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

Abstract

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 Ω 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 σ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> =130 pm and σ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</inf> =250 μm 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.