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Biological dosimetry using the micronucleus assay for lymphocytes: interindividual differences in dose response.
H Thierens1, A Vral, L de Ridder
1Medical Physics Laboratory, University of Gent, Belgium.
Health Physics
|November 1, 1991
Summary
This study investigated micronuclei in lymphocytes after X-ray exposure, finding a linear-quadratic dose response. Interindividual variability impacts dose assessment accuracy, especially at lower radiation doses.
Area of Science:
- Radiobiology
- Cytogenetics
- Radiation dosimetry
Background:
- The cytokinesis-blocked micronucleus assay is a tool for biological dosimetry.
- Understanding dose-response relationships and interindividual variability is crucial for accurate radiation dose assessment.
Purpose of the Study:
- To investigate the dose-response relationship of micronuclei in human lymphocytes after in-vitro X-ray irradiation.
- To evaluate the accuracy and limitations of the micronucleus assay for radiation dose assessment in a heterogeneous population.
Main Methods:
- Whole blood from 10 donors was irradiated in vitro with X-rays (0-4 Gy).
- Micronuclei were scored in 1,000 binucleated lymphocytes per donor.
- A linear-quadratic model was fitted to the dose-response data.
Main Results:
- A linear-quadratic dose dependency was observed for micronucleus yields.
- Interindividual differences in X-ray-induced micronucleus yields were the main source of uncertainty for doses >= 2 Gy.
- Doses below 0.3 Gy were not reliably detected at the 95% confidence level due to baseline variability and limited cell scoring.
Conclusions:
- The cytokinesis-blocked micronucleus assay shows a clear dose response but is affected by interindividual variability.
- Improving low-dose sensitivity requires individual baseline data and increased cell scoring, potentially through automation.
- The assay's accuracy for radiation accident dose assessment is limited at low doses (<0.3 Gy) without further optimization.