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Mechanisms and prevention of thermal injury from gamma radiosurgery headframes during 3T MR imaging

Magnetic resonance imaging (MRI) is regularly used for stereotactic imaging of Gamma Knife (GK) radiosurgery patients for GK treatment planning. MRI‐induced thermal injuries have occurred and been reported for GK patients with attached metallic headframes. Depending on the specific MR imaging and he...

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Autores principales: Bennett, Marcus C., Wiant, David B., Gersh, Jacob A., Dolesh, Wendy, Ding, X., Best, Ryan C. M., Bourland, J. D.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5100895/
https://www.ncbi.nlm.nih.gov/pubmed/22766940
http://dx.doi.org/10.1120/jacmp.v13i4.3613
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author Bennett, Marcus C.
Wiant, David B.
Gersh, Jacob A.
Dolesh, Wendy
Ding, X.
Best, Ryan C. M.
Bourland, J. D.
author_facet Bennett, Marcus C.
Wiant, David B.
Gersh, Jacob A.
Dolesh, Wendy
Ding, X.
Best, Ryan C. M.
Bourland, J. D.
author_sort Bennett, Marcus C.
collection PubMed
description Magnetic resonance imaging (MRI) is regularly used for stereotactic imaging of Gamma Knife (GK) radiosurgery patients for GK treatment planning. MRI‐induced thermal injuries have occurred and been reported for GK patients with attached metallic headframes. Depending on the specific MR imaging and headframe conditions, a skin injury from MRI‐induced heating can potentially occur where the four headframe screws contact the skin surface of the patient's head. Higher MR field strength has a greater heating potential. Two primary heating mechanisms, electromagnetic induction and the antenna effect, are possible. In this study, MRI‐induced heating from a 3T clinical MRI scanner was investigated for stereotactic headframes used in gamma radiosurgery and neurosurgery. Using melons as head phantoms, optical thermometers were used to characterize the temperature profile at various points of the melon headframe composite as a function of two 3T MR pulse sequence protocols. Different combinations of GK radiosurgery headframe post and screw designs were tested to determine best and worst combinations for MRI‐induced heating. Temperature increases were measured for all pulse sequences tested, indicating that the potential exists for MRI‐induced skin heating and burns at the headframe attachment site. This heating originates with electromagnetic induction caused by the RF fields inducing current in a loop formed by the headframe, mounting screws, and the region of the patient's head located between any of the two screws. This induced current is then resistively dissipated, with the regions of highest resistance, located at the headframe screw–patient head interface, experiencing the most heating. Significant heating can be prevented by replacing the metallic threads holding the screw with electrically insulated nuts, which is the heating prevention and patient safety recommendation of the GK manufacturer. Our results confirm that the manufacturer's recommendation to use insulating nuts reduces the induced currents in the headframe nearly to zero, effectively preventing heating and minimizing the likelihood of thermal injury. PACS numbers: 87.57.‐s, 87.61.‐c, 87.61.Tg, 87.57.c‐
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spelling pubmed-51008952018-04-02 Mechanisms and prevention of thermal injury from gamma radiosurgery headframes during 3T MR imaging Bennett, Marcus C. Wiant, David B. Gersh, Jacob A. Dolesh, Wendy Ding, X. Best, Ryan C. M. Bourland, J. D. J Appl Clin Med Phys Radiation Oncology Physics Magnetic resonance imaging (MRI) is regularly used for stereotactic imaging of Gamma Knife (GK) radiosurgery patients for GK treatment planning. MRI‐induced thermal injuries have occurred and been reported for GK patients with attached metallic headframes. Depending on the specific MR imaging and headframe conditions, a skin injury from MRI‐induced heating can potentially occur where the four headframe screws contact the skin surface of the patient's head. Higher MR field strength has a greater heating potential. Two primary heating mechanisms, electromagnetic induction and the antenna effect, are possible. In this study, MRI‐induced heating from a 3T clinical MRI scanner was investigated for stereotactic headframes used in gamma radiosurgery and neurosurgery. Using melons as head phantoms, optical thermometers were used to characterize the temperature profile at various points of the melon headframe composite as a function of two 3T MR pulse sequence protocols. Different combinations of GK radiosurgery headframe post and screw designs were tested to determine best and worst combinations for MRI‐induced heating. Temperature increases were measured for all pulse sequences tested, indicating that the potential exists for MRI‐induced skin heating and burns at the headframe attachment site. This heating originates with electromagnetic induction caused by the RF fields inducing current in a loop formed by the headframe, mounting screws, and the region of the patient's head located between any of the two screws. This induced current is then resistively dissipated, with the regions of highest resistance, located at the headframe screw–patient head interface, experiencing the most heating. Significant heating can be prevented by replacing the metallic threads holding the screw with electrically insulated nuts, which is the heating prevention and patient safety recommendation of the GK manufacturer. Our results confirm that the manufacturer's recommendation to use insulating nuts reduces the induced currents in the headframe nearly to zero, effectively preventing heating and minimizing the likelihood of thermal injury. PACS numbers: 87.57.‐s, 87.61.‐c, 87.61.Tg, 87.57.c‐ John Wiley and Sons Inc. 2012-07-05 /pmc/articles/PMC5100895/ /pubmed/22766940 http://dx.doi.org/10.1120/jacmp.v13i4.3613 Text en © 2012 The Authors. This is an open access article under the terms of the http://creativecommons.org/licenses/by/3.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Radiation Oncology Physics
Bennett, Marcus C.
Wiant, David B.
Gersh, Jacob A.
Dolesh, Wendy
Ding, X.
Best, Ryan C. M.
Bourland, J. D.
Mechanisms and prevention of thermal injury from gamma radiosurgery headframes during 3T MR imaging
title Mechanisms and prevention of thermal injury from gamma radiosurgery headframes during 3T MR imaging
title_full Mechanisms and prevention of thermal injury from gamma radiosurgery headframes during 3T MR imaging
title_fullStr Mechanisms and prevention of thermal injury from gamma radiosurgery headframes during 3T MR imaging
title_full_unstemmed Mechanisms and prevention of thermal injury from gamma radiosurgery headframes during 3T MR imaging
title_short Mechanisms and prevention of thermal injury from gamma radiosurgery headframes during 3T MR imaging
title_sort mechanisms and prevention of thermal injury from gamma radiosurgery headframes during 3t mr imaging
topic Radiation Oncology Physics
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5100895/
https://www.ncbi.nlm.nih.gov/pubmed/22766940
http://dx.doi.org/10.1120/jacmp.v13i4.3613
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