Positron emission tomography (PET) of the brain and heart has made important contributions in clinical and research applications in the fields of neurology and cardiology. The more recent applications of PET in tumor imaging has marked oncology as the next frontier in PET; however, the dilemma of rising health care cost will challenge the application of new technologies. This challenge can be approached by innovative and appropriate use of sophisticated technology in both the research and clinical realms. The current developments of PET imaging technology to accurately stage the extent of tumor, as well as monitor the effectiveness or ineffectiveness of new or current therapies will be an extremely valuable tool in research and in the cost effective management of cancer patients. In the future, the oncologist may be able to adjust the chemotherapy to the tumor response based on PET imaging. In other situations, PET may be able to predict that no existing therapy will elicit a durable response, resolving the patients' and families' uncertainty of whether extreme therapeutic measures would have made a significant difference. This paper reviews some of the recent developments and areas of research in tumor PET imaging, and describes some of the practical and technical aspects involved with FDG tumor quantitation and whole body PET imaging.