A computer tomograph (1) for X-ray imaging includes a rotationally fixed gantry (2) that is displaceable at most in the axial direction (z). A plurality of X-ray emitters (3) and X-ray detectors (4) is arranged in the gantry (2) in a fixed manner about a central geometrical axis (z), in each case opposite to one another and offset with respect to each other in the direction of the central axis (z). The X-ray emitters (3) have cathodes (5) as electron emitters, which are separately connected to emitter controls (25) and cooperate with a common extraction grid (26) connected upstream of at least one focusing electrode (27). In comparison to conventional computer tomographs having rotating or rigidly arranged technical X-ray components, the computer tomograph (1) has a light and compact design.

A device and method for creating controlled radio frequency (RF) modulated X-ray radiation is described. The device includes an anode housed within a vacuum enclosure which acts to accelerate and convert an electron beam into X-ray radiation. A RF enclosure is housed within the vacuum enclosure and houses a field emission device, such as a carbon nanotube field emission device or similar cold cathode field emission device. The field emission device is biased to emit the electron beam from a field emission cathode via an extraction electrode in the RF enclosure towards the anode. Additionally an RF impedance matching and coupling circuit is connected electrically to the field emission device. The field emission device is thus directly driven with a RF signal to produce an RF modulated electron current to produce an RF modulated X-ray radiation.

Disclosed herein is an X-ray source, comprising: a cathode in a recess of a first substrate; a counter electrode on a sidewall of the recess, configured to cause field emission of electrons from the cathode; and a metal anode configured to receive the electrons emitted from the cathode and to emit X-ray from impact by the electrons on the metal anode.

The X-ray imager combines a pulsed X-ray source with a time-sensitive X-ray detector to provide a measure of ballistic photons with a reduction of scattered photons. The imager can provide a comparable contrast-to-noise X-ray image using significantly less radiation exposure than conventional X-ray imagers, notably about half of the radiation.

An emitter (3) and a target (7) are arranged so as to face each other in a vacuum chamber (1), and a guard electrode (5) is provided at an outer circumferential side of an electron generating portion (31) of the emitter (3). The emitter (3) is supported movably in both end directions of the vacuum chamber (1) by the emitter supporting unit (4) having a movable body (40). The emitter supporting unit (4) is operated by an operating unit (6) connected to the emitter supporting unit (4). By operating the emitter supporting unit (4) by the operating unit (6), a distance between the electron generating portion (31) of the emitter (3) and the target (7) is changed, and a position of the emitter (3) is fixed at an arbitrary distance, then field emission is performed with the position of the emitter (3) fixed.

A device for generating a source current of charge carriers and a method for stabilizing a source current of charge carriers are disclosed. In an embodiment the device includes at least one field emission element configured to emit charge carriers, which lead to an emission current in the field emission element, at least one extraction electrode configured to apply an extraction voltage in order to extract the charge carriers from the field emission element, wherein a first part of the extracted charge carriers contributes to the source current, and a second part of the extracted charge carriers impinges on the extraction electrode and leads to an extraction current in the extraction electrode and a control device configured to reduce fluctuations of a controlled variable Q which is a characteristic for the source current, wherein Q is a function of a difference between the emission current and the extraction current.

A cylindrical X-ray tube having an outer insulating layer, a cathode electrode and an anode electrode disposed at both ends of the outer insulating layer, a gate electrode disposed between the cathode and anode electrodes, an emitter, and a target, comprises an inner insulating layer which is disposed between the cathode electrode and the outer insulating layer, is formed to extend downward in a coaxial direction with the outer insulating layer, and is pre-adjusted in order to secure an insulating distance between the cathode electrode and the gate electrode. Thus, by providing a separate internal insulating layer extending coaxially with the external insulating layer between the cathode electrode and the external insulating layer, the insulating distance between the cathode electrode and the gate electrode, the insulating distance between the cathode electrode and the anode electrode may be easily adjusted, so that a desired insulating capability can be secured.

A target assembly for an x-ray emission apparatus, the apparatus assembly including: a vacuum chamber having at least one conductive wall; an insulating element projecting through the conductive wall; a conductive high voltage element extending along the insulating element from outside the chamber to an end portion of the insulating element furthest from the conductive wall; an x-ray-generating target arranged at the end portion of the insulating element and electrically connected to the high voltage element; and a suppressive electrode arranged at the end portion of the insulating element and configured to suppress acceleration toward the outer surface of the insulating element of electrons which are emitted from a junction between the outer surface of the insulating element and an inner surface of the conductive wall.

A radiation source of a mammography apparatus includes plural first radiation tubes and one second radiation tube. The first radiation tubes are used for tomosynthesis imaging. In contrast, the second radiation tube is used for pre-imaging which is performed before the tomosynthesis imaging in order to set the irradiation conditions of radiation in the tomosynthesis imaging. The first radiation tubes are provided at plural positions where the focuses of the radiation are set so as to be arranged in a linear shape or an arc shape at equal intervals. The second radiation tube is provided at a position that is offset from the plural positions where the first radiation tubes are provided to a rear side which is a side opposite to the irradiation side of the radiation.

Emitter (3) and target (7) are arranged so as to face each other in vacuum chamber (1), and guard electrode (5) is provided at outer circumferential side of electron generating portion (31) of emitter (3). Guard electrode (5) is supported movably in directions of both ends of vacuum chamber (1) by guard electrode supporting unit (6). To perform regeneration process of guard electrode (5), guard electrode (5) is moved to opening (22) side (to separate position) by operating guard electrode supporting unit (6), and a state in which field emission of electron generating portion (31) is suppressed is set, then by applying voltage across guard electrode (5), discharge is repeated. After performing regeneration process, by operating guard electrode supporting unit (6) again, guard electrode (5) is moved to opening (21) side (to emitter position), and a state in which field emission of electron generating portion (31) is possible is set.