Electron contamination and build-up doses in conformal radiotherapy fields.

2.50
Hdl Handle:
http://hdl.handle.net/10541/87913
Title:
Electron contamination and build-up doses in conformal radiotherapy fields.
Authors:
Hounsell, Alan R; Wilkinson, John M
Abstract:
The dose in the build-up region depends upon the primary photon beam, backscattered radiation from the patient and contamination radiation from outside the patient. In this paper, a model based on measured data is proposed which allows the build-up dose for arbitrarily shaped treatment fields to be determined. The dose in the build-up region is assumed to comprise a primary photon component and a contamination component that is a function of the field size and shape. This contamination component, for modelling purposes, is subdivided into contributions that correspond to elements of 1 cm by 1 cm cross-sectional area at the plane of the isocentre. The magnitude of these components has been obtained by fitting measured data to an exponential function. The exponent was found to vary linearly with depth for energies between 4 MV and 20 MV. The coefficient decreased linearly with depth at 4, 6 and 8 MV, but exhibited a broad build-up region at 20 MV. The primary component, in the build-up region, could be approximated by a 100 - (100 - PSD) e(-mu d) function, where PSD is the primary surface dose. The values obtained during the fitting procedure were used to calculate dose in the build-up region for arbitrarily shaped fields. Good agreement was found in each case.
Affiliation:
North Western Medical Physics, Christie Hospital NHS Trust, Manchester, UK. alan.hounsell@physics.cr.man.ac.uk
Citation:
Electron contamination and build-up doses in conformal radiotherapy fields. 1999, 44 (1):43-55 Phys Med Biol
Journal:
Physics in Medicine and Biology
Issue Date:
Jan-1999
URI:
http://hdl.handle.net/10541/87913
DOI:
10.1088/0031-9155/44/1/005
PubMed ID:
10071874
Type:
Article
Language:
en
ISSN:
0031-9155
Appears in Collections:
All Christie Publications

Full metadata record

DC FieldValue Language
dc.contributor.authorHounsell, Alan Ren
dc.contributor.authorWilkinson, John Men
dc.date.accessioned2009-12-14T16:03:36Z-
dc.date.available2009-12-14T16:03:36Z-
dc.date.issued1999-01-
dc.identifier.citationElectron contamination and build-up doses in conformal radiotherapy fields. 1999, 44 (1):43-55 Phys Med Biolen
dc.identifier.issn0031-9155-
dc.identifier.pmid10071874-
dc.identifier.doi10.1088/0031-9155/44/1/005-
dc.identifier.urihttp://hdl.handle.net/10541/87913-
dc.description.abstractThe dose in the build-up region depends upon the primary photon beam, backscattered radiation from the patient and contamination radiation from outside the patient. In this paper, a model based on measured data is proposed which allows the build-up dose for arbitrarily shaped treatment fields to be determined. The dose in the build-up region is assumed to comprise a primary photon component and a contamination component that is a function of the field size and shape. This contamination component, for modelling purposes, is subdivided into contributions that correspond to elements of 1 cm by 1 cm cross-sectional area at the plane of the isocentre. The magnitude of these components has been obtained by fitting measured data to an exponential function. The exponent was found to vary linearly with depth for energies between 4 MV and 20 MV. The coefficient decreased linearly with depth at 4, 6 and 8 MV, but exhibited a broad build-up region at 20 MV. The primary component, in the build-up region, could be approximated by a 100 - (100 - PSD) e(-mu d) function, where PSD is the primary surface dose. The values obtained during the fitting procedure were used to calculate dose in the build-up region for arbitrarily shaped fields. Good agreement was found in each case.en
dc.language.isoenen
dc.subject.meshElectrons-
dc.subject.meshHumans-
dc.subject.meshPhantoms, Imaging-
dc.subject.meshPhotons-
dc.subject.meshRadiotherapy Dosage-
dc.subject.meshRadiotherapy Planning, Computer-Assisted-
dc.subject.meshRadiotherapy, Conformal-
dc.subject.meshReproducibility of Results-
dc.subject.meshScattering, Radiation-
dc.titleElectron contamination and build-up doses in conformal radiotherapy fields.en
dc.typeArticleen
dc.contributor.departmentNorth Western Medical Physics, Christie Hospital NHS Trust, Manchester, UK. alan.hounsell@physics.cr.man.ac.uken
dc.identifier.journalPhysics in Medicine and Biologyen

Related articles on PubMed

All Items in Christie are protected by copyright, with all rights reserved, unless otherwise indicated.