TOTAL BODY IRRADIATION WITH A FOUR-FIELD TECHNIQUE USING A 10 MV LINEAR ACCELERATOR

Recently, total body irradiation (TBI) is being used as a method of preparation for bone marrow transplantation (BMT). However, many variations exist in the TBI procedure, such as the irradiation technique, total dose, dose rate and dose fractionation. In TBI treatment, it is important to apply a homogeneous dose to the total body, and avoid interstitial pneumonitis and cataracta. Therefore, we applied a four-field technique using 10 MV X-rays with a shield for lungs and eyeballs, and employed tissue compensators and bolus to obtain a homogeneous dose distribution. The midpoint doses in 12 positions of the total body have been achieved within±10% of that of the pelvis with the use of this technique. Also, this TBI technique is capable of accurately controlling absorbed doses to the lungs and eyes.