Improvements of lateral penumbra at various depth regions in proton pencil beam scanning with a multileaf collimator: Dose verifications and plan comparisons

Tominaga, Yuki; Wakisaka, Yushi; Kato, Takahiro; Yasui, Keisuke; Kato, Ryohei; Ichihara, Masaya; Tomida, Masashi; Sasaki, Motoharu; Oita, Masataka; Nishio, Teiji

doi:https://doi.org/10.1016/j.ejmp.2025.105684

Improvements of lateral penumbra at various depth regions in proton pencil beam scanning with a multileaf collimator: Dose verifications and plan comparisons

Tominaga, Yuki; Wakisaka, Yushi; Kato, Takahiro et al.

Physica Medica, 2025, 140, 105684

アクセス数:117件（2026-02-16 10:17 集計）

固定URL: https://hdl.handle.net/11094/103578

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タイトル	Improvements of lateral penumbra at various depth regions in proton pencil beam scanning with a multileaf collimator: Dose verifications and plan comparisons
著者	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 Wakisaka, Yushi
	NRID 1000090778804 1000090778804 著者名 Kato, Takahiro
	NRID 1000050804514 1000050804514 著者名 Yasui, Keisuke
	NRID 1000090867566 1000090867566 著者名 Kato, Ryohei
	著者名 Ichihara, Masaya
	著者名 Tomida, Masashi
	NRID 1000000885600 1000000885600 著者名 Sasaki, Motoharu
	NRID 1000010380023 1000010380023 著者名 Oita, Masataka
	NRID 1000040415526 1000040415526 researchmap permalink 551214 551214 Scopus Author ID 55822203900 55822203900 著者名 Nishio, Teiji
キーワード等	Lateral penumbra
	Multileaf collimator
	Pencil beam scanning
	Proton therapy
	Treatment planning
内容	Tominaga Y., Wakisaka Y., Kato T., et al. Improvements of lateral penumbra at various depth regions in proton pencil beam scanning with a multileaf collimator: Dose verifications and plan comparisons. Physica Medica 140, 105684 (2025); https://doi.org/10.1016/j.ejmp.2025.105684.
抄録	Purpose In scanned proton therapy, the current consensus is that the effective range of the collimator’s contribution to lateral penumbra improvement is up to approximately 150 mm depth. We characterized the penumbra variations for scanned proton beams with or without a new type of multileaf collimator (MLC) under various air gaps, depth, and with or without range shifter (RS). Methods Eighty-six uniform dose plans were created (38 RS-negative and 48 RS-positive plans) for nine box targets of 60 × 60 × 54 mm3 at 0–280 mm depths in water. They were created with or without MLC, with 50–300 mm air gaps. The penumbra and average doses of MLC-positive and MLC-negative plans at the organs at risk (OAR) region of each box plan were compared. Besides, several plan doses were validated by measurements with penumbra (with an average of 80–20 % dose point widths for both side profiles) differences and 2D gamma analysis. Results The MLC-positive plans reduced the penumbra and mean OAR doses by 1.0–5.1 mm and 3.3–13.5 %, respectively, compared to MLC-negative plans even at >150 mm depths. The penumbra differences in measurements were <±1.5 mm for all plans. The mean gamma scores at 2 %/2 mm were 97.9 ± 2.3 % and 97.4 ± 3.1 % for the MLC-negative and MLC-positive plans, respectively. Conclusions The MLC-positive beams improved the penumbra and reduced the OAR dose in every depth region and air gap. We have shown that PBS with MLCs can be useful at more than 150 mm regions, depending on the machine.
出版者	Associazione Italiana di Fisica Medica
収録物名	Physica Medica
巻(号)	140
ページ	105684
刊行年月	2025-12-01
言語	英語
ハンドルURL	https://hdl.handle.net/11094/103578
PISSN	11201797
eISSN	1724191X
関連情報 (isIdenticalTo)	DOI (出版社版) https://doi.org/10.1016/j.ejmp.2025.105684
アクセス権	open access
権利情報	This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 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, 140, p. 105684
DC.title	Improvements of lateral penumbra at various depth regions in proton pencil beam scanning with a multileaf collimator: Dose verifications and plan comparisons
DC.creator	Tominaga, Yuki
	Wakisaka, Yushi
	Kato, Takahiro
	Yasui, Keisuke
	Kato, Ryohei
	Ichihara, Masaya
	Tomida, Masashi
	Sasaki, Motoharu
	Oita, Masataka
	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	2025-12-01
DC.identifier	https://doi.org/10.1016/j.ejmp.2025.105684
DC.subject	Lateral penumbra
	Multileaf collimator
	Pencil beam scanning
	Proton therapy
	Treatment planning
DC.description	Tominaga Y., Wakisaka Y., Kato T., et al. Improvements of lateral penumbra at various depth regions in proton pencil beam scanning with a multileaf collimator: Dose verifications and plan comparisons. Physica Medica 140, 105684 (2025); https://doi.org/10.1016/j.ejmp.2025.105684.
DCTERMS.abstract	Purpose In scanned proton therapy, the current consensus is that the effective range of the collimator’s contribution to lateral penumbra improvement is up to approximately 150 mm depth. We characterized the penumbra variations for scanned proton beams with or without a new type of multileaf collimator (MLC) under various air gaps, depth, and with or without range shifter (RS). Methods Eighty-six uniform dose plans were created (38 RS-negative and 48 RS-positive plans) for nine box targets of 60 × 60 × 54 mm3 at 0–280 mm depths in water. They were created with or without MLC, with 50–300 mm air gaps. The penumbra and average doses of MLC-positive and MLC-negative plans at the organs at risk (OAR) region of each box plan were compared. Besides, several plan doses were validated by measurements with penumbra (with an average of 80–20 % dose point widths for both side profiles) differences and 2D gamma analysis. Results The MLC-positive plans reduced the penumbra and mean OAR doses by 1.0–5.1 mm and 3.3–13.5 %, respectively, compared to MLC-negative plans even at >150 mm depths. The penumbra differences in measurements were <±1.5 mm for all plans. The mean gamma scores at 2 %/2 mm were 97.9 ± 2.3 % and 97.4 ± 3.1 % for the MLC-negative and MLC-positive plans, respectively. Conclusions The MLC-positive beams improved the penumbra and reduced the OAR dose in every depth region and air gap. We have shown that PBS with MLCs can be useful at more than 150 mm regions, depending on the machine.
DC.rights	This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
DC.format	103578
citation_title	Improvements of lateral penumbra at various depth regions in proton pencil beam scanning with a multileaf collimator: Dose verifications and plan comparisons
citation_author	Tominaga, Yuki
	Wakisaka, Yushi
	Kato, Takahiro
	Yasui, Keisuke
	Kato, Ryohei
	Ichihara, Masaya
	Tomida, Masashi
	Sasaki, Motoharu
	Oita, Masataka
	Nishio, Teiji
citation_publisher	Associazione Italiana di Fisica Medica
citation_language	英語
citation_date	2025-12-01
citation_journal_title	Physica Medica
citation_volume	140
citation_firstpage	105684
citation_doi	https://doi.org/10.1016/j.ejmp.2025.105684
citation_public_url	https://hdl.handle.net/11094/103578

Improvements of lateral penumbra at various depth regions in proton pencil beam scanning with a multileaf collimator: Dose verifications and plan comparisons

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