Radioactive tracers are used in imaging tests that help find problems inside the body. These tracers give off particles that can be detected and turned into a picture to help find problems in organs or other structures.

The tracer is usually given through an intravenous (IV) line placed in a vein. But the tracer also may be given by mouth or by inhaling it into the lungs. The tracer then travels through the body and may collect in a certain organ or area.

The types of tests that use radioactive tracers include positron emission tomography (PET) and nuclear medicine scans to look at specific organs such as the liver, lungs, kidneys, and gallbladder.