A macropencil beam model: clinical implementation for conformal and intensity modulated radiation therapy.

2.50
Hdl Handle:
http://hdl.handle.net/10541/87890
Title:
A macropencil beam model: clinical implementation for conformal and intensity modulated radiation therapy.
Authors:
Phillips, Mark H; Singer, Karen M; Hounsell, Alan R
Abstract:
The increasing use of irregularly shaped, off-centre fields in advanced treatment techniques, particularly intensity modulated radiation therapy, has strained the limits of conventional, broad-beam dose calculation algorithms. More recent models, such as kernel-based pencil beams and Monte Carlo methods, are accurate but suffer from the time needed for calculations and from the lack of clearly established methods for determining the parameters needed to match calculations with the particular dosimetric characteristics of an individual machine. This paper presents the implementation of a model that uses an extended source model to calculate the variation of fluence at the patient surface for any arbitrarily shaped field. It uses a macropencil beam model to calculate phantom scatter. Both head scatter and phantom scatter models use exponential functions fit to a series of measurements to determine the model's parameters. The means by which the model can be implemented in a clinical setting using standard dosimetric equipment is presented. Results for two separate machines and three energies are presented. Comparisons with measurements for a set of regular and irregular fields demonstrate the accuracy of the model for conventional, conformal and intensity modulated treatments. For rectangular and irregular fields at depths up to 20 cm, the accuracy was better than < or =1.5%, compared with errors of up to 7.5% with a standard algorithm. For a 20-step intensity modulated field, the accuracy was 3.4% compared with 18% with the conventional algorithm. The advantages of this model for IMRT are discussed.
Affiliation:
Department of Radiation Oncology, University of Washington Medical Center, Seattle 98195-6043, USA.
Citation:
A macropencil beam model: clinical implementation for conformal and intensity modulated radiation therapy. 1999, 44 (4):1067-88 Phys Med Biol
Journal:
Physics in Medicine and Biology
Issue Date:
Apr-1999
URI:
http://hdl.handle.net/10541/87890
DOI:
10.1088/0031-9155/44/4/018
PubMed ID:
10232815
Type:
Article
Language:
en
ISSN:
0031-9155
Appears in Collections:
All Christie Publications

Full metadata record

DC FieldValue Language
dc.contributor.authorPhillips, Mark Hen
dc.contributor.authorSinger, Karen Men
dc.contributor.authorHounsell, Alan Ren
dc.date.accessioned2009-12-14T14:44:25Z-
dc.date.available2009-12-14T14:44:25Z-
dc.date.issued1999-04-
dc.identifier.citationA macropencil beam model: clinical implementation for conformal and intensity modulated radiation therapy. 1999, 44 (4):1067-88 Phys Med Biolen
dc.identifier.issn0031-9155-
dc.identifier.pmid10232815-
dc.identifier.doi10.1088/0031-9155/44/4/018-
dc.identifier.urihttp://hdl.handle.net/10541/87890-
dc.description.abstractThe increasing use of irregularly shaped, off-centre fields in advanced treatment techniques, particularly intensity modulated radiation therapy, has strained the limits of conventional, broad-beam dose calculation algorithms. More recent models, such as kernel-based pencil beams and Monte Carlo methods, are accurate but suffer from the time needed for calculations and from the lack of clearly established methods for determining the parameters needed to match calculations with the particular dosimetric characteristics of an individual machine. This paper presents the implementation of a model that uses an extended source model to calculate the variation of fluence at the patient surface for any arbitrarily shaped field. It uses a macropencil beam model to calculate phantom scatter. Both head scatter and phantom scatter models use exponential functions fit to a series of measurements to determine the model's parameters. The means by which the model can be implemented in a clinical setting using standard dosimetric equipment is presented. Results for two separate machines and three energies are presented. Comparisons with measurements for a set of regular and irregular fields demonstrate the accuracy of the model for conventional, conformal and intensity modulated treatments. For rectangular and irregular fields at depths up to 20 cm, the accuracy was better than < or =1.5%, compared with errors of up to 7.5% with a standard algorithm. For a 20-step intensity modulated field, the accuracy was 3.4% compared with 18% with the conventional algorithm. The advantages of this model for IMRT are discussed.en
dc.language.isoenen
dc.subject.meshModels, Statistical-
dc.subject.meshPhantoms, Imaging-
dc.subject.meshRadiotherapy Planning, Computer-Assisted-
dc.subject.meshRadiotherapy, Computer-Assisted-
dc.titleA macropencil beam model: clinical implementation for conformal and intensity modulated radiation therapy.en
dc.typeArticleen
dc.contributor.departmentDepartment of Radiation Oncology, University of Washington Medical Center, Seattle 98195-6043, USA.en
dc.identifier.journalPhysics in Medicine and Biologyen

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