Energy weighting technique in Quantum Computed Tomography using a MPGD

Abstract

In the present work a new system for Quantum Computed Tomography was developed and tested, envisaging its application to small animals and mammography imaging. It consists of a Micro-Patterned Gas Detector based on the Micro-Hole and Strip Plate, operating in single-photon counting mode. The Micro-Hole and Strip Plate allows the storage of the position of interaction and the energy information of each single X-ray photon. With this information it is possible to select the energy range to reconstruct the images of cross sections, enabling the enhancement of different structures according to their attenuation coeficients. It is also possible to use the energy information to weight each photon in the sinogram construction. In the present work we consider three types of weighting factors giving rise to three different types of images, namely Integrating, Counting and Energy Weighting Technique (EWT). For each CT acquisition the system allows us to construct any of these types of images without the need for extra measurements. Some features of the CT image improve with the application of the Energy Weighting Technique, namely the Signal-to-Noise Ratio (SNR), the image Contrast, and the Contrast-to-Noise Ratio (CNR). The maximum contrast enhancement was about 23%, the maximum SNR improvement was about 22% and the maximum CNR improvement was about 31% between integrating and EWT images. © 2011 IOP Publishing Ltd and SISSA.