Oak Ridge Center for Risk Analysis partnered with the University of California San Francisco to carry out a nationwide study of disease mortality and incidence from radiation exposures in a cohort of 63,715 tuberculosis patients treated in Canada between 1930 and 1969.
A new FLUoroscopy X-ray ORgan-specific dosimetry system (FLUXOR) was developed to estimate radiation doses and their uncertainties to patients who received fluoroscopy and chest radiography examinations.
Doses to each patient were estimated using parameter values inferred from interviews with 91 physicians practicing at the time, historical literature, and the number of procedures estimated from patient records. Probability distributions were developed to represent alternative realizations of the unknown true average value for each dose estimation parameter. The uncertainty of each average parameter was shared across all patients within specific subgroups of the cohort, defined by age at treatment, sex, type of procedure, time period of procedure, and region (Nova Scotia or other provinces). Monte Carlo techniques were used to propagate these uncertainties by generating 1,000 alternative average values for each parameter and combining them to produce 1,000 alternative cohort vectors of average annual organ doses per individual.
A major feature of FLUXOR is the use of age-, sex- and body-size dependent dose coefficients for fluoroscopy and radiography exams, estimated using up-to-date hybrid anthropomorphic phantoms created by the University of Florida and the US National Cancer Institute. The phantoms include lymphatic nodes, an updated heart model, and were adjusted to match the mean height and weight of tuberculosis patients in Canada. Dose coefficients were estimated for 58 female and 57 male organs and tissues.
The Canadian Fluoroscopy Cohort is an important addition to existing radio-epidemiological cohorts, given the moderate-to-high doses received fractionated over several years, the type of irradiation (external exposure only), radiation type (x-rays only), the balanced combination of people of both genders, and inclusion of all age categories.
For more information, check out the following peer-reviewed publications produced for this project:
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