4-dimensional computed tomography (4D CT) - its concepts and preliminary development

4D CT is a dynamic volume imaging system of moving organs with an image quality comparable to conventional CT. Dynamic cone-beam CT can realize it with several breakthroughs. They are: 1) large-area 2-dimensional (2D) detector, 2) high-speed data transfer system, 3) reconstruction algorithm, 4) ultra-high-speed reconstruction computer and 5) high-speed and continuous rotating gantry. Among them the development of the 2D detector is one of the biggest tasks because it should have as wide dynamic range and high data acquisition speed (view rate) as present CT detectors. We are now developing a 4D CT-scanner together with the key-components. It will take one volume in 0.5 sec with a 3D matrix of 512 × 512 × 512. This paper describes its concepts and design, as well as preliminary development of the 2D detector.