[Fractionated stereotaxic radiotherapy with the Leksell gamma knife]

Stereotactic radiotherapy is treatment of a small or medium-sized intracranial focus, using a fractionated regime and the stereotactic method. It is carried out usually on linear accelerators. The objective of the present investigation was to test the possibility of stereotactic radiotherapy using Leksell's gamma knife and Leksell's stereotactic frame.

During the period between April 1993 and November 1994 38 patients (16 women and 22 men aged 15-72 years) were indicated for stereotactic radiotherapy. The patients had the following diagnoses: adenoma of the epipharynx (1), low-grade gliomas (10), ependymoma (1), germinoma (1), meningioma (2), solitary metastases into the CNS (19), pinealomas (3) and chordoma (1). The volume of the tumour varied from 740 mm3 to 37,000 mm3. Stereotactic fractionated radiotherapy was carried out using a Leksell Gamma Knife, Electa Instrument AB, Sweden. For assessment of the total fractionated dose a linear quadratic model was used. Thus assessed value was further modified in relation to the volume and radiobiology of the tumour, critical structures surrounding the treated lesion and other factors. The total fractionated dose to the maximum varied from 20 Gy to 60 Gy and the total fractionated dose on the periphery of the tumour from 12 Gy to 30 Gy. With regard to the short time interval which has elapsed since treatment it is not yet possible to evaluate completely the achieved results; it will be possible to do so after a time interval of 1-5 years following the operation. The patients tolerated the 2-5 day fixation with a stereotactic Leksell frame very well and none of the patients developed complications.

Fractionated stereotactic radiotherapy with Leksell's gamma knife, using Leksell's stereotactic frame, is a very accurate therapeutic method with a minimal radiation load of surrounding brain tissue. It requires a short hospitalization period and is associated with no or only minimal complications and improves the quality of patient's lives.