{"title":"Comparing different boost concepts and beam configurations for proton therapy of pancreatic cancer","authors":"Taiki Takaoka , Takeshi Yanagi , Shinsei Takahashi , Yuta Shibamoto , Yuto Imai , Dai Okazaki , Masanari Niwa , Akira Torii , Nozomi Kita , Seiya Takano , Natsuo Tomita , Akio Hiwatashi","doi":"10.1016/j.phro.2024.100583","DOIUrl":null,"url":null,"abstract":"<div><h3>Background and Purpose</h3><p>Interfractional geometrical and anatomical variations impact the accuracy of proton therapy for pancreatic cancer. This study investigated field-in-field (FIF) and simultaneous integrated boost (SIB) concepts for scanned proton therapy treatment with different beam configurations.</p></div><div><h3>Materials and Methods</h3><p>Robustly optimized treatment plans for fifteen patients were generated using FIF and SIB techniques with two, three, and four beams. The prescribed dose in 20 fractions was 60 Gy(RBE) for the internal gross tumor volume (IGTV) and 46 Gy(RBE) for the internal clinical target volume. Verification computed tomography (vCT) scans was performed on treatment days 1, 7, and 16. Initial treatment plans were recalculated on the rigidly registered vCTs. V<sub>100%</sub> and D<sub>95%</sub> for targets and D<sub>2cm</sub><sup>3</sup> for the stomach and duodenum were evaluated. Robustness evaluations (range uncertainty of 3.5 %) were performed to evaluate the stomach and duodenum dose-volume parameters.</p></div><div><h3>Results</h3><p>For all techniques, IGTV V<sub>100%</sub> and D<sub>95%</sub> decreased significantly when recalculating the dose on vCTs (p < 0.001). The median IGTV V<sub>100%</sub> and D<sub>95%</sub> over all vCTs ranged from 74.2 % to 90.2 % and 58.8 Gy(RBE) to 59.4 Gy(RBE), respectively. The FIF with two and three beams, and SIB with two beams maintained the highest IGTV V<sub>100%</sub> and D<sub>95%</sub>. In robustness evaluations, the ΔD<sub>2cm</sub><sup>3</sup> of stomach was highest in two beams plans, while the ΔD<sub>2cm</sub><sup>3</sup> of duodenum was highest in four beams plans, for both concepts.</p></div><div><h3>Conclusion</h3><p>Target coverage decreased when recalculating on CTs at different time for both concepts. The FIF with three beams maintained the highest IGTV coverage while sparing normal organs the most.</p></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":3.4000,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2405631624000538/pdfft?md5=ffe03b8cff6b4534dcb55deeb2392584&pid=1-s2.0-S2405631624000538-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physics and Imaging in Radiation Oncology","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2405631624000538","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ONCOLOGY","Score":null,"Total":0}
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Abstract
Background and Purpose
Interfractional geometrical and anatomical variations impact the accuracy of proton therapy for pancreatic cancer. This study investigated field-in-field (FIF) and simultaneous integrated boost (SIB) concepts for scanned proton therapy treatment with different beam configurations.
Materials and Methods
Robustly optimized treatment plans for fifteen patients were generated using FIF and SIB techniques with two, three, and four beams. The prescribed dose in 20 fractions was 60 Gy(RBE) for the internal gross tumor volume (IGTV) and 46 Gy(RBE) for the internal clinical target volume. Verification computed tomography (vCT) scans was performed on treatment days 1, 7, and 16. Initial treatment plans were recalculated on the rigidly registered vCTs. V100% and D95% for targets and D2cm3 for the stomach and duodenum were evaluated. Robustness evaluations (range uncertainty of 3.5 %) were performed to evaluate the stomach and duodenum dose-volume parameters.
Results
For all techniques, IGTV V100% and D95% decreased significantly when recalculating the dose on vCTs (p < 0.001). The median IGTV V100% and D95% over all vCTs ranged from 74.2 % to 90.2 % and 58.8 Gy(RBE) to 59.4 Gy(RBE), respectively. The FIF with two and three beams, and SIB with two beams maintained the highest IGTV V100% and D95%. In robustness evaluations, the ΔD2cm3 of stomach was highest in two beams plans, while the ΔD2cm3 of duodenum was highest in four beams plans, for both concepts.
Conclusion
Target coverage decreased when recalculating on CTs at different time for both concepts. The FIF with three beams maintained the highest IGTV coverage while sparing normal organs the most.