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.

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Energy resolved imaging has been possible with a newest generation of radiation detectors with photon counting and spectroscopic capabilities. This innovation gives the possibility to enhance the image quality by applying techniques using the energy information. In this work two X-ray Computed Tomography (CT) Systems were assembled with two different energy resolving detectors: Medipix2 and MicroHole & Strip Plate (MHSP). These detectors have the aforesaid characteristics and showed a good performance for X-ray imaging. The Energy Weighting Technique (EWT) and Basis Material Decomposition (BMD) techniques were applied with good results. An improvement of 31% in the CNR was achieved by applying the EWT in the MHSP data and, using Medipix2, two basis materials (Carbon based and Aluminium) were decomposed successfully with densities close to the real values.

The present work reports a new system for Computed Tomography (CT) with Multi-Slice (MS) capability using the 2D-MicroHole & Strip Plate (MHSP) detector. The system is based on the third generation of CT scanners and includes a MHSP based detector which achieves gains above 10 4 and has the capability to discriminate the interaction position of the incoming radiation in 2D. The possibility of operating in single photon counting mode with energy discrimination allows the selection of energy ranges for image reconstruction and the application of the Energy Weighting Technique (EWT). The EWT improves the image contrast and the Signal to Noise Ratio of the images. The reconstruction of three-dimensional images of a PMMA phantom with holes filled with chalk and air or brass are shown as a good representation of the studied objects.