Removal of Cerebral Cortical Tissue with Negligible Scar Formation Using a Beam of High-Energy Particles

W HEN the cerebral cortex is invaded surgically, blood flow in the vessels in the area of incision terminates abrupt ly with infarction of the area those vessels supply and subsequent formation of a cicatrix within the area of necrosis, a In the course of studies on the histopathogenesis of injury to brain tissue of rats resulting from exposure to a nearly monoenergetic alphaparticle beam from the 60-inch cyclotron at Berkeley, we observed tha t at high doses the brain tissue disappeared from the irradiated area, and healing occurred without gross or microscopic evidence of formation of scar. 4 The type of healing observed was a t t r ibu ted to the unique characteristics of the beam of ionizing radiation used. However, because healing of wounds in the ra t is so efficient, we considered it impor tan t to investigate the nature of the healing process following the same irradiation of cerebral cortical tissue in monkeys. High-energy particles produce dense ionization in tissue, and unlike roentgen or gamma irradiation produce the so-called Bragg curve resulting in large depth dose compared to surface dose. Such densely ionizing radiation has also a greater relative biological effect per unit dose. This type of irradiation has already found many investigative uses in biology and medicine. 5,s