Evidence map›Paper›PMID 28470816›Full record

ArticleJournal of applied clinical medical physics2017

Patient specific methods for room-mounted x-ray imagers for monoscopic/stereoscopic prostate motion monitoring.

M Tynan R Stevens, Dave D Parsons, James L Robar

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Article in Journal of applied clinical medical physics, 2017. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

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1citing papers in PubMed
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1 · What the graph read from it

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3 · Its place in the literature

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1 citing paper in PubMed.

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5 · Who and what money

Authors and funding

3 authors.

M Tynan R StevensDepartment of Radiation Oncology, Dalhousie University, Halifax, NS, Canada.
Dave D ParsonsDepartment of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada.
James L RobarDepartment of Radiation Oncology, Dalhousie University, Halifax, NS, Canada.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

purposeTo investigate the improvement of combined monoscopic/stereoscopic prostate motion monitoring with room-mounted dual x-ray systems by adopting patient specific methods.

methodsThe linac couch was used as a motion stage to simulate 40 highly dynamic real patient prostate trajectories. For each trajectory, 40 s pretreatment and 120 s treatment periods were extracted to represent a typical treatment fraction. Motion was monitored via continuous stereoscopic x-ray imaging of a single gold fiducial and images were retrospectively divided into periods of stereoscopic and monoscopic imaging to simulate periodic blocking of the room-mounted system by the gantry during arc-based therapy. The accuracy of the combined motion monitoring was assessed by comparison with the linac couch log files. To estimate 3-D marker position during monoscopic imaging, the use of population statistics was compared to both maximum likelihood estimation and stereoscopic localization based estimation of individualized prostate probability density functions (PDFs) from the pretreatment period. The inclusion of intrafraction updating was compared to pretreatment initialization alone.

resultsCombined mono/stereoscopic localization was successfully implemented. During the transitions from stereoscopic to monoscopic imaging, fiducial localization exhibits sharp discontinuities when population PDFs were employed. Patient specific PDFs successfully reduced the localization error when estimated from stereoscopic localizations, whereas maximum likelihood estimation (MLE) was too unstable in the room-mounted geometry. Intrafraction stereoscopic updating provided further increases in accuracy. Residual error tended to decrease throughout the treatment fraction, as the patient-specific PDFs became more refined.

conclusionsThis is the first demonstration of toggled monoscopic/stereoscopic localization using room-mounted dual x-ray imagers, enabling continuous intrafraction motion monitoring for these systems. We showed that both pretreatment individualization and intrafraction updating should be used to provide the most accurate motion monitoring.

Indexed as

Organ MotionEquipment DesignHumansLikelihood FunctionsMaleProstateRadiographyintrafraction motionmonoscopicpatient specificprostate cancerstereoscopicx-ray imaging

Identifiers

PMID28470816
PMCPMC5874929

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