Various requirements need to be met before running a radiotracer investigation. The most important of these is to select an appropriate radiotracer. It is of fundamental importance that the radiotracer compound behaves in the same way as the material to be traced. To obtain reliable and meaningful results, an industrial radiotracer must also meet other basic requirements, such as a suitable half-life and radiation energy, as well as physical and chemical stability. It must also be easily and unambiguously detectable.

Before injecting a tracer into a system it must be clear how it will behave inside it. In certain circumstances, the tracer may undergo decomposition, phase change, undesirable absorption and adsorption, or chemical interaction with system constituents. All this can lead to incorrect results.

It is often difficult to meet all the requirements of an ideal tracer. Certain compromises have to be made. Even if a radiotracer meets the required criteria, it may not be available to tracer groups in developing countries.