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ESR Dosimetry with Magnesium Sulphate

1993; Oxford University Press; Volume: 47; Issue: 1-4 Linguagem: Inglês

10.1093/oxfordjournals.rpd.a081746

1742-3406

Jason Morton, F.J. Ahlers, C.C.J. Schneider,

Advanced Chemical Sensor Technologies

Abstract The aim of the investigation is to enhance the ESR dosemeter sensitivity in the therapy dose range below 10 Gy, where the ESR spectrum of the a-alanine radical becomes increasingly difficult to evaluate for dosimetry. Anhydrous magnesium sulphate, MgSO4, appears to be an excellent candidate from the spectrometric point of view. On irradiation with 60Co ? rays the stable radical SO3 is produced whose ESR signal amplitude increases linearly with dose up to about 105 Gy. Ignoring the abundant isotopes 17O (0.04%) and 33S (0.74%), the spectrum of SO3 is a single line at g = 2.0036 of width 0.5 mT which is stable at temperatures up to at least 120 oC. Using the conventional peak-to-peak method of dosemeter readout, the MgSO4 dosemeter is somewhat more sensitive than the traditional alanine dosemeter of the same mass. Its main advantage over the alanine dosemeter is, however, the ease of computer enhancement and the possibility of integration which the single-line spectrum offers.