Development of a Low-Background Neutron Autoradiographic Technique

Publisher Website
Google Scholar
Abstract
The cellular distribution of 10B in tissue is of interest in neutron capture therapy, since the efficacy of the 10B(n, [alpha]) 7Li reaction is dependent on localization within cells. Experimental results showed that air nitrogen in conjunction with emulsion of greater than optimum thickness was responsible for high background encountered in previous attempts to develop a technique capable of determining intracellular distribution in human tissues. Irradiation of slides coated with liquid emulsion, with thermal neutrons (6.23 x 1010 cm-2) in a CO2 atmosphere, gave a heavy-particle background of 2 tracks per microscopic field (1.77 x 10-4 cm+2), i a tissue section 5 microns thick, containing 60 [mu]g of 10B per gram of tissue (roughly the maximum amount tolerable to human tissues), is irradiated with the same fluence, the number of countable [alpha]-tracks per field from the 10B(n, [alpha])7Li reaction would be 25.6 or 10.2 tracks per field, depending on whether or not attenuation in tissue was taken into consideration. Both of the above numbers were verified by experiment. Therefore, it is now possible to investigate the intracellular distribution of boron attached to water-insoluble proteins or, in conjunction with previously established freeze-drying techniques, to investigate the distribution of water-soluble compounds used in previous clinical trials.