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Impact of two-dimensional dosimetric leaf gap on SRS-VMAT for single-isocenter multi-target brain metastases

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Název: Impact of two-dimensional dosimetric leaf gap on SRS-VMAT for single-isocenter multi-target brain metastases
Autoři: Xuemin Wang, Chao Ma, Te Zhang, Xiaobin Chang, Jun Liang, Lin Li
Zdroj: Scientific Reports, Vol 15, Iss 1, Pp 1-13 (2025)
Informace o vydavateli: Nature Portfolio, 2025.
Rok vydání: 2025
Sbírka: LCC:Medicine
LCC:Science
Témata: Dosimetric leaf gap, Electronic portal image device, Multiple target brain metastases, Gamma pass rate, Multileaf collimators, Sweep gap, Medicine, Science
Popis: Abstract To explore the effects of two-dimensional dosimetric leaf gap (DLG) on the gamma pass rate (GPR) for single-isocenter multi-target (SIMT) stereotactic radiosurgery for patients with brain metastases. Two-dimensional DLG data were measured by an electronic portal imaging device (EPID) with the sweeping gap methods provided by Varian. A total of 56 arc fields from 28 SIMT patients were analyzed, including 19 with multiple targets and 9 with single targets. The leaf gap in patients’ plan were modified using an in-house program, which adjusted the multileaf collimator positions based on the DLG values from the two-dimensional DLG distribution. Dose measurements were performed with EPID for both the original and modified plans. Comparisons were made between the measurements and the predicted dose planes from the treatment planning system using 3%/2 mm gamma criteria. Additionally, factors influencing the improvements in measurement results were analyzed.Compared to the original plan, the GPR for sweep test plans with leaf gaps of 2 mm, 4 mm, 6 mm, 10 mm, 14 mm, 16 mm and 20 mm increased by 12.2%, 17.6%, 25.4%, 58.2%, 83.6%, 84.3%, and 82%, respectively, after modification. For the clinical VMAT fields, GPR improvements fluctuated significantly due to the variations of modulation complexity score, the monitor units, as well as the number and volume of targets. The maximum GPR improvements with 16% and 36.3% were observed for the single-isocenter single-target and SIMT patients respectively. A linear relationship was found between GPR improvement and both modulation complexity score and the number of targets, whereas no significant correlation was found with monitor units or target volume. The two-dimensional DLG significantly impacts treatment plans for SIMT and single-isocenter single-target patients, particularly for SIMT cases. The GPR improvement correlates linearly with increases in modulation complexity score and the number of targets, while the monitor units and target volume show minimal correlation with GPR improvement. This study underscores the importance of accurate beam modeling as a key factor influencing GPR improvement.
Druh dokumentu: article
Popis souboru: electronic resource
Jazyk: English
ISSN: 2045-2322
Relation: https://doaj.org/toc/2045-2322
DOI: 10.1038/s41598-025-14300-9
Přístupová URL adresa: https://doaj.org/article/f52ad377721d497595ce0448fcbf20a9
Přístupové číslo: edsdoj.f52ad377721d497595ce0448fcbf20a9
Databáze: Directory of Open Access Journals
Popis
Abstrakt:Abstract To explore the effects of two-dimensional dosimetric leaf gap (DLG) on the gamma pass rate (GPR) for single-isocenter multi-target (SIMT) stereotactic radiosurgery for patients with brain metastases. Two-dimensional DLG data were measured by an electronic portal imaging device (EPID) with the sweeping gap methods provided by Varian. A total of 56 arc fields from 28 SIMT patients were analyzed, including 19 with multiple targets and 9 with single targets. The leaf gap in patients’ plan were modified using an in-house program, which adjusted the multileaf collimator positions based on the DLG values from the two-dimensional DLG distribution. Dose measurements were performed with EPID for both the original and modified plans. Comparisons were made between the measurements and the predicted dose planes from the treatment planning system using 3%/2 mm gamma criteria. Additionally, factors influencing the improvements in measurement results were analyzed.Compared to the original plan, the GPR for sweep test plans with leaf gaps of 2 mm, 4 mm, 6 mm, 10 mm, 14 mm, 16 mm and 20 mm increased by 12.2%, 17.6%, 25.4%, 58.2%, 83.6%, 84.3%, and 82%, respectively, after modification. For the clinical VMAT fields, GPR improvements fluctuated significantly due to the variations of modulation complexity score, the monitor units, as well as the number and volume of targets. The maximum GPR improvements with 16% and 36.3% were observed for the single-isocenter single-target and SIMT patients respectively. A linear relationship was found between GPR improvement and both modulation complexity score and the number of targets, whereas no significant correlation was found with monitor units or target volume. The two-dimensional DLG significantly impacts treatment plans for SIMT and single-isocenter single-target patients, particularly for SIMT cases. The GPR improvement correlates linearly with increases in modulation complexity score and the number of targets, while the monitor units and target volume show minimal correlation with GPR improvement. This study underscores the importance of accurate beam modeling as a key factor influencing GPR improvement.
ISSN:20452322
DOI:10.1038/s41598-025-14300-9