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Services & Therapies
Total Body Irradiation (TBI)

For certain leukemic diseases (ALL, CML), bone marrow transplant (BMT) has been shown to be an effective form of treatment. Prior to the transplant, radiation is usually used to eradicate tumor cells and/or suppress patients’ immune system to enhance chances of marrow graft. The most common pretreatment conditioning is a combination of chemotherapy and total body irradiation (TBI). TBI gives a dose of radiation to the whole body, which can destroy cancer cells and body’s immune system so that it will not attack donor’s cells during transplant. Since leukemic cells have limited capacity to repair following radiation, a fractionated TBI scheme with small dose fractions is used. This approach maximizes leukemic cell-kill with minimal damage to normal tissue. Two treatment techniques are commonly used for TBI: right-left lateral X-ray beams with patient seated and anterior-posterior radiation with patient standing or semi-reclining. The radiation beam (X-rays) is delivered using a linear accelerator, which is a high energy radiation source.

The main treatment goal of TBI is to deliver ± 10% of prescription dose to the entire body. In our department, the anterior-posterior technique using 6 MV photons is used. The patient is seated in a semi-reclining position about 3 meters from the radiation source or a linear accelerator. A plexi-glass window is placed in front of the patient to allow uniform distribution of dose. A total dose of 12 Gy is given in 1.5 Gy fractions twice daily. Each treatment session may last approximately 30 minutes. On the first day of treatment a set of measurements are carried out with patient in the treatment position. This information is used to determine total machine on time. During the course of treatment, X-rays may be taken to determine areas to be treated and those that need to be blocked. For example, your physician may decide to use beam modifiers (or blocks) to limit dose received by healthy tissues, such as, lung and/or kidneys.

Some of the short term side effects that you may encounter during TBI are nausea, diarrhea, hair-loss and fatigue.