POCI - A COMPACT HIGH-RESOLUTION GAMMA-CAMERA FOR INTRAOPERATIVE SURGICAL USE

The development of a hand-held gamma imaging probe for inside body loc alization of small tumors is of first interest for radio-guided operat ive cancer surgery. In that context, we have developed a sub-millimete r spatial resolution, small field of view, gamma per-operative compact imager (POCI). It consists of a head module composed of a high resolu tion tungsten collimator and a YAP:Ce crystal plate, optically coupled to an intensified position sensitive diode (IPSD). We report here the essential imaging performance characteristics of the POCI camera (spa tial resolution, position linearity, efficiency and energy response). These were obtained by studying the influence of the collimator and th e crystal design to evaluate the optimal configuration. The present ve rsion of POCI has a 24 mm diameter usable field of view and an intrins ic spatial resolution of 0.9 mm to 1.2 mm FWHM at 120 keV. These good detection performance characteristics combined with the small size of the camera make the device well suited to provide intra-operative moni toring in several medical procedures, such as thyroid and breast tumor removal.