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dc.contributor.authorMartyn, Men_US
dc.contributor.authorO'Shea, TPen_US
dc.contributor.authorHarris, Een_US
dc.contributor.authorBamber, Jen_US
dc.contributor.authorGilroy, Sen_US
dc.contributor.authorFoley, MJen_US
dc.coverage.spatialUnited Statesen_US
dc.date.accessioned2018-02-14T15:09:41Z
dc.date.issued2017-10en_US
dc.identifierhttps://www.ncbi.nlm.nih.gov/pubmed/28688115en_US
dc.identifier.citationMed Phys, 2017, 44 (10), pp. 5020 - 5033en_US
dc.identifier.urihttps://repository.icr.ac.uk/handle/internal/1079
dc.identifier.eissn2473-4209en_US
dc.identifier.doi10.1002/mp.12464en_US
dc.description.abstractPURPOSE: The aim of this study was to estimate changes in surface dose due to the presence of the Clarity Autoscan™ ultrasound (US) probe during prostate radiotherapy using Monte Carlo (MC) methods. METHODS: MC models of the Autoscan US probe were developed using the BEAMnrc/DOSXYZnrc code based on kV and MV CT images. CT datasets were converted to voxelized mass density phantoms using a CT number-to-mass density calibration. The dosimetric effect of the probe, in the contact region (an 8 mm × 12 mm single layer of voxels), was investigated using a phantom set-up mimicking two scenarios (a) a transperineal imaging configuration (radiation beam perpendicular to the central US axial direction), and (b) a transabdominal imaging configuration (radiation beam parallel to the central US axial direction). For scenario (a), the dosimetric effect was evaluated as a function of the probe to inferior radiation field edge distance. Clinically applicable distances from 5 mm separation to 2 mm overlap were determined from the radiotherapy plans of 27 patients receiving Clarity imaging. Overlaps of 3 to 14 (1 to 3 SD) mm were also considered to include the effect of interfraction motion correction. The influence of voxel size on surface dose estimation was investigated. Approved clinical plans from two prostate patients were used to simulate worst-case dosimetric impact of the probe when large couch translations were applied to correct for interfraction prostate motion. RESULTS: The dosimetric impact of both the MV and kV probe models agreed within ±2% for both beam configurations. For scenario (a) and 1 mm voxel model, the probe gave mean dose increases of 1.2% to 4.6% (of the dose at isocenter) for 5 mm separation to 0 mm overlap in the probe-phantom contact region, respectively. This increased to 27.5% for the largest interfraction motion correction considered (14 mm overlap). For separations of ≥ 2 mm dose differences were < 2%. Simulated dose perturbations were found to be superficial; for the 14 mm overlap the dose increase reduced to < 3% at 5.0 mm within the phantom. For scenario (b), dose increases due to the probe were < 5% in all cases. The dose increase was underestimated by up to ~13% when the voxel size was increased from 1 mm to 3 mm. MC simulated dose to the PTV and OARs for the two clinical plans considered showed good agreement with commercial treatment planning system results (within 2%). Mean dose increases due to the presence of the probe, after the maximum interfraction motion correction, were ~16.3% and ~8.0%, in the contact region, for plan 1 and plan 2, respectively. CONCLUSIONS: The presence of the probe results in superficial dose perturbations for patients with an overlap between the probe and the radiation field present in either the original treatment plan or due to translation of the radiation field to simulate correction of interfraction internal prostate motion.en_US
dc.format.extent5020 - 5033en_US
dc.languageengen_US
dc.language.isoengen_US
dc.subjectMonte Carloen_US
dc.subjectdosimetryen_US
dc.subjectimage-guided radiotherapyen_US
dc.subjectprostate canceren_US
dc.subjectultrasound-guided radiotherapyen_US
dc.subjectDose Fractionation, Radiationen_US
dc.subjectHumansen_US
dc.subjectMaleen_US
dc.subjectMonte Carlo Methoden_US
dc.subjectMovementen_US
dc.subjectPhantoms, Imagingen_US
dc.subjectProstatic Neoplasmsen_US
dc.subjectRadiotherapy Planning, Computer-Assisteden_US
dc.subjectRadiotherapy, Intensity-Modulateden_US
dc.subjectTomography, X-Ray Computeden_US
dc.subjectTransducersen_US
dc.subjectUltrasonographyen_US
dc.titleA Monte Carlo study of the effect of an ultrasound transducer on surface dose during intrafraction motion imaging for external beam radiation therapy.en_US
dc.typeJournal Article
dcterms.dateAccepted2017-07-04en_US
rioxxterms.versionofrecord10.1002/mp.12464en_US
rioxxterms.licenseref.startdate2017-10en_US
rioxxterms.typeJournal Article/Reviewen_US
dc.relation.isPartOfMed Physen_US
pubs.issue10en_US
pubs.notesNot knownen_US
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/Imaging for Radiotherapy Adaptation
pubs.organisational-group/ICR/Primary Group/ICR Divisions/Radiotherapy and Imaging/Ultrasound & Optical Imaging
pubs.organisational-group/ICR/Primary Group/Royal Marsden Clinical Units
pubs.publication-statusPublisheden_US
pubs.volume44en_US
pubs.embargo.termsNot knownen_US
icr.researchteamImaging for Radiotherapy Adaptationen_US
icr.researchteamUltrasound & Optical Imagingen_US
dc.contributor.icrauthorHarris, Emmaen_US
dc.contributor.icrauthorBamber, Jeffreyen_US
dc.contributor.icrauthorMarsden,en_US


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