DESCRIPTION: (Adapted from the investigator's abstract.) Pituitary tumors comprise about ten percent of all brain tumors. The clinical presentation of these tumors is diverse, the morbidity and mortality is high, and the treatment modalities are inadequate. Loading pituitary corticotrophs and somatotrophs with 10Boron linked to either corticotrophin releasing hormone or growth hormone releasing hormone, will allow killing of targeted cells when irradiated with thermal neutrons, leading to more effective cancer therapy with the Boron Neutron Capture Therapy (BNCT) technique.The availability of a technique enabling accurate measurements of parts per billion boron concentration in micro, or sub-microliter samples will be an important ingredient in the development of boron delivery mechanisms to specific cells. An emerging analytical technique, Resonance Ionization Spectroscopy (RIS), has demonstrated extremely high selectivity and sensitivity in elemental analysis. RIS utilizes lasers tuned to states unique to the desired element, thereby, achieving efficient ionization of the analyte with essentially no background. These characteristics are extendable to boron, and would provide a solution to the aims described above. Instrumental and chemical developments are proposed to apply this method specifically to boron in biological matrices. Sample atomization options will be investigated together with quantitation options, including isotope dilution, to minimize complexity and assure reliability.