The mapping of natural boron in histological sections of mouse tissues by the use of neutron-capture radiography

Abstract

Neutron-capture radiography has been applied to the mapping of natural boron in mouse histological sections. The method is based on the fact that the stable isotope boron-10 has an extremely large cross-section for the thermal-neutron reaction 10B(n, alpha)7Li. The local tissue boron concentrations were evaluated from the corresponding track densities of the nuclear reaction using an equation derived from a theoretical model of the system. The adjustable parameters of this equation were determined in two separate calibration experiments using standardized samples prepared by the addition of known amounts of boron. Interference from other nuclides engaged in nuclear reactions with thermal neutrons was also estimated. In the present experimental conditions the natural boron lower detection limit was 0.03 p.p.m. (fresh weight), and the spatial resolution was of the order of a few micrometers. Boron concentrations in mouse serum and urine were close to 0.22 and 0.57 micrograms ml-1, respectively. In the solid mouse tissues--liver, heart, brain, muscle and spleen--the concentration was usually low, ranging from 0.12 to 0.16 p.p.m. (fresh weight). They were significantly higher in the kidney, especially in the papilla (6.2 p.p.m. fresh weight). Apart from the kidney papilla, where boron was particularly concentrated in wall tubules, the boron distribution in most tissues appeared to be practically homogeneous. Natural boron, and even more so its enriched stable isotope 10B, appear as good candidates for molecular labelling using non-radioactive tracers.

Boron Determination—A Review of Analytical Methods

“…Following irradiation, the film is stained, reversed, and etched with KOH or NaOH. This technique has been used for mapping the distribution of natural B in histological sections of mouse tissue (157) and in parenchyma cells of clover leaves (158). The quantification of B is possible using an image analyzer (159).…”

Quantitative neutron capture radiography for boron in biological specimens

“…The size of the hole depends on the energy deposition of the incident particle and on the etching parameters (Durani and Bull 1987). By measuring the total area of the etched tracks or the number of tracks in a region of known area, the concentration of ' OB in the samples can be evaluated from a calibration curve obtained from a standard specimen of known ' OB concentration, piepared in the same or simiIar material as the samples (Gabel et al 1987b, Laurent-Pettersson et a[ 1992.…”

Neutron Capture Radiography: Neutron Capture Radiography:a technique for isotopic labelling and analytical imaging with a few stable isotopes

“…The big, dark tracks originating from 10 B are easily discriminated from the small, grey tracks originating from 14 N. Bar = 10 µm. Modified from Laurent-Pettersson et al[37].…”