV displacement did not change according to gel/prostate volume ratio. The spacer can limit inter-fraction motion of SVs. The gel/prostate volume ratio was not clinically significant.
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spelling doaj-art-3bee5d2ed5ee4e76960379f7da1d0cc72025-08-20T02:31:04ZengNature PortfolioScientific Reports2045-23222025-06-011511810.1038/s41598-025-04475-6Effect of hydrogel rectal spacer on seminal vesicle inter-fraction motion during prostate stereotactic body radiotherapyHiroaki Kunogi0Nana Shimoyachi1Itsuko Serizawa2Tatsuya Kamima3Noboru Numao4Junji Yonese5Yasuo Yoshioka6Department of Radiation Oncology, Cancer Institute Hospital, Japanese Foundation for Cancer ResearchDepartment of Radiation Oncology, Cancer Institute Hospital, Japanese Foundation for Cancer ResearchDepartment of Radiation Oncology, Cancer Institute Hospital, Japanese Foundation for Cancer ResearchDepartment of Radiation Oncology, Cancer Institute Hospital, Japanese Foundation for Cancer ResearchDepartment of Genitourinary Oncology, Cancer Institute Hospital, Japanese Foundation for Cancer ResearchDepartment of Genitourinary Oncology, Cancer Institute Hospital, Japanese Foundation for Cancer ResearchDepartment of Radiation Oncology, Cancer Institute Hospital, Japanese Foundation for Cancer ResearchAbstract The study aimed to assess the effect of a rectal spacer on the inter-fraction motion of the seminal vesicles (SV) during prostate stereotactic body radiotherapy (SBRT). Clinical data from 60 consecutive patients (300 fractions) with localized prostate cancer treated with definitive SBRT alone (five fractions), between June 2022 and January 2024 were retrospectively reviewed. Of the 60 patients, 44 had a spacer implanted. The residual displacement of SVs in the cone-beam CT relative to those in the planning CT was compared between with and without spacer. The maximum displacement of the proximal SV in 90% of the patients was also evaluated. Additionally, the relationship between the gel/prostate volume ratio and SV displacement was analyzed. The gel/prostate volume ratio was 30 ± 15%. Proximal SV displacement significantly differed with and without the spacer (2.0 vs. 3.8 mm, P < 0.001). Maximum proximal SV displacement also significantly differed with and without the spacer (3.0 vs. 5.1 mm, P < 0.001). In 90% of patients with the spacer, the maximum proximal SV displacement was within 4 mm. SV displacement did not change according to gel/prostate volume ratio. The spacer can limit inter-fraction motion of SVs. The gel/prostate volume ratio was not clinically significant.https://doi.org/10.1038/s41598-025-04475-6Inter-fraction motionRectal spacerStereotactic body radiotherapySeminal vesicle
spellingShingle Hiroaki Kunogi
Nana Shimoyachi
Itsuko Serizawa
Tatsuya Kamima
Noboru Numao
Junji Yonese
Yasuo Yoshioka
Effect of hydrogel rectal spacer on seminal vesicle inter-fraction motion during prostate stereotactic body radiotherapy
Scientific Reports
Inter-fraction motion
Rectal spacer
Stereotactic body radiotherapy
Seminal vesicle
title Effect of hydrogel rectal spacer on seminal vesicle inter-fraction motion during prostate stereotactic body radiotherapy
title_full Effect of hydrogel rectal spacer on seminal vesicle inter-fraction motion during prostate stereotactic body radiotherapy
title_fullStr Effect of hydrogel rectal spacer on seminal vesicle inter-fraction motion during prostate stereotactic body radiotherapy
title_full_unstemmed Effect of hydrogel rectal spacer on seminal vesicle inter-fraction motion during prostate stereotactic body radiotherapy
title_short Effect of hydrogel rectal spacer on seminal vesicle inter-fraction motion during prostate stereotactic body radiotherapy
title_sort effect of hydrogel rectal spacer on seminal vesicle inter fraction motion during prostate stereotactic body radiotherapy
topic Inter-fraction motion
Rectal spacer
Stereotactic body radiotherapy
Seminal vesicle
url https://doi.org/10.1038/s41598-025-04475-6
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