Characterization of an MR-compatible motion platform for quality assurance of motion-compensated treatments on the 1.5 T MR-linac

Stijn Oolbekkink; Pim T S Borman; Jochem W H Wolthaus; Bram van Asselen; Astrid L H M W van Lier; Stephanie Dunn; Grant R Koenig; Nick Hartman; Niusha Kheirkhah; Bas W Raaymakers; Martin F Fast

doi:10.1002/mp.17632

Characterization of an MR-compatible motion platform for quality assurance of motion-compensated treatments on the 1.5 T MR-linac

Stijn Oolbekkink, Pim T S Borman, Jochem W H Wolthaus, Bram van Asselen, Astrid L H M W van Lier, Stephanie Dunn, Grant R Koenig, Nick Hartman, Niusha Kheirkhah, Bas W Raaymakers, Martin F Fast

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

BACKGROUND: Novel motion-compensated treatment techniques on the MR-linac can address adverse intra-fraction motion effects. These techniques involve beam gating or intra-fraction adaptations of the treatment plan based on real-time magnetic resonance imaging (MRI) performed during treatment. For quality assurance (QA) of these workflows, a multi-purpose motion platform is desirable. This platform should accommodate various phantoms, enabling multiple QA workflows.

PURPOSE: This study aims to evaluate the new IBA QUASAR Motion MR Platform for use in the 1.5 T MR-linac.

METHODS: The motion platform was assessed for several magnetic resonance (MR) characteristics, including spurious noise generation and B0&B1 homogeneity. In addition, the motion platform's motion accuracy and beam attenuation were assessed. An application was shown with a ScandiDos Delta4 Phantom+ MR demonstrating patient-specific plan QA of gated treatments using time-resolved dosimetry that includes motion based on a patient's respiratory motion trace.

RESULTS: All MR characterization measurements were within the set tolerances for MRI QA. The motion platform motion accuracy showed excellent agreement with the reference, with a standard deviation of the amplitude of 0.01 mm (20 kg load) for the motor's self-estimated positions and 0.22 mm (no load) for the images acquired with the electronic portal imager. Beam attenuation was found to be 11.8%. The combination of the motion platform and Delta4 demonstrated motion-included dosimetry at high temporal and spatial resolutions. Motion influenced the measured dose in non-gated treatments by up to -20.1%, while gated deliveries showed differences of up to -1.7% for selected diodes.

CONCLUSION: The motion platform was found to be usable in a 1.5 T magnetic field, and for all MR characterization experiments, no influence from the motion platform was observed. This motion platform enables to perform motion-included QA, with a measurement device of choice.

Original language	English
Pages (from-to)	3391-3397
Number of pages	7
Journal	Medical Physics
Volume	52
Issue number	5
Early online date	31 Jan 2025
DOIs	https://doi.org/10.1002/mp.17632
Publication status	Published - May 2025

Keywords

motion-included dosimetry
MR-linac
quality assurance

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Medical Physics - 2025 - Oolbekkink - Characterization of an MR‐compatible motion platform for quality assurance ofFinal published version, 1.61 MBLicence: CC BY

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Oolbekkink, S., Borman, P. T. S., Wolthaus, J. W. H., van Asselen, B., van Lier, A. L. H. M. W., Dunn, S., Koenig, G. R., Hartman, N., Kheirkhah, N., Raaymakers, B. W., & Fast, M. F. (2025). Characterization of an MR-compatible motion platform for quality assurance of motion-compensated treatments on the 1.5 T MR-linac. Medical Physics, 52(5), 3391-3397. https://doi.org/10.1002/mp.17632

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title = "Characterization of an MR-compatible motion platform for quality assurance of motion-compensated treatments on the 1.5 T MR-linac",

abstract = "BACKGROUND: Novel motion-compensated treatment techniques on the MR-linac can address adverse intra-fraction motion effects. These techniques involve beam gating or intra-fraction adaptations of the treatment plan based on real-time magnetic resonance imaging (MRI) performed during treatment. For quality assurance (QA) of these workflows, a multi-purpose motion platform is desirable. This platform should accommodate various phantoms, enabling multiple QA workflows.PURPOSE: This study aims to evaluate the new IBA QUASAR Motion MR Platform for use in the 1.5 T MR-linac.METHODS: The motion platform was assessed for several magnetic resonance (MR) characteristics, including spurious noise generation and B0&B1 homogeneity. In addition, the motion platform's motion accuracy and beam attenuation were assessed. An application was shown with a ScandiDos Delta4 Phantom+ MR demonstrating patient-specific plan QA of gated treatments using time-resolved dosimetry that includes motion based on a patient's respiratory motion trace.RESULTS: All MR characterization measurements were within the set tolerances for MRI QA. The motion platform motion accuracy showed excellent agreement with the reference, with a standard deviation of the amplitude of 0.01 mm (20 kg load) for the motor's self-estimated positions and 0.22 mm (no load) for the images acquired with the electronic portal imager. Beam attenuation was found to be 11.8%. The combination of the motion platform and Delta4 demonstrated motion-included dosimetry at high temporal and spatial resolutions. Motion influenced the measured dose in non-gated treatments by up to -20.1%, while gated deliveries showed differences of up to -1.7% for selected diodes.CONCLUSION: The motion platform was found to be usable in a 1.5 T magnetic field, and for all MR characterization experiments, no influence from the motion platform was observed. This motion platform enables to perform motion-included QA, with a measurement device of choice.",

keywords = "motion-included dosimetry, MR-linac, quality assurance",

author = "Stijn Oolbekkink and Borman, {Pim T S} and Wolthaus, {Jochem W H} and {van Asselen}, Bram and {van Lier}, {Astrid L H M W} and Stephanie Dunn and Koenig, {Grant R} and Nick Hartman and Niusha Kheirkhah and Raaymakers, {Bas W} and Fast, {Martin F}",

note = "Publisher Copyright: {\textcopyright} 2025 The Author(s). Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.",

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doi = "10.1002/mp.17632",

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volume = "52",

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AU - Oolbekkink, Stijn

AU - Borman, Pim T S

AU - Wolthaus, Jochem W H

AU - van Asselen, Bram

AU - van Lier, Astrid L H M W

AU - Dunn, Stephanie

AU - Koenig, Grant R

AU - Hartman, Nick

AU - Kheirkhah, Niusha

AU - Raaymakers, Bas W

AU - Fast, Martin F

PY - 2025/5

Y1 - 2025/5

N2 - BACKGROUND: Novel motion-compensated treatment techniques on the MR-linac can address adverse intra-fraction motion effects. These techniques involve beam gating or intra-fraction adaptations of the treatment plan based on real-time magnetic resonance imaging (MRI) performed during treatment. For quality assurance (QA) of these workflows, a multi-purpose motion platform is desirable. This platform should accommodate various phantoms, enabling multiple QA workflows.PURPOSE: This study aims to evaluate the new IBA QUASAR Motion MR Platform for use in the 1.5 T MR-linac.METHODS: The motion platform was assessed for several magnetic resonance (MR) characteristics, including spurious noise generation and B0&B1 homogeneity. In addition, the motion platform's motion accuracy and beam attenuation were assessed. An application was shown with a ScandiDos Delta4 Phantom+ MR demonstrating patient-specific plan QA of gated treatments using time-resolved dosimetry that includes motion based on a patient's respiratory motion trace.RESULTS: All MR characterization measurements were within the set tolerances for MRI QA. The motion platform motion accuracy showed excellent agreement with the reference, with a standard deviation of the amplitude of 0.01 mm (20 kg load) for the motor's self-estimated positions and 0.22 mm (no load) for the images acquired with the electronic portal imager. Beam attenuation was found to be 11.8%. The combination of the motion platform and Delta4 demonstrated motion-included dosimetry at high temporal and spatial resolutions. Motion influenced the measured dose in non-gated treatments by up to -20.1%, while gated deliveries showed differences of up to -1.7% for selected diodes.CONCLUSION: The motion platform was found to be usable in a 1.5 T magnetic field, and for all MR characterization experiments, no influence from the motion platform was observed. This motion platform enables to perform motion-included QA, with a measurement device of choice.

AB - BACKGROUND: Novel motion-compensated treatment techniques on the MR-linac can address adverse intra-fraction motion effects. These techniques involve beam gating or intra-fraction adaptations of the treatment plan based on real-time magnetic resonance imaging (MRI) performed during treatment. For quality assurance (QA) of these workflows, a multi-purpose motion platform is desirable. This platform should accommodate various phantoms, enabling multiple QA workflows.PURPOSE: This study aims to evaluate the new IBA QUASAR Motion MR Platform for use in the 1.5 T MR-linac.METHODS: The motion platform was assessed for several magnetic resonance (MR) characteristics, including spurious noise generation and B0&B1 homogeneity. In addition, the motion platform's motion accuracy and beam attenuation were assessed. An application was shown with a ScandiDos Delta4 Phantom+ MR demonstrating patient-specific plan QA of gated treatments using time-resolved dosimetry that includes motion based on a patient's respiratory motion trace.RESULTS: All MR characterization measurements were within the set tolerances for MRI QA. The motion platform motion accuracy showed excellent agreement with the reference, with a standard deviation of the amplitude of 0.01 mm (20 kg load) for the motor's self-estimated positions and 0.22 mm (no load) for the images acquired with the electronic portal imager. Beam attenuation was found to be 11.8%. The combination of the motion platform and Delta4 demonstrated motion-included dosimetry at high temporal and spatial resolutions. Motion influenced the measured dose in non-gated treatments by up to -20.1%, while gated deliveries showed differences of up to -1.7% for selected diodes.CONCLUSION: The motion platform was found to be usable in a 1.5 T magnetic field, and for all MR characterization experiments, no influence from the motion platform was observed. This motion platform enables to perform motion-included QA, with a measurement device of choice.

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Characterization of an MR-compatible motion platform for quality assurance of motion-compensated treatments on the 1.5 T MR-linac

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Keywords

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