Electron contamination and build-up doses in conformal radiotherapy fields.
AffiliationNorth Western Medical Physics, Christie Hospital NHS Trust, Manchester, UK. firstname.lastname@example.org
MetadataShow full item record
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.
CitationElectron contamination and build-up doses in conformal radiotherapy fields. 1999, 44 (1):43-55 Phys Med Biol
JournalPhysics in Medicine and Biology
- The development and experimental evaluation of a simple analytical model for the TPR in the build-up region of megavoltage photon beams.
- Authors: Godin M, Galiano E
- Issue date: 2012 Jan
- Electron contamination in 8 and 18 MV photon beams.
- Authors: Zhu TC, Palta JR
- Issue date: 1998 Jan
- Monte Carlo study of in-field and out-of-field dose distributions from a linear accelerator operating with and without a flattening-filter.
- Authors: Almberg SS, Frengen J, Lindmo T
- Issue date: 2012 Aug
- Modelling of electron contamination in clinical photon beams for Monte Carlo dose calculation.
- Authors: Yang J, Li JS, Qin L, Xiong W, Ma CM
- Issue date: 2004 Jun 21
- Whole-body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy.
- Authors: Hauri P, Schneider U
- Issue date: 2019 Mar