Quenching of the sensitivity of dosimeters with the increase of the radiation LET.

Radiotherapies that exploit the high linear energy transfer (LET) related to charged particles, are receiving increasing interest. Hadrontherapy currently uses protons or carbon ions and BNCT exploits the alpha particles generated by thermal neutron reactions with the B-10 isotope. Worldwide, adequate dosimetric methods are therefore in development to achieve a good quality of the treatments. A limit to the possible dose accuracy in measurements with non-gaseous detectors is determined by the fact that their sensitivity depends on the radiation LET: as the LET increases, the sensitivity of the dosimeters decreases. This means that dosimeters underestimate just the absorbed energy that has a greater biological effectiveness. Given the importance of correcting experimental results for the quenching effect, many researchers have challenged this problem, which is difficult to investigate because the radiation effects are manifold and dissimilar in the various detector materials. The problems are more complex in hadrontherapy and easier to be solved in BNCT. For both therapies, methodological proposals and experimental verifications were carried out in our laboratory.