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Characterization of radiotherapy component impact on MR imaging quality for an MRgRT system

Radiotherapy components of an magnetic resonnace‐guided radiotherapy (MRgRT) system can alter the magnetic fields, causing spatial distortion and image deformation, altering imaging and radiation isocenter coincidence and the accuracy of dose calculations. This work presents a characterization of ra...

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Autores principales: Lewis, Benjamin C., Gu, Bruce, Klett, Ryan, Lotey, Rajiv, Green, Olga L., Kim, Taeho
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/PMC7769410/
https://www.ncbi.nlm.nih.gov/pubmed/33211375
http://dx.doi.org/10.1002/acm2.13054
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author Lewis, Benjamin C.
Gu, Bruce
Klett, Ryan
Lotey, Rajiv
Green, Olga L.
Kim, Taeho
author_facet Lewis, Benjamin C.
Gu, Bruce
Klett, Ryan
Lotey, Rajiv
Green, Olga L.
Kim, Taeho
author_sort Lewis, Benjamin C.
collection PubMed
description Radiotherapy components of an magnetic resonnace‐guided radiotherapy (MRgRT) system can alter the magnetic fields, causing spatial distortion and image deformation, altering imaging and radiation isocenter coincidence and the accuracy of dose calculations. This work presents a characterization of radiotherapy component impact on MR imaging quality in terms of imaging isocenter variation and spatial integrity changes on a 0.35T MRgRT system, pre‐ and postupgrade of the system. The impact of gantry position, MLC field size, and treatment table power state on imaging isocenter and spatial integrity were investigated. A spatial integrity phantom was used for all tests. Images were acquired for gantry angles 0–330° at 30° increments to assess the impact of gantry position. For MLC and table power state tests all images were acquired at the home gantry position (330°). MLC field sizes ranged from 1.66 to 27.4 cm edge length square fields. Imaging isocenter shift caused by gantry position was reduced from 1.7 mm at gantry 150° preupgrade to 0.9 mm at gantry 120° postupgrade. Maximum spatial integrity errors were 0.5 mm or less pre‐ and postupgrade for all gantry angles, MLC field sizes, and treatment table power states. However, when the treatment table was powered on, there was significant reduction in SNR. This study showed that gantry position can impact imaging isocenter, but spatial integrity errors were not dependent on gantry position, MLC field size, or treatment table power state. Significant isocenter variation, while reduced postupgrade, is cause for further investigation.
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spelling pubmed-77694102020-12-31 Characterization of radiotherapy component impact on MR imaging quality for an MRgRT system Lewis, Benjamin C. Gu, Bruce Klett, Ryan Lotey, Rajiv Green, Olga L. Kim, Taeho J Appl Clin Med Phys Radiation Oncology Physics Radiotherapy components of an magnetic resonnace‐guided radiotherapy (MRgRT) system can alter the magnetic fields, causing spatial distortion and image deformation, altering imaging and radiation isocenter coincidence and the accuracy of dose calculations. This work presents a characterization of radiotherapy component impact on MR imaging quality in terms of imaging isocenter variation and spatial integrity changes on a 0.35T MRgRT system, pre‐ and postupgrade of the system. The impact of gantry position, MLC field size, and treatment table power state on imaging isocenter and spatial integrity were investigated. A spatial integrity phantom was used for all tests. Images were acquired for gantry angles 0–330° at 30° increments to assess the impact of gantry position. For MLC and table power state tests all images were acquired at the home gantry position (330°). MLC field sizes ranged from 1.66 to 27.4 cm edge length square fields. Imaging isocenter shift caused by gantry position was reduced from 1.7 mm at gantry 150° preupgrade to 0.9 mm at gantry 120° postupgrade. Maximum spatial integrity errors were 0.5 mm or less pre‐ and postupgrade for all gantry angles, MLC field sizes, and treatment table power states. However, when the treatment table was powered on, there was significant reduction in SNR. This study showed that gantry position can impact imaging isocenter, but spatial integrity errors were not dependent on gantry position, MLC field size, or treatment table power state. Significant isocenter variation, while reduced postupgrade, is cause for further investigation. John Wiley and Sons Inc. 2020-11-19 /pmc/articles/PMC7769410/ /pubmed/33211375 http://dx.doi.org/10.1002/acm2.13054 Text en © 2020 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals LLC 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 Radiation Oncology Physics
Lewis, Benjamin C.
Gu, Bruce
Klett, Ryan
Lotey, Rajiv
Green, Olga L.
Kim, Taeho
Characterization of radiotherapy component impact on MR imaging quality for an MRgRT system
title Characterization of radiotherapy component impact on MR imaging quality for an MRgRT system
title_full Characterization of radiotherapy component impact on MR imaging quality for an MRgRT system
title_fullStr Characterization of radiotherapy component impact on MR imaging quality for an MRgRT system
title_full_unstemmed Characterization of radiotherapy component impact on MR imaging quality for an MRgRT system
title_short Characterization of radiotherapy component impact on MR imaging quality for an MRgRT system
title_sort characterization of radiotherapy component impact on mr imaging quality for an mrgrt system
topic Radiation Oncology Physics
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7769410/
https://www.ncbi.nlm.nih.gov/pubmed/33211375
http://dx.doi.org/10.1002/acm2.13054
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