This project consists on the realization followed by the clinical validation of two medical instruments dedicated to the precise sentinel lymph nodes identification and localization in the case of breast cancer: an intra operative probe and an operative mini gamma camera. The sentinel lymph node technique, based on the propagation of cancer cells in the lymphatic system, allows a better evaluation of tumor staging, prognosis and therapeutic strategy determination. The goal of these instruments designed by physicians and physicists is to significantly improve the detection efficiency of the technique in order to reduce the false negative rate and then the recurrence risk, as well as the operative morbidity.Clinical oncologist surgeons and fundamental physics applied to medical imaging researchers are involved in this project. The clinical validation of the medical instruments will be organized in the Gynaecologic and Obstetric department of the Hospices Civils de Strasbourg with a series of 25 patients in the framework of a regular french protocol of clinical research.