This paper deals with an intra-operative irradiation technique for advanced stomach cancer. 1) An operating table for intra-operative irradiation was made in such a way as to be movable up and down, left and right, so that a treatment cone can be precisely positioned. 2) A treatment cone of pentagonel shape was especially made, which encompasses the lymph nood groups around the celiac axis. 3) The isodose distribution curves of electron beams through this treatment cone were obtained. i) When the entry surface is flat or smooth, the isodose lines run parallel to the surface. However, when it shows sharp irregularity, the lines are very complex. ii) When air space exists between the treatment cone and the tumor surface, the exposure on the tumor surface can be corrected by an inverse-square law. The absorbed dose at a given point in tissues was measured according to the measurement method of ICRU Report(21).
