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Purpose: To develop and characterize a large-area multi-strip ionization chamber (MSIC) for efficient measurement of proton beam spot size and position at a synchrotron-based proton therapy facility.
Methods And Materials: A 420 mm x 320 mm MSIC was designed with 240 vertical strips and 180 horizontal strips at 1.75 mm pitch. The MSIC was characterized by irradiating a grid of proton spots across 17 energies from 73.5 MeV to 235 MeV and comparing to simultaneous measurements made with a reference Gafchromic EBT3 film. Beam profiles, spot sizes, and positions were analyzed. Short term measurement stability and sensitivity were evaluated.
Results: Excellent agreement was demonstrated between the MSIC and EBT3 film for both spot size and position measurements. Spot sizes agreed within ± 0.18 mm for all energies tested. Measured beam spot positions agreed within ± 0.17 mm. The detector showed good short term measurement stability and low noise performance.
Conclusion: The large-area MSIC enables efficient and accurate proton beam spot characterization across the clinical energy range. The results indicate the MSIC is suitable for pencil beam scanning proton therapy commissioning and quality assurance applications requiring fast spot size and position quantification.
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http://dx.doi.org/10.1016/j.ejmp.2024.103411 | DOI Listing |
Phys Med Biol
September 2025
Department of oncology, Laboratory of Experimental Radiotherapy, KU Leuven, Herestraat 49, Leuven, Vlaanderen, 3001, BELGIUM.
Objective: The FLASH effect, characterized by potential sparing of organs at risk (OAR) through ultra-high dose rate irradiation, has garnered significant attention for its capability to address indications previously untreatable at conventional dose rates (DR) with hypofractionated schemes. While considerable biological research is needed to understand the FLASH effect and determine the FLASH modifying factors (FMF) for individual OARs, treatment planning studies have also emerged. This study evaluates the feasibility of achieving FLASH conditions in proton stereotactic body radiotherapy for spine metastases and establishes the required FMFs under different fractionation regimens.
View Article and Find Full Text PDFPhys Med Biol
September 2025
School of Mathematics and Statistics, Wuhan University, No. 299, Bayi Road, Wuchang District, Wuhan, Hubei, 430072, CHINA.
Objective: Spot-scanning proton arc therapy (SPArc) is an innovative planning and delivery framework for proton arc therapy that achieves conformal dose distribution via the rotating gantry. The clinical implementation of SPArc relies on efficient treatment delivery and smooth gantry rotation, with gantry velocity scheduling playing a crucial role in addressing this challenge. This study proposes a bidirectional scan-based gantry velocity scheduling algorithm, designated as BDS, to enhance the delivery efficiency and generate smooth gantry velocity profiles for SPArc plans concerning the mechanical and clinical requirements.
View Article and Find Full Text PDFMed Phys
September 2025
Department of Radiation Oncology, Brigham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, USA.
Background: Online adaptive radiation therapy (ART) offers a paradigm shift in radiotherapy by enabling adjustments to the planned dose based on daily anatomical variation. In the context of cone-beam computed tomography (CBCT) for online ART on a standard linac, thoracic and abdominal treatment sites in particular present unique challenges due to the typically large treatment volumes, mobile anatomy, scatter-induced image quality degradation, and hounsfield unit (HU) limitations. A recent hardware and software upgrade for a standard linac, Varian TrueBeam (TB) v4.
View Article and Find Full Text PDFMed Phys
September 2025
Division of Applied Quantum Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan.
Background: Tracking irradiation to moving targets in spot-scanning particle therapy, which corrects the spot position and energy in real-time, may decrease treatment time and increase accuracy. However, because of the temporal performance of the system, clinical translation remains challenging. Processing time, including image acquisition, volumetric image synthesis, correction assessment, and system response, is required to control the actual treatment system.
View Article and Find Full Text PDFJ Appl Clin Med Phys
September 2025
Department of Radiology, Emory University School of Medicine, Atlanta, Georgia, USA.
Background: Ultra-wide coverage CT (> 128 detector rows) makes it possible to image a heart or brain in a single rotation but are associated with large cone angles, which can severely degrade the image quality.
Purpose: This study evaluate the image quality and artifact levels of a dual-focal-spot single-detector (DFSSD) CT geometry designed to achieve 140 mm z-axis coverage, through a simulation study.
Methods: The DFSSD CT system employs two x-ray focal spots spaced 90 mm apart along the z-axis and a 100 mm CT detector.