CT high voltage generator with grid control function

Abstract

The utility model discloses a CT (Computed Tomography) high-voltage generator with a grid control function, which comprises a generator main control board, a grid controller interface board, a G1 high-voltage module, a G2 high-voltage module, a G1 voltage monitoring module and a G2 voltage monitoring module, the grid controller interface board is electrically connected with the G1 high-voltage module, the G2 high-voltage module, the G1 voltage monitoring module and the G2 voltage monitoring module, the G1 module and the G2 module are connected to the cathode of the X-ray tube through high-voltage cables, grid voltage is applied to a grid plate in the bulb tube, and the G1 high-voltage module and the G2 high-voltage module are connected with a grid voltage control circuit, a PWM driving circuit and a boost voltage doubling rectifying circuit; the device is suitable for different types of CT bulb tubes and meets the requirements of various clinical application modes; a hardware circuit is simple, different configuration output of two groups of grid voltages can be realized through one group of circuits, four grid voltage values in one group can correspond to various KV values, focus sizes and focus position combinations, and the control is convenient.

Description

Technical Field

[0001] The utility model relates to the technical field of CT high-voltage generators, in particular to a CT high-voltage generator with a grid control function. Background Art

[0002] The X-ray tube is a key component in the medical CT system, and its function is to generate diagnostic X-rays. The grid-controlled X-ray tube is a new type of CT tube developed in recent years. It adds a grid structure near the cathode filament of the conventional tube. By applying different voltages on the grid, the electron beam bombarding the cathode to the anode target can be deflected or even cut off without stopping the KV voltage at both ends of the tube, thereby controlling the size and position of the tube focus, or quickly interrupting and emitting X-rays. The application of the grid-controlled tube reduces the radiation dose, eliminates the excess radiation caused by the ramping and tailing of pulse fluoroscopy, further shortens the single pulse time, and enables a lower pulse frequency to be achieved, thereby further reducing the radiation of low-frequency moving organ examinations.

[0003] Conventional CT high-voltage generators provide high-voltage power supply, load drive power supply such as anode and filament, and exposure control functions for both ends of the X-ray tube, while the grid-controlled tube also needs a high-voltage generator with a grid modulator, which provides dynamic programmable voltage for the two grid plates of the grid-controlled tube. Its output is a continuous square wave from 0 to 4kHz, the voltage is from 0 to -3kV, the voltage establishment time must be less than 10us, and the voltage switching time is less than 1s. In addition, because the grid modulator is suspended above the cathode high voltage of the tube, it should be able to withstand the energy impact of high voltage or tube ignition without damage, so the technical difficulty is relatively high. At present, mass production of grid-controlled high-voltage generators for CT has not been achieved in China. Utility Model Content

[0004] In view of the deficiencies in the prior art, the purpose of the utility model is to provide a CT high voltage generator with a grid control function.

[0005] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0006] A CT high-voltage generator with a gate control function comprises a generator main control board, a gate controller interface board, a G1 high-voltage module, a G2 high-voltage module, a G1 voltage monitoring module, and a G2 voltage monitoring module. The generator main control board is electrically connected to the gate controller interface board, and the gate controller interface board is electrically connected to the G1 high-voltage module, the G2 high-voltage module, the G1 voltage monitoring module, and the G2 voltage monitoring module. The G1 high-voltage module and the G2 high-voltage module are connected to the cathode of an X-ray tube through a high-voltage cable, and the gate voltage is applied to the gate plate inside the tube. The G1 high-voltage module and the G2 high-voltage module are connected to a gate voltage control circuit, a PWM drive circuit, and a voltage-boosting and voltage-doubling rectifier circuit.

[0007] In the utility model, preferably, the PWM drive circuit includes a controller U2, the input end of the controller U2 is connected in series with pin 1 of an operational amplifier U9A, the 3rd pin of the operational amplifier U9A is connected in series with a resistor R8 and then connected to a V1H signal, the 2nd pin is connected in series with a resistor R26 and then connected to pin 7 of an operational amplifier U9B, the 6th pin of the operational amplifier U9B is connected in series with a resistor R12 and then connected to a V1H-C signal, and the 5th pin of the operational amplifier U9B is grounded.

[0008] In the present invention, preferably, the pin 1 and the pin 2 of the operational amplifier U9A are directly connected in series with the resistor R2, and a series branch of a resistor R25 and a capacitor C14 is also connected in parallel at both ends of the resistor R2.

[0009] In the present invention, preferably, the 11-pin of the controller U2 is connected in series with the resistor R7 and then connected to the gate of the field effect transistor Q1, the source of the field effect transistor Q1 is connected in series with the resistor R22 and then grounded, and at the same time, the resistor R17 is connected in series with the 9-pin of the controller U2, and the drain is connected to the T1B signal.

[0010] In the utility model, preferably, the voltage-boosting rectifier circuit includes a boost transformer T1, and the 2nd and 4th pins of the boost transformer T1 are respectively connected in series with capacitors C1 and C3, a diode D1 is connected in series between capacitors C1 and C3, and then connected in series with resistor R2 to output a V1L signal, capacitor C3 is connected in series with capacitor C4 and resistor R1 to output a V1H signal, and capacitor C1 is also connected in series with diode D2 to access one end of the resistor R1.

[0011] In the present invention, preferably, the gate voltage control circuit includes a driving transformer T5 and a driving transformer T6, the driving transformer T5 includes a secondary winding T5D and a secondary winding T5H, and the driving transformer T6 includes a secondary winding T6D and a secondary winding T6H.

[0012] In the present invention, preferably, one pin of the winding T5D is connected in series with a resistor R27 and then connected to the gate of the field effect transistor Q22, the drain of the field effect transistor Q22 is connected to the V1H signal, and the other pin of the winding T5D is connected to the G1 module.

[0013] In the present invention, preferably, a diode D47 is connected in parallel to both ends of the winding T5D through a resistor R27.

[0014] In the present invention, preferably, one pin of the secondary winding T5D and the secondary winding T5H is connected to the G1 module, and one pin of the secondary winding T6D and the secondary winding T6H is connected to the G2 module.

[0015] In the present invention, preferably, a gate-controlled power supply is also included, and the gate-controlled power supply is electrically connected to the gate controller interface board, the G1 high-voltage module, and the G2 high-voltage module.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] The device of the utility model can adapt to different models of CT tubes and meet the needs of various clinical application modes;

[0018] The hardware circuit is simple and can realize two groups of gate voltage outputs with different configurations through one set of circuits. For various KV values, focal size, and focal position, a set of four gate voltage values ​​can be used to correspond thereto. It is easy to control and can be mass-produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The utility model is a structural block diagram of a CT high voltage generator with a grid control function.

[0020] Figure 2 This is a schematic diagram of the cathode wiring of an X-ray tube.

[0021] Figure 3 This is the PWM drive circuit diagram described in the utility model.

[0022] Figure 4 This is the voltage-boosting and voltage-doubling rectifier circuit diagram described in the utility model.

[0023] Figure 5 This is a gate voltage control circuit diagram described in the utility model. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0027] Please also see Figures 1 to 5 , a preferred embodiment of the utility model provides a CT high-voltage generator with a gate control function, wherein the gate modulator includes GRID1 (G1 high-voltage module) and GRID2 (G2 high-voltage module), and the output voltages of the two modules are quickly switched between a high voltage and a low voltage respectively. The switching timing is controlled by a PWM pulse signal. As shown in Figure 2, the gate modulator is connected to the X-ray tube through the terminal, GRID1 is connected to the grid plate 1 inside the tube, GRID2 is connected to the grid plate 2 inside the tube, and GRID1, GRID2 and the filament are all suspended on the cathode KV. This modulator has a complete protection function. If the control circuit detects a clock loss of more than 80ms, or the deviation between the feedback value of the gate voltage and the set value exceeds 300V and lasts for more than 800ms, the gate control power supply will be turned off and a fault status signal will be given. Specifically, it includes a generator main control board, a grid controller interface board, a G1 high voltage module, a G2 high voltage module, a G1 voltage monitoring module, and a G2 voltage monitoring module. The generator main control board is electrically connected to the grid controller interface board, and the grid controller interface board is electrically connected to the G1 high voltage module, the G2 high voltage module, the G1 voltage monitoring module, and the G2 voltage monitoring module. The G1 module and the G2 module are connected to the cathode of the X-ray tube through a high voltage cable, and the grid voltage is applied to the grid plate inside the tube. The G1 high voltage module and the G2 high voltage module are connected to a grid voltage control circuit, a PWM drive circuit, and a boost and voltage doubler rectifier circuit. The G1 high voltage module and the G2 high voltage module are electrically connected to the grid plate G1 and the grid plate G2, respectively.

[0028] Specifically, it also includes a gate-controlled power supply, which is electrically connected to the gate controller interface board, the G1 high-voltage module, and the G2 high-voltage module. The generator main control board is in communication with the CT system control board. The CT system control board sends two gate voltage setting instructions and a gate voltage switching pulse signal (B_POS) to the generator main control board through the SPI bus and the I / O control line, and the generator main control board feeds back the status signal to the system control board through the SPI bus; the generator main control board then sends the control signal through the bus to the gate controller interface board, and the gate controller interface board sends status signals such as faults and sampling voltages to the generator main control board. The gate controller interface board sends control instructions to the gate-controlled power supply, the G1 high-voltage module, and the G2 high-voltage module through optical fibers; the gate-controlled power supply turns on or off the power supply according to the instructions; the G1 high-voltage module and the G2 high-voltage module turn off or switch the voltage output to the gate according to the instructions. The G1 voltage monitoring module and the G2 voltage monitoring module collect the voltage actually output to the gate through the voltage divider circuit, and then feed it back to the gate controller interface board in the form of an analog signal, and then feed it back to the high-voltage main control board and the system control board in turn through the bus to form a closed loop. The gate voltage switching pulse signal B_POS is a square wave signal with a duty cycle of 50%. When the level is high, the G1 high-voltage module outputs the voltage G1H to the gate plate G1, and the G2 high-voltage module outputs the voltage G2L to the gate plate G2; when the level is low, the G1 high-voltage module outputs the voltage G1L to the gate plate G1, and the G2 high-voltage module outputs the voltage G2H to the gate plate G2, and repeats in sequence until the system control board sends a GRID OFF gate control power shutdown signal.

[0029] Furthermore, a PWM drive circuit is connected between the gate-controlled power supply and the G1 high-voltage module and the G2 high-voltage module. The PWM drive circuit includes a controller U2. The input end of the controller U2 is connected in series with the pin 1 of the operational amplifier U9A. The pin 3 of the operational amplifier U9A is connected in series with a resistor R8 and then connected to the V1H signal. The pin 2 is connected in series with a resistor R26 and then connected to the pin 7 of the operational amplifier U9B. The pin 6 of the operational amplifier U9B is connected in series with a resistor R12 and then connected to the V1H-C signal. The pin 5 of the operational amplifier U9B is grounded. The pins 6 and 7 of the operational amplifier U9B are connected in series with a resistor R9, and capacitor C8 is connected in parallel at both ends of the resistor R9. The pins 1 and 2 of the operational amplifier U9A are directly connected in series with a resistor R2, and a series branch of a resistor R25 and a capacitor C14 is also connected in parallel at both ends of the resistor R2.

[0030] Specifically, the 11th pin of the controller U2 is connected to the gate of the field effect transistor Q1 in series with the resistor R7, the source of the field effect transistor Q1 is connected to the ground in series with the resistor R22, and the 9th pin of the controller U2 is connected to the series resistor R17, and the drain is connected to the T1B signal. The function of the field effect transistor Q1 is to increase the driving capability of the PWM waveform output by U2.

[0031] Specifically, the V1H signal is the analog reference signal output by the DAC circuit on the gate-controlled power supply of the voltage set by the system; V1H-C is the analog sampling signal returned by the gate voltage through the voltage divider circuit; capacitor C8, resistor R9 and op amp U9B form a proportional differential circuit, which is used to shape the V1H-C signal, and the shaped signal is output through pin 7 of op amp U9B. Resistor R2, resistor R25, capacitor C14 and op amp U9A form a bipolar compensation network, and the reference signal V1H is compared with the feedback signal V1H-C through the network. The result is input to the op amp input pin 2 of the PWM controller U2, and its size determines the duty cycle of the output pin 11 of U2, thereby forming a closed-loop control. When the feedback value V1H-C is lower than the reference value V1H, the output of the compensation network increases, the output pulse duty cycle of the controller U2 increases, and the output of the subsequent upgraded voltage doubler circuit also increases until the output gate voltage reaches a steady-state balance with the set value; when the feedback value V1H-C is higher than the reference value V1H, the output of the compensation network decreases, the output pulse duty cycle of the controller U2 decreases, and the output of the subsequent upgraded voltage doubler circuit also decreases until the output gate voltage reaches a steady-state balance with the set value.

[0032] Specifically, the boost voltage doubler rectifier circuit is connected between the PWM drive circuit and the high-voltage module and the G2 high-voltage module. The boost voltage doubler rectifier circuit includes a boost transformer T1. The 2nd and 4th pins of the boost transformer T1 are connected in series with capacitors C1 and C3 respectively. A diode D1 is connected in series between capacitors C1 and C3, and then a resistor R2 is connected in series to output a V1L signal. Capacitor C3 is connected in series with capacitors C4 and resistor R1 to output a V1H signal. Capacitor C1 is also connected in series with a diode D2 to access one end of the resistor R1. The driving waveform output by the controller U2 enters the primary of the transformer T1, and the secondary is connected to the voltage doubler circuit. Capacitors C1, C3, and C4 are high-voltage capacitors, and diodes D1 and D2 are high-voltage diodes, which form a two-stage voltage doubler rectifier circuit. V1H and V1L are two DC outputs, which are applied to the G1 high-voltage module. The same circuit generates V2H and V2L, which are applied to the G2 high-voltage module.

[0033] Furthermore, the gate voltage control circuit is arranged on the G1 high voltage module and in the G2 high voltage module, and a CPLD processor is arranged on the G1 high voltage module and inside the G2 high voltage module, and the gate voltage control circuit is connected to the CPLD processor to control the output voltage of the controller. The gate voltage control circuit specifically includes a drive transformer T5 and a drive transformer T6, the drive transformer T5 includes a secondary winding T5D and a secondary winding T5H, and the drive transformer T6 includes a secondary winding T6D and a secondary winding T6H, and the connection circuit structure of each secondary winding is the same.

[0034] Specifically, one pin of the winding T5D is connected in series with a resistor R27 and then connected to the gate of the field effect transistor Q22, the drain of the field effect transistor Q22 is connected to the V1H signal, and another pin of the winding T5D is connected to the G1 module. Two ends of the winding T5D are connected in parallel with a diode D47 through a resistor R27. One pin of the secondary winding T5D and the secondary winding T5H are connected to the G1 module, and one pin of the secondary winding T6D and the secondary winding T6H are connected to the G2 module.

[0035] Specifically, the pulse control signal B_POS is transmitted to the CPLD processor of the high-voltage module, and the processor outputs four mutually exclusive drive signals T5_A, T5_B, T6_A, and T6_B according to the high and low levels of the pulse control signal. When T5_A is at a high level and T5_B is at a low level, the same-name ends of the two secondary windings T5D and T5H of T5 are at a high level, the field effect transistor Q4 and the field effect transistor Q22 are turned on, the V1H signal is output to the gate plate G1 through the field effect transistor Q22, and the V2L signal is output to the gate plate G2 through the field effect transistor Q4; at this time, the same-name ends of the two secondary windings T6D and T6H of the driving transformer T6 are at a low level, and the field effect transistor Q2 and the field effect transistor Q46 are turned off. On the contrary, when T6_A is high and T6_B is low, the same-name ends of the two secondary windings T6D and T6H of the driving transformer T6 are high, the field effect tubes Q2 and Q46 are turned on, V2H is output to the gate plate G2 through the field effect tube Q2, and the V1L signal is output to the gate plate G1 through the field effect tube Q46; at this time, the same-name ends of the two secondary windings T5D and T5H of the driving transformer T5 are low, and the field effect tubes Q4 and Q22 are turned off. The high and low level switching of the B_POS pulse signal realizes the fast switching of different voltages on the gate plates G1 and G2.

[0036] The above description is a detailed description of the preferred feasible embodiment of the utility model, but the embodiment is not used to limit the scope of the patent application of the utility model. All equivalent changes or modified changes completed under the technical spirit suggested by the utility model should fall within the patent scope covered by the utility model.

Claims

1. A CT high voltage generator with a grid control function, characterized in that: It includes a generator main control board, a grid controller interface board, a G1 high-voltage module, a G2 high-voltage module, a G1 voltage monitoring module, and a G2 voltage monitoring module. The generator main control board is electrically connected to the grid controller interface board, and the grid controller interface board is electrically connected to the G1 high-voltage module, the G2 high-voltage module, the G1 voltage monitoring module, and the G2 voltage monitoring module. The G1 high-voltage module and the G2 high-voltage module are connected to the cathode of the X-ray tube through a high-voltage cable, and the grid voltage is applied to the grid plate inside the tube. The G1 high-voltage module and the G2 high-voltage module are connected to a grid voltage control circuit, a PWM drive circuit, and a boost and voltage doubler rectifier circuit.

2. A CT high voltage generator with a gate control function according to claim 1, characterized in that: The PWM drive circuit includes a controller U2, the input end of the controller U2 is connected in series to pin 1 of an operational amplifier U9A, the 3rd pin of the operational amplifier U9A is connected in series to a resistor R8 and then to a V1H signal, the 2nd pin is connected in series to a resistor R26 and then to pin 7 of an operational amplifier U9B, the 6th pin of the operational amplifier U9B is connected in series to a resistor R12 and then to a V1H-C signal, and the 5th pin of the operational amplifier U9B is grounded.

3. A CT high voltage generator with a gate control function according to claim 2, characterized in that: Pins 1 and 2 of the operational amplifier U9A are directly connected in series with a resistor R2, and a series branch of a resistor R25 and a capacitor C14 is also connected in parallel at both ends of the resistor R2.

4. A CT high voltage generator with a gate control function according to claim 2, characterized in that: Pin 11 of the controller U2 is connected in series with resistor R7 and then connected to the gate of the field effect transistor Q1. The source of the field effect transistor Q1 is connected in series with resistor R22 and then grounded. Meanwhile, resistor R17 is connected in series with pin 9 of the controller U2 and the drain is connected to the T1B signal.

5. A CT high voltage generator with a gate control function according to claim 4, characterized in that: The voltage-boosting rectifier circuit includes a boost transformer T1, and the 2nd and 4th pins of the boost transformer T1 are connected in series with capacitors C1 and C3 respectively. A diode D1 is connected in series between capacitors C1 and C3, and then connected in series with resistor R2 to output a V1L signal. Capacitor C3 is connected in series with capacitor C4 and resistor R1 to output a V1H signal. Capacitor C1 is also connected in series with a diode D2 to access one end of the resistor R1.

6. The CT high voltage generator with a gate control function according to claim 1, characterized in that: The gate voltage control circuit includes a driving transformer T5 and a driving transformer T6. The driving transformer T5 includes a secondary winding T5D and a secondary winding T5H. The driving transformer T6 includes a secondary winding T6D and a secondary winding T6H.

7. A CT high voltage generator with a gate control function according to claim 6, characterized in that: One pin of the winding T5D is connected in series with a resistor R27 and then connected to the gate of the field effect transistor Q22. The drain of the field effect transistor Q22 is connected to the V1H signal. The other pin of the winding T5D is connected to the G1 module.

8. The CT high voltage generator with a gate control function according to claim 6, characterized in that: The two ends of the winding T5D are connected in parallel with a diode D47 via a resistor R27.

9. The CT high voltage generator with a gate control function according to claim 1, characterized in that: A pin of the secondary winding T5D and a pin of the secondary winding T5H are connected to the G1 module, and a pin of the secondary winding T6D and a pin of the secondary winding T6H are connected to the G2 module.

10. The CT high voltage generator with a gate control function according to claim 1, characterized in that: It also includes a gate-controlled power supply, which is electrically connected to the gate controller interface board, the G1 high-voltage module, and the G2 high-voltage module.

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