- a radioactive isotope of iodine having a mass number 131 and a half-life of 8.6 days, used in the diagnosis and treatment of disorders of the thyroid gland.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- A radioisotope of iodine that emits beta and gamma rays, has a half-life of 8.05 days, and is used as a tracer in thyroid studies and as therapy in hyperthyroidism and thyroid cancer.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.