X-ray edge subtraction imaging of gold nanoparticle concentrations for biological imaging

Nanoparticles may be used as biomarkers to locate tumours and provide information on tumour characteristics. This paper reports on the development of a high resolution imaging system sensitive to gold nanoparticle concentration and distribution and possibly to cell structure. X-ray subtraction techniques have proven beneficial for identifying high atomic number contrast agents. X-ray subtraction makes use of the large difference in attenuation properties of high Z materials at energies either side of absorption edges, and can provide considerable enhancement in contrast over conventional X-ray imaging. X-ray subtraction, in this case, is being used to locate the presence of nanoparticles, such as gold, which are embedded into tissues as biomarkers to map the disease state. In this project X-ray subtraction imaging techniques are being combined with other techniques to form quantitative images of nanoparticle concentration and distribution. The assessment of the technique is based on the use of synchrotron radiation to irradiate the sample and of a CCD camera behind the sample to perform transmission images just above and just below the L_ιπ-edge of gold (11.92 keV). Results will report on system performance, demonstrate sensitivity to nanoparticle biomarker concentration and present images of biomarker concentrations in cylindrical test objects.