Investigation of X-ray photon-counting using ceramic-substrate silicon diode and its application to gadolinium imaging

X-ray photon counting was performed using a silicon X-ray diode (Si-XD) at tube voltages ranging from 20 to 100 kV. The Si-XD is a high-sensitivity Si photodiode selected for detecting X-ray photons, and the photons are directly counted using the Si-XD. Photocurrent from the diode is amplified using charge-sensitive and shaping amplifiers. To investigate the X-ray-electric conversion, we measured event-pulse-height (EPH) spectra using a multichannel analyzer (MCA). In the EPH spectra, the maximum photon energy corresponded to the tube voltage, and the photon count substantially increased with decreasing photon energy. Photon-counting computed tomography (PC-CT) is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan at a tube current of 2.0 mA. At a tube voltage of 100 kV, the gadolinium K-edge imaging was accomplished with an energy range of 50-100 keV.