Isotopes of lutetium
Naturally occurring lutetium is composed of one stable isotope 175Lu and one long-lived radioisotope, 176Lu with a half-life of 37 billion years. Forty synthetic radioisotopes have been added from 149Lu to 190Lu, with the most stable being 174Lu with a half-life of 3.31 years and 173Lu with a half-life of 1.37 years. All of the remaining radioactive isotopes have half-lives that are less than 9 days, and the majority of these have half-lives that are less than half an hour. Of the meta states known for this element, the most stable are 177m3Lu and 174mLu.
The primary decay mode before the most abundant stable isotope, 175Lu, is electron capture, leading to ytterbium or less often thulium isotopes, and the primary mode after is beta emission giving hafnium isotopes.
All isotopes of lutetium are either radioactive or, for the lone stable isotope 175Lu, observationally stable, meaning that it is predicted to be radioactive but no decay has been observed.
Lutetium-177
Lutetium, that decays with emission of a low-energy electron, is a useful for treating some cancerous tumors. Several compounds of 177Lu are available for this purpose:1) Lutetium chloride, LuCl3, sold under the brand name Lumark among others, is used for radiolabeling other medicines, either as an anti-cancer therapy or for scintigraphy. Its most common side effects are anaemia, thrombocytopenia, leucopenia, lymphopenia, nausea, vomiting and mild and temporary hair loss.
2) Lutetium (177Lu) oxodotreotide has been approved for some types of tumors.
3) Lutetium (177Lu) vipivotide tetraxetan "Pluvicto" has also been approved.
4) Lutetium (177Lu) dotatate "Lutathera" has also been approved.