A tube current adaptive control method based on X-ray tube operating point

Abstract

This invention discloses an adaptive tube current control method based on the operating point of an X-ray tube, relating to the field of medical equipment technology. The invention first obtains the tube current I through a tube current sampling circuit and a tube voltage sampling circuit. a With tube voltage V a‑k The obtained tube voltage V a‑k The obtained tube current I is directly fed into the PID controller. a With preset tube current I ref Simultaneously, the values ​​are fed into an error amplifier for difference calculation, and the result is sent to the PID controller; the filament voltage V is obtained through the filament voltage sampling circuit and the filament current sampling circuit. d and filament current I d ; Filament voltage V d and filament current I d The filament power P is calculated using a multiplier. d , the filament power P d The current is directly fed into the PID controller. This invention results in a short rise time and small overshoot for the tube current waveform, solving the problem of tube current variation caused by tube voltage changes and filament attenuation in traditional X-ray tube current control methods, and ensuring that the rise waveform of the tube current remains consistent under any operating conditions.

Description

Technical Field

[0001] This invention relates to the field of medical equipment technology, and in particular to an adaptive control method for tube current based on the operating point of an X-ray tube. Background Technology

[0002] X-ray tubes are important non-destructive testing devices. In the medical field, X-ray tubes are also commonly used for disease diagnosis and treatment. The tube current of an X-ray tube directly affects the X-ray dose. The dynamic waveform of the tube current is of great significance for medical imaging diagnosis. When an X-ray tube is working, if the rise time of the tube current waveform is slow, it will lead to an increase in the ineffective X-ray dose. If the rise time of the tube current waveform is too fast, the overshoot is large, and overshoot occurs, it will also lead to an increase in the ineffective X-ray dose. Excessive ineffective radiation dose to patients will affect their health.

[0003] During the operation of an X-ray tube, its tube current is mainly affected by two factors: filament heating power and tube voltage. The effect of filament heating power on tube current: Increasing the filament heating power leads to an increase in filament temperature, which in turn increases electron emission, thus increasing the tube current. This is because higher temperatures allow electrons on the filament surface to gain more energy, making it easier for them to escape from the filament surface and form an electron flow. Therefore, increasing the filament heating power can increase the tube current of the X-ray tube. The effect of tube voltage on tube current: Tube voltage determines the electric field strength for electron acceleration, thereby affecting electron energy. When the tube voltage increases, the electric field strength strengthens, and the energy gained by electrons increases, making it easier for electrons to be emitted from the cathode filament and form a current. Therefore, increasing the tube voltage can increase the tube current of the X-ray tube.

[0004] To ensure a short rise time and small overshoot in the X-ray tube current waveform, it is necessary to control the X-ray tube current. The traditional X-ray tube current control method has the following problems: changes in tube voltage affect the electric field strength for electron acceleration, which in turn affects the electron energy and the waveform of the tube current. At the same filament temperature, the decaying filament emits fewer electrons than the initial filament, resulting in the waveform of the tube current after filament decay being inconsistent with the waveform of the tube current corresponding to the initial filament, thus failing to achieve the expected goal.

[0005] To address this, we propose an adaptive control method for tube current based on the operating point of the X-ray tube. Summary of the Invention

[0006] The purpose of this invention is to provide an adaptive control method for tube current based on the operating point of an X-ray tube, which solves the problems of optimal dynamic response and rapid stabilization of X-ray tube current.

[0007] This invention is achieved through the following technical solution:

[0008] This invention relates to an adaptive tube current control method based on the operating point of an X-ray tube, comprising a preset tube current I. ref The tube current adaptive control method based on the X-ray tube operating point includes the following steps: tube current sampling circuit, tube voltage sampling circuit, error amplifier, filament voltage sampling circuit, filament current sampling circuit, multiplier, and PID controller.

[0009] S1: Obtain the tube current I through the tube current sampling circuit and the tube voltage sampling circuit. a With tube voltage V a-k ;

[0010] S2: The obtained tube voltage V a-k The obtained tube current I is directly fed into the PID controller. a With preset tube current I ref At the same time, the result is fed into the error amplifier for difference calculation, and then sent to the PID controller.

[0011] S3: Obtain the filament voltage V through the filament voltage sampling circuit and the filament current sampling circuit. d and filament current I d ;

[0012] S4: Filament voltage V d and filament current I d The filament power P is calculated using a multiplier. d , the filament power P d Directly fed into the PID controller;

[0013] S5: Finally, set the preset tube current I... ref The current is directly fed into the PID controller, which adjusts the filament power supply to form a closed-loop control of the X-ray tube current.

[0014] Preferably, the preset tube current I ref The tube current output curve under ideal X-ray management conditions.

[0015] Preferably, the expression for the PID controller is:

[0016]

[0017] Preferably, in step S5, the filament power supply is adjusted by a PID controller to form a closed-loop control of the X-ray tube current, which makes the rise time of the tube current waveform short and the overshoot small, and ensures that the rise waveform of the tube current remains consistent under any operating condition.

[0018] The present invention has the following beneficial effects:

[0019] This invention discloses an adaptive tube current control method based on the operating point of an X-ray tube, wherein the PID controller incorporates a preset tube current I. ref Filament power P d and tube voltage V a-k In the traditional X-ray tube current control method, the PID controller parameters are fixed. In this invention, the PID controller parameter K... p K i K d Able to determine the preset tube current I ref Filament power P d and tube voltage V a-k The three variables are dynamically adjusted.

[0020] Regardless of how the filament decays or how the tube voltage changes, the PID controller in this invention will make corresponding dynamic adjustments based on these changes, so that the tube current waveform rises rapidly and the overshoot is small, ensuring that the rising waveform of the tube current remains consistent under any operating condition.

[0021] This invention provides an adaptive control method for tube current based on the operating point of an X-ray tube. The tube current rises rapidly and has a small overshoot, which can reduce the ineffective radiation dose received by the patient.

[0022] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a circuit diagram of the tube current adaptive control based on the operating point of the X-ray tube according to the present invention;

[0025] Figure 2 This is a traditional X-ray tube current control circuit diagram;

[0026] Figure 3 This is a flowchart of the tube current adaptive control method based on the operating point of the X-ray tube according to the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Traditional X-ray tube current control methods, such as Figure 2 As shown, it includes an error amplifier, a PID controller, and a preset tube current I. ref and tube current sampling circuit;

[0029] The working principle of traditional X-ray tube current control method: preset tube current I ref The tube current I obtained by the tube current sampling circuit a The difference is calculated by an error amplifier and then fed into a PID controller. The PID controller adjusts the filament power supply to stabilize the tube current. The drawback of this method is that it does not take into account the influence of tube voltage changes and filament decay on the tube current. Different tube voltages correspond to different tube current waveforms, and the tube current waveform after filament decay is also different from the tube current waveform corresponding to the initial filament.

[0030] This invention relates to an adaptive tube current control method based on the operating point of an X-ray tube, comprising a preset tube current I. ref The circuit includes a tube current sampling circuit, a tube voltage sampling circuit, an error amplifier, a filament voltage sampling circuit, a filament current sampling circuit, a multiplier, and a PID controller, wherein the preset tube current I... ref The tube current output curve under ideal X-ray management conditions, such as Figure 1 and Figure 3 As shown;

[0031] The filament voltage V is obtained through the filament voltage and filament current sampling circuit. d and filament current I d Then, the filament power P is calculated using a multiplier. d The obtained filament power P d Directly fed into the PID controller;

[0032] The tube current I is obtained through the tube current sampling circuit and the tube voltage sampling circuit, respectively. a and tube voltage V a-k The tube voltage V a-k The current I is fed into the PID controller and the tube current is... a With preset tube current I ref The difference is calculated by the error amplifier and then fed into the PID controller to set the preset tube current I. ref The data is fed into the PID controller.

[0033] The input variable for the PID controller is the feedback tube current I. a With preset tube current I ref The difference, filament power P d tube voltage V a-k Preset tube current I ref The PID controller output value adjusts the filament power supply to make the tube current waveform rise time short and the overshoot small, and ensures that the tube current rise waveform remains consistent under any operating condition.

[0034] The expression for the PID controller in this invention is:

[0035]

[0036] The characteristic of this PID controller is that the X-ray tube itself operates at the (I) point. ref V a-k P d The PID coefficient is directly determined by the K coefficient, which is determined using a multivariate polynomial regression method. p K i K d The optimal value is obtained, which enables the PID controller to more accurately and quickly achieve a rapid rise in tube current waveform with small overshoot when adjusting the filament power supply, and to ensure that the rise waveform of tube current remains consistent under any operating condition.

[0037] Simulations can be used to obtain the I value of the X-ray tube at 10 different operating points. ref V a-k P d The value, based on I at these 10 different working points ref V a-k P d The value of K can be obtained p、 K i、 K d The value of K can be obtained by using multivariate polynomial regression and the MATLAB curve fitting toolbox. p (I ref V a-k P d )=f1(x,y,z),K i (I ref V a-k P d ) = f2(x, y, z) and K d (I ref V a-k P d The relationship between f3(x, y, z) is used to determine K. p、 Ki、K dThe optimal value is the internal parameter of the PID controller.

[0038] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A tube current adaptive control method based on the operating point of an X-ray tube, characterized in that, Including preset tube current I ref The tube current adaptive control method based on the X-ray tube operating point includes the following steps: tube current sampling circuit, tube voltage sampling circuit, error amplifier, filament voltage sampling circuit, filament current sampling circuit, multiplier, and PID controller. S1: Obtain the tube current I through the tube current sampling circuit and the tube voltage sampling circuit. a With tube voltage V a-k ; S2: The obtained tube voltage V a-k The obtained tube current I is directly fed into the PID controller. a With preset tube current I ref At the same time, the result is fed into the error amplifier for difference calculation, and then sent to the PID controller. S3: Obtain the filament voltage V through the filament voltage sampling circuit and the filament current sampling circuit. d and filament current I d ; S4: Filament voltage V d and filament current I d The filament power P is calculated using a multiplier. d , the filament power P d Directly fed into the PID controller; S5: Finally, set the preset tube current I... ref The current is directly fed into the PID controller, which adjusts the filament power supply to form a closed-loop control of the X-ray tube current.

2. The tube current adaptive control method based on the operating point of an X-ray tube according to claim 1, characterized in that, The preset tube current I ref The tube current output curve under ideal X-ray management conditions.

3. The tube current adaptive control method based on the operating point of an X-ray tube according to claim 1, characterized in that, The expression for the PID controller is:

4. The tube current adaptive control method based on the operating point of an X-ray tube according to claim 1, characterized in that, In S5, the filament power supply is adjusted by a PID controller to form a closed-loop control of the X-ray tube current, which makes the rise time of the tube current waveform short and the overshoot small, and ensures that the rise waveform of the tube current remains consistent under any operating condition.

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