Monte Carlo Simulations to Supplement Experimental Microdosimetric Spectra

Tissue-equivalent proportional counters (TEPCs) can be used for characterizing the radiation quality in radiation protection and radiotherapy environments. Usually, they are filled with tissue equivalent gases to simulate tissue site-sizes comparable to the cell size (1 or 2 µm). This affirmation is valid if the energy deposited in the counter is the same as that in the tissue volume. However, TEPCs do not measure the energy deposited in the counter but the ionizations produced microdosimetric sites by the passage of a single ionizing particle. The ionization number is then converted to energy (lineal energy) by a calibration procedure that involves a constant W-value. On the other side, modelled TEPCs using Monte Carlo (MC) techniques give the energy absorbed inside the cavity by single events. In some cases, MC calculations can be complementary to the experimental microdosimetric data, allowing situations to be tested that would otherwise be difficult or impossible to attain. To this end, theoretical models employed in MC codes need to be validated with experimental data. In this context, the capability of two general-purpose MC codes, FLUKA and PENELOPE have been investigated and presented in reference