[Computer tomographic follow-up in radiotherapy of brain tumors].

33 patients with primary and secondary brain tumours received radiotherapy. The therapeutic success was computer tomographically controlled. Only a temporary reduction in the size of the tumour could be observed during the radiotherapy. In connection with the reduction of the pathological findings in the CT, an improvement in the neurological findings was determined. A change in the tumour absorption may occur under the radiotherapy. An important indicator for tumour growth or regression is the change in the tumour absorption in computed tomography with the contrast medium. If the enhancement remains inspite of the radiotherapy, it can prognostically be considered as a detrimental factor. In the case of 10 of the 33 patients undergoing radiotherapy the tumour became isodense. No more enhancement was detectable. Isodensity may not be seen as a complete normalization of the brain tissue as could be established by histological investigations. On the other hand if again hypodense areas are revealed, it does not necessarily mean recurrence of tumour. Such an hypodense region then implies a radiogenic tumour-necrosis. Only the renewed enhancement after administering of the contrast medium in the area of the tumour must be considered as recurrence.