Bench, G., Grant, P. G., Ueda, D. L., Autry-Conwell, S. A., Hou, Y. and Boggan, J. E. Assessment of Proton Microbeam Analysis of ¹¹B for Quantitative Microdistribution Analysis of Boronated Neutron Capture Agents in Biological Tissues. Radiat. Res. 160, 667–676 (2003).

The ¹¹B(p,α)⁸Be* nuclear reaction was assessed for its ability to quantitatively map the in vivo subcellular distribution of boron within gliosarcomas treated with a boronated neutron capture therapy agent. Intracranial 9L gliosarcomas were produced in Fischer 344 rats. Fourteen days later, the majority of the rats were treated with f-boronophenylalanine and killed humanely 30 or 180 min after intravenous injection. Freeze-dried tumor cryosections were imaged using the ¹¹B(p,α)⁸Be* nuclear reaction and proton microbeams obtained from the nuclear microprobe at Lawrence Livermore National Laboratory. The ¹¹B distributions within cells could be imaged quantitatively with spatial resolutions down to 1.5 μm, minimum detection limits of 0.8 mg/kg, and acquisition times of several hours. These capabilities offer advantages over α-particle track autoradiography, electron energy loss spectroscopy, and secondary ion mass spectrometry (SIMS) for quantification of ¹¹B in tissues. However, the spatial resolution, multi-isotope capability, and analysis times achieved with SIMS are superior to those achieved with ¹¹B(p,α)⁸Be* analysis. When accuracy in quantification is crucial, the ¹¹B(p,α)⁸Be* reaction is well suited for assessing the microdistribution of ¹¹B. Otherwise, SIMS may well be better suited to image the microdistribution of boron associated with neutron capture therapy agents in biological tissues.