Singh V, Loughran B, Pope L, Bednarek D, Rudin S
Toshiba Stroke Research Center, University at Buffalo, Buffalo, NY.
Med Phys. 2012 Jun;39(6Part5):3651. doi: 10.1118/1.4734829.
To explore the possible applications for a newly developed ultra-high resolution, small field-of-view (FOV) micro-solid state x-ray image intensifier (micro-SSXII) detector.
The micro-SSXII is based on an 8 micron, 1004 by 1002 electron-multiplying CCD (EMCCD) optically coupled to a 100-micron thick CsI(Tl) phosphor through a fiber optic window resulting in a FOV of 8 mm with a resolution limit of more than 20 lp/mm. The system has the capability of providing real-time images at low exposures because of the high variable gain of the EMCCD. Several phantoms were prepared by filling catheter tubes of 470 micron internal diameter with separate mixtures of a casting resin with different ratios of three different contrast agents (Omnipaque 350, barium sulphate, tantalum powder). These were imaged with the micro-SSXII at 50 kVp to help select the best mixture for use in making a cast of a rat kidney whose vasculature would then be made radiopaque and visualized.
The images of all phantoms showed clumping of these contrast agents within the resin resulting in a non-uniform mix. The image of the phantom filled with Omnipaque and resin in a 1:4 ratio showed the best mixture although large bubble formation of the iodine was observed. This combination was used to make a cast of a rat kidney vasculature and imaged with the micro-SSXII. Small iodine bubbles with diameters as small as 25 microns were clearly delineated in the rat kidney vessels confirming the sharp detail capability of the micro-SSXII.
The micro-SSXII in combination with a soft x-ray spectrum can provide excellent images of small animal casts prepared with an appropriate radiopaque resin to study finer details of the vasculature. This new imager has the potential to be used for region-of-interest x-ray image guidance for interventional studies in small animals. Supported in part by: NIH Grants R01-EB008425, R01-EB002873 and an equipment grant from Toshiba Medical Systems Corp.
