A semi-automated FISH-based micronucleus-centromere assay for biomonitoring of hospital workers exposed to low doses of ionizing radiation

The aim of the present study was to perform cytogenetic analysis by means of a semi-automated micro-nucleus-centromere assay in lymphocytes from medical radiation workers. Two groups of workers receiving the highest occupational doses were selected: 10 nuclear medicine technicians and 10 interventional radiologists/cardiologists. Centromere-negative micronucleus (MNCM−) data, obtained from these two groups of medical radiation workers were compared with those obtained in matched controls. The blood samples of the matched controls were additionally used to construct a 'low-dose' (0–100 mGy) MNCM− dose-response curve to evaluate the sensitivity and suitability of the micronucleus-centromere assay as an 'effect' biomarker in medical surveillance programs. The physical dosimetry data of the 3 years preceding the blood sampling, based on single or double dosimetry practices, were collected for the interpretation of the micronucleus data. The in vitro radiation results showed that for small sized groups, semi-automated scoring of MNCM− enables the detection of a dose of 50 mGy. The comparison of MNCM− yields in medical radiation workers and control individuals showed enhanced MNCM− scores in the medical radiation workers group (P=0.15). The highest MNCM− scores were obtained in the interventional radiologists/cardiologists group, and these scores were significantly higher compared with those obtained from the matched control group (P=0.05). The higher MNCM− scores observed in interventional radiologists/cardiologists compared with nuclear medicine technicians were not in agreement with the personal dosimetry records in both groups, which may point to the limitation of 'double dosimetry' procedures used in interventional radiology/cardiology. In conclusion, the data obtained in the present study supports the importance of cytogenetic analysis, in addition to physical dosimetry, as a routine biomonitoring method in medical radiation workers receiving the highest occupational radiation burdens.