Sparse and energy discriminating collimated detector elements to assist scatter evaluation in CT imaging

A computed-tomography (CT) apparatus, comprising:

• a CT scanner including an X-ray source;
• and
• a detector covering respective angle ranges in axial and transaxial planes of the CT scanner, the CT detector including a plurality of detector elements including
• a first plurality of detector elements disposed on a first surface to capture incident X-ray photons emitted from the X-ray source;
• and
• a second plurality of detector elements being individually collimated and sparsely disposed on a second surface different from the first surface, the second surface being farther away from the X-ray source than the first surface by a predetermined distance, the second plurality of detector elements being smaller in number than the first plurality of detector elements,
• wherein each detector element of the second plurality of detector elements is reachable only by X-ray photons originating in a small angle range around a line connecting the X-ray source and a center of the surface of the detector element, the small angle range being determined by the predetermined distance separating the first and second surfaces and a size of the detector element, and
• the second plurality of detector elements are individually collimated so that X-ray photons directly reaching the second plurality of detector elements do not reach the first plurality of detector elements.

A computed-tomography (CT) apparatus, comprising:

• a CT scanner including an X-ray source;
• and
• a detector covering respective angle ranges in axial and transaxial planes of the CT scanner, the CT detector including a plurality of detector elements including
• a first plurality of detector elements disposed on a first surface to capture incident X-ray photons emitted from the X-ray source;
• and
• a second plurality of detector elements being individually collimated and sparsely disposed on a second surface different from the first surface, the second surface being farther away from the scanner than the first surface by a predetermined distance, the second plurality of detector elements being smaller in number than the first plurality of detector elements, and each of the second plurality of detector elements is an energy-discriminating detector element,
• wherein each detector element of the second plurality of detector elements is reachable only by X-ray photons originating in a small angle range around a line connecting the X-ray source and a center of the surface of the detector element, the small angle range being determined by the predetermined distance separating the first and second surfaces and a size of the detector element, and
• the second plurality of detector elements are individually collimated so that X-ray photons directly reaching the second plurality of detector elements do not reach the first plurality of detector elements.