[Physical dose distribution].

In radiotherapy planning it is essential to compose dose distribution curves on a transverse section of patient. For this purpose we have developed the radiotherapy planning system using a computer (Modulex), in which CT images and CT numbers were input on off-line with a CT magnetic tape, CT numbers were converted into relative electron densities and then, dose distribution curves calculated were output directly on CT images. One of problems lying in this system was that the three-dimensional dose distribution had to be surmised with a couple of two-dimensional ones. Clinical application of this system has been applied to planning of intraoperative radiotherapy that was considered to provide ideal dose distributions, and its effectiveness was discussed.