On the behavior of f_(c,Q) factors with quality indexes for medium energy X-ray beams: A Monte Carlo study with penelope

摘要

A series of Monte Carlo simulations has been performed to determine the behavior of the factor f_(c,Q) as a function of the usual quality indexes for medium energy X-ray beams. Up to 46 beams, with spectra generated with the codes xcomp5r and S_(PCK)C_(ALC), for potentials up to 300 kV, were transported using the Monte Carlo code penelope to calculate the doses in water and in a PTW 30001 ionization chamber, both at the reference depth. The half-value layer (the usual quality index for these beams) and other two quality indexes, the generating potential and the homogeneity coefficient, have been considered. The calculated f_(c,Q) factors are well described with a function that involves the power of the half-value layer up to the square and a second quality index linearly. The predictive power of this combination has been studied.