Studies on novel molecular imaging using X-rays

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Utilizing cadmium telluride (CdTe) detectors, we developed four-types of energy-discrimination X-ray imaging systems as follows: two transmission-type X-ray cameras (ED-CAM), two reflection-type X-ray fluorescence cameras (XRF-CAM), two energy-discrimination X-ray CT (ED-CT) systems, and two XRF-CT systems. Using ED-CAMs, we performed K-edge imaging using contrast media and suspensions of iodine, cerium, and gadolinium, and spatial resolutions were 0.2×0.2 mm^2. Mapping of iodine, cerium, and gadolinium atoms in cancerous region was carried out by use of XFR-CAMs. K-edge CT for imaging the three atoms was accomplished using ED-CT systems with spatial resolutions of 0.5×0.5 mm^2. Although the skin doses were high using XRF-CT systems, weakly remained iodine atoms in the cancerous region were observed at high contrast. To decrease X-ray exposure time for ED-CT, we developed an oscillation linear CdTe detector, and the scan velocity was increased from 5.0 to 25.0 mm/s. We also developed a 15 Mcps energy-discrimination CT system with a scan velocity of 600 mm/s. Embossed radiography (ER) was carried out using single- or dual-energy subtraction radiography after shifting of the second image, and concavoconvex images such as phase-differential images were obtained. Furthermore, the spatial resolutions were improved to 40×40・m by magnification embossed radiography (MER) using a 100・m-focus X-ray tube.