Prompt gamma ray spectrometry for in vivo measurement of boron-10 concentration in rabbit brain tissue.

Boron-10 concentrations in the brain of live rabbits were measured by prompt gamma ray spectrometry at intervals over a 24-hour period. Boron-10 concentrations in the blood and cerebrospinal fluid (CSF) were also measured. Animals were killed at each interval to obtain brain tissues to measure the boron-10 concentration in the brainstem, cerebral cortex, cerebellar cortex, and basal ganglia, as well as the whole brain. Boron-10 concentrations in the live brain did not differ significantly from those measured in whole brain tissue. Boron-10 concentrations in the blood were much higher than in the brain at each interval after injection. These boron-10 concentrations showed a similar pattern of initial rapid decrease, followed by a more gradual decrease. There was little boron-10 present in the CSF. The brainstem contained a significantly larger concentration of boron-10 than the other tissues. Prompt gamma ray spectrometry has the potential for direct measurement of boron-10 concentrations in the brain of patients undergoing boron neutron capture therapy.