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dc.contributor.authorBernstein, D
dc.contributor.authorTaylor, A
dc.contributor.authorNill, S
dc.contributor.authorImseeh, G
dc.contributor.authorKothari, G
dc.contributor.authorLlewelyn, M
dc.contributor.authorDe Paepe, KN
dc.contributor.authorRockall, A
dc.contributor.authorShiarli, A-M
dc.contributor.authorOelfke, U
dc.date.accessioned2021-03-31T14:07:49Z
dc.date.available2021-03-31T14:07:49Z
dc.date.issued2021-02-24
dc.identifier.citationClinical oncology (Royal College of Radiologists (Great Britain)), 2021
dc.identifier.issn0936-6555
dc.identifier.urihttps://repository.icr.ac.uk/handle/internal/4483
dc.identifier.eissn1433-2981
dc.identifier.doi10.1016/j.clon.2021.02.003
dc.description.abstractAims Target delineation uncertainty is arguably the largest source of geometric uncertainty in radiotherapy. Several factors can affect it, including the imaging modality used for delineation. It is accounted for by applying safety margins to the target to produce a planning target volume (PTV), to which treatments are designed. To determine the margin, the delineation uncertainty is measured as the delineation error, and then a margin recipe used. However, there is no published evidence of such analysis for recurrent gynaecological cancers (RGC). The aims of this study were first to quantify the delineation uncertainty for RGC gross tumour volumes (GTVs) and to calculate the associated PTV margins and then to quantify the difference in GTV, delineation uncertainty and PTV margin, between a computed tomography-magnetic resonance imaging (CT-MRI) and MRI workflow.Materials and methods Seven clinicians delineated the GTV for 20 RGC tumours on co-registered CT and MRI datasets (CT-MRI) and on MRI alone. The delineation error, the standard deviation of distances from each clinician's outline to a reference, was measured and the required PTV margin determined. Differences between using CT-MRI and MRI alone were assessed.Results The overall delineation error and the resulting margin were 3.1 mm and 8.5 mm, respectively, for CT-MRI, reducing to 2.5 mm and 7.1 mm, respectively, for MRI alone. Delineation errors and therefore the theoretical margins, varied widely between patients. MRI tumour volumes were on average 15% smaller than CT-MRI tumour volumes.Discussion This study is the first to quantify delineation error for RGC tumours and to calculate the corresponding PTV margin. The determined margins were larger than those reported in the literature for similar patients, bringing into question both current margins and margin calculation methods. The wide variation in delineation error between these patients suggests that applying a single population-based margin may result in PTVs that are suboptimal for many. Finally, the reduced tumour volumes and safety margins suggest that patients with RGC may benefit from an MRI-only treatment workflow.
dc.formatPrint-Electronic
dc.languageeng
dc.language.isoeng
dc.rights.urihttps://creativecommons.org/licenses/by/4.0
dc.titleAn Inter-observer Study to Determine Radiotherapy Planning Target Volumes for Recurrent Gynaecological Cancer Comparing Magnetic Resonance Imaging Only With Computed Tomography-Magnetic Resonance Imaging.
dc.typeJournal Article
dcterms.dateAccepted2021-02-05
rioxxterms.versionVoR
rioxxterms.versionofrecord10.1016/j.clon.2021.02.003
rioxxterms.licenseref.urihttps://creativecommons.org/licenses/by/4.0
rioxxterms.licenseref.startdate2021-02-24
rioxxterms.typeJournal Article/Review
dc.relation.isPartOfClinical oncology (Royal College of Radiologists (Great Britain))
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.embargo.termsNot known
icr.researchteamRadiotherapy Physics Modelling
icr.researchteamRadiotherapy Physics Modellingen_US
dc.contributor.icrauthorOelfke, Uween
dc.contributor.icrauthorNill, Simeonen


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