Atomic emission method for total boron in blood during neutron-capture therapy

Background: Boron neutron-capture therapy (BNCT) is a drug-targeted binary radiotherapy for cancer. The B-10 capture of thermal neutrons induces secon dary radiation within cells during irradiation. The most widely used boron carrier is 4-dihydroxyborylphenylalanine (BPA). The duration and timing of the irradiation is adjusted by monitoring 10B concentrations in whole blood . Methods: We developed a new method for boron determination that uses induct ively coupled plasma atomic emission spectrometry (ICP-AES) and protein rem oval with trichloroacetic acid before analysis. This method was compared wi th the established but tedious inductively coupled plasma mass spectrometry (ICP-MS), which uses wet ashing as sample pretreatment. Erythrocyte boron concentrations were determined indirectly on the basis of plasma and whole blood boron concentrations and the hematocrit. The hematocrit was determine d indirectly by measuring calcium concentrations in plasma and whole blood. Results: Within- and between-day CVs were <5%. The recoveries for boron in whole blood were 95.6-96.2%. A strong correlation was found between results of the ICP-AES and ICP-MS (r = 0.994). Marked differences in plasma and er ythrocyte boron concentrations were observed during and after infusion of B PA fructose complex. Conclusions: The present method is feasible, accurate, and one of the faste st for boron determination during BNCT. Our results indicate that it is pre ferable to determine boron in plasma and in whole blood. Indirect erythrocy te-boron determination thus becomes possible and avoids the impact of prean alytical confounding factors, such as the influence of the hematocrit of th e patient. Such an approach enables a more reliable estimation of the irrad iation dose. (C) 2001 American Association for Clinical Chemistry.