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dc.contributor.authorBillas, I
dc.contributor.authorBouchard, H
dc.contributor.authorOelfke, U
dc.contributor.authorShipley, D
dc.contributor.authorGouldstone, C
dc.contributor.authorDuane, S
dc.date.accessioned2020-05-21T12:01:33Z
dc.date.issued2020-06-03
dc.identifier.citationPhysics in medicine and biology, 2020, 65 (11), pp. 115001 - ?
dc.identifier.issn0031-9155
dc.identifier.urihttps://repository.icr.ac.uk/handle/internal/3621
dc.identifier.eissn1361-6560
dc.identifier.doi10.1088/1361-6560/ab8148
dc.description.abstractReference dosimetry in the presence of a strong magnetic field is challenging. Ionisation chambers have shown to be strongly affected by magnetic fields. There is a need for robust and stable detectors in MRI-guided radiotherapy (MRIgRT). This study investigates the behaviour of the alanine dosimeter in magnetic fields and assesses its suitability to act as a reference detector in MRIgRT. Alanine pellets were loaded in a waterproof holder, placed in an electromagnet and irradiated by 60Co and 6 MV and 8 MV linac beams over a range of magnetic flux densities. Monte Carlo simulations were performed to calculate the absorbed dose, to water and to alanine, with and without magnetic fields. Combining measurements with simulations, the effect of magnetic fields on alanine response was quantified and a correction factor for the presence of magnetic fields on alanine was determined. This study finds that the response of alanine to ionising radiation is modified when the irradiation is in the presence of a magnetic field. The effect is energy independent and may increase the alanine/electron paramagnetic resonance (EPR) signal by 0.2% at 0.35 T and 0.7% at 1.5 T. In alanine dosimetry for MRIgRT, this effect, if left uncorrected, would lead to an overestimate of dose. Accordingly, a correction factor, [Formula: see text], is defined. Values are obtained for this correction as a function of magnetic flux density, with a standard uncertainty which depends on the magnetic field and is 0.6% or less. The strong magnetic field has a measurable effect on alanine dosimetry. For alanine which is used to measure absorbed dose to water in a strong magnetic field, but which has been calibrated in the absence of a magnetic field, a small correction to the reported dose is required. With the inclusion of this correction, alanine/EPR is a suitable reference dosimeter for measurements in MRIgRT.
dc.formatElectronic
dc.format.extent115001 - ?
dc.languageeng
dc.language.isoeng
dc.rights.urihttps://creativecommons.org/licenses/by/4.0
dc.subjectCobalt Radioisotopes
dc.subjectAlanine
dc.subjectMagnetic Resonance Imaging
dc.subjectRadiotherapy
dc.subjectCalibration
dc.subjectMonte Carlo Method
dc.subjectRadiometry
dc.subjectParticle Accelerators
dc.subjectMagnetic Fields
dc.subjectRadiation Dosimeters
dc.titleAlanine dosimetry in strong magnetic fields: use as a transfer standard in MRI-guided radiotherapy.
dc.typeJournal Article
rioxxterms.versionofrecord10.1088/1361-6560/ab8148
rioxxterms.licenseref.urihttps://creativecommons.org/licenses/by/4.0
rioxxterms.licenseref.startdate2020-06-03
rioxxterms.typeJournal Article/Review
dc.relation.isPartOfPhysics in medicine and biology
pubs.issue11
pubs.notesNot known
pubs.organisational-group/ICR
pubs.organisational-group/ICR/Primary Group
pubs.organisational-group/ICR/Primary Group/ICR Divisions
pubs.organisational-group/ICR/Primary Group/ICR Divisions/Radiotherapy and Imaging
pubs.organisational-group/ICR/Primary Group/ICR Divisions/Radiotherapy and Imaging/Radiotherapy Physics Modelling
pubs.organisational-group/ICR
pubs.organisational-group/ICR/Primary Group
pubs.organisational-group/ICR/Primary Group/ICR Divisions
pubs.organisational-group/ICR/Primary Group/ICR Divisions/Radiotherapy and Imaging
pubs.organisational-group/ICR/Primary Group/ICR Divisions/Radiotherapy and Imaging/Radiotherapy Physics Modelling
pubs.publication-statusPublished
pubs.volume65
pubs.embargo.termsNot known
icr.researchteamRadiotherapy Physics Modellingen_US
dc.contributor.icrauthorOelfke, Uween


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