The objective is to develop a new positron multi-detector brain analysis system. The project includes the feasibility demonstration of a computer controlled system to analyze brain tumors using registered images such as MR/CT. A mathematical model incorporating anatomical information from MR is provided to calculate the activity of the tumor. The use of registered MRI/CT images provides a technique for following the course of radiation treatment. This technique is new and innovative since it combines both image mensuration of the size of the tumors as well as their physiologic activity. It provides this capability at approximately 8-10% of the cost of a PET scanner making it a viable supplement or replacement for PET in many types of studies. It has application as a monitoring instrument in the treatment of tumors where it is often necessary to observe tissue condition repeatedly over a long period of time. The system allows reduced radiation exposure (permits up to 200 scans per year versus a limit of 3 per year for PET). The design of the device also significantly reduces the time required to perform a single measurement.