Routine Diagnostic x-ray Examinations and Increased Frequency of Chromosome Translocations among United States Radiologic Technologists

Purpose Low radiation doses and potentially inaccurate recall of the number of past x-ray examinations have hampered designing informative studies of cancer risk associated with medical radiation exposure. We investigated whether cumulative exposure from personal diagnostic x-rays was associated with increased frequencies of chromosome translocations among radiologic technologists because they may recall past radiographic procedures better than the general public. Methods 150 U. S. radiologic technologists who began working before 1950 were selected for blood collection and telephone interview, including past x-ray examinations. The number of and the examination types were converted to a radiation dose score with units that were an approximation of cGy. For each study subject, the frequencies of translocations were identified by whole chromosome painting. A linear Poisson regression model was used to assess the relationship between radiation dose score and translocation frequency. Results After adjustment for age, translocation frequencies increased with increasing diagnostic RBM dose score with an estimate of 0.04 translocations per 100 CEs per unit RBM score (95% CI, 0.02 to 0.07; P=0.003). Adjustment for gender, cigarette smoking, occupational radiation dose, allowing practice x-rays while training, work with radioisotopes, and radiotherapy for benign conditions did not materially affect the slope estimate. Conclusions Cumulative radiation exposure from routine x-ray examinations was associated with increased numbers of chromosome translocations. While the enormous benefit of radiation in disease diagnosis and patient treatment remains unquestioned, potential long-term chromosome damage and other associated health risks argue against excess use or unnecessary repeats of diagnostic x-ray examinations.