Dosimetric and temporal evaluation of dynamic collimation with multi-leaf collimator in scanned proton therapy: A planning study

Wakisaka, Yushi; Tominaga, Yuki; Furutani, Keith M.; Nishio, Teiji

doi:https://doi.org/10.1016/j.ejmp.2025.105088

Dosimetric and temporal evaluation of dynamic collimation with multi-leaf collimator in scanned proton therapy: A planning study

Wakisaka, Yushi; Tominaga, Yuki; Furutani, Keith M. et al.

Physica Medica, 2025, 137, 105088

アクセス数:1件（2025-11-04 19:26 集計）

固定URL: https://hdl.handle.net/11094/102870

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タイトル	Dosimetric and temporal evaluation of dynamic collimation with multi-leaf collimator in scanned proton therapy: A planning study
著者	著者名 Wakisaka, Yushi
	NRID 1000080978370 1000080978370 ORCID 0000-0002-7851-6213 0000-0002-7851-6213 researchmap permalink 2762656 2762656 Scopus Author ID 56374322100 56374322100 著者名 Tominaga, Yuki
	著者名 Furutani, Keith M.
	NRID 1000040415526 1000040415526 researchmap permalink 551214 551214 Scopus Author ID 55822203900 55822203900 著者名 Nishio, Teiji
キーワード等	Dynamic collimation
	Multi-leaf collimator
	Pencil beam scanning
	Proton therapy
	Treatment planning
内容	Wakisaka Y., Tominaga Y., Furutani K.M., et al. Dosimetric and temporal evaluation of dynamic collimation with multi-leaf collimator in scanned proton therapy: A planning study. Physica Medica 137, 105088 (2025); https://doi.org/10.1016/j.ejmp.2025.105088.
抄録	Purpose: The MELTHEA V proton therapy system incorporates a beam nozzle capable of both passive scattering and active scanning, featuring a multi-leaf collimator (MLC). This study evaluates the dosimetric and temporal efficiency of dynamic collimation using the universal MLC with the scanning method. Methods: Three MLC configurations were defined: (1) nMLC – no MLC use; (2) sMLC – static leaf positioning across all energy layers; and (3) dMLC – dynamic leaf positioning changing with each energy layer. Since the treatment planning system does not support dMLC natively, it was implemented via scripting. First, various MLC margins were evaluated through phantom simulations. Then, using a representative margin, treatment plans for nine liver cancer cases were assessed for each MLC configuration. Irradiation delay time was simulated considering monitor units, dose rates, and the time characteristics of the irradiation system. Results: Phantom simulations demonstrated that an MLC margin of 0.5σ (with σ representing the in-medium spot size) effectively reduced the surrounding dose while preserving target coverage. For liver cancer cases, the average conformity index at the 50 % isodose line for nMLC, sMLC, and dMLC was 3.27 ± 0.60, 2.61 ± 0.28, and 2.28 ± 0.24, respectively. The mean doses in a 10-mm ring surrounding the target were 54.9 ± 2.5, 48.3 ± 3.9, and 41.4 ± 3.8 Gy, respectively. The average irradiation delay time of the dMLC was 8.4 %. Conclusion: The dMLC demonstrated enhanced dosimetric performance compared to nMLC and sMLC, with minimal irradiation time delays, making it suitable for clinical liver cancer treatment.
出版者	Associazione Italiana di Fisica Medica
収録物名	Physica Medica
巻(号)	137
ページ	105088
刊行年月	2025-09-01
言語	英語
ハンドルURL	https://hdl.handle.net/11094/102870
PISSN	11201797
eISSN	1724191X
関連情報 (isIdenticalTo)	DOI (出版社版) https://doi.org/10.1016/j.ejmp.2025.105088
アクセス権	open access
権利情報	This article is licensed under a Creative Commons Attribution 4.0 International License.
出版タイプ	Version of Record
カテゴリ	学術雑誌論文 Journal Article

資源タイプ	学術雑誌論文
ローカル資源タイプ	学術雑誌論文
DCMI資源タイプ	text
DCTERMS.bibliographicCitation	Physica Medica. 2025, 137, p. 105088
DC.title	Dosimetric and temporal evaluation of dynamic collimation with multi-leaf collimator in scanned proton therapy: A planning study
DC.creator	Wakisaka, Yushi
	Tominaga, Yuki
	Furutani, Keith M.
	Nishio, Teiji
DC.publisher	Associazione Italiana di Fisica Medica
DC.language' scheme='DCTERMS.RFC1766	英語
DC.type' scheme='DCTERMS.DCMIType	text
DCTERMS.issued' scheme='DCTERMS.W3CDTF	2025-09-01
DC.identifier	https://doi.org/10.1016/j.ejmp.2025.105088
DC.subject	Dynamic collimation
	Multi-leaf collimator
	Pencil beam scanning
	Proton therapy
	Treatment planning
DC.description	Wakisaka Y., Tominaga Y., Furutani K.M., et al. Dosimetric and temporal evaluation of dynamic collimation with multi-leaf collimator in scanned proton therapy: A planning study. Physica Medica 137, 105088 (2025); https://doi.org/10.1016/j.ejmp.2025.105088.
DCTERMS.abstract	Purpose: The MELTHEA V proton therapy system incorporates a beam nozzle capable of both passive scattering and active scanning, featuring a multi-leaf collimator (MLC). This study evaluates the dosimetric and temporal efficiency of dynamic collimation using the universal MLC with the scanning method. Methods: Three MLC configurations were defined: (1) nMLC – no MLC use; (2) sMLC – static leaf positioning across all energy layers; and (3) dMLC – dynamic leaf positioning changing with each energy layer. Since the treatment planning system does not support dMLC natively, it was implemented via scripting. First, various MLC margins were evaluated through phantom simulations. Then, using a representative margin, treatment plans for nine liver cancer cases were assessed for each MLC configuration. Irradiation delay time was simulated considering monitor units, dose rates, and the time characteristics of the irradiation system. Results: Phantom simulations demonstrated that an MLC margin of 0.5σ (with σ representing the in-medium spot size) effectively reduced the surrounding dose while preserving target coverage. For liver cancer cases, the average conformity index at the 50 % isodose line for nMLC, sMLC, and dMLC was 3.27 ± 0.60, 2.61 ± 0.28, and 2.28 ± 0.24, respectively. The mean doses in a 10-mm ring surrounding the target were 54.9 ± 2.5, 48.3 ± 3.9, and 41.4 ± 3.8 Gy, respectively. The average irradiation delay time of the dMLC was 8.4 %. Conclusion: The dMLC demonstrated enhanced dosimetric performance compared to nMLC and sMLC, with minimal irradiation time delays, making it suitable for clinical liver cancer treatment.
DC.rights	This article is licensed under a Creative Commons Attribution 4.0 International License.
DC.format	102870
citation_title	Dosimetric and temporal evaluation of dynamic collimation with multi-leaf collimator in scanned proton therapy: A planning study
citation_author	Wakisaka, Yushi
	Tominaga, Yuki
	Furutani, Keith M.
	Nishio, Teiji
citation_publisher	Associazione Italiana di Fisica Medica
citation_language	英語
citation_date	2025-09-01
citation_journal_title	Physica Medica
citation_volume	137
citation_firstpage	105088
citation_doi	https://doi.org/10.1016/j.ejmp.2025.105088
citation_public_url	https://hdl.handle.net/11094/102870

Dosimetric and temporal evaluation of dynamic collimation with multi-leaf collimator in scanned proton therapy: A planning study

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