ELECTRON-PARAMAGNETIC RESONANCE RADIATION-DOSIMETRY - POSSIBLE INORGANIC ALTERNATIVES TO THE EPR ALANINE DOSIMETER

The intensity of the EPR spectrum of gamma-irradiated L-alpha-alanine has been accepted by the International Atomic Energy Agency as a secondary standard for high-dose (10-100 000 Gy) dosimetry. The alanine dosimeter is not without its disadvantages, however, and in this article alternative EPR dosimeters are explored. These include SO3- in irradiated K2CH2(SO3)2 and CO2- in irradiated sodium formate (NaHCO2), both of which have some advantages over CH3CHCO2- in L-alpha-alanine. Using as a readout parameter the peak-to-peak excursion of the strongest line, these systems have a four-fold sensitivity advantage over alanine. The radicals SO3- and CO2- are, moreover, found in a wide variety of matrices, and it may be possible find one in which they are even stronger. The need to discover a dosimeter material sensitive enough to function in the 'clinical' dose range (below 10 Gy) is emphasized.