Ammonium tartrate as an ESR dosimeter material

This study is one step in the search for an ESR dosimeter material with a h igher signal intensity than the commonly used L-a-alanine, to be useful in the clinical dose range (approximately 0.1-20 Gy). The substance ammonium t artrate was found and investigated regarding signal intensity, radical stab ility, dose response and dose resolution. The ESR signal intensity of ammon ium tartrate was shown to be more than twice the intensity of the alanine s ignal, The data indicate that an unstable radiation induced radical contrib utes to the ESR signal initially; after a couple of hours it has converted to a secondary radical which has a decay slow enough to be considered stabl e during the first two weeks after irradiation. Ammonium tartrate has a lin ear dose response in the investigated range of 0.5-4000 Gy and a dose resol ution of 0.1 Gy at the 0.5 Gy level where, as a comparison, the correspondi ng value for alanine is 0.3 Gy. We thus find the substance suitable for cli nical dosimetry. (C) 1999 Elsevier Science Ltd. All rights reserved.