Methods and systems are provided for increasing a quality of computed tomography (CT) images generated by a CT system by altering a shape of a focal spot of an X-ray emitter of the CT system. In one embodiment, a method comprises controlling the CT system to focus a beam of electrons generated by a cathode of the CT system at a plurality of focal spots on a surface of an target of the CT system; generating a composite focal spot from the plurality of focal spots; and obtaining projection data of the CT system with the composite focal spot. For example, two focal spots may be combined to generate the composite focal spot. By combining focal spots to generate composite focal spots, a quality of a resulting view produced by the CT system may be increased.

Some embodiments include an x-ray source, comprising: an anode; a field emitter configured to generate an electron beam; a first grid configured to control field emission from the field emitter; a second grid disposed between the first grid and the anode; and a middle electrode disposed between the first grid and the anode wherein the second grid is either disposed between the first grid and middle electrode or between the middle electrode and the anode.

Some embodiments include an x-ray source, comprising: an anode; a field emitter configured to generate an electron beam; a first grid configured to control field emission from the field emitter; a second grid disposed between the first grid and the anode; a third grid disposed between the first grid and the anode; and a middle electrode disposed between the first grid and the anode wherein the second grid is either disposed between the first grid and middle electrode or between the middle electrode and the anode; wherein the third grid is a mesh grid.

According to one embodiment, an X-ray CT apparatus includes processing circuitry. The processing circuitry is configured to acquire set tube current waveform, and specify, based on the set tube current waveform, a period of a first tube current and a period of a second tube current lower than the first tube current. The processing circuitry is further configured to determine a waveform of a grid voltage such that a first grid voltage is applied during a period corresponding to the period of the first tube current and a second grid voltage, which is higher than the first grid voltage, is applied during a period corresponding to the period of the second tube current.

An X-ray imaging apparatus and a consumption level estimation method for an X-ray source, which estimate the consumption level of an X-ray source without measuring grid voltage. An X-ray control part includes: a tube current value setting part setting a tube current value supplied to an X-ray source; a tube current value measurement part measuring a cathode current value as the tube current value by a cathode current detector; a time measurement part measuring the time when the tube current value is set by the tube current value setting part and the time when the tube current value measured by the tube current value measurement part reaches the set value; and a consumption level estimation part estimating the consumption level of a cathode in the X-ray source based one the time until the tube current value reaches the set value after the tube current value has been set.

A radiation tube that is used in a radiation source for radiography includes: an electron emitting unit that includes a cathode unit having an emitter electrode which emits electrons and a gate electrode; an anode unit that has an anode surface facing the cathode unit and collides with the electrons to generate radiation; a constant voltage supply unit that supplies a constant driving voltage to the gate electrode; and a vacuum tube that accommodates the constant voltage supply unit, the electron emitting unit, and the anode unit.

Systems and methods for digitally switching x-ray emission systems include a digital switching unit operable to selectively connect a low voltage driving circuit to activate a field emission type electron emitting construct such that electrons are accelerated by a high voltage towards an anode target thereby generating a pulse of x-rays. The x-ray pulses directed towards a scintillator are detected by an optical imager when its shutter is open. Shutter signals and the activation signals may be synchronized to produce required x-ray detection profiles.

An X-ray diagnostic apparatus according to an embodiment includes: an X-ray tube including a target configured to generate X-rays in response to emission of electrons thereto, a plurality of filaments configured to emit electrons into substantially the same position on the target, and a grid used in common among the plurality of filaments; intermediate potential setting circuitry configured to set intermediate potential in a position between the plurality of filaments and the target by using the grid; and filament potential controlling circuitry configured to change one or more filaments selected from among the plurality of filaments to emit the electrons to the target, by controlling potential levels of the plurality of filaments with respect to the intermediate potential for each filament, in conjunction with switching of X-ray tube voltage.

The present disclosure provides a reliable X-ray generating tube that forms a focus with a stable size and shape. The X-ray generating tube includes an electron gun including an electron emitting portion, a plurality of grid electrodes, and an insulating support member that supports the plurality of grid electrodes. The electron gun includes a conductive section that hides the insulating support member to prevent the insulating support member from being directly viewed from an electron through path of electrons emitted from the electron emitting portion and passing through the grid electrodes.

According to one embodiment, an X-ray CT apparatus includes processing circuitry. The processing circuitry is configured to acquire set tube current waveform, and specify, based on the set tube current waveform, a period of a first tube current and a period of a second tube current lower than the first tube current. The processing circuitry is further configured to determine a waveform of a grid voltage such that a first grid voltage is applied during a period corresponding to the period of the first tube current and a second grid voltage, which is higher than the first grid voltage, is applied during a period corresponding to the period of the second tube current.