MCNP5 evaluation of photoneutron production from the Alexandria University 15 MV Elekta Precise medical LINAC
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W M Abou-Taleb1, M H Hassan2, E A El Mallah3
1Physics and Chemistry Department, Faculty of Education, Alexandria University, Alexandria, Egypt.
Abstract:
Photoneutron production, and the dose equivalent, in the head assembly of the 15 MV Elekta Precise medical linac; operating in the faculty of Medicine at Alexandria University were estimated with the MCNP5 code. Photoneutron spectra were calculated in air and inside a water phantom to different depths as a function of the radiation field sizes. The maximum neutron fluence is 3.346×10-9 n/cm2-e for a 30×30 cm2 field size to 2-4 cm-depth in the phantom. The dose equivalent due to fast neutron increases as the field size increases, being a maximum of 0.912 ± 0.05 mSv/Gy at depth between 2 and 4 cm in the water phantom for 40×40 cm2 field size. Photoneutron fluence and dose equivalent are larger to 100 cm from the isocenter than to 35 cm from the treatment room wall.
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