ELECTRON-PARAMAGNETIC-RESONANCE TECHNIQUES AND SPACE BIODOSIMETRY

This paper was presented at a workshop addressing the potential of bio dosimetry techniques for use in the interplanetary space program. Some of the concerns for adequate dosimetry in space include: (1) a dosime ter that provides a permanent record of the cumulative dose and can be read independently on return to Earth; (2) a dosimeter which cannot b e lost, forgotten or inadvertently removed by an individual; and (3) a ppropriate assessments of radiation exposures that pose an acute healt h risk and could jeopardize the success of an interplanetary mission. Tooth enamel is a permanent, stable biological dosimeter showing great promise in retrospective dosimetry of radiation accidents. With a pro per technique, the minimum detectable dose can be in the range of tens of milligrays in extracted, prepared teeth. In addition to transient accidental doses, the cumulative dose from chronic low-level exposures (which individually may be below reportable limits) is recorded in th e enamel of teeth. While many teeth remain with an individual over all or most of a lifetime, one or more are often removed due to dental pr oblems and provide an opportunity to make dosimeteric measurements. Th e collection and analysis of extracted teeth in later life allows meas urement of cumulative lifetime dose using the high-sensitivity techniq ues described in this paper. The goal of a lightweight, high-sensitivi ty, in vivo EPR spectrometer has not yet been realized, but its benefi t to all aspects of retrospective dosimetry, terrestrial or otherwise, would be great. This paper reviews the current status of EPR dosimetr y of teeth as applied to retrospective measurements of accidental expo sures and outlines future research directions which will further reduc e the limits of detection. (C) 1997 by Radiation Research Society.