Keywords: physical dosimetry, radiation accidents, emergency, prodromal symptom, whole body counter, bioassay, low radiation, radiation dose, radiation exposure, dose assessment, gamma radiation, biological dosimetry
Physical dosimetry system in radiation accidents
We experience various types of radiation accidents. When a radiation accident happens, one of the important aspects that we have to consider is the radiation dose to the victims of the accident. To judge the health effects due to radiation exposure, it is necessary to make a dose assessment. There is a variety of dose assessment methods, of two types: biological dosimetry and physical dosimetry. In this paper, mainly physical dosimetry is reviewed to find out the problems we face at present. We consider (a) personal dosimeters, (b) area monitors, (c) dose reconstruction, (d) Electron Paramagnetic Resonance or EPR (ESR) dosimetry, (e) TL materials, (f) measurement of activated products, (g) whole body counters, (h) thyroid monitors, (i) lung monitors, (j) bioassay, (k) swab methods and (l) survey meters. Some of these are not designed to be used for personal dose assessment and cannot provide accurate dose estimates. Some are very time consuming and cannot provide the estimate within two days. Especially when an exposure occurs with gamma emitters and the victim is not a radiation worker, personal dosimeters are not in place and no trace of the exposure can be observed except through prodromal symptoms, chromosome aberrations or EPR of extracted tooth enamels. Therefore, it is urgently required to find some prompt dose estimation method for gamma exposures. In vivo EPR is now highlighted to be one of the promising prompt dose estimation methods. Based on the present situation of limited physical dosimetry systems, we have to use biological dosimetry as a complementary dose assessment although it cannot provide precise dose estimation.