X-ray Accident, Belgium

Accident scenario 

      An X-ray technician (41 yrs) involved in the electronic maintenance of X-ray equipment     In January 2003, during the maintenance work on 50 kV contact radiography X-ray device, he had been close contact with the X-ray tube while the beam was on, for several minutes. At the time he was not wearing his apron with attached film badge. At the end of January 2003, he visited medicine service with complaints of skin lesions. On 19 April 2004 (at thime of second blood sampling) chronoc radiiation dermatitis and ulceration on his back were apparent. Based on the clinical signs, it was assumed that he was exposed to a partial skin dose of about 10 to 20 Sv.

     Blood sample was taken on 7 April 2003, 6 months after the accidental exposure, for biological dosimetry. A second blood sample was taken 19 April 2004, about 1 yr later.  Dicentrics frequencies, micronucleus frequencies in CB arrested cells, and translocation frequencies by FISH (chromosome 1, 3 and 4 colored) pained chromosomes. 
Reference 

     Thierens, H., De Ruyck, K., Vral, A., de Gelder, V., Whiehouse, C. A., Tawn, E. J. and Boesman, I. (2005): Cytogenetic biodosimetry of an accidental exposure of a radiological worker using multiple assay. Radiat. Prot. Dosimet., 113:408-414. 
Chromosome aberration analysis 
.
Sampling time Cell with indicated no. of dicentrics CB cells with indicated no. of MN Translocations by FISH
0 1 2 3 0 1 2 3 Observed Genome equivalent
6 mo post-exposure 962 36 2 931 63 6 - -
18 mo post-exposure 980 19 1 959 38 3 37 Tr in 1524 cells FG=0.069/cells

     In the direct comparison of dicentric frequency to in vitro dose-response curve 0.62 (0.45-0.90) Gy was inferred as the 60Co gamma-ray dose equivalent. Similarly, the MN frequency corresponds to 0.73 (0.54-0.96) Gy as X-ray equivalent dose. The age-adjusted translocation frequency by FISH corresponds to 0.79 (0.61-0.99) Gy. The range of estimated doses are lower and upper limits of extrapolated values derived from 95 % confidence intervals of the in vitro calibration curves.

Commentary

       Dose assessment by unfolding dicentric distribution. The lymphocyte survival for 50 kV X-rays was set to D0=1.5 Gy. The average dose to the lymphocytes is estimated to be on average about 1 Gy, but doses could distribute up to as high as about 3 Gy. (Right panel). (This comment is added during the data compiling process and does not necessarily reflect the conclusion of the authors)