The present invention provides improved CT systems and methods that enjoy substantially increased FOV. The diameter of the in-plane FOV of CT systems according to the present invention can be larger than the in-plane extent of the detector (or source) array. Stanford scientists have created a method that provides CT systems with increased FOV without the expense and complication of larger detector (or source) array sizes required in the past.
In a forward-geometry implementation, multiple x-ray point sources emit corresponding fan beams at a single detector array at different corresponding times. X-ray image data is acquired at the detector array as the x-ray point sources and the detector are both rotated together around a rotational axis. Each of the fan beams has a central ray passing from the source to the midpoint of the detector. Thus, the central rays of at least two fan beams intersect at the detector midpoint, and the central ray of at least one fan beam is offset from the rotational axis by an offset distance. The diameter of the in-plane field of view provided by the combination of the fan beams is preferably larger than an in plane extent of the detector array. This can be expanded to include two sources, an possibly three or more sources, where at least one source has a fan beam whose central ray is offset from the rotational axis. The other source has a fan beam whose central ray may pass through the rotational axis (i.e., have no offset) or may be offset from the rotational axis.
