Monte-Carlo simulations of Al2O3 dosimetry in uniform MV photon beams: Influence of field and detector size

This work was to evaluate the absorbed dose to different sizes Al₂O₃ dosimeter in uniform MV photon beams using Monte Carlo simulation. The absorbed dose ratio factor f_md of Al₂O₃ dosimeters was calculated. The incident beams included 4 MV–24 MV X-rays using Mohan's spectra with different field sizes. Results show that the maximum variation of f_md due to different dosimeter sizes is 5%. As the field diameter increases from 1 cm to 3 cm, the difference of f_md can be up to 8%. The results of this work show that the effect of dosimeter size and the field size can't be neglected when using Al₂O₃ dosimeter.