Advantage of using compact gamma cameras for sentinel node radio-guided surgery: Monte Carlo simulation and first clinical evaluation of an intra-operative imager

Summary form only received as follows: The main application of radio-guided surgery concerns sentinel node detection for breast and melanoma cancer staging. In that context, when used as complementary tools of gamma probes, compact cameras are very attractive to provide more efficient node localization. The authors report on Monte Carlo simulations designed to compare performances of a standard commercially available counter to those of the POCl compact gamma camera they developed. A 3-D phantom patient with 8 mm diameter node embedded in a scattering medium (including background activity from the injection site) were generated for various node-to-tumor distances and activity ratios. Other parameters considered included detector energy resolution and acquisition time. Detection performances were compared in terms of contrast and statistical fluctuations. Simulations demonstrate that compact cameras have significant advantages over counters when sentinel node is placed close to the injection site. For a 1/100 activity ratio, the minimum node-to-tumor distance required to identify the node is 11.5 and 1 cm for the probe and the camera respectively. In order to evaluate experimentally the interest of intra-operative imaging, eight patients included in sentinel node protocol have been also investigated with POCl. Clinical results show the reliability of the camera which ensures localization of sentinel node in all patients.