[en] Moving beam technique in performing total body irradiation (TBI), which sweeps the X-ray beam completely over the whole body axis, is a useful technique for small treatment room in our hospital. However, homogenous dose distributions for patients cannot be obtained without changing the output during gantry rotation. We developed a method for obtaining a homogenous dose distribution by changing the software of the control unit of the linac without any change in the construction of the machine. The change of output/degree and/or the field width at each gantry angle can be automatically calculated by our method, the result, homogenous dose of ±3% at the reference plane was obtained in treating a useful length of 200 cm. From this study, though the results are still preliminary, our method might be promising in performing TBI. (author)