An exceptional nucleus
Technetium 99m, widely used in nuclear medicine, is a long-lived intermediary step in the life of a technetium nucleus obtained through the decay of molybdenum 99. According to the flowchart, the emission of a beta electron leaves behind an excited nucleus, which returns to its ground state by emitting a gamma photon. This excited state persists for a few hours, which gives hospitals the time to isolate it, inject it into a patient as a radioactive marker and then image the body using in this case a bone scintigraphy.