||How is it possible to determine the dose of radiation a person has been exposed to?
The complexity and intricacy of estimating the dose of radiation exposure after the Chernobyl accident is great. Estimation of radiation doses to any organ can be made, but routinely, most interest is focused on measuring the:
- Exposure of the thyroid gland
- Exposure of the whole body
Fig. 5: Steps in Radiological Assessment
Measurement of radiation exposure of the whole body is subdivided into internal and external irradiation. In the confines of each group of procedures, there are unique instrumental and calculated methods of dose estimation. Currently, direct measurements of doses of external irradiation have been conducted for only 1% of the total number of cases.
The primary methodology for determination of doses of irradiation of the population is not from actual dose measurement. It is based on data on the contamination of the areas of Russia, Belarus and Ukraine territories with dose-forming radioactive nuclides combined with data on the behavior and nutrition of the people during this time period. The International Program on the Health Effects from the Chernobyl Accident (IPHECA) proposed a model for reconstruction of the radiation dose of the thyroid for the population which resided in the settlements where direct measurements of iodine-131 content were not conducted.
Fig. 6: Breakdown of the exposure of radiation (1993 data)
Fig. 6a: Total accidental dose
Fig 6b: External radiation dose
Fig. 6c: Doses of internal radiation
Because physical dosimetry cannot always be conducted at the time of an accident, biological dosimetry procedures together with calculations of radiation doses are used for reconstruction of radiation doses. A culture of lymphocytes in peripheral blood is used for these procedures due to simplicity of tested material, high sensitivity of lymphocytes to radiation, and their capability to accumulate cytogenetic disturbances during the life cycle.