Biological and biophysical techniques to assess radiation exposure: A perspective

Abstract

Biological dosimeters measure biologically relevant effects of radiation exposure that are in some sense an estimate of effective dose, whereas biophysical indicators serve as surrogates of absorbed dose in a manner analogous to conventional thermoluminescent dosimeters (TLD). The biological and biophysical dosimeters have the potential to play an important role in assessing unanticipated or occupational radiation exposures. For example, where the exposure is large and uncertain (i.e. radiation accidents), accurate dose information can help in deciding the most appropriate therapy and medical treatment. Another useful area is that of lifetime accumulated dose determination, and the ability to distinguish between and integrate the exposures from natural and anthropogenic (medical X-rays, indoor radon, natural background radiation, occupational and non-occupational exposures). Also, the possibility to monitor individual response and differences in inherent or induced radiation sensitivity may have important implications for radiation protection. More commonly, this type of dosimetry could be used for routine monitoring to detect and quantify unsuspected exposure, for regulatory purposes or for epidemiological studies of the long-term effects of radiation exposure (e.g. in Japanese A-bomb survivors or in the population surrounding Chernobyl). This review is a comparative study of the existing techniques and their future prospects. It summarizes the sensitivity, reproducibility, limiting dose, dose-rate, energy, LET response, sources of variability and uncertainty, and other practical aspects of each bio-indicator. The strengths and weaknesses of each approach are evaluated on the basis of common criteria for particular applications, and are summarized for each assay both in the text and in tabular form, for convenience. It is clear that no single indicator qualifies to reliably measure occupational exposures at the current levels of sensitivity conventional dosimetry services provide. Most of the bio-techniques are applicable to the detection of relatively high radiation exposures at relatively short times after exposure. Some of the bio-indicators have been identified that are, or offer future prospects for becoming, appropriate bio-indicators for dosimetry needs. However, all methods are subject to biological and other variables that are presently uncontrolled, and represent a major source of uncertainty. These include variations in background signals not directly associated with radiation exposure, inter- and intra-individual variability of radiation response, and genetic and environmental effects. Although these factors contribute to the lack of confidence in biological dosimetry, promising bio-indicators may be applied to large populations to establish the inherent variability and confounding factors that limit quantitative data collection and analysis, and reduce reliability and reproducibility.

Relative alterations in blood mononuclear cell populations reflect radiation injury in mice

“…Therapeutic treatment for a group of exposed persons, according to the average exposure dose to the group, is impractical. Individuals differ in sensitivity to radiation injury (14); it would therefore be beneficial to develop a simple, rapid, sensitive assay to determine the extent of radiation injury sustained by an individual, in order to determine the most effective course of intervention for that individual.…”

“…Currently, there are several ''biological dosimeters'' (biological indicators) to help determine either the dose received by an individual or the severity of damage sustained at the cellular or molecular level. Dose can be determined at any time after any uniform ␥-irradiation, by analysis of electron spin resonance of tooth enamel (3) or by conventional thermoluminescent dosimeters (14), both of which give a measure of absorbed dose. However, absorbed dose determination plays a limited role in diagnosis, prognosis, or in selecting therapeutic approaches: instead, the severity of the effect of dose on, or damage sustained by critical organ systems is a desirable parameter on which to base these judgments (5).…”

Study of EPR/ESR Dosimetry in Fingernails as a Method for Assessing Dose of Victims of Radiological Accidents/Incidents

“…The development of dose-response curves that would match EPR data to dose is difficult and has many limitations, including limited sensitivity [12,34]. This research builds on previous studies of exposed nail biological samples [27,28] and involves exposing samples to gamma radiation fields in a similar fashion to that done by Trompier in 2004 with tooth enamel [35].…”

Collective Radiation Biodosimetry for Dose Reconstruction of Acute Accidental Exposures: A Review

“…(31). Thus, it may be most reasonable to establish truth in radiation dosimetry through a consensus of the various techniques commonly in use (22,25). Collective biodosimetric data could, for example, be treated in a manner analogous to that described by Baranov et al.…”

“…Examples of such outcomes are health effects, radiation protection, radiobiological effects, and risk analysis. While requirements of a biodosimeter can be enumerated (25), the concept of a successful dosimeter continues to evolve.…”