Its maximum specific activity is 58,000 Ci/g.

Actinium-225 (225Ac) generates 4 net alpha particle isotopes in a short decay chain to stable 209Bi, and as such can be described as an alpha particle nanogenerator.

Alpha particles offer key advantages over beta particles - the high linear energy transfer (LET) and the limited range in tissue. The high alpha particle LET is on the order of 100 keV/μm and it can produce substantially more lethal double strand DNA breaks per alpha track than beta particles when traversing a cell nucleus.

As alpha particle tracks are relatively short they have a limited range in tissue.