To better interpret our PET brain images in the above clinical trials, we need more baseline data on the variability in brain activation from person-to person, especially in people with no or minimal pain. Clinical oncology utilizes PET imaging for the diagnosis and monitoring of many types of cancer, e.g. Hodgkin's disease, non-Hodgkin's lymphoma, and lung cancer. The brain of these individuals can be considered within normal range and could be a control for our other studies involving postoperative pain and its alleviation. To obtain these 'control' brain scans, a patient being scanned for diseases outside the brain would not have to have an additional radionuclide injection. Instead, after the primary body scan is completed, the patient platform would be moved slightly so the head is now centered in the scanner, and the scanning process resumed, for approximately 20 minutes. Since the half-life of the FDG radionuclide is about 110 min, there will still be adequate signal available to be picked up by the detector during this secondary scan.