POCI: a compact high resolution γ camera for per-operative surgical use

The development of a hand-held γ-imaging probe for inside body localization of small tumors is of first interest for radio-guided operative cancer surgery. In that context, the authors have developed a sub-millimeter spatial resolution, small field of view, γ-per-operative compact imager (POCI). It consists of a head module composed of a high resolution tungsten collimator and a YAP:Ce crystal plate, optically coupled to an intensified position sensitive diode (IPSD). The authors report here the essential imaging performances of the POCI camera (spatial resolution, position linearity, efficiency and energy response), by studying the influence of the collimator and the crystal design to evaluate the optimal configuration. The present version of POCI has a 25 mm diameter usable field of view and an intrinsic spatial resolution of 0.9 mm to 1.2 mm FWHM at 120 keV. These good detection performances combined with its small size are well suited to provide intra-operative monitoring of several medical applications, such as thyroid and breast tumor removal