[Stereoradiotherapy of small brain lesions]

Stereoradiotherapy is the stereotaxy guided high-dose irradiation of small (less than 3 cm) intracerebral lesions. Its aim is to induce necrosis or sclerosis inside the target volume. Several techniques permit us to obtain a steep dose gradient between the lesion and the adjacent healthy cerebral parenchyma. They use minibeams (diameter less than 3 cm) of different types of radiations: protons (Kjellberg from Harvard, since 1962); gamma rays of cobalt 60 (Leksell from Stockholm, since 1968); and X-rays from a linear accelerator (Betti from Buenos-Aires, since 1982). The most commonly treated lesions are arterio-venous malformations, hypophyseal adenomas and low grade parenchymatous tumors. The stereotaxic technique is the only means by which to insure that these high dose irradiations, administered in a single session, are actually delivered to the small lesions situated in the cerebral parenchyma.