Performance characterization and first clinical evaluation of a intra-operative compact gamma imager

The growing interest of cancer surgeons for intra-operative probes has led to the development of several prototypes of high resolution mini gamma cameras. The aim of this paper is to present a global characterization of the one the authors developed and the corresponding first evaluation in a clinical context. The current prototype of POCI (peroperative compact imager) is a 24 mm diameter intensified position sensitive diode. In order to face the various clinical situations, two sets of collimator/scintillator imaging head have been developed either for high spatial resolution or high efficiency purposes, Both of them have been first optimized for ^99mTc labeled tumor detection. Intrinsic performances are the following: the spatial resolution ranges from 1 mm up to 1.9 mm (without significant distortion) and the corresponding efficiency ranges from 6.10^-h up to 2.10^-4 . Phantom studies illustrating these results are proposed. First clinical evaluation of POCI concerned sentinel lymph node imaging which is included in melanoma and breast cancer staging protocols. Preliminary results already show that performances of POCI are compatible with intra-operative imaging purposes and suggest how such mini-cameras can improve the success rate of tumor removal surgeries