Temporal resolution requirements for intensity modulated radiation therapy delivered by multileaf collimators.

2.50
Hdl Handle:
http://hdl.handle.net/10541/87889
Title:
Temporal resolution requirements for intensity modulated radiation therapy delivered by multileaf collimators.
Authors:
Budgell, Geoff J
Abstract:
Intensity modulated radiation therapy may be delivered via dynamic control of a multileaf collimator by defining dynamic leaf trajectories at a series of control points which are spaced at arbitrary intervals throughout an exposure. Leaves move linearly between the positions defined at the control points and hence leaf motion is a linear approximation to the planned trajectories. When many control points are used, very complex modulations can be defined accurately. If too few are used, dose errors are introduced which depend on the complexity of the modulation and the number of control points chosen. Proposed intensity modulations, of varying complexity, have been converted to trajectory plans where the number of equally spaced control points varied between 11 and 99. In each case the fluence map generated by the resulting leaf motions was computed, and this was quantitatively compared with the desired modulation by calculating the root mean square (RMS) error. It is shown that in no case can the RMS error be significantly reduced by increasing the number of control points beyond 50. Guidelines are derived such that compensators and simple modulations may be very accurately delivered with about 20 control points, moderately complex modulations require 30-35 control points and very complex modulations 50 control points. A similar analysis of the step and shoot technique suggests that very accurate deliveries are always achieved with a maximum of 25 equally weighted static fields and reasonable accuracy with 15 fields.
Affiliation:
North Western Medical Physics, Christie Hospital NHS Trust, Manchester, UK. prsgjb@dalpha2.cr.man.ac.uk
Citation:
Temporal resolution requirements for intensity modulated radiation therapy delivered by multileaf collimators. 1999, 44 (7):1581-96 Phys Med Biol
Journal:
Physics in Medicine and Biology
Issue Date:
Jul-1999
URI:
http://hdl.handle.net/10541/87889
DOI:
10.1088/0031-9155/44/7/301
PubMed ID:
10442698
Type:
Article
Language:
en
ISSN:
0031-9155
Appears in Collections:
All Christie Publications

Full metadata record

DC FieldValue Language
dc.contributor.authorBudgell, Geoff Jen
dc.date.accessioned2009-12-14T14:40:34Z-
dc.date.available2009-12-14T14:40:34Z-
dc.date.issued1999-07-
dc.identifier.citationTemporal resolution requirements for intensity modulated radiation therapy delivered by multileaf collimators. 1999, 44 (7):1581-96 Phys Med Biolen
dc.identifier.issn0031-9155-
dc.identifier.pmid10442698-
dc.identifier.doi10.1088/0031-9155/44/7/301-
dc.identifier.urihttp://hdl.handle.net/10541/87889-
dc.description.abstractIntensity modulated radiation therapy may be delivered via dynamic control of a multileaf collimator by defining dynamic leaf trajectories at a series of control points which are spaced at arbitrary intervals throughout an exposure. Leaves move linearly between the positions defined at the control points and hence leaf motion is a linear approximation to the planned trajectories. When many control points are used, very complex modulations can be defined accurately. If too few are used, dose errors are introduced which depend on the complexity of the modulation and the number of control points chosen. Proposed intensity modulations, of varying complexity, have been converted to trajectory plans where the number of equally spaced control points varied between 11 and 99. In each case the fluence map generated by the resulting leaf motions was computed, and this was quantitatively compared with the desired modulation by calculating the root mean square (RMS) error. It is shown that in no case can the RMS error be significantly reduced by increasing the number of control points beyond 50. Guidelines are derived such that compensators and simple modulations may be very accurately delivered with about 20 control points, moderately complex modulations require 30-35 control points and very complex modulations 50 control points. A similar analysis of the step and shoot technique suggests that very accurate deliveries are always achieved with a maximum of 25 equally weighted static fields and reasonable accuracy with 15 fields.en
dc.language.isoenen
dc.subject.meshCalibration-
dc.subject.meshFourier Analysis-
dc.subject.meshHumans-
dc.subject.meshPhantoms, Imaging-
dc.subject.meshRadiotherapy Dosage-
dc.subject.meshRadiotherapy Planning, Computer-Assisted-
dc.subject.meshRadiotherapy, Conformal-
dc.subject.meshReproducibility of Results-
dc.titleTemporal resolution requirements for intensity modulated radiation therapy delivered by multileaf collimators.en
dc.typeArticleen
dc.contributor.departmentNorth Western Medical Physics, Christie Hospital NHS Trust, Manchester, UK. prsgjb@dalpha2.cr.man.ac.uken
dc.identifier.journalPhysics in Medicine and Biologyen

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