The built-in capacity of CT D'Or's static ring for scatter correction

The new scanner geometry CT D'OR ("CT with Dual Optimal Reading"), developed at the Helmholtz Zentrum München (former GSF-National Research Center for Environment and Health), consists of a discontinuous ring of detectors facing toward the ring center, which are fixated on an x-ray absorbing material. The x-ray source and an additional outer detector are mounted on a gantry which rotates around the inner static detector and thus the patient. When the source is moving, the detectors are alternately exposed and shielded from the source. Data recorded during periods of direct exposure can be combined and are used for the reconstruction of the image. When the detectors are shielded, their signal is solely caused by scatter. Therefore, direct scatter correction is possible. This can be used to considerably improve the image quality, when scatter radiation yields a strong deterioration of the reconstructed image. The advantage of CT D'OR is thus, that information about scatter radiation is obtained without additional effort or exposure. This property of CT D'OR is investigated and its feasibility is demonstrated by the use of Monte Carlo simulations.