Method and apparatus for projection domain truncation correction in computed-tomography (ct)

A computed tomography (CT) scanner, comprising:

• a support member,
• a rotating member configured rotatably in the support member, the rotating member including
• an X-ray source configured to emit X-rays,
• an X-ray detector arranged on the rotating member diametrically opposed to the X-ray source and configured to detect, using a plurality of detector elements, the X-rays emitted to generate projection data representing an intensity of the X-rays detected at the plurality of detector elements, the plurality of detector elements having an axial and a trans-axial direction, and
• a space provided between the X-ray source and the X-ray detector to accommodate an object to be imaged, which is at least partially within a an image volume within which an image is to be reconstructed from the projection data, and in one or more views represented in the projection data a part of the object is outside of a field of view of the radiation detected by the plurality of detector elements;
• and
• processing circuitry configured to
• determine extrapolation widths for extending the projection data corresponding to the one or more views by filling a truncation region extrapolated from the projection data,
• smooth the extrapolation widths by decreasing differences between extrapolation widths that are adjacent in the axial direction and by decreasing differences between extrapolation widths that are adjacent in a view direction,
• extrapolate, using the smoothed extrapolation widths, extended projection data to fill truncation regions and generate non-truncated projection data, and
• reconstruct an image from the non-truncated projection data.

A method, comprising:

• obtaining projection data representing an intensity of radiation detected at a plurality of detector elements having an axial and a trans-axial direction, the radiation having been transmitted through an object to be imaged, and in one or more views represented in the projection data a part of the object is outside of a field of view of the radiation detected by the plurality of detector elements,
• determining extrapolation widths for extending the projection data corresponding to the one or more views by filling a truncation region extrapolated from the projection data,
• smoothing the extrapolation widths by decreasing differences between extrapolation widths that are adjacent in the axial direction and by decreasing differences between extrapolation widths that are adjacent in a view direction,
• extrapolating, using the smoothed extrapolation widths, extended projection data to fill truncation regions and generate non-truncated projection data, and
• reconstructing an image from the non-truncated projection data.