|
|
Historical Dose Reconstruction for U.S. Radiologic Technologists
During the past four years, we have been continuously
refining annual and cumulative estimates of radiation dose for each radiologic
technologist. The latest version is termed "Version 3.5." This
version estimates both badge and organ doses for each year an individual
worked. In addition, because the doses are estimates, the uncertainty
(a mathematical measure of our knowledge) for each estimate is also included.
Key features of this version include:
- <1960 (divided further into pre-1940, 1940-1949, and 1950-1959)
- 1960-1976
- 1977-1984
|
- 350,000 annual cohort badge dose readings during 1958-1984 from
computerized and microfilm records of the nation's largest commercial
dosimetry provider
- 20,000 military badge readings from the Army, Navy, and Air
Force
- 150 hospital badge readings from Massachusetts General Hospital
- Literature reports on badge dose and other radiation measurements
before 1960
- Extensive work history data provided by cohort members in three
comprehensive surveys
|
- Estimated annual and cumulative badge doses are currently available
for 110,000 cohort members who completed the first or second survey
- 1977-1984 doses based on individual cohort badge dose readings
or regression model using survey data on procedures performed
and related protection practices
- Pre-1960 and 1960-1976 doses based on standard densities of
actual cohort badge dose readings by facility type (hospital or
physician office)
- All annual badge doses take into account the fraction-of-year
an individual worked during each year, 1901-1984
|
- Uses apron and shielding information by type of procedure performed
(diagnostic x-rays, fluoroscopy, internal diagnostic radioisotopes,
external therapeutic radioisotopes, external beam therapy)
- Total apron protection is weighted by frequency performed each
type of procedure
- Apron thickness (0.25 or 0.5 mm) is assigned a probabilistic
density to allow for uncertainty
- Apron and shield transmission factors (the fraction of exposure
that passes through an apron) are assigned probabilistic densities
based on apron thickness, characteristics of aprons in particular
time periods, and the peak kilovoltage (termed kVp)
|
- Dose factors for each organ are not treated as constant, but
are mean estimates with uncertainty
- Each organ dose factor is specific for: time-period; probabilistic
values of peak X-ray energy; ratio of tissue or organ dose to
air kerma free-in-air; and ratio of personal dose equivalent or
badge dose to air kerma free-in-air
- Each organ dose factor is further refined for badge location
under versus outside an apron
|
- The badge doses (estimated or actual individual badge readings)
are used together with protection/shielding data and organ dose
factors to estimate organ doses
- Estimated annual and cumulative organ doses for female breast,
thyroid, and red bone marrow are currently available for 110,000
cohort members who completed the first or second surveys
|
Simon SL, Weinstock RM, Doody MM, Neton J, Wenzl T, Stewart
P, Mohan AK, Yoder C, Hauptmann M, Freedman M, Cardarelli J, Feng HA,
Bouville A, Linet M. Status report on estimating historical radiation
doses to a cohort of U.S. radiologic technologists. In: Proceedings of
the 11th International Congress of the International Radiation Protection
Association, Madrid, 2004.
|
