Compared to that from 225Ac, the absorbed dose from 227Ac would make up a very small component (< 0.04%) of the total absorbed dose delivered to the 6 highest dose tissues: red marrow, spleen, endosteal cells, liver, lungs and kidneys when accelerator produced 225/7Ac-conjugated anti-CD33 antibody would be used to treat leukemia patients. Here, CD33 is linked to leukemia.