tracer [L, trahere, to draw] , 1. a radioactive isotope that is used in diagnostic x-ray techniques to allow a biological process to be seen. After introduction into the body, the tracer binds with a specific substance and is followed with a scanner or fluoroscope as it passes through various organs or systems. Kinds include radioactive iodine, radioactive carbon. See also radioisotope scan. 2. a mechanical device that graphically records the outline or movements of an object or part of the body. 3. a dissecting instrument that is used to isolate vessels and nerves. −trace, v.
