PET/CT Scan Positron emission tomography (PET)/(CT) Closer Look Imaging's equipment uses small amounts of radioactive materials called radiotracers, a special camera and a computer to help evaluate your organ and tissue functions. By identifying body changes at the cellular level, PET may detect the early onset of disease before it is evident on other imaging tests. CAT scanning is a painless and a non-invasive medical test that helps physicians diagnose and treat medical conditions. CT uses a lithely thin special beam to produce detailed, cross sectional views of the area being studied. CT is the most often the preferred method of diagnosing causes of pain and various forms of oncological studies.