ArticleJournal of applied clinical medical physics2020
Impact of magnetic field regulation in conjunction with the volumetric repainting technique on the spot positions and beam range in pencil beam scanning proton therapy.
Article in Journal of applied clinical medical physics, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.
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5 citing papers in PubMed, 7 citations in OpenAlex.
- Towards ultra-fast treatments: large energy acceptance beam delivery systems and opportunities for proton beam therapy.Frontiers in oncology · 2026Review
- A novel adaptive energy switching algorithm for proton arc therapy based on the machine-specific delivery characteristics.Medical physics · 2025Article
- Small spot size versus large spot size: Effect on plan quality for lung cancer in pencil beam scanning proton therapy.Journal of applied clinical medical physics · 2022Article
- Impact of errors in spot size and spot position in robustly optimized pencil beam scanning proton-based stereotactic body radiation therapy (SBRT) lung plans.Journal of applied clinical medical physics · 2021Article
- Investigating volumetric repainting to mitigate interplay effect on 4D robustly optimized lung cancer plans in pencil beam scanning proton therapy.Journal of applied clinical medical physics · 2021Article
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Authors and funding
4 authors at 2 institutions in 2 countries.
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No grant is acknowledged in the PubMed record.
Abstract
purposeThe objective of this study was to evaluate the impact of the magnetic field regulation in conjunction with the volumetric repainting technique on the spot positions and range in pencil beam scanning proton therapy.
methods"Field regulation" - a feature to reduce the switching time between layers by applying a magnetic field setpoint (instead of a current setpoint) has been implemented on the proton beam delivery system at the Miami Cancer Institute. To investigate the impact of field regulation for the volumetric repainting technique, several spot maps were generated with beam delivery sequence in both directions, that is, irradiating from the deepest layer to the most proximal layer ("down" direction) as well as irradiating from the most proximal layer to the deepest layer ("up" direction). Range measurements were performed using a multi-layer ionization chamber array. Spot positions were measured using two-dimensional and three-dimensional scintillation detectors. For range and central-axis spot position, spot maps were delivered for energies ranging from 70-225 MeV. For off-axis spot positions, the maps were delivered for high-, medium, and low-energies at eight different gantry angles. The results were then compared between the "up" and "down" directions.
resultsThe average difference in range for given energy between "up" and "down" directions was 0.0 ± 0.1 mm. The off-axis spot position results showed that 846/864 of the spots were within ±1 mm, and all off-axis spot positions were within ±1.2 mm. For spots (n = 126) at the isocenter, the evaluation between "up" and "down" directions for given energy showed the spot position difference within ±0.25 mm. At the nozzle entrance, the average differences in X and Y positions for given energy were 0.0 ± 0.2 mm and -0.0 ± 0.4 mm, respectively. At the nozzle exit, the average differences in X and Y positions for given energy were 0.0 ± 0.1 mm and -0.1 ± 0.1 mm, respectively.
conclusionThe volumetric repainting technique in magnetic field regulation mode resulted in acceptable spot position and range differences for our beam delivery system. The range differences were found to be within ±1 mm (TG224). For the spot positions (TG224: ±1 mm), the central axis measurements were within ±1 mm, whereas for the off-axis measurements, 97.9% of the spots were within ±1 mm, and all spots were within ±1.2 mm.
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