> "Actinide’s flagship commercial product: enriched ytterbium-176,"

To save HN a search: a stable isotope used as a neutron capture target, to produce lutetium-177[i], used in targeted radioligand therapies[ii]. Discussed once on HN[iii].

[i] https://isotopes.gov/Ytterbium-176_is_Available_Now

[ii] https://en.wikipedia.org/wiki/Lutetium_(177Lu)_vipivotide_te...

[iii] https://news.ycombinator.com/item?id=40690196 ("Radioactive drugs strike cancer with precision (knowablemagazine.org)")