Related Experiment Videos
Diagnostic thyroid procedures and corresponding radiation doses in Manitoba: 1981-1985
W Huda1, K Gordon, I D Greenberg
1Department of Medical Physics, Manitoba Cancer Treatment and Research Foundation, Winnipeg, Canada.
Health Physics
|September 1, 1990
Summary
Nuclear medicine thyroid exams show reduced cancer risk with modern radiotracers. Replacing iodine-131 significantly lowered estimated population detriment and thyroid cancer induction rates.
Area of Science:
- Nuclear medicine
- Radiology
- Medical physics
Background:
- Nuclear medicine thyroid examinations are a common diagnostic procedure.
- Historical data from 1981-1985 and detailed patient data from 1987-1988 were analyzed.
- Thyroid examinations constituted 8.4% of all nuclear medicine procedures in Manitoba.
Purpose of the Study:
- To assess the radiation dose and associated risks of nuclear medicine thyroid examinations.
- To evaluate the impact of changing radiotracer usage on population detriment.
- To estimate thyroid cancer induction rates based on specific patient demographics and radionuclides.
Main Methods:
- Analysis of nuclear medicine procedure data from Manitoba (population 1 million).
- Collection of detailed demographic and procedural data for 1,100 consecutive patients.
- Calculation of effective dose (HE) per patient for 99mTc, 123I, and 131I.
- Application of National Council on Radiation Protection and Measurements (NCRP) risk estimates with age, sex, and radionuclide corrections.
Main Results:
- Average annual thyroid examinations: 2,081 (81% female, 19% male).
- Typical effective doses: 1.5 mSv (99mTc), 1.2 mSv (123I), 3.9 mSv (131I).
- Estimated thyroid cancer induction rate: <0.56 y-1, with ~10% fatality.
- Risk estimates adjusted for demographics were ~4 times lower than general population averages.
- Transition from 131I to current radiotracers reduced estimated population detriment by 3.6 times.
Conclusions:
- Modern radiotracers for thyroid evaluation significantly reduce estimated radiation risks compared to older agents like 131I.
- Specific risk assessments incorporating age, sex, and radionuclide provide more accurate detriment estimations.
- The shift in radiotracer use has led to a substantial decrease in the overall radiation detriment to the population undergoing thyroid examinations.