A new method to predict the response of thermoluminescent detectors exposed at different positions within a clinical proton beam

The proton depth dose profile measured by luminescent detectors differs from the one measured with reference dosimeters (i.e. ionization chambers) because of several effects including efficiency quenching and changes in the attenuation of the emitted light in case of partial detector irradiation. Using the Microdosimetric d(z) Model in combination with the Monte Carlo radiation transport code PHITS, a methodology was developed to tackle all these factors and calculate the response of luminescent when exposed at different positions along a proton Bragg peak. The results were compared against experimental data gathered with 7LiF:Mg,Ti (MTS-7) and 7LiF:Mg,Cu,P (MCP-7) thermoluminescent detectors, showing a very good agreement (average relative deviation ~ 3% for both detector types, smaller than the combined experimental uncertainty).