A new CT concept: Inverse geometry CT

Since its introduction in 1970s, Computed Tomography (CT) has evolved enormously to achieve fast temporal resolution, improved spatial resolution, better noise performance, and high image quality. While the conventional cone beam CT system provides 16 cm volumetric coverage in a single gantry rotation, large cone angles due to the increased detector size degrade image quality caused by insufficient data sampling. To overcome this, Inverse Geometry CT (IGCT) system was proposed. Instead of using a single focal spot and a large 2D detector array, the IGCT system uses a small 2D detector array and a multiple x-ray source array. Because of its inverted system geometry, the IGCT system can provide several benefits such as reduced scatter, isotropic resolution, improved temporal resolution, and reduced cone beam artifacts. A variant of IGCT system was proposed and in this paper we review three design schemes of the IGCT system; scanned source based IGCT, multiple source based IGCT, and stationary source based IGCT.