Doses and population irradiation factors for Canadian radiation technologists (1978 to 1988)

Individual and collective radiation doses received by Canadian radiation technologists (RTs) working in diagnostic radiology, nuclear medicine and radiotherapy are summarized for the period 1978 to 1988. The data were obtained directly from the National Dose Registry, Department of National Health and Welfare. Over the 11-year study period the mean annual dose equivalent fluctuated around 0.2, 1.8 and 1.1 mSv for RTs working in diagnostic radiology, nuclear medicine and radiotherapy respectively. Over the same period the occupational collective dose equivalent decreased in diagnostic radiology (by 44%) and radiotherapy (by 35%) and increased in nuclear medicine (by 45%). Approximately 10,000 RTs are monitored each year, with an estimated total occupational collective dose equivalent of about 3.6 person-sieverts. Analysis of dose distribution data showed that only 1.3% of all monitored RTs received an annual whole-body dose equivalent greater than the current legal limit for members of the public (5 mSv). Approximately half of the RTs working in nuclear medicine and radiotherapy received an annual dose equivalent in excess of 0.5 mSv; only 7.3% of their diagnostic radiology counterparts exceeded this level. Demographic data showed a high preponderance of young women in all three RT classifications, and an analysis of the radiation risks to this occupational group revealed increases of up to 12% above the risk associated with a "standard" adult working population exposed to the same collective dose equivalent.