Evidence map›Paper›PMID 37535938›Full record

ArticleJournal of applied clinical medical physics2023

Characterization of mechanical and radiation isocenter on an MR-guided radiotherapy (MRgRT) Linac.

Nema Bassiri, John E Bayouth, Kathryn E Mittauer

Abstract read
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Article in Journal of applied clinical medical physics, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

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1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

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2 · The registry

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3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

3 authors.

Nema BassiriDepartment of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida, USA.
John E BayouthDepartment of Radiation Medicine, Oregon Health and Science University, Portland, Oregon, USA.
Kathryn E MittauerDepartment of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida, USA.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

background and purposeIn the emerging paradigm of stereotactic radiosurgery being proposed for MR-guided radiotherapy (MRgRT), assessment of mechanical geometric accuracy is critical for the implementation of stereotactic delivery. We benchmarked the mechanical accuracy of an MR Linac system that lacks an onboard detector/array. Our mechanical tests utilize a half beam block (HBB) geometry that takes advantage of the sensitivity of a partially occluded detector. MATERIALS AND

methodsMechanical tests benchmarked the couch, MLC, and gantry geometric accuracy for an MR-Linac system. An HBB technique was used to irradiate an ionization chamber profiler (ICP) array with partial occlusion of individual detectors for characterization of MLC skew, beam divergence displacement, and RT isocenter localization. The sensitivity of the partially occluded detector's ICP-X (detector width) and ICP-Y (detector length) was characterized by displacing the detector relative to radiation isocenter by 0.2 mm increments, introduced through couch motion. The accuracy of the HBB ICP technique was verified with a starshot using radiochromic film, and the reproducibility was verified on a conventional C-arm Linac and compared to Winston-Lutz.

resultsThe sensitivity of the HBB technique as quantified through the dose difference normalized to open field as a function of displacement from RT isocenter was 6.4%/mm and 13.0%/mm for the ICP-X and ICP-Y orientation, respectively, due to the oblong detector orientation. Couch positional accuracy and sag was within ±0.1 mm. Maximum MLC positional displacement was 0.7 mm with mean MLC skew at 0.07°. The maximum beam divergence displacement was 0.03 mm. The gantry angle was within 0.1°. Independent verification of the RT isocenter localization procedure produced repeatable results.

conclusionThis work serves for characterizing the mechanical and geometric radiation accuracy for the foundation of an MR-guided stereotactic radiosurgery program, as demonstrated with high sensitivity and independent validation.

Indexed as

Particle AcceleratorsRadiosurgeryHumansMagnetic Resonance ImagingPhantoms, ImagingReproducibility of ResultsisocentermechanicalMLCMRgRTMR-guidanceMR-RT QA

Identifiers

PMID37535938
PMCPMC10647948

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.