Thyroid Tumors Following131I or Localized X Irradiation to the Thyroid and Pituitary Glands in Rats

Three thousand 6-week-old female Long-Evans rats were randomly assigned to 10 equal treatment groups. Three groups were injected intraperitoneally with 0.48, 1.9, and 5.4 μCi of Na131I yielding mean thyroid doses of 80, 330, and 850 rad, respectively. Three groups were irradiated with 94, 410, and 1...

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Bibliographic Details
Published in:Radiation research 1982-11, Vol.92 (2), p.307-319
Main Authors: Lee, Wah, Chiacchierini, Richard P., Shleien, Bernard, Telles, Norman C.
Format: Article
Language:English
Subjects:
Adenoma
Dosage
Dose response relationship
Inductive reasoning
Irradiation
Radiation dose response relationship
Radiotherapy
Solar X rays
Thyroid cancer
Tumors
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Summary:Three thousand 6-week-old female Long-Evans rats were randomly assigned to 10 equal treatment groups. Three groups were injected intraperitoneally with 0.48, 1.9, and 5.4 μCi of Na131I yielding mean thyroid doses of 80, 330, and 850 rad, respectively. Three groups were irradiated with 94, 410, and 1060 rad from localized X ray to the thyroid. One group was irradiated with 410 rad to the pituitary, and another group was given 410 rad to both the thyroid and the pituitary with localized X rays. The remaining two groups of animals were used as separate sham-irradiated controls for the two types of radiation. All the surviving animals were killed 2 years later. Results derived from this study indicate that: (a) The proportion of animals with thyroid carcinoma is similar for131I and X irradiation within the dose range of 0-1000 rad. (b) The thyroid carcinoma dose-response functions fitted by the least-squares method are nearly proportional to the square root of the thyroid dose. (c) Thyroid carcinoma induction appears to be independent of the dose rates resulting from the radiations used in this study. (d) A localized X-ray dose of 410 rad to the pituitary, whether the dose was administered concomitantly with thyroid irradiation or without thyroid irradiation, did not modify the risk of thyroid tumor.
ISSN:0033-7587
1938-5404