Development and validation of commissioning tests for volumetric modulated arc therapy on the 1.5T MR-linac

C R Hoek; D E Hyer; T A Foppen; P T S Borman; P L Woodhead; L E van Heerden; B W Raaymakers; M F Fast; S L Hackett

doi:10.1016/j.radonc.2026.111568

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Development and validation of commissioning tests for volumetric modulated arc therapy on the 1.5T MR-linac

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Development and validation of commissioning tests for volumetric modulated arc therapy on the 1.5T MR-linac

C R Hoek, D E Hyer, T A Foppen, P T S Borman, P L Woodhead, L E van Heerden, B W Raaymakers, M F Fast and S L Hackett

Radiotherapy and oncology, Vol.221, 111568

05/13/2026

DOI: 10.1016/j.radonc.2026.111568

PMID: 42134660

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Abstract

The MR-Linac enables adaptive radiotherapy using MRI guidance. Volumetric modulated arc therapy (VMAT) has been shown to be feasible on the MR-Linac and offers many advantages, but commissioning tests are needed. This study establishes and demonstrates a framework of commissioning tests to facilitate clinical implementation of VMAT on the MR-linac. A framework of tests was developed to verify stability and accuracy of the radiation, mechanical and imaging systems during dynamic delivery for MR-linac platforms. Beam stability is assessed under static and dynamic gantry conditions using the portal imager and detector array. The beam-limiting device (BLD) is evaluated through sliding-window measurements and a modified strip test to determine its suitability for dynamic delivery. MRI stability during gantry rotation is examined using B and B mapping, geometric fidelity phantoms, and isocenter alignment tests. All tests were performed on two MR-linacs to demonstrate feasibility. All static beam profiles met clinical tolerances (symmetry <3%, flatness <3%). Profiles remained stable during dynamic delivery for all gantry speeds (all gamma passing rates> 95%). The BLD is sufficiently well modeled in the planning system, and strip tests showed accurate leaf positioning and dynamic stability. MRI stability measurements demonstrated minimal B , and B variations, and geometric fidelity was within tolerances. No degradation in image quality was observed during gantry rotation. The presented tests provide a foundation for VMAT commissioning for the MR-linac that verifies the stability of the mechanical, radiation, and imaging components.

MR-linac

VMAT

Commissioning

Details

Title: Subtitle: Development and validation of commissioning tests for volumetric modulated arc therapy on the 1.5T MR-linac
Creators: C R Hoek - University Medical Center Utrecht
D E Hyer - University of Iowa
T A Foppen - University Medical Center Utrecht
P T S Borman - University Medical Center Utrecht
P L Woodhead - Elekta (Sweden)
L E van Heerden - University Medical Center Utrecht
B W Raaymakers - University Medical Center Utrecht
M F Fast - Altrecht GGZ
S L Hackett - University Medical Center Utrecht
Resource Type: Journal article
Publication Details: Radiotherapy and oncology, Vol.221, 111568
DOI: 10.1016/j.radonc.2026.111568
PMID: 42134660
ISSN: 1879-0887
eISSN: 1879-0887
Publisher: Elsevier
Language: English
Date published: 05/13/2026
Academic Unit: Roy J. Carver Department of Biomedical Engineering; Radiation Oncology
Record Identifier: 9985164081102771

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