Boron microquantification in oral muscosa and skin following administration of a neutron capture therapy agent

Clinical trials of boron neutron capture therapy (BNCT) for intracranial tumours using boronophenylalanine-fructose undertaken at Harvard-MIT and Brookhaven National Laboratory have observed acute normal tissue reactions in the skin and oral mucosa. Because the range of the 10B(n, alpha)7Li reaction products is very short, 10-14 microns combined, knowledge of the 10B microdistribution in tissue is critical for understanding the microdosimetry and radiobiology of BNCT. This paper reports measurements of the microdistribution of 10B in an animal model, rat skin and tongue, using high resolution quantitative autoradiography (HRQAR), a neutron-induced etched track autoradiographic technique. The steep spatial gradient and high absolute value relative to blood of the 10B concentration observed in some strata of the rat tongue epithelium and skin are important for properly evaluating the radiobiology and the biological effectiveness factors for normal tissue reactions such as oral mucositis, which are generally assessed using the blood boron concentration rather than the tissue boron concentration.