It is not true that the node closest to the primary tumor is by definition the (only) sentinel node. It is also not so that the hottest node is by definition the (only) sentinel node. The radioactivity content of a node is determined by parameters such as its size and the lymph flow rate. A large second-tier node occasionally accumulates more radioactivity than a small first-echelon node. For these reasons, it is questionable to use the radioactivity content or the sentinel node-to-background ratio to determine whether a node is a sentinel node.
How hot a node appears on the images is not only determined by its radioactivity content. One must also reckon with the inverse square law of physics. A superficial node lies closer to the gamma camera and is depicted brighter than an equally radioactive node that is situated deeper and, as a result, lies further away from the gamma camera.
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Complete Guide to Preventing Skin Cancer. We all know enough to fear the name, just as we do the words tumor and malignant. But apart from that, most of us know very little at all about cancer, especially skin cancer in itself. If I were to ask you to tell me about skin cancer right now, what would you say? Apart from the fact that its a cancer on the skin, that is.