GENERATING X-RAY PULSES DURING X-RAY IMAGING

Abstract

Systems and methods are provided for generating X-ray pulses during X-ray imaging. A high voltage of an X-ray tube is automatically switched off. The tube voltage decays and upon reaching a predefined threshold value of the tube voltage or a predefined waiting time after switching off the high voltage, a grating voltage of a grating arranged between an emitter and an anode of the X-ray tube is automatically switched on. No electrons reach the anode from the emitter, and the tube current drops to the value zero.

Claims

1. A method for generating X-ray pulses during X-ray imaging, the method comprising: automatically switching off a high voltage of an X-ray tube, wherein a tube voltage of the X-ray tube decays; and automatically switching on a grating voltage of a grating arranged between an emitter and an anode of the X-ray tube when a predefined threshold value of the tube voltage or a predefined waiting time after switching off the high voltage is reached, wherein no electrons reach the anode from the emitter, and a tube current of the X-ray tube drops to the value zero.

2. The method of claim 1, further comprising selecting the predefined threshold value and the predefined waiting time so that the emitter is completely separable from the high voltage in terms of time by the grating.

3. The method of claim 2, wherein the predefined threshold value or the waiting time are determined experimentally or computationally.

4. The method of claim 1, wherein the predefined threshold value or the waiting time are determined experimentally or computationally.

5. In a non-transitory computer readable storage medium that stores instructions executable by one or more processors to generate X-ray pulses during X-ray imaging, the instructions comprising: automatically switching off a high voltage of an X-ray tube, wherein a tube voltage of the X-ray tube decays; and automatically switching on a grating voltage of a grating arranged between an emitter and an anode of the X-ray tube when a predefined threshold value of the tube voltage or a predefined waiting time after switching off the high voltage is reached, wherein no electrons reach the anode from the emitter, and a tube current of the X-ray tube drops to the value zero.

6. The non-transitory computer readable storage medium of claim 5, wherein the instructions further comprise selecting the predefined threshold value and the predefined waiting time so that the emitter is completely separable from the high voltage in terms of time by the grating.

7. The non-transitory computer readable storage medium of claim 5, wherein the predefined threshold value or the waiting time are determined experimentally or computationally.

8. The non-transitory computer readable storage medium of claim 6, wherein the predefined threshold value or the waiting time are determined experimentally or computationally.

9. An apparatus for generating X-ray pulses during X-ray imaging, the apparatus comprising: an X-ray tube comprising an emitter and an anode; a high voltage generation unit, the high voltage generation unit configured to build a high voltage between the emitter and the anode; a grating located between the emitter and the anode, the grating configured to block electrons of the emitter from the anode when a grating voltage is applied; a grating voltage generation unit, the grating voltage generation unit configured to build the grating voltage; and a controller configured to automatically switch off the high voltage of the high voltage supply unit and automatically switch on the grating voltage of the grating voltage generation unit when a predefined threshold value of the tube voltage or a predefined waiting time after switching off the high voltage is reached.

10. The apparatus of claim 9, further comprising: a tube voltage measuring unit electrically connected to the controller and configured to calculate the tube voltage of the X-ray tube and transfer the tube voltage to the controller.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0022] FIG. 1 depicts a cross-section of an X-ray tube.

[0023] FIG. 2 depicts a tube voltage characteristic for a primary pulsed X-ray radiation according to an embodiment.

[0024] FIG. 3 depicts a tube voltage characteristic for a secondary pulsed X-ray radiation according to an embodiment.

[0025] FIG. 4 depicts a flow diagram of an embodiment.

[0026] FIG. 5 depicts a tube voltage characteristic according to an embodiment.

[0027] FIG. 6 depicts a block diagram of an apparatus for generating X-ray pulses according to an embodiment.

DETAILED DESCRIPTION

[0028] FIG. 2 depicts exemplary tube voltage U.sub.T in kV as a function of time tin ms for a primary pulsed X-ray radiation in a graph. After the pulse duration PT, the high voltage is switched off, and the tube voltage drops to the value zero after some time.

[0029] FIG. 3 depicts exemplary tube voltage U.sub.T in kV as a function of the time tin ms for a secondary pulsed X-ray radiation in a graph. After the pulse duration PT, a grating voltage is switched on, and tube current I.sub.T immediately drops to the value zero, since no further electrons may now reach the anode from the emitter. The drop only happens, however, if the tube current or the tube voltage U.sub.T is not too great, as only then is the grating fully effective and all electrons may be blocked. The X-ray pulse is cut off cleanly, as depicted in FIG. 3.

[0030] FIG. 4 depicts a flow diagram of one embodiment of a method for generating an X-ray pulse during X-ray imaging. In act 101, the high voltage of the X-ray tube is switched on. In act 102, the high voltage is switched off after the pulse duration PT has expired. Once the tube voltage U.sub.T has reached the threshold value TH, the grating is activated in act 103. The tube current I.sub.T drops to the value zero. After a pause, in act 104 the grating 8 is deactivated, and the method jumps again to act 101.

[0031] The method results in a graph according to FIG. 5. The tube current I.sub.T in A is depicted as a function of the time tin ms. The high voltage is switched off after the pulse duration PT and, when the tube voltage U.sub.T has reached the threshold value TH, the grating is activated by switching on the grating voltage and the tube current I.sub.T drops to the value zero. The resulting pulse duration is therefore composed of the pulse duration PT and the waiting time WT. Only high-energy quanta are generated, although the quanta also travel with large tube currents.

[0032] FIG. 6 depicts a block diagram of an apparatus for generating an X-ray pulse during X-ray imaging. The emitter 2 of an X-ray tube 14 is made to anneal with a heating voltage generation unit 13. The high voltage of the high voltage generation unit 9 is applied between the emitter 2 and the anode 4. The grating 8 is powered by the grating voltage generation unit 10. With the aid of the tube voltage measuring unit 12, the tube voltage U.sub.T may be measured. The aforementioned components are controlled by a control unit 11 (e.g., a controller).

[0033] The current tube voltage U.sub.T is supplied to the control unit 11 by the tube voltage measuring unit 12. When the previously calculated threshold value TH of the tube voltage U.sub.T is reached, the grating 8 is activated via the control unit 11. Alternatively, after a previously calculated waiting time WT, the grating 8 may be activated. The tube current no longer flows. The X-ray pulse is cut off cleanly. Subsequently, the grating 8 is deactivated, and the high voltage is switched on again.

[0034] It is to be understood that the elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent, and that such new combinations are to be understood as forming a part of the present specification.

[0035] While the present invention has been described above by reference to various embodiments, it may be understood that many changes and modifications may be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.