[Development of transXend detector and its application to low dose exposure CT]

For practical energy-resolved computed tomography (CT), a transXend detector is proposed. The transXend detector consists of several segment detectors which are aligned along the direction of X-ray incidence. With response functions of segment detectors, the energy distribution of incident X-rays is obtained after unfolding process. Because the transXend detector measures X-rays as electric currents, it has no limit of counting rate: the number of X-rays in medical diagnosis ranges 10(6)-10(9)n/mm2/s, measuring energy of each X-ray is not practical at this stage. The operation principle and ways of application of the transXend detector are described. With defining narrow energy ranges in an unfolding process, effective atomic numbers are estimated with using white X-rays: the transXend detector can cut out quasi-monochromatic X-rays out of white X-rays. With the transXend detector with absorbers among the segment detectors, the directions of material thickness increment are shown different in the graph made of electric current ratios measured by the segment detectors. Using the current ratio graph, the thicknesses of the materials along the line X-rays passed are estimated. In other words, cancers marked by contrast agent can be detected with one transmission measurement, and possibly are measured and positioned by transmission measurements from two directions.