Biological dosimetry-knowing what happened

Effective medical management of a suspected radiation overexposure incident necessitates recording dynamic medical data and measuring appropriate radiation bioassays in order to provide diagnostic information to the treating physician and dose assessment for the personnel radiation protection records. Biological Assessment Tool (BAT), a radiation casualty management software application available at the AFRRI's website (www.afrri.usuhs.mil), was developed to facilitate medical recording and to assist in bioassay dose predictions. Prodromal signs and symptoms as well as the body location and degree of transitory radiation-induced erythema should be recorded. Goans and colleagues have recently published dose prediction models for the prodromal symptom, time until onset of vomiting, following photon and criticality accident exposures. A complete blood cell count (CBC) with white cell differential should be obtained immediately after exposure, three times a day for the next 2-3 days, and then twice a day for the following 3- 6 days. Lymphocyte cell counts and lymphocyte depletion kinetics provide a dose assessment prediction between 1 and 10 Gy photon equivalent dose range. A blood sample should also be taken for dose assessment, following coordination with a qualified radiation cytogenetic biodosimetry laboratory, typically 24 hours after exposure using the 'gold standard' lymphocyte-dicentric radiation bioassay. Several of these cytogenetic biodosimetry laboratories use the premature chromosome condensation (PCC) bioassay, which permits dose assessment at higher doses (>5 Gy photon equivalent and acute high-dose rate exposures). Other opportunistic dosimetry approaches should be considered if available. Automated instrumentation to accomplish sample preparation and analysis for the conventional cytogenetic-based bioassays need to be integrated and beta tested in reference cytogenetic biodosimetry laboratories. Complimentary novel interphase-based cytological bioassays that detect cells with chromosomal type aberrations and radiation responsive molecular biomarkers (i.e., gene expression, protein) need to be validated and optimized for rapid radiation dose assessment applications