What is the relationship between radiopharmaceuticals, tracers, and radionuclides?

A radionuclide is the radioactive atom or component used in a radiopharmaceutical. The radiopharmaceutical is administered so its movement or distribution can be followed in the body; in that role, it functions as a tracer. Therefore, the correct choice is “A radionuclide is part of a radiopharmaceutical, which functions as a tracer.”

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