Accurate EPR radiosensitivity calibration using small sample masses

We demonstrate a procedure in retrospective EPR dosimetry which allows for virtually nondestructive sample evaluation in terms of sample irradiations. For this procedure to work, it is shown that corrections must be made for cavity response characteristics when using variable mass samples. Likewise, methods are employed to correct for empty tube signals, sample anisotropy and frequency drift while considering the effects of dose distribution opti mization. A demonstration of the method's utility is given by comparing sam ple portions evaluated using both the described methodology and standard fu ll sample additive dose techniques. The samples used in this study are toot h enamel from teeth removed during routine dental care. We show that by mak ing all the recommended corrections, very small masses can be both accurate ly measured and correlated with measurements of other samples. Some issues relating to dose distribution optimization are also addressed. (C) 2000 Els evier Science B.V. All rights reserved.