title: Theoretical and experimental determination of phantom scatter factors for photon fields with different radial energy variation.
abstract: The output factor used for monitor unit determination in radiotherapy can be divided into two factors: the head scatter factor and the phantom scatter factor. Theoretical and experimental phantom scatter factors have been compared for different beam qualities between 4 MV and 50 MV and field sizes from 5 cm x 5 cm to 30 cm x 30 cm. The theoretical data were obtained through a convolution method based on Monte Carlo calculated energy spectra and dose kernels. The calculations have been performed both for accelerators with a rather large energy variation within the field and for accelerators with a constant energy distribution in the field. Deviations between theoretical and experimental data were found to be less than 1%.
authors.affiliation: Department of Radiation Physics, Umeå University, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Sätherberg
authors.forename: M
authors.initials: M
authors.lastname: Karlsson
authors.forename: M
authors.initials: M
authors.lastname: Karlsson
mesh_terms: D006801:Humans; D008962:Models, Theoretical; D010315:Particle Accelerators; D019047:Phantoms, Imaging; D017785:Photons; D012542:Scattering, Radiation