ArticleMedical physics2020
Optical imaging method to quantify spatial dose variation due to the electron return effect in an MR-linac.
Article in Medical physics, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 8 papers.
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Who cites it
8 citing papers in PubMed, 11 citations in OpenAlex.
- Enhancement of electron beam conformity in MRI-guided radiotherapy with parallel magnetic fields: a Monte Carlo analysis.Radiological physics and technology · 2026Article
- Innovative approaches in precision radiation oncology: advanced imaging technologies and challenges which shape the future of radiation therapy.Frontiers in medicine · 2025Review
- Assessment of scintillation and Cherenkov imaging as beam shape verification method in CyberKnife® radiotherapy.Journal of applied clinical medical physics · 2024Article
- Effect of 0.35 T and 1.5 T magnetic fields on superficial dose in MR-guided radiotherapy of laryngeal cancer.Clinical and translational radiation oncology · 2023Article
- Commissioning a secondary dose calculation software for a 0.35 T MR-linac.Journal of applied clinical medical physics · 2022Article
- Optical emission-based phantom to verify coincidence of radiotherapy and imaging isocenters on an MR-linac.Journal of applied clinical medical physics · 2021Article
- Machine QA for the Elekta Unity system: A Report from the Elekta MR-linac consortium.Medical physics · 2021Review
- Scintillation imaging as a high-resolution, remote, versatile 2D detection system for MR-linac quality assurance.Medical physics · 2020Article
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Authors and funding
6 authors at 2 institutions in 1 country.
Funding
Abstract
purposeTreatment planning systems (TPSs) for MR-linacs must employ Monte Carlo-based simulations of dose deposition to model the effects of the primary magnetic field on dose. However, the accuracy of these simulations, especially for areas of tissue-air interfaces where the electron return effect (ERE) is expected, is difficult to validate due to physical constraints and magnetic field compatibility of available detectors. This study employs a novel dosimetric method based on remotely captured, real-time optical Cherenkov and scintillation imaging to visualize and quantify the ERE.
methodsAn intensified CMOS camera was used to image two phantoms with designed ERE cavities. Phantom A was a 40 cm × 10 cm × 10 cm clear acrylic block drilled with five holes of increasing diameters (0.5, 1, 2, 3, 4 cm). Phantom B was a clear acrylic block (25 cm × 20 cm × 5 cm) with three cavities of increasing diameter (3, 2, 1 cm) split into two halves in the transverse plane to accommodate radiochromic film. Both phantoms were imaged while being irradiated by 6 MV flattening filter free (FFF) beams within a MRIdian Viewray (Viewray, Cleveland, OH) MR-linac (0.34 T primary field). Phantom A was imaged while being irradiated by 6 MV FFF beams on a conventional linac (TrueBeam, Varian Medical Systems, San Jose, CA) to serve as a control. Images were post processed in Matlab (Mathworks Inc., Natick, MA) and compared to TPS dose volumes.
resultsControl imaging of Phantom A without the presence of a magnetic field supports the validity of the optical image data to a depth of 6 cm. In the presence of the magnetic field, the optical data shows deviations from the commissioned TPS dose in both intensity and localization. The largest air cavity examined (3 cm) indicated the largest dose differences, which were above 20% at some locations. Experiments with Phantom B illustrated similar agreement between optical and film dosimetry comparisons with TPS data in areas not affected by ERE.
conclusionThere are some appreciable differences in dose intensity and spatial dose distribution observed between the novel experimental data set and the dose models produced by the current clinically implemented MR-IGRT TPS.
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