Development of a dual-probe detection system for positron emission radiotracer detection.

BACKGROUND: Positron emission radiotracers are very useful in biochemical and pharmacological research. The purpose of this work was to develop and build a simple and inexpensive dual-probe detector system (DPDS) for detecting the activity of positron emission radiotracers. MATERIALS AND METHODS: The design of the DPDS was based on the coincident detection of two 511 KeV annihilation gamma-rays, which determined the positron activity in the body. A pair of sodium iodide (NaI) scintillators coupled to a photomultiplier tube (PMT) were positioned face-to-face as in a dual-probe system. The signals from each probe were then sent to a preamplifier, a linear amplifier, a single channel analyzer (SCA), and the primary and secondary coincidence units, respectively, to determine the number of total coincidence events and random events. Validation of basic characteristics, including stability, sensitivity, linearity and geometric counting efficiency, were tested. RESULTS: The sensitivity and linearity of the DPDS worked well in detecting radioactivity within 100 microCi. The DPDS was very stable in continuous counting for more than 2 hours. The geometric counting efficiency changed less than 5% when the source was placed 2 cm from the central coincidence line. CONCLUSION: This DPDS is a promising tool for positron emission radiotracer detection. It may be helpful in future in both clinical and basic biomedical research, such as neuroreceptor occupancy or glucose metabolic studies. Eventually, we will be able to use the DPDS in the human or animal body for evaluating position emission radiotracer metabolism and distribution.