The Use of Computers in Radiation Therapy pp 466-468 | Cite as
A Monte Carlo study of backscatter in the monitor ion chamber for clinical photon and electron beams
Abstract
For monitor unit calculations based on dose-to-fluence formalisms [1] the contribution of backscattered radiation from the jaws into the monitor ion chamber of a linear accelerator has to be known. In principle, Monte Carlo (MC) simulations of the complete accelerator geometry for Monte Carlo treatment planning can take the backscatter to the monitor chamber into account, provided an accurate model for the energy deposited in it is available. Output factors for different fields are influenced by forward scatter towards the measuring point and by backscatter towards the monitor chamber. When MC simulations are used to calculate output factors, only the first effect is automatically taken into account. In order to be able to compare MC calculated output factors to measured ones, the backscatter contribution should be used as a correction to the MC output factors. The effect is also of importance when modelling a dynamic wedge.
Keywords
Monte Carlo Photon Beam Monte Carlo Model Output Factor Backscatter RadiationPreview
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