Total body irradiation as a method of preparation for bone marrow transplantation: a new technique and review.
Recently total body irradiation has been used as a method of preparation for the bone marrow transplantation. However, it has become apparent that total body irradiation is one of the causes of interstitial pneumonia. There are several factors in total body irradiation that may induce interstitial pneumonia. 1) Total dose. Usually 10 Gy which is used in America, reduces the survival of the leukemic cells to about 0.001% while the normal tissue cells are reduced to about 1%. However there is no evidence that 10 Gy is enough for bone marrow transplantation. 2) Dose rate. A dose of 10 Gy given at a high dose rate is about 10 times more effective than at a low dose rate. However, the dose-rate effects become less pronounced when the single dose is under 2 Gy. 3) Dose fractionation. The effect on cell survival of dose fractionation is discussed. Since the recovery from the radiation damage is usually greater in normal cells than in the malignant cells, fractionated radiation will have great advantages. 4) Dose distribution and new irradiation technique. It is difficult to obtain homogeneous distribution if a single large radiation field is used. In our hospital the patients receive total body irradiation by a moving treatment couch method under X-rays exposure. Homogeneous dose distribution is achieved with this method. Total body irradiation will become an almost routine treatment method for bone marrow transplantation with multifractionated irradiation.
D016026:Bone Marrow Transplantation; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D007165:Immunosuppression Therapy / Q000379:methods; D011829:Radiation Dosage; D014916:Whole-Body Irradiation / Q000379:methods*