Beam commissioning of the first compact proton therapy system with spot scanning and dynamic field collimation
| Autor: | Jonathan Martens, Gloria Vilches-Freixas, Mirko Unipan, Erik Roijen, Geert Bosmans, Esther Decabooter, Ilaria Rinaldi, Isabel P. Almeida |
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| Přispěvatelé: | RS: GROW - R3 - Innovative Cancer Diagnostics & Therapy, Radiotherapie |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Certification Cyclotron Radiation Collimated light 030218 nuclear medicine & medical imaging law.invention ION-BEAMS 03 medical and health sciences 0302 clinical medicine Optics law Calibration Proton Therapy Humans Radiology Nuclear Medicine and imaging Proton therapy special feature: Full Paper Radiometry Proton therapy Spot scanning Netherlands business.industry Phantoms Imaging Air Absorption Radiation Reproducibility of Results Water Particle accelerator General Medicine Equipment Design Cyclotrons 030220 oncology & carcinogenesis business Beam (structure) |
| Zdroj: | Br J Radiol British Journal of Radiology, 93(1107):20190598. British Institute of Radiology |
| ISSN: | 0007-1285 |
| Popis: | Objectives: To describe the measurements and to present the results of the beam commissioning and the beam model validation of a compact, gantry-mounted, spot scanning proton accelerator system with dynamic layer-by-layer field collimation. Methods: We performed measurements of depth dose distributions in water, spot and scanned field size in air at different positions from the isocenter plane, spot position over the 20 × 20 cm2 scanned area, beam monitor calibration in terms of absorbed dose to water and specific field collimation measurements at different gantry angles to commission the system. To validate the beam model in the treatment planning system (TPS), we measured spot profiles in water at different depths, absolute dose in water of single energy layers of different field sizes and inversely optimised spread-out Bragg peaks (SOBP) under normal and oblique beam incidence, field size and penumbra in water of SOBPs, and patient treatment specific quality assurance in homogeneous and heterogeneous phantoms. Results: Energy range, spot size, spot position and dose output were consistent at all gantry angles with 0.3 mm, 0.4 mm, 0.6 mm and 0.5% maximum deviations, respectively. Uncollimated spot size (one sigma) in air with an air-gap of 10 cm ranged from 4.1 to 16.4 mm covering a range from 32.2 to 1.9 cm in water, respectively. Absolute dose measurements were within 3% when comparing TPS and experimental data. Gamma pass rates >98% and >96% at 3%/3 mm were obtained when performing 2D dose measurements in homogeneous and in heterogeneous media, respectively. Leaf position was within ±1 mm at all gantry angles and nozzle positions. Conclusions: Beam characterisation and machine commissioning results, and the exhaustive end-to-end tests performed to assess the proper functionality of the system, confirm that it is safe and accurate to treat patients. Advances in knowledge: This is the first paper addressing the beam commissioning and the beam validation of a compact, gantry-mounted, pencil beam scanning proton accelerator system with dynamic layer-by-layer multileaf collimation. |
| Databáze: | OpenAIRE |
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