Four-dimensional motion estimation and compensation by using feature reconstruction

A medical image processing apparatus, comprising:

• processing circuitry configured to
• obtain a set of projection data acquired in a computed tomography (CT) scan of a three-dimensional region of an object to be examined;
• generate for each time point of a plurality of time points of the CT scan based on a part of the obtained set of projection data corresponding to the time point, a pair of feature maps for estimating motion at the time point so as to generate a plurality of pairs of feature maps, each feature map representing a feature of an image reconstructed from the part of the obtained set of projection data;
• estimate, based on the generated plurality of pairs of feature maps, a four-dimensional motion field, wherein the four-dimensional motion field indicates change of a motion of the object in the three-dimensional region over time;
• and
• reconstruct, based on the estimated four-dimensional motion field and the obtained set of projection data, a CT image of the object.