Regional cerebral blood flow (rCBF) is an important parameter of brain function in acutely and chronically ill patients. Instruments currently available for measurement of rCBF are large, immobile and lack the flexibility and utility required to study rCBF in multiple situations such as the operating room and outpatient services. We propose to split the process of rCBF measurement into a portable microprocessor-based data acquisition device and a high-speed host computer capable of fast data analysis, long term data storage and graphical report generation. We will employ the use of a new detector technology and develop solid-state cadmium telluride (CdTe) detectors which will be more stable and of lighter weight than detectors currently available. This project is a joint effort between Radiation Monitoring Devices, Inc., a manufacturer of CdTe detectors, and Cerebral Monitoring Systems, an instrumentation R & D establishment, to develop a mobile rCBF measurement system with high speed graphic output and multi-use capability. In addition, experts in the fields of data analysis and clinical rCBF from the Bowman Gray School of Medicine will be consulted for their experience and expertise. In the Phase I project, we will demonstrate the feasibility of developing such a portable device using new low-voltage solid-state cadmium telluride detectors. The system functions will be split into a portable data collection device and a nonportable data analysis, storage and reporting system. Communication between the two units will be achieved via telephone. We will investigate the reliability of telephone communications and develop appropriate algorithms for error detection and correction. Development of light weight, stable CdTe detectors will add a higher degree of reliability and mobility to the system. Such detectors have been used reliably in other commercial and military devices. Studies will be undertaken to determine an optimal design for their use in rCBF measurements. Based on our experience and preliminary feasibility studies we expect no problems in demonstrating a working data collection stystem.