Background: Most of our current understanding of the biological effects of exposure to ionising radiation is based on conventional cytogenetic techniques, which enable us to determine the relationship between chromosomal aberration and dose received by radiation workers. However, conventional techniques have numerous limitations and chromosomal aberrations can be easily missed. Since FISH plays an important role in detecting chromosomal changes, this method was used to reassess data derived from previous studies employing conventional techniques.

Materials and Methods: Two groups of radiographers were the subject of a study on conventional chromosomal aberration and fluorescence in situ hybridisation (FISH) for translocation. The first group was chosen following an accidental contamination incident in a nuclear medicine department. The second group was composed of six radiographers working in an X-ray department with a previous record of overdose as recorded by film-badges these workers had been the subjects of a previous chromosomal study. Coded blood samples from 11 radiographers and 11 controls were analysed for chromosomal aberration and by FISH for translocation. 200 metaphases from the peripheral blood lymphocytes per subject were analysed to investigate possible frequencies of chromosome and chromatid type aberration and 2000 metaphases per subject were scored in FISH method.

Results: There was no significant difference between the radiographers and the control groups in conventional analysis also there was no significant difference at the 95% level of confidence in FISH analysis. There was no correlation between levels of translocation and total lifetime doses from occupational (according film-badge and TLD) and/or background irradiation.

Conclusion: The overall conclusion is that the frequency of chromosomal damage in both groups of radiographers did not exceed that of the control group. Iran . J. Radiat. Res., 2004 1(4): 195-198