Computed tomography scanner with large gantry bore

A computed tomography imaging system including:

• a rotating gantry defining an examination region, the examination region including a central region that contains a center of rotation of the rotating gantry and a surrounding region that surrounds the central region, the rotating gantry further defining a gantry plane of gantry rotation and an axial direction;
• a first radiation source disposed on the rotating gantry, the first radiation source producing first radiation directed into the examination region;
• a first radiation detector array arranged to receive the first radiation after the first radiation passes through the examination region, the first detector array including:
• a high resolution portion with detector elements of a first size that receive first radiation that passes through the central region, and
• a low resolution portion with detector elements of a second size that receive first radiation that passes through the surrounding region but not the central region, wherein the second size is larger than the first size;
• a second radiation source disposed on the rotating gantry, the second radiation source being positioned at an angular offset on the rotating gantry relative to the first radiation source, the second radiation source producing second radiation directed into the examination region;
• a second radiation detector array arranged to receive the second radiation after the second radiation passes through the examination region, the second detector array including:
• a high resolution portion with detector elements of a third size that receive second radiation that passes through the central region, and
• a low resolution portion with detector elements of a fourth size that receive second radiation that passes through the surrounding region but not the central region, wherein the fourth size is larger than the third size,
• wherein the high resolution portions of the first and second radiation detector arrays are arranged on the rotating gantry between the low resolution portions of the first and second radiation detector arrays;
• wherein the first and second radiation detector arrays together define a single unitary radiation detector array, the single unitary radiation detector array including:
• a central high resolution portion defined b the high resolution portions of the first and second radiation detector arrays;
• a first outer low resolution portion defined by the low resolution portion of the first radiation detector array;
• and
• a second outer low resolution portion defined b the low resolution portion of the second radiation detector array, wherein the central high resolution portion is arranged between the first and second outer low resolution portions;
• and
• a reconstruction processor that reconstructs projection data acquired during gantry rotation by the first and second radiation detector arrays into an image representation.

A computed tomography imaging method including:

• passing first radiation through an examination region, the examination region including a central region and a surrounding region;
• measuring central projections, corresponding to rays of first radiation that intersect the central region, using a first high-resolution detector array that has a first spacing of detector elements;
• measuring surrounding projections, corresponding to rays of first radiation that intersect the surrounding region without intersecting the central region, using a first low-resolution detector array that has a second spacing of detector elements, the second spacing being larger than the first spacing;
• passing second radiation through the examination region;
• measuring central projections, corresponding to rays of second radiation that intersect the central region, using a second high-resolution detector array that has the first spacing of detector elements;
• measuring surrounding projections, corresponding to rays of second radiation that intersect the surrounding region without intersecting the central region, using a second low-resolution detector array that has the second spacing of detector elements;
• and
• reconstructing the central projections and the surrounding projections corresponding to the first radiation and the second radiation to generate a reconstructed image representation, wherein the reconstructing includes:
• combining 90° contiguous angular segments of the central projections corresponding to the first radiation and the second radiation during reconstructing of voxels within the central region;
• and
• combining 180° contiguous angular segments of the central and surrounding projections corresponding to the first radiation and the second radiation during reconstructing of voxels in the surrounding region outside a transition radius.