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dc.contributor.authorBillas, Ien_US
dc.contributor.authorBouchard, Hen_US
dc.contributor.authorOelfke, Uen_US
dc.contributor.authorShipley, Den_US
dc.contributor.authorGouldstone, Cen_US
dc.contributor.authorDuane, Sen_US
dc.identifier.citationPhysics in medicine and biology, 2020, 65 (11), pp. 115001 - ?en_US
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.en_US
dc.format.extent115001 - ?en_US
dc.titleAlanine dosimetry in strong magnetic fields: use as a transfer standard in MRI-guided radiotherapy.en_US
dc.typeJournal Article
rioxxterms.typeJournal Article/Reviewen_US
dc.relation.isPartOfPhysics in medicine and biologyen_US
pubs.notesNot knownen_US
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.embargo.termsNot knownen_US
icr.researchteamRadiotherapy Physics Modellingen_US
dc.contributor.icrauthorOelfke, Uween_US

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