The axial computed tomography of the skull has become an important part of the neuroradiologic diagnostics. The intracranial CT diagnosis is completed by the coronal sections which is used in particular in case of processes in the posterior cranial fossa and its differentiation of the supra- and infratentorial dimensions and in order to localize tumors in the sella region. The accurate determination of the tumor volume and the para-, supra-, and retrosellar dimensions makes possible an exact operation and irradiation planning. Solid, cystic and calcified tissues of the craniopharyngioma can be delimited. The quantitative evaluation by means of a computed tomogram of a tumor reduction obtained by surgery and irradiation with ultrahard X-rays (42 MV) with a target volume dose of about 5000 rd is illustrated by two examples. Under the above mentioned radiotherapeutic conditions, one partially resected craniopharyngioma with cystic, calcified and solid tissues showed a diminuation of the tumor volume of 60%, whereas the volume of a craniopharyngioma consisting of solid and calcified parts which had not been operated upon was reduced by about 40% two weeks after the end of the radiotherapy.