Chapter 23: Total Body Irradiation and Total Skin Electron Therapy

Total body irradiation (TBI) is a key step in the preparation for bone marrow transplants in the treatment of lymphoma or leukemia. This technique was a major advancement in the treatment of these diseases, and E. Donnall Thomas of the Fred Hutchinson Cancer Research Center was awarded the Nobel Prize in Medicine or Physiology in 1990 for its development. Prior to receiving a bone marrow transplant from a donor or from themselves, the patient undergoes a conditioning regimen that includes TBI. TBI can be delivered with myeloablative intent, i.e., to eradicate stem cells in the bone marrow; in this case, a typical prescription would be 12–15.5 Gy delivered in six to ten fractions BID (twice per day), sometimes with a boost to the testes in male patients. Alternatively, TBI can be delivered in a non-myeloablative fashion for the purpose of suppressing the immune system prior to transplant. In this case, the dose is much lower (e.g., 2 Gy in one fraction); note that circulating T lymphocytes are very radiation-sensitive.