Bulg. J. Phys. vol.45 no.1 (2018), pp. 067-075



Study of 6 MV Photon Beam Dose Profiles, Investigation and Evaluation of Scattered photons and Electrons Contamination Effects on Beam Dose Profiles

M. Bencheikh1, A. Maghnouj1, J. Tajmouati1, A. Didi1, A. Lamrabet1, Y. Benkhouya2,3
1LISTA Laboratory, Physics Department, Faculty of Sciences Dhar El-Mahraz, University of Sidi Mohamed Ben Abdellah, Fez, Morocco
2Radiotherapy Department, Al Kawtar Clinic, Fez, Morocco
3Nuclear Physics Laboratory, Faculty of Sciences Agdal, University of Mohammed V, Rabat, Morocco
Abstract. In this study we have investigated the scattered photons and electrons contamination effects on dose profiles due beam modifiers and jaw system motion. Firstly, we have calculated the increasing relative dose on beam profile as a function of field size and depth along central beam axis and we have normalized the increasing relative dose on beam profile to the increasing relative dose of standard filed size of 10×10 cm2. Secondly, we have calculated the width of dose profiles as function of field size and depth; then we have investigated the beam symmetry on central beam axis and the jaw motion effects on delivered dose, we have calculated two parameters: the normalized width and the width difference between left and right width of dose profiles as a function of field size and depth. We concluded that scattered photons and electrons contamination effects on dose profiles must be taken in consideration when the physicians treat the tumor because the dose profile peaks have an increasing in dose that increased with irradiation field size and in shallow depths (10 cm) in water phantom 10×10 cm2 due to scattered photons and electrons contamination coming from beam modifiers near the phantom surface. This study was an experimentation investigation of delivered dose from linear accelerator; our results will be an investigation by Monte Carlo method to improve the dosimetry and linac in the future.

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