[Computed tomography changes during radiotherapy of intracranial tumors]

722 CT examinations were carried out in 178 patients having intracranial tumours. The CT changes resulting from radiotherapy have been analysed. The examinations were performed at the beginning of treatment, after 30 and 50 Gy, after a three months' pause and at the conclusion of the planned total irradiation with 70 Gy. The results indicate that CT of intracranial tumours is an excellent method of demonstrating the effect of treatment. Information regarding the surroundings of the tumour (eg. cerebral oedema, displacement, herniation, compression of the ventricular system etc.) may be as important as that concerning the tumour itself. For evaluating the effect of radiation therapy, measurements of the size of the tumour are much more informative than density measurements. Even after 30 Gy, there was a change in tumour size in 49% of patients. Planned CT control used in conjunction with clinical information provides an effective means of adapting treatment to the changes in the tumour.