The rooms in most good bone marrow centers have HEPA filtered air, which is kept at positive pressure so any contaminants are carried out, not in, the room. The purpose of an autologous transplant is to give big doses of anticancer therapy. Because the upper dose of many drugs is limited by toxicity to the bone marrow, by removing bone marrow cells from the body, five to 10 times as much drug can be given. What limits giving say 100 times the dose is toxicity to other organs such as the heart, liver and lungs. The type of preparative regimen depends on the type of cancer.
Some cancers respond very well to radiation, so radiation is given to the whole body.
Radiation treatment is like getting an X-ray but the amount of radiation given is obviously much greater. The lungs are more sensitive to radiation than the rest of the body so they are shielded for one dose. Most people tolerate the radiation treatment well although it may cause nausea and mouth ulcers, but these usually occur several days after the treatment is completed. Radiation treatment is always given with at least one chemotherapy drug. If no radiation is given then several different drugs are combined.