Patent Application
20180027641
The present application is related generally to x-ray sources.
An x-ray source can include an x-ray tube and a power supply. Analog signals can control the x-ray tube. The analog signals can include a pair of voltages, one of which controls a voltage differential across the x-ray tube and the other of which controls an electrical current flow through an electron emitter (e.g. filament).
The x-ray source can be supplied by an x-ray source manufacturer. A user of the x-ray source, or a subsequent manufacturer who incorporates the x-ray source into another device, can supply the analog signals. The analog signals can be transferred to the x-ray source by a cable, typically with a length of many centimeters.
There are problems of the above configuration. For example, the user or subsequent manufacturer may have difficulty providing proper analog input, due to the need for additional equipment to develop the analog signals. Also, due to variation in manufacture of the x-ray tube, the same analog signals can result in variation in x-ray tube output. Another problem is electronic noise resulting from transfer of the voltages of the analog signals across the cable.
It has been recognized that it would be advantageous to make operation of an x-ray source easier for the user, avoid or minimize problems in x-ray source operation due to variation between manufactured x-ray tubes, and reduce electronic noise associated with control of an x-ray source. The present invention is directed to various embodiments of a power supply for an x-ray tube that satisfy these needs. Each embodiment may satisfy one, some, or all of these needs.
The power supply for the x-ray tube can comprise a digital controller, a first digital-to-analog converter (first DAC), a second digital-to-analog converter (second DAC), and an x-ray tube control circuit. The digital controller can emit a first digital signal to indicate a desired x-ray tube voltage and a second digital signal to indicate a desired x-ray tube electrical current for an electron emitter. The first DAC can be electrically-coupled to the digital controller, can receive the first digital signal, and can emit a voltage corresponding to the first digital signal, defining a first analog signal. The second DAC can be electrically-coupled to the digital controller, can receive the second digital signal, and can emit a voltage corresponding to the second digital signal, defining a second analog signal. The x-ray tube control circuit can be electrically-coupled to the first DAC, can receive the first analog signal, and can provide a voltage differential to the x-ray tube based on the first analog signal. The x-ray tube control circuit can also be electrically-coupled to the second DAC can receive the second analog signal, and can provide an electrical current to the electron emitter based on the second analog signal.
In one embodiment, there can be a relatively short linear-distance between an output of the first DAC and an input of the x-ray tube control circuit for the first DAC and between an output of the second DAC and an input of the x-ray tube control circuit for the second DAC.
In another embodiment, the power supply can include an electronic circuit consisting of a single circuit board with associated electronic components mounted thereon or multiple circuit boards rigidly-mounted together with associated electronic components mounted thereon. The electronic components on the circuit board (or these multiple circuit boards rigidly-mounted together) can comprise the digital controller, the first DAC, the second DAC, and the x-ray tube control circuit.
In another embodiment, the digital controller, the first DAC, the second DAC, and the x-ray tube control circuit can be rigidly-mounted within a housing.
As illustrated in
The x-ray tube 16 can include a cathode 16c that is electrically-insulated from an anode 16a, such as by an electrically-insulative enclosure 16e (e.g. ceramic or glass). The cathode 16c can include an electron emitter 16f (e.g.
filament) capable of emitting electrons to the anode 16a. The anode 16a can include a target material capable of emission of x-rays in response to impinging electrons from the electron emitter 16f.
The x-ray tube 16 can include a window 16w for transmission of the x-rays outside of the x-ray tube 16. A transmission-target x-ray tube 16 is shown in the figures. The invention is also applicable to a side-window x-ray tube. The x-ray window 16 can include some or all of the properties (e.g. low deflection, high x-ray transmissivity, low visible and infrared light transmissivity) of the x-ray window described in U.S. Patent Publication Number 2015/0303024, which is incorporated herein by reference in its entirety.
The power supply 10 can include a digital controller 12, a first digital-to-analog converter, defining a first DAC 17a, a second digital-to-analog converter, defining a second DAC 17b, and an x-ray tube control circuit 13. The digital controller 12 can emit a first digital signal 14a to indicate a desired x-ray tube 16 voltage and a second digital signal 14b to indicate a desired x-ray tube 16 electrical current for the electron emitter 16f. The first DAC 17, can be electrically-coupled to the digital controller 12, can receive the first digital signal 14a, and can emit a voltage corresponding to the first digital signal 14a, defining a first analog signal 15a. The second DAC 17b can be electrically-coupled to the digital controller 12, can receive the second digital signal 14b, and can emit a voltage corresponding to the second digital signal 14b, defining a second analog signal 15b.
The x-ray tube control circuit 13 can be electrically-coupled to the first DAC 17a, can receive the first analog signal 15a, and can provide a voltage differential to the x-ray tube 16 (e.g. between the cathode 16c and the anode 16a) based on the first analog signal 15a. This voltage differential can be large enough to be a cause of electron emission from the electron emitter 16f to the anode 16a. Examples of the magnitude of this voltage differential include >1 kV in one aspect, >4 kV in another aspect, or >9 kV in another aspect. For example, a portion of the x-ray tube control circuit 13 that can receive the first analog signal 15a and can provide the voltage differential can be a high-voltage generator 13a, such as a Cockcroft-Walton generator or multiplier.
The x-ray tube control circuit 13 can also be electrically-coupled to the second DAC 17b, can receive the second analog signal 15b, and can provide an electrical current to the electron emitter 16f based on the second analog signal 15b. For example, a portion of the x-ray tube control circuit 13 that can receive the second analog signal 15b and can provide the electrical current to the electron emitter 16f can be an electrical current source 13b, typically be an alternating current source.
Actual voltage and electrical current provided to the x-ray tube 16 can vary from desired, so feedback to the digital controller 12 can allow the digital controller 12 to adjust the first digital signal 14a and the second digital signal 14b so that actual voltage and electrical current can equal, or at least be closer to, desired voltage and electrical current. To accomplish this objective, the power supply 10 can further comprise a first analog-to-digital converter, defining a first ADC 18a, to provide feedback to the digital controller 12 of actual x-ray tube 16 voltage, and a second analog-to-digital converter, defining a second ADC 18b to provide feedback to the digital controller 12 of actual electrical current through the electron emitter 16f.
The first ADC 18a can be electrically-coupled to the x-ray tube control circuit 13 and to the digital controller 12. The first ADC 18a can convert an analog signal received from the x-ray tube control circuit 13, defining a third analog signal 15c, into a digital signal, defining a third digital signal 14c. The third analog signal 15c and the third digital signal 14c can provide feedback to the digital controller 12 of actual x-ray tube 16 voltage. The digital controller 12 can then adjust the first digital signal 14a based on the third digital signal 14c received from the first ADC 18a.
The second ADC 18b can be electrically-coupled to the x-ray tube control circuit 13 and to the digital controller 12. The second ADC 18b can convert an analog signal received from the x-ray tube control circuit 13, defining a fourth analog signal 15d, into, a digital signal, defining a fourth digital signal 14d. The fourth analog signal 15d and the fourth digital signal 14d can provide feedback to the digital controller 12 of actual electrical current through the electron emitter 16f. The digital controller 12 can then adjust the second digital signal 14b based on the fourth digital signal 14d received from the second ADC 18b.
Some or all of the following electronic components of the power supply 10 can be part of an electronic circuit mounted on a single circuit board with associated electronic components mounted thereon or multiple circuit boards rigidly-mounted together: the digital controller 12, the first DAC 17a, the second DAC 17b, the x-ray tube control circuit 13, the first ADC 18a, and the second ADC 18b. Placing these electronic components on a single circuit board with associated electronic components mounted thereon or multiple circuit boards rigidly-mounted together can allow them to be located in close proximity to each other, reducing electronic noise that otherwise could result from transferring electricity across larger distances.
Some or all of these components of the power supply 10 (the digital controller 12, the first DAC 17a, the second DAC 17b, the x-ray tube control circuit 13, the first ADC 18a, and the second ADC 18b) can be rigidly-mounted within a housing 21. The housing 21 can be a single housing. The housing 21 can be relatively small. For example, the housing 21 can have an internal volume of less than 100 cm3 in one aspect, less than 1000 cm3 in another aspect, less than 5000 cm3 in another aspect, less than 10,000 cm3 in another aspect, or less than 30,000 cm3 in another aspect. The housing 21 can be electrically-conductive and can be metallic, to allow transfer of electric charges to ground, for heat transfer, and to shield the electronic components therein. Placing these electronic components in a single housing 21 can allow them to be located in close proximity to each other, reducing electronic noise that otherwise could result from transferring electricity across larger distances.
As shown in
Operation of the x-ray sources described herein can be relatively easier for the user. The x-ray source manufacturer can make the x-ray tube 16 and power supply 10, capable of electrically-coupling to a user digital circuit 11 and receiving digital signals 19 of user-desired x-ray tube 16 voltage and x-ray tube 16 electrical current from the user digital circuit 11. The digital controller 12 can then emit the first digital signal 14a and the second digital signal 14b based on these digital signals 19 from the user. The user thus does not need to provide analog signals. Also, the user does not need to be concerned with variation between x-ray tubes. The x-ray source manufacturer can calibrate each x-ray tube 16 to its power supply 10.
Another benefit of the x-ray sources described herein is the ability for the x-ray source manufacturer to record and use certain information to improve the x-ray sources. For example, the digital controller 12 can record and export duration of x-ray tube 16 operation, number of times the x-ray tube 16 has been energized, faults, or combinations thereof. Such export can be digital signal(s) to the user digital circuit 11.
This application claims priority to U.S. Provisional Patent Application No. 62/364,659, filed on Jul. 20, 2016, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62364659 | Jul 2016 | US |
