Readout Architecture Based on a Novel Photon-Counting and Energy Integrating Processing for X-Ray Imaging

In this article, a new readout architecture for X-ray imaging is proposed, which is based on the energy weighting function. This architecture utilizes a spectrometer and an energy weighting logic per pixel. Various weights can be realized inside a pixel by changing only the logic implementation, and energy weighted pixel values are calculated without external calculations. The proposed architecture was confirmed that its weighting function could be modified by fabricating two weighting functions in the form of two test large-scale integrated circuits (LSIs) with a 0.18-mu m complementary metal-oxide-semiconductor (CMOS) process. They were designed for a photon counting and an energy integrating imager with 80-mu m pitch pixels, and their abilities to deal with different fluxes were evaluated after obtaining each simulation result. Their sensitivity to single photons and their capability in measuring the energy information of X-ray photons has been demonstrated by measuring the spectra of radiation isotopes.