Sentinel lymph node biopsy of the breast.  The first of three panels shows a  radioactive substance and/or blue dye injected near the tumor; the middle panel shows that the injected material is followed visually and/or with a probe that detects radioactivity to find the sentinel nodes (the first lymph nodes to take up the material); the third panel shows the removal of the tumor and the sentinel nodes to check for cancer cells.
Sentinel lymph node biopsy of the breast. A radioactive substance and/or blue dye is injected near the tumor (first panel). The injected material is detected visually and/or with a probe that detects radioactivity (middle panel). The sentinel nodes (the first lymph nodes to take up the material) are removed and checked for cancer cells (last panel).