Photon-counting radiography with the gas microstrip detector.

We have built a proof of-concept photon-counting x-ray imaging system using a Xe:CH4 gas microstrip detector (GMD) as the image receptor, and have used this system to demonstrate several advantages of photon counting over energy integration. Our experiments spanned x-ray spectra from 10 to 50 kVp and Xe:CH4 pressures from 1 to 4 atm. When photon counting is done, the energy deposited in the detector by each incident photon can be measured on adjacent anode strips and a centroid calculation can be used to provide spatial resolution significantly better than the anode strip pitch.