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dc.contributor.authorKamerling, CP
dc.contributor.authorFast, MF
dc.contributor.authorZiegenhein, P
dc.contributor.authorMenten, MJ
dc.contributor.authorNill, S
dc.contributor.authorOelfke, U
dc.date.accessioned2016-11-23T12:03:10Z
dc.date.issued2016-11-01
dc.identifier.citationMedical physics, 2016, 43 (11), pp. 6072 - ?
dc.identifier.issn0094-2405
dc.identifier.urihttps://repository.icr.ac.uk/handle/internal/239
dc.identifier.eissn2473-4209
dc.identifier.doi10.1118/1.4965045
dc.description.abstractPURPOSE: This study provides a proof of concept for real-time 4D dose reconstruction for lung stereotactic body radiation therapy (SBRT) with multileaf collimator (MLC) tracking and assesses the impact of tumor tracking on the size of target margins. METHODS: The authors have implemented real-time 4D dose reconstruction by connecting their tracking and delivery software to an Agility MLC at an Elekta Synergy linac and to their in-house treatment planning software (TPS). Actual MLC apertures and (simulated) target positions are reported to the TPS every 40 ms. The dose is calculated in real-time from 4DCT data directly after each reported aperture by utilization of precalculated dose-influence data based on a Monte Carlo algorithm. The dose is accumulated onto the peak-exhale (reference) phase using energy-mass transfer mapping. To investigate the impact of a potentially reducible safety margin, the authors have created and delivered treatment plans designed for a conventional internal target volume (ITV) + 5 mm, a midventilation approach, and three tracking scenarios for four lung SBRT patients. For the tracking plans, a moving target volume (MTV) was established by delineating the gross target volume (GTV) on every 4DCT phase. These were rigidly aligned to the reference phase, resulting in a unified maximum GTV to which a 1, 3, or 5 mm isotropic margin was added. All scenarios were planned for 9-beam step-and-shoot IMRT to meet the criteria of RTOG 1021 (3 × 18 Gy). The GTV 3D center-of-volume shift varied from 6 to 14 mm. RESULTS: Real-time dose reconstruction at 25 Hz could be realized on a single workstation due to the highly efficient implementation of dose calculation and dose accumulation. Decreased PTV margins resulted in inadequate target coverage during untracked deliveries for patients with substantial tumor motion. MLC tracking could ensure the GTV target dose for these patients. Organ-at-risk (OAR) doses were consistently reduced by decreased PTV margins. The tracked MTV + 1 mm deliveries resulted in the following OAR dose reductions: lung V20 up to 3.5%, spinal cord D2 up to 0.9 Gy/Fx, and proximal airways D2 up to 1.4 Gy/Fx. CONCLUSIONS: The authors could show that for patient data at clinical resolution and realistic motion conditions, the delivered dose could be reconstructed in 4D for the whole lung volume in real-time. The dose distributions show that reduced margins yield lower doses to healthy tissue, whilst target dose can be maintained using dynamic MLC tracking.
dc.formatPrint
dc.format.extent6072 - ?
dc.languageeng
dc.language.isoeng
dc.publisherWILEY
dc.rights.urihttps://creativecommons.org/licenses/by/4.0
dc.subjectHumans
dc.subjectLung Neoplasms
dc.subjectRadiosurgery
dc.subjectRadiotherapy Planning, Computer-Assisted
dc.subjectRadiation Dosage
dc.subjectMovement
dc.subjectTime Factors
dc.subjectFour-Dimensional Computed Tomography
dc.subjectDose Fractionation, Radiation
dc.titleReal-time 4D dose reconstruction for tracked dynamic MLC deliveries for lung SBRT.
dc.typeJournal Article
dcterms.dateAccepted2016-10-05
rioxxterms.versionofrecord10.1118/1.4965045
rioxxterms.licenseref.urihttps://creativecommons.org/licenses/by/4.0
rioxxterms.licenseref.startdate2016-11
rioxxterms.typeJournal Article/Review
dc.relation.isPartOfMedical physics
pubs.issue11
pubs.notesNo embargo
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.volume43
pubs.embargo.termsNo embargo
icr.researchteamRadiotherapy Physics Modelling
dc.contributor.icrauthorMenten, Martin
dc.contributor.icrauthorNill, Simeon


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