Initial performance evaluation of a modular, large-area detector PET scanner for small animal imaging

The biophysical conditions under which most positron emission tomography (PET) imaging of small animals takes place are often poorly characterized and highly variable. And as such, one frequently needs to balance the desire to achieve high spatial resolution with the need to, for example, capture transient phenomena or survey large regions in brief periods. Since these tradeoffs are application dependent, it is desirable that such imaging systems be flexible for meeting varying needs in imaging performance. To this end we describe a PET system under development that incorporates modular detectors and provides application-specific scanning configurations. Our current prototype consists of two opposing flat-panel single-layer LSO detector heads from a high resolution research tomograph system - with adjustable detector separation, energy and coincidence window widths, and scan geometry. Preliminary measurements demonstrate a spatial resolution of 1.6 mm and an absolute detection sensitivity of /spl sim/8% at the center of the prototype. For mouse-sized phantoms and 7 cm detector separation, the 250-750 keV energy window was found to yield the optimal noise equivalent count rate curve.