There are several ongoing medical trials to use Bi-213 conjugated to monoclonal antibodies to kill tumour-cells of various cancer types. The institute is supplying Ac-225 generators for the test and is itself engaged in in-vitro cytotoxicity tests. Nuclear reactions leading to Ac-225 are discussed. The present supply of Ac-225 stems from Th-229 decay obtained from aged U-233. From the possible alternative the reactions Ra-226 (p, 2n) Ac-225 is presently favoured. The fabrication of a Ac-225 for Bi-213 generator will be described.