Electron microscopic study on the response of the normal canine brain to boron-neutron capture therapy.

The response of normal cerebral tissue of dogs to boron-neutron capture therapy by the currently available improved method was studied by electron microscopy. Peripheral blood capillaries of the neutron-irradiated area in the left cerebral hemisphere were compared with their counterparts in the shielded and non-irradiated right hemisphere. No ultrastructural changes, as those noted in classical method of boron-neutron irradiation by the improved technique of boron-neutron capture therapy. There was no swelling of endothelial cells, disappearance of cristae of mitochondria, increased pinocytosis, disappearance of ribosomes, enlargement of Golgi apparatus, or increased appearance of endoplasmic reticulum. Basement membrane was not disrupted and was uniform. Pericytes, synaptosomes, and other glial elements remained intact. In contrast to the old clinical trials up to 1961, the renewed boron-neutron capture therapy is regarded not to cause serious damage to the central nervous system.