Sohaimi, Norhanna
(2004)
Study of output factors of electron
beam based on the simple model.
Masters thesis, Universiti Sains Malaysia.
Abstract
The output factors for clinical electron beams have been shown to be
dependant on beam energy, field size and collimator design. The purpose of this
study was to investigate the application of the equation of the output factors for a
rectangular field size, which developed from Gaussian scatter model for electron
beams used in Radiotherapy Department, Universiti Sains Malaysia Hospital. The
output factors were measured for 5 MeV and 10 MeV electron beams for various
applicators and square or rectangular insert combinations used in clinical
services. The field sizes ranged from 3 em x 3 em to 25 em x 25 em at source to
surface distance of 1 00 em. The parallel plate ionization chamber was used to
collect the charge and was placed at dmax inside the solid water material for each
electron beam energies. Calculated output factors for the fields studied agreed
with the measured output factors within ±2o/o. This demonstrated that for this
Linear Accelerator {MXE; LINAC MEVATRON), the output factors calculated in
homogenous solid water phantom could be predicted accurately using theoretical
formula.
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