Sentinel lymph node biopsy (SLNB) is applied to some cancer patients to determine the nodal stage of their disease. This is mostly assured by injecting a tracer material near the tumor, which are transported by the lymph vessels to the lymph node(s) in the drain of the tumor. These lymph nodes are called the sentinel lymph node(s), short SLNs. Under control of a proper imaging modality, the SLNs can be localized pre- or intra-operatively.