Conventional Cone-Beam CT Scanner. Describing hardware geometrical characteristicsIn Cobra detector positions in every spot of its trajectory are defined by the terms of a central ray and a central ray crossing point. Central ray is the ray coming from a focal spot of x-ray source and perpendicular to the axis of rotation. In ideal cone-beam CT central ray trajectory forms an ideal plane usually called as equatorial plane. Central ray crossing point is the point where a central ray is crossing the detector Detector pivot (tilt)Detector offsetsDescribing detector positions To make an accurate reconstruction it is necessary to know positions of source and detector in every spot where x-ray beam exposes an object. Cobra utilizes the following parameters illustrated on this page. Horizontal and vertical distances between a central ray crossing point and a physical center of the detector (called in Cobra U- and V- offsets) Detector pivot (tilt): detector rotation angle around its norm measured relatively a projection (“shadow”) of axis of rotation |
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Describing a reconstruction task
Tags controlling scanner geometry