Radiation Dose Estimation for Medical Radiation Workers
DCEG investigators in the Radiation Epidemiology Branch (REB) have reconstructed radiation dose for radiation technologists included in the United States Radiologic Technologists (USRT) study. Different sources of data as well as relevant dosimetric models were used in the process, including extensive historical information collected from the literature; more than 1,000,000 film-badge measurements from private laboratories, employers, the military and commercial dosimetric service providers; and detailed work history data. Annual and cumulative occupational badge doses for radiation technologists were reconstructed and used to estimate organ-specific radiation absorbed doses: the thyroid, female breast, ovary, lens of eye, lung, colon, testes, heart, skin, and red bone marrow. The uncertainty of both badge and organ doses for each year of each technologist’s working career was characterized using Monte Carlo simulation methods.
Major improvements in the revision included:
- Increased numbers of annual badge dose measurements
- Additional information on individual apron usage
- Refined modeling of annual badge dose probability density functions
- Refinements in organ dose conversion coefficients to account for uncertainties in machine settings and radiographic techniques
In addition, investigators found a statistically significant dose response using chromosome aberrations with estimated dose to bone marrow.
New Initiatives for Improved Occupational Exposure Assessment
Two new initiatives have been undertaken to improve estimation of occupational radiation doses in radiologic technologists administering radionuclides and those conducting fluoroscopically-guided interventional procedures. Investigators collected historical information on nuclear medicine practices in the 1950s – 1970s through a focus group meeting with experts to estimate occupational doses for each procedure and radiopharmaceuticals available at that time.
In addition, the fourth survey in the USRT cohort includes two specialized work history modules for the radiologic technologists administering radionuclides and those carrying out fluoroscopically-guided interventional procedures. The survey has been completed and results are being used to refine dose estimates for those technologists.