D3 Biological dosimetry: dose estimation from effects on living tissue

Topic

When a physical dosimeter is unavailable, the radiation dose—which the previous model sought to measure—can be estimated based on the effects radiation leaves on a person's own tissue. The reference method involves counting dicentric chromosomes (chromosomal aberrations characteristic of radiation damage) in peripheral blood lymphocytes; this count is then converted into an estimated dose using response curves previously calibrated against known doses in a laboratory setting.

Serial total lymphocyte counts over time offer a second, faster—though less precise—approach: this method is useful for the initial triage of large numbers of potentially exposed individuals when applying the reference method to each person individually is neither feasible nor practical. This type of dose estimation is precisely what the clinical exposure process outlined in this catalog requires urgently in order to determine the appropriate medical treatment for each patient.

For this reason, the model—which begins by counting damaged chromosomes in a blood sample—also serves as the central tool for major long-term epidemiological studies on radiation-exposed populations; much of what is currently known about the stochastic risk of radiation-induced cancer was established by comparing these estimated doses with the health outcomes observed in those populations years later.

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