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Commissioning of a 1.5T Elekta Unity MR‐linac: A single institution experience

MR image‐guided radiotherapy has the potential to improve patient care, but integration of an MRI scanner with a linear accelerator adds complexity to the commissioning process. This work describes a single institution experience of commissioning an Elekta Unity MR‐linac, including mechanical testin...

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Autores principales: Snyder, Jeffrey E., St‐Aubin, Joël, Yaddanapudi, Sridhar, Boczkowski, Amanda, Dunkerley, David A.P., Graves, Stephen A., Hyer, Daniel E.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7386194/
https://www.ncbi.nlm.nih.gov/pubmed/32432405
http://dx.doi.org/10.1002/acm2.12902
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author Snyder, Jeffrey E.
St‐Aubin, Joël
Yaddanapudi, Sridhar
Boczkowski, Amanda
Dunkerley, David A.P.
Graves, Stephen A.
Hyer, Daniel E.
author_facet Snyder, Jeffrey E.
St‐Aubin, Joël
Yaddanapudi, Sridhar
Boczkowski, Amanda
Dunkerley, David A.P.
Graves, Stephen A.
Hyer, Daniel E.
author_sort Snyder, Jeffrey E.
collection PubMed
description MR image‐guided radiotherapy has the potential to improve patient care, but integration of an MRI scanner with a linear accelerator adds complexity to the commissioning process. This work describes a single institution experience of commissioning an Elekta Unity MR‐linac, including mechanical testing, MRI scanner commissioning, and dosimetric validation. Mechanical testing included multileaf collimator (MLC) positional accuracy, measurement of radiation isocenter diameter, and MR‐to‐MV coincidence. Key MRI tests included magnetic field homogeneity, geometric accuracy, image quality, and the accuracy of navigator‐triggered imaging for motion management. Dosimetric validation consisted of comparison between measured and calculated PDDs and profiles, IMRT measurements, and end‐to‐end testing. Multileaf collimator positional accuracy was within 1.0 mm, the measured radiation isocenter walkout was 0.20 mm, and the coincidence between MR and MV isocenter was 1.06 mm, which is accounted for in the treatment planning system (TPS). For a 350‐mm‐diameter spherical volume, the peak‐to‐peak deviation of the magnetic field homogeneity was 4.44 ppm and the geometric distortion was 0.8 mm. All image quality metrics were within ACR recommendations. Navigator‐triggered images showed a maximum deviation of 0.42, 0.75, and 3.0 mm in the target centroid location compared to the stationary target for a 20 mm motion at 10, 15, and 20 breaths per minute, respectively. TPS‐calculated PDDs and profiles showed excellent agreement with measurement. The gamma passing rate for IMRT plans was 98.4 ± 1.1% (3%/ 2 mm) and end‐to‐end testing of adapted plans showed agreement within 0.4% between ion‐chamber measurement and TPS calculation. All credentialing criteria were satisfied in an independent end‐to‐end test using an IROC MRgRT phantom.
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spelling pubmed-73861942020-07-30 Commissioning of a 1.5T Elekta Unity MR‐linac: A single institution experience Snyder, Jeffrey E. St‐Aubin, Joël Yaddanapudi, Sridhar Boczkowski, Amanda Dunkerley, David A.P. Graves, Stephen A. Hyer, Daniel E. J Appl Clin Med Phys Medical Imaging MR image‐guided radiotherapy has the potential to improve patient care, but integration of an MRI scanner with a linear accelerator adds complexity to the commissioning process. This work describes a single institution experience of commissioning an Elekta Unity MR‐linac, including mechanical testing, MRI scanner commissioning, and dosimetric validation. Mechanical testing included multileaf collimator (MLC) positional accuracy, measurement of radiation isocenter diameter, and MR‐to‐MV coincidence. Key MRI tests included magnetic field homogeneity, geometric accuracy, image quality, and the accuracy of navigator‐triggered imaging for motion management. Dosimetric validation consisted of comparison between measured and calculated PDDs and profiles, IMRT measurements, and end‐to‐end testing. Multileaf collimator positional accuracy was within 1.0 mm, the measured radiation isocenter walkout was 0.20 mm, and the coincidence between MR and MV isocenter was 1.06 mm, which is accounted for in the treatment planning system (TPS). For a 350‐mm‐diameter spherical volume, the peak‐to‐peak deviation of the magnetic field homogeneity was 4.44 ppm and the geometric distortion was 0.8 mm. All image quality metrics were within ACR recommendations. Navigator‐triggered images showed a maximum deviation of 0.42, 0.75, and 3.0 mm in the target centroid location compared to the stationary target for a 20 mm motion at 10, 15, and 20 breaths per minute, respectively. TPS‐calculated PDDs and profiles showed excellent agreement with measurement. The gamma passing rate for IMRT plans was 98.4 ± 1.1% (3%/ 2 mm) and end‐to‐end testing of adapted plans showed agreement within 0.4% between ion‐chamber measurement and TPS calculation. All credentialing criteria were satisfied in an independent end‐to‐end test using an IROC MRgRT phantom. John Wiley and Sons Inc. 2020-05-20 /pmc/articles/PMC7386194/ /pubmed/32432405 http://dx.doi.org/10.1002/acm2.12902 Text en © 2020 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Medical Imaging
Snyder, Jeffrey E.
St‐Aubin, Joël
Yaddanapudi, Sridhar
Boczkowski, Amanda
Dunkerley, David A.P.
Graves, Stephen A.
Hyer, Daniel E.
Commissioning of a 1.5T Elekta Unity MR‐linac: A single institution experience
title Commissioning of a 1.5T Elekta Unity MR‐linac: A single institution experience
title_full Commissioning of a 1.5T Elekta Unity MR‐linac: A single institution experience
title_fullStr Commissioning of a 1.5T Elekta Unity MR‐linac: A single institution experience
title_full_unstemmed Commissioning of a 1.5T Elekta Unity MR‐linac: A single institution experience
title_short Commissioning of a 1.5T Elekta Unity MR‐linac: A single institution experience
title_sort commissioning of a 1.5t elekta unity mr‐linac: a single institution experience
topic Medical Imaging
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7386194/
https://www.ncbi.nlm.nih.gov/pubmed/32432405
http://dx.doi.org/10.1002/acm2.12902
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