Single photon counting x-ray imaging system using a micro hole and strip plate

A single photon counting x-ray imaging system based on a MicroHole and Strip Plate (MHSP) using a resistive charge division method was implemented. The MHSP is a hybrid microstructure that combines within the same device the features of the Gas Electron Multiplier (GEM) and the Micro-strip Gas Chamber (MSGC). The MHSP presents two multiplication stages thus allowing reaching high gains. Two thin orthogonal resistive lines of about 100 Omega between each strip (top side) and between each anode strip (bottom side) allows us to obtain the actual position in both x and y directions. The readout electronics use only two charge preamplifiers in each dimension and a TNT module with four independent ADCs controlled through FPGAs that allow converting and registering the four signals through the USB port of a computer. Position resolution in both dimensions as a function of the detector parameters are presented for a 30 keV copper-target x-ray tube. Detector position resolution of sigma_x=130 mum and sigma_y=250 mum were achieved for 8keV, making it suitable for many applications in single photon X-ray imaging. The first x-ray images produced by the system are also presented together with a discussion of the image quality and the future prospects.