Gamma probe
A gamma probe is a handheld device used with a Geiger-Muller tube or scintillation counter, for intraoperative use following interstitial injection of a radionuclide, to locate regional lymph nodes by their radioactivity. It is used primarily for sentinel lymph node mapping and parathyroid surgery. The Gamma Probe is also used for RSL (Radioactive Seed Localization), to locate small and non-palpable breast lesions.