Evaluation of a CZT intra-operative gamma camera

An experimental imaging probe with a 4 cm×4 cm field of view and utilizing CZT (cadmium zinc telluride) technology has been constructed and evaluated for intra-operative applications. CZT is well suited to the application because of its compact size and good spatial and energy resolution as compared to other technologies. The CZT is instrumented to produce a pixilated image. The pixels are 2.5 mm×2.5 mm on a 16×16 Cartesian lattice. An interface to standard NM software allows the acquired data to be viewed as dithered images. The complete imaging system includes a general-purpose collimator contained in a handheld instrument with an ergonomic design, dimensions of 20 cm×4 cm×4 cm, and weight 1.2 kg. The usefulness of the instrument in the surgical application has been assessed by a systematic study using the probe to search for radioisotope filled plastic spheres immersed in a water tank, representing radiolabeled tumors inside a body. A number of animal surgeries verified the radiotracer lymphatic mapping technique and the effectiveness of the CZT probe for pre-incision planning. The utility of the probe has been further investigated during human surgeries of complete axillary node dissection. The probe has consistently shown the ability to verify the completeness of the surgery better than conventional non-imaging probes.