In the present work, the microdosimetric one-hit detector model is evaluated by calculating the relative energy response of radiographic films. A small sample of typical radiographic films including the covering paper and the polyester base coated on by one emulsion layer is simulated by Geant4 toolkit. Silver bromide grains with the same cubical shape and dimensions of 1 mm randomly positioned in the emulsion are considered as the targets of the model. The relative energy response for eleven photon energies between 20 keV and 1.25 MeV is determined using the microdosimetric distributions of single energy deposition events in the grains. Calculations are performed for a few weight fractions of the silver bromide in the emulsion. The results show that for the weight fraction 13.3% of the silver bromide in the emulsion, calculated values of the relative energy response are in agreement with the experimental data within 20% difference. It can be concluded that the microdosimetric one-hit detector model satisfactorily predicts the energy response of radiographic films.
