The application of EPR dosimetry for radiotherapy and radiation protection.

This paper reports the first clinical trial of the application of the continuous wave electron paramagnetic resonance (CW-EPR) spectrum of alanine to determine the radiation dose received by a patient. The results of these measurements are compared with those obtained using thermoluminescent dosimetry (TLD) simultaneously. The 9 GHz EPR measurements were made at 13 degrees C. The time stability of the radiation induced radicals in alanine was confirmed. The fractionated radiation doses received in the clinical trial were determined from a calibration curve (linear regression coefficient r = 0.9995) obtained by irradiating L-alanine samples with 60-800 cGy doses using cobalt 60 gamma rays obtained from an Eldorado 8 Cobalt 60 unit at a rate of approximately 60 cGy/min. It is shown that the absorbed dose in tissue-equivalent material can be determined using EPR spectroscopy with an accuracy of approximately 3% at low dose levels (60 cGy) whereas the error using TLD is approximately 5% and that this method of dose determination is preferable to the present TLD method because it is simpler and more accurate.