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dc.contributor.authorCosta, F
dc.contributor.authorDoran, SJ
dc.contributor.authorHanson, IM
dc.contributor.authorAdamovics, J
dc.contributor.authorNill, S
dc.contributor.authorOelfke, U
dc.date.accessioned2020-07-08T14:34:43Z
dc.date.issued2020-05-04
dc.identifier.citationPhysics in medicine and biology, 2020, 65 (9), pp. 095003 - ?
dc.identifier.issn0031-9155
dc.identifier.urihttps://repository.icr.ac.uk/handle/internal/3831
dc.identifier.eissn1361-6560
dc.identifier.doi10.1088/1361-6560/ab7d52
dc.description.abstractPrevious work has shown that PRESAGE® can be used successfully to perform 3D dosimetric measurements of complex radiotherapy treatments. However, measurements near the sample edges are known to be difficult to achieve. This is an issue when the doses at air-material interfaces are of interest, for example when investigating the electron return effect (ERE) present in treatments delivered by magnetic resonance (MR)-linac systems. To study this effect, a set of 3.5 cm-diameter cylindrical PRESAGE® samples was uniformly irradiated with multiple dose fractions, using either a conventional linac or an MR-linac. The samples were imaged between fractions using an optical-CT, to read out the corresponding accumulated doses. A calibration between TPS-predicted dose and optical-CT pixel value was determined for individual dosimeters as a function of radial distance from the axis of rotation. This data was used to develop a correction that was applied to four additional samples of PRESAGE® of the same formulation, irradiated with 3D-CRT and IMRT treatment plans, to recover significantly improved 3D measurements of dose. An alternative strategy was also tested, in which the outer surface of the sample was physically removed prior to irradiation. Results show that for the formulation studied here, PRESAGE® samples have a central region that responds uniformly and an edge region of 6-7 mm where there is gradual increase in dosimeter response, rising to an over-response of 24%-36% at the outer boundary. This non-uniform dose response increases in both extent and magnitude over time. Both mitigation strategies investigated were successful. In our four exemplar studies, we show how discrepancies at edges are reduced from 13%-37% of the maximum dose to between 2 and 8%. Quantitative analysis shows that the 3D gamma passing rates rise from 90.4, 69.3, 63.7 and 43.6% to 97.3, 99.9, 96.7 and 98.9% respectively.
dc.formatElectronic
dc.format.extent095003 - ?
dc.languageeng
dc.language.isoeng
dc.rights.urihttps://creativecommons.org/licenses/by/4.0
dc.subjectHumans
dc.subjectLung Neoplasms
dc.subjectImaging, Three-Dimensional
dc.subjectRadiotherapy, Conformal
dc.subjectRadiotherapy Dosage
dc.subjectRadiotherapy Planning, Computer-Assisted
dc.subjectCalibration
dc.subjectRadiometry
dc.subjectPhantoms, Imaging
dc.subjectParticle Accelerators
dc.subjectGamma Rays
dc.titleEdge effects in 3D dosimetry: characterisation and correction of the non-uniform dose response of PRESAGE®.
dc.typeJournal Article
rioxxterms.versionofrecord10.1088/1361-6560/ab7d52
rioxxterms.licenseref.urihttps://creativecommons.org/licenses/by/4.0
rioxxterms.licenseref.startdate2020-05-04
rioxxterms.typeJournal Article/Review
dc.relation.isPartOfPhysics in medicine and biology
pubs.issue9
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/Magnetic Resonance
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/Magnetic Resonance
pubs.organisational-group/ICR/Primary Group/ICR Divisions/Radiotherapy and Imaging/Radiotherapy Physics Modelling
pubs.publication-statusPublished
pubs.volume65en_US
pubs.embargo.termsNot known
icr.researchteamMagnetic Resonanceen_US
icr.researchteamRadiotherapy Physics Modellingen_US
dc.contributor.icrauthorDoran, Simonen
dc.contributor.icrauthorOelfke, Uween
dc.contributor.icrauthorNill, Simeonen
dc.contributor.icrauthorCosta, Filipaen


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