This book will provide readers with a good overview of some of most recent advances in the field of Photon Counting CT technology for X-ray medical imaging, especially as it pertains to new detectors. There will be a good mixture of general chapters in both technology and applications in CT medical imaging. The book will have an in-depth review of the research topics from world-leading specialists in the field. The conversion of the X-ray signal into analogue/digital value will be covered in some chapters. The authors also provide a review of CMOS chips for X-ray image sensors, methods of material discrimination and image reconstruction techniques.