ABSTRACT
Molecules labeled with radioactive isotopes (radionuclides) have been used extensively to study transformations and distributions of endogenous compounds and Pharmaceuticals, since it allows for detection of very low levels of materials. Thus, it is a useful technique to track transformed compounds with a common origin without the need for development of specific analytical methods for each of the constituents. Recently, this field has entered a new area with the development of techniques to measure and display radioactivity in 3D by computerized tomography.
