Electron dose distributions in experimental phantoms: a comparison with 2D pencil beam calculations
- 1 September 1987
- journal article
- Published by IOP Publishing in Physics in Medicine & Biology
- Vol. 32 (9), 1073-1086
- https://doi.org/10.1088/0031-9155/32/9/001
Abstract
Dose distributions were measured and computed within inhomogeneous phantoms irradiated with beams of electrons having initial energies of 10 and 18 MeV. The measurements were made with a small p-type silicon diode and the calculations were performed using the pencil beam algorithm developed originally at the M D Anderson Hospital (MDAH). This algorithm, which is available commercially on many radiotherapy planning computers, is based on the Fermi-Eyges theory of electron transport. The phantoms used in this work were composed of water into which two- and three-dimensional inhomogeneities of aluminium and air (embedded in wax) were introduced. This was done in order to simulate the small bones and the air cavities encountered clinically in radiation therapy of the chest wall or neck. The authors intent was to test the adequacy of the two-dimensional implementation of the pencil beam approach. The agreement between measured and computed doses is very good for inhomogeneities which are essentially two-dimensional but discrepancies as large as 40% were observed for more complex three-dimensional inhomogeneities. The authors can only trace the discrepancies to the complex interplay of numerous approximations in the Fermi-Eyges theory of multiple scattering and its adaptation for practical computer-aided radiotherapy planning.Keywords
This publication has 6 references indexed in Scilit:
- Electron beam dose distributions near standard inhomogeneitiesPhysics in Medicine & Biology, 1986
- Second‐order multiple‐scattering theory for charged‐particle teletherapy beamsMedical Physics, 1985
- Effects of radiation damage on p-type silicon detectorsPhysics in Medicine & Biology, 1983
- The application of multiple scattering theory to therapeutic electron dosimetryMedical Physics, 1983
- Electron beam dose calculationsPhysics in Medicine & Biology, 1981
- Multiple Scattering with Energy LossPhysical Review B, 1948