Emitting radiation that results from atomic disintegration. The electromagnetic energy of, for example, X-rays and gamma rays is radioactive.
Soft tissue is radiolucent to some extent.
A test of thyroid function in which the patient is given radioactive iodine by mouth. Radioisotopes can be used to label certain chemicals to measure body function. It does not permit the passage of X-rays. The radioactive material allows differentiation between healthy and diseased tissue. A substance used to produce a specific chemical reaction.