[The use of computer tomography in individual treatment planning (author's transl)]

Computer tomography provides the possibility of individual treatment planning. For this purpose it is necessary to obtain the matrix of linear absorption coefficient for the type of radiation used during radiotherapy. In this paper it is shown that it is necessary to obtain a cross section of the patient using rays of two different qualities. From these results and previous measurements on phantoms it is possible to calculate the density and effective atomic number. It is also shown that the most significant information is obtained from the density matrix, if ultra hard X-rays are used for radiation therapy; With this density matrix it is possible in a simple manner to take account of inhomogeneities within individual patients.