Large area 2-dimensional detector for real-time 3-dimensional CT (4D-CT)

Real-time 3-dimensional CT (4D-CT) is a high-speed cone-beam CT with good low-contrast detectability. In a single rotation, a voxel data set with higher spatial resolution over a wide z-axis range can be obtained. Using continuous rotation, temporarily continuous voxel data sets and three-dimensional dynamic images can be acquired. We have developed a large area 2-dimensional detector for 4D-CT, and we have got the first 4D-CT test images. The requirements for a 2-dimensional detector are (1) dynamic-range must be more than 16-bits, (2) the sampling rate (speed) must be at least 900 views(frame) per second, (3) the size of the FOV must be at least 500mm in diameter and 128mm in height at the center of rotation, and (4) the size of each element must correspond to 0.5mm-slice. Each element of the detector consists of scintillator and photo-diode, similar to the detector of the multi-slice CT. Elements are arranged in two dimensions. There are 912 channels, and 256 segments in the z-direction in each channel. We have evaluated temporal response, and we have got images of magic hand phantom. The detector has met the requirements for a 4D-CT system. We show that a 4D-CT system with higher spatial resolution, and higher temporal resolution is a promising technique.