Assessment of Proton Microbeam Analysis of 11 B for Quantitative Microdistribution Analysis of Boronated Neutron Capture Agents in Biological Tissues

• Published in: Radiation research 2003-12, Vol.160 (6), p.667-676
• Main Authors: Bench, Graham, Grant, Patrick G., Ueda, Dawn L., Autry-Conwell, Susan A., Hou, Yongjin, Boggan, James E.
• Format: Article
• Language: English
• Subjects: Boron; Brain neoplasms; Cell nucleus; Imaging; Ions; Neutron capture; Neutron capture therapy; Nuclear reactions; Pixels; Tumors
• ISSN: 0033-7587; 1938-5404
• DOI: 10.1667/RR3085

The ^{11}{\rm B}({\rm p},\alpha)^{8}{\rm Be}^{\ast}$ 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 ^{11}{\rm B}({\rm p},\alpha)^{8}{\rm Be}^{\ast}$ nuclear reaction and proton microbeams obtained from the nuclear microprobe at Lawrence Livermore National Laboratory. The 11 B 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 11 B in tissues. However, the spatial resolution, multi-isotope capability, and analysis times achieved with SIMS are superior to those achieved with ^{11}{\rm B}({\rm p},\alpha)^{8}{\rm Be}^{\ast}$ analysis. When accuracy in quantification is crucial, the ^{11}{\rm B}({\rm p},\alpha)^{8}{\rm Be}^{\ast}$ reaction is well suited for assessing the microdistribution of 11 B. Otherwise, SIMS may well be better suited to image the microdistribution of boron associated with neutron capture therapy agents in biological tissues.