Patent ID: 8537965

Claim:
Apparatus for CT cone beam scanning, comprising: a table for holding a subject; a gantry defining a rotation axis of the apparatus; a first detector array, mounted on the gantry; an X-ray source system comprising: a plurality of X-ray sources, wherein each X-ray source of the plurality is provided with a cathode from which an electron beam is emitted, an anode to receive the electron beam and at least one grid electrode, wherein the grid electrodes are configured to selectively block radiation from the plurality of X-ray sources; a high voltage generator for applying voltage to the plurality of X-ray sources; a grid modulator configured to apply voltage to grid electrodes of each of the plurality of X-ray sources in turn; a controller for controlling the grid modulator so that only one of the plurality of X-ray sources emits a cone beam at any one time; and a collimator that collimates cone beams from two of the plurality of X-ray sources such that the cone beams are asymmetrical with respect to a plane defined by each respective X-ray source trajectory about the rotation axis, and an edge of at least one asymmetrical cone beam which is farther from the other X-ray source makes a larger angle to the detector array than does the beam edge closer to the other X-ray source; and such that the farther edge of the at least one asymmetrical cone beam makes an angle of between 87 and 90 degrees with the detector array; and a scanning controller that acquires data responsive to radiation from the plurality of X-ray sources from the detector array, wherein the radiation acquired is attenuated by at least part of a common volume of a subject irradiated by the plurality of X-ray sources.