Magnetic shielding investigation for a 6 MV in-line linac within the parallel configuration of a linac-MR system.
Identifieur interne : 000283 ( PubMed/Corpus ); précédent : 000282; suivant : 000284Magnetic shielding investigation for a 6 MV in-line linac within the parallel configuration of a linac-MR system.
Auteurs : D M Santos ; J. St Aubin ; B G Fallone ; S. SteciwSource :
- Medical physics [ 0094-2405 ] ; 2012.
English descriptors
- KwdEn :
- Artifacts, Computer Simulation, Computer-Aided Design, Equipment Design, Equipment Failure Analysis, Image Enhancement (instrumentation), Magnetic Resonance Imaging (instrumentation), Models, Theoretical, Particle Accelerators, Radiation Protection (instrumentation), Radiotherapy, High-Energy (instrumentation), Radiotherapy, Image-Guided (instrumentation).
- MESH :
Abstract
In our current linac-magnetic resonance (MR) design, a 6 MV in-line linac is placed along the central axis of the MR's magnet where the MR's fringe magnetic fields are parallel to the overall electron trajectories in the linac waveguide. Our previous study of this configuration comprising a linac-MR SAD of 100 cm and a 0.5 T superconducting (open, split) MR imager. It showed the presence of longitudinal magnetic fields of 0.011 T at the electron gun, which caused a reduction in target current to 84% of nominal. In this study, passive and active magnetic shielding was investigated to recover the linac output losses caused by magnetic deflections of electron trajectories in the linac within a parallel linac-MR configuration.
DOI: 10.1118/1.3676692
PubMed: 22320788
Links to Exploration step
pubmed:22320788Le document en format XML
<record><TEI><teiHeader><fileDesc><titleStmt><title xml:lang="en">Magnetic shielding investigation for a 6 MV in-line linac within the parallel configuration of a linac-MR system.</title><author><name sortKey="Santos, D M" sort="Santos, D M" uniqKey="Santos D" first="D M" last="Santos">D M Santos</name><affiliation><nlm:affiliation>Department of Oncology, University of Alberta, Edmonton, Alberta, Canada. dsantos@ualberta.ca</nlm:affiliation></affiliation></author><author><name sortKey="St Aubin, J" sort="St Aubin, J" uniqKey="St Aubin J" first="J" last="St Aubin">J. St Aubin</name></author><author><name sortKey="Fallone, B G" sort="Fallone, B G" uniqKey="Fallone B" first="B G" last="Fallone">B G Fallone</name></author><author><name sortKey="Steciw, S" sort="Steciw, S" uniqKey="Steciw S" first="S" last="Steciw">S. Steciw</name></author></titleStmt><publicationStmt><idno type="wicri:source">PubMed</idno><date when="2012">2012</date><idno type="doi">10.1118/1.3676692</idno><idno type="RBID">pubmed:22320788</idno><idno type="pmid">22320788</idno><idno type="wicri:Area/PubMed/Corpus">000283</idno></publicationStmt><sourceDesc><biblStruct><analytic><title xml:lang="en">Magnetic shielding investigation for a 6 MV in-line linac within the parallel configuration of a linac-MR system.</title><author><name sortKey="Santos, D M" sort="Santos, D M" uniqKey="Santos D" first="D M" last="Santos">D M Santos</name><affiliation><nlm:affiliation>Department of Oncology, University of Alberta, Edmonton, Alberta, Canada. dsantos@ualberta.ca</nlm:affiliation></affiliation></author><author><name sortKey="St Aubin, J" sort="St Aubin, J" uniqKey="St Aubin J" first="J" last="St Aubin">J. St Aubin</name></author><author><name sortKey="Fallone, B G" sort="Fallone, B G" uniqKey="Fallone B" first="B G" last="Fallone">B G Fallone</name></author><author><name sortKey="Steciw, S" sort="Steciw, S" uniqKey="Steciw S" first="S" last="Steciw">S. Steciw</name></author></analytic><series><title level="j">Medical physics</title><idno type="ISSN">0094-2405</idno><imprint><date when="2012" type="published">2012</date></imprint></series></biblStruct></sourceDesc></fileDesc><profileDesc><textClass><keywords scheme="KwdEn" xml:lang="en"><term>Artifacts</term><term>Computer Simulation</term><term>Computer-Aided Design</term><term>Equipment Design</term><term>Equipment Failure Analysis</term><term>Image Enhancement (instrumentation)</term><term>Magnetic Resonance Imaging (instrumentation)</term><term>Models, Theoretical</term><term>Particle Accelerators</term><term>Radiation Protection (instrumentation)</term><term>Radiotherapy, High-Energy (instrumentation)</term><term>Radiotherapy, Image-Guided (instrumentation)</term></keywords><keywords scheme="MESH" qualifier="instrumentation" xml:lang="en"><term>Image Enhancement</term><term>Magnetic Resonance Imaging</term><term>Radiation Protection</term><term>Radiotherapy, High-Energy</term><term>Radiotherapy, Image-Guided</term></keywords><keywords scheme="MESH" xml:lang="en"><term>Artifacts</term><term>Computer Simulation</term><term>Computer-Aided Design</term><term>Equipment Design</term><term>Equipment Failure Analysis</term><term>Models, Theoretical</term><term>Particle Accelerators</term></keywords></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en">In our current linac-magnetic resonance (MR) design, a 6 MV in-line linac is placed along the central axis of the MR's magnet where the MR's fringe magnetic fields are parallel to the overall electron trajectories in the linac waveguide. Our previous study of this configuration comprising a linac-MR SAD of 100 cm and a 0.5 T superconducting (open, split) MR imager. It showed the presence of longitudinal magnetic fields of 0.011 T at the electron gun, which caused a reduction in target current to 84% of nominal. In this study, passive and active magnetic shielding was investigated to recover the linac output losses caused by magnetic deflections of electron trajectories in the linac within a parallel linac-MR configuration.</div></front></TEI><pubmed><MedlineCitation Owner="NLM" Status="MEDLINE"><PMID Version="1">22320788</PMID><DateCreated><Year>2012</Year><Month>02</Month><Day>10</Day></DateCreated><DateCompleted><Year>2012</Year><Month>05</Month><Day>01</Day></DateCompleted><Article PubModel="Print"><Journal><ISSN IssnType="Print">0094-2405</ISSN><JournalIssue CitedMedium="Print"><Volume>39</Volume><Issue>2</Issue><PubDate><Year>2012</Year><Month>Feb</Month></PubDate></JournalIssue><Title>Medical physics</Title><ISOAbbreviation>Med Phys</ISOAbbreviation></Journal><ArticleTitle>Magnetic shielding investigation for a 6 MV in-line linac within the parallel configuration of a linac-MR system.</ArticleTitle><Pagination><MedlinePgn>788-97</MedlinePgn></Pagination><ELocationID EIdType="doi" ValidYN="Y">10.1118/1.3676692</ELocationID><Abstract><AbstractText Label="PURPOSE" NlmCategory="OBJECTIVE">In our current linac-magnetic resonance (MR) design, a 6 MV in-line linac is placed along the central axis of the MR's magnet where the MR's fringe magnetic fields are parallel to the overall electron trajectories in the linac waveguide. Our previous study of this configuration comprising a linac-MR SAD of 100 cm and a 0.5 T superconducting (open, split) MR imager. It showed the presence of longitudinal magnetic fields of 0.011 T at the electron gun, which caused a reduction in target current to 84% of nominal. In this study, passive and active magnetic shielding was investigated to recover the linac output losses caused by magnetic deflections of electron trajectories in the linac within a parallel linac-MR configuration.</AbstractText><AbstractText Label="METHODS" NlmCategory="METHODS">Magnetic materials and complex shield structures were used in a 3D finite element method (FEM) magnetic field model, which emulated the fringe magnetic fields of the MR imagers. The effects of passive magnetic shielding was studied by surrounding the electron gun and its casing with a series of capped steel cylinders of various inner lengths (26.5-306.5 mm) and thicknesses (0.75-15 mm) in the presence of the fringe magnetic fields from a commercial MR imager. In addition, the effects of a shield of fixed length (146.5 mm) with varying thicknesses were studied against a series of larger homogeneous magnetic fields (0-0.2 T). The effects of active magnetic shielding were studied by adding current loops around the electron gun and its casing. The loop currents, separation, and location were optimized to minimize the 0.011 T longitudinal magnetic fields in the electron gun. The magnetic field solutions from the FEM model were added to a validated linac simulation, consisting of a 3D electron gun (using OPERA-3d/scala) and 3D waveguide (using comsol Multiphysics and PARMELA) simulations. PARMELA's target current and output phase-space were analyzed to study the linac's output performance within the magnetic shields.</AbstractText><AbstractText Label="RESULTS" NlmCategory="RESULTS">The FEM model above agreed within 1.5% with the manufacturer supplied fringe magnetic field isoline data. When passive magnetic shields are used, the target current is recoverable to greater than 99% of nominal for shield thicknesses greater than 0.75 mm. The optimized active shield which resulted in 100% target current recovery consists of two thin current rings 110 mm in diameter with 625 and 430 A-turns in each ring. With the length of the passive shield kept constant, the thickness of the shield had to be increased to achieve the same target current within the increased longitudinal magnetic fields.</AbstractText><AbstractText Label="CONCLUSIONS" NlmCategory="CONCLUSIONS">A ≥99% original target current is recovered with passive shield thicknesses >0.75 mm. An active shield consisting of two current rings of diameter of 110 mm with 625 and 430 A-turns fully recovers the loss that would have been caused by the magnetic fields. The minimal passive or active shielding requirements to essentially fully recover the current output of the linac in our parallel-configured linac-MR system have been determined and are easily achieved for practical implementation of the system.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Santos</LastName><ForeName>D M</ForeName><Initials>DM</Initials><AffiliationInfo><Affiliation>Department of Oncology, University of Alberta, Edmonton, Alberta, Canada. dsantos@ualberta.ca</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>St Aubin</LastName><ForeName>J</ForeName><Initials>J</Initials></Author><Author ValidYN="Y"><LastName>Fallone</LastName><ForeName>B G</ForeName><Initials>BG</Initials></Author><Author ValidYN="Y"><LastName>Steciw</LastName><ForeName>S</ForeName><Initials>S</Initials></Author></AuthorList><Language>eng</Language><PublicationTypeList><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList></Article><MedlineJournalInfo><Country>United States</Country><MedlineTA>Med Phys</MedlineTA><NlmUniqueID>0425746</NlmUniqueID><ISSNLinking>0094-2405</ISSNLinking></MedlineJournalInfo><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName MajorTopicYN="Y" UI="D016477">Artifacts</DescriptorName></MeshHeading><MeshHeading><DescriptorName MajorTopicYN="N" UI="D003198">Computer Simulation</DescriptorName></MeshHeading><MeshHeading><DescriptorName MajorTopicYN="N" UI="D017076">Computer-Aided Design</DescriptorName></MeshHeading><MeshHeading><DescriptorName MajorTopicYN="N" UI="D004867">Equipment Design</DescriptorName></MeshHeading><MeshHeading><DescriptorName MajorTopicYN="N" UI="D019544">Equipment Failure Analysis</DescriptorName></MeshHeading><MeshHeading><DescriptorName MajorTopicYN="N" UI="D007089">Image Enhancement</DescriptorName><QualifierName MajorTopicYN="Y" UI="Q000295">instrumentation</QualifierName></MeshHeading><MeshHeading><DescriptorName MajorTopicYN="N" UI="D008279">Magnetic Resonance Imaging</DescriptorName><QualifierName MajorTopicYN="Y" UI="Q000295">instrumentation</QualifierName></MeshHeading><MeshHeading><DescriptorName MajorTopicYN="N" UI="D008962">Models, Theoretical</DescriptorName></MeshHeading><MeshHeading><DescriptorName MajorTopicYN="Y" UI="D010315">Particle Accelerators</DescriptorName></MeshHeading><MeshHeading><DescriptorName MajorTopicYN="N" UI="D011835">Radiation Protection</DescriptorName><QualifierName MajorTopicYN="Y" UI="Q000295">instrumentation</QualifierName></MeshHeading><MeshHeading><DescriptorName MajorTopicYN="N" UI="D011882">Radiotherapy, High-Energy</DescriptorName><QualifierName MajorTopicYN="Y" UI="Q000295">instrumentation</QualifierName></MeshHeading><MeshHeading><DescriptorName MajorTopicYN="N" UI="D061089">Radiotherapy, Image-Guided</DescriptorName><QualifierName MajorTopicYN="Y" UI="Q000295">instrumentation</QualifierName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="entrez"><Year>2012</Year><Month>2</Month><Day>11</Day><Hour>6</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="pubmed"><Year>2012</Year><Month>2</Month><Day>11</Day><Hour>6</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2012</Year><Month>5</Month><Day>2</Day><Hour>6</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="doi">10.1118/1.3676692</ArticleId><ArticleId IdType="pubmed">22320788</ArticleId></ArticleIdList></PubmedData></pubmed></record>Pour manipuler ce document sous Unix (Dilib)
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