Characterization and quenching correction for a 2D real time radioluminescent system in therapeutic proton and carbon charged beams

Two dimensional radioluminescence (RL) films were investigated for application in proton and carbon therapy dosimetry. The films are made of Al2O3:C,Mg micro powder in two sizes (38 µm and 7 µm) mixed with a water-equivalent binder. The films were irradiated behind different thicknesses of solid slabs and behind wedge shaped plastic absorbers. Bragg curves presented quenching effect attributed to the non-linear response of the RL signal as a function of proton linear energy transfer (LET). Experimental data and Monte Carlo simulations were utilized to acquire a quenching correction method, adapted from Birks’ formula, to restore the linear dose response for particle therapy beams. The method for quenching correction was applied, reaching an agreement at the Bragg peak of 3 % for films with 38 µm median grain size phosphor and 1.5 % for films with 7 µm median grain size phosphor for the proton beams; and 2 % for films with 38 µm median grain size phosphor and 3 % for films with 7 µm median grain size phosphor for the carbon charged particles.