X-ray machine exposure dose control method and electronic device

Abstract

The application belongs to the technical field of X-ray machines, and discloses an X-ray machine exposure dose control method and an electronic device. In the Nth frame of exposure, after X-rays are emitted, a MA feedback value is detected and compared with a MA value issued by a workstation; if the MA error value is less than or equal to 0.1 times the MA value issued by the workstation, no MA calibration is performed; if the MA error value is greater than 0.1 times the MA value issued by the workstation and less than 0.3 times the MA value issued by the workstation, the MA is corrected by using an integral separation PID control algorithm; if the MA error value is greater than or equal to 0.3 times the MA value issued by the workstation, an alarm is issued; if the Nth frame of exposure ends and the MA value correction by the integral separation PID control algorithm is not completed, exposure is performed once with a set time increased, so that the MA value correction by the integral separation PID control algorithm is completed. The integral separation PID control algorithm is used to adjust the MA value of the X-ray machine, so that the problem of excessive MA adjustment and excessive dose radiation caused by the PID control is avoided.

Description

Technical Field

[0001] This invention relates to the field of X-ray machine technology, and more specifically, to an X-ray machine exposure dose control method and electronic device. Background Technology

[0002] X-ray machines have become an indispensable clinical medical device in modern hospital operating rooms. In current X-ray machine systems, the frame is usually a C-arm or G-arm, on which X-ray transmitters and image receivers are installed to provide fluoroscopic imaging of patients.

[0003] X-ray machine C-arm or G-arm systems have very high requirements for the accuracy of exposure dosage. This not only affects image quality, but excessive exposure dosage can also be very harmful to doctors and patients. Generally, X-ray machines undergo a dosage calibration during factory testing. However, over long-term use, the performance of the X-ray source and the system's control circuitry can vary, especially with frequent exposures, leading to significant deviations in the X-ray machine's exposure dosage. Furthermore, each dosage calibration takes a considerable amount of time, making it impractical to perform calibration at the start of every surgery.

[0004] During exposure, the dose is related to tube voltage (KV) and tube current (MA). The tube voltage, a parameter of the X-ray machine, is generated by a high-voltage generator in the machine frame. The high-voltage output of the generator maintains a strictly linear relationship with the low-voltage input. As long as the low-voltage input of the high-voltage generator is kept stable and accurate, the KV of the generator can be stably controlled and will not change with time or the number of exposures. However, MA is a non-linear relationship; it can deviate unpredictably with time, oil temperature, and the number of exposures. Ensuring the accuracy of the exposure dose requires ensuring the accuracy of MA for each exposure. Currently, MA control typically uses PID regulation, but overshoot during the regulation process generates excess X-ray radiation, increasing the radiation exposure time for doctors and patients. Summary of the Invention

[0005] To address the above problems, the X-ray machine exposure dose control method of this application includes:

[0006] In the Nth frame of exposure, after the X-ray is emitted, the MA feedback value is detected and compared with the MA value sent by the workstation to obtain the MA error value, where N is greater than or equal to 1.

[0007] If the MA error value is less than or equal to 0.1 times the MA value sent by the workstation, no MA calibration will be performed; if the MA error value is greater than 0.1 times the MA value sent by the workstation but less than 0.3 times the MA value sent by the workstation, the integral separation PID control algorithm will be used to correct the MA; if the MA error value is greater than or equal to 0.3 times the MA value sent by the workstation, an alarm message will be sent to the workstation.

[0008] If the exposure of the Nth frame ends and the integral separation PID control algorithm has not completed the MA value correction, then the exposure is increased once by a set time so that the integral separation PID control algorithm can complete the MA value correction.

[0009] Optionally, in the integral separation PID control algorithm,

[0010] The threshold is set to 0.15 times the MA value issued by the workstation. When the MA error value is greater than the threshold, PD control is used; when the MA error value is less than or equal to the threshold, PID control is used.

[0011] Optionally, the formula for the integral separation PID control algorithm is expressed as follows:

[0012]

[0013] In the formula, error(k) is the current MA error value;

[0014] j is the number of integrations, and error(j) is the MA error value of the j-th integration.

[0015] k i The integral coefficient;

[0016] k d These are differential coefficients.

[0017] u(k) is the adjusted MA error value; T is the sampling time, which can be 20us; β is the switching coefficient of the integral term. When |error(k)|≤ threshold, β=1; when |error(k)|> threshold, β=0.

[0018] kp is the proportional coefficient; ki is the integral coefficient; kd is the differential coefficient.

[0019] Optionally, the Nth frame is the 1st frame.

[0020] Optionally, the step of detecting the MA feedback value after the X-ray is emitted and comparing it with the MA value sent by the workstation means detecting the MA feedback value and comparing it with the MA value sent by the workstation 1ms after the X-ray is emitted.

[0021] Optionally, the set time is 3ms.

[0022] This application also discloses an electronic device, including a processor and a memory connected thereto, wherein the memory stores an X-ray machine exposure dose control program, and when the processor runs the X-ray machine exposure dose control program, it executes the X-ray machine exposure dose control method described above.

[0023] This application uses an integral separation PID control algorithm to adjust the MA value of the X-ray machine, which can avoid the problem of excessive MA adjustment and unnecessary dose radiation caused by using PID control. Furthermore, if the PID adjustment to correct MA is not completed after the first frame of exposure ends, the accuracy of integral separation PID adjustment can be increased by adding a short exposure pulse. Attached Figure Description

[0024] Figure 1 Current connection diagram for MA calibration of X-ray machine;

[0025] Figure 2 This is a flowchart of the X-ray machine exposure dose control method according to an embodiment of the present invention;

[0026] Figure 3 This is a flowchart of the integral separation PID control algorithm according to an embodiment of the present invention;

[0027] Figure 4 This is an exposure timing diagram for exposure dose adjustment in an embodiment of the present invention;

[0028] Figure 5 This is a simulation waveform diagram of the MA feedback value in an embodiment of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0030] DA: The digital-to-analog conversion value output by the workstation controlling the high-voltage generator;

[0031] PID: Proportional, Integral, and Derivative control method;

[0032] PD: Proportional and derivative control method.

[0033] The X-ray machine exposure dose control method in this embodiment, such as Figure 2 As shown, it includes the following steps:

[0034] Step S1: In the first frame of the exposure, 1ms after the X-ray is emitted, the MA feedback value is detected and compared with the MA value sent by the workstation to obtain the MA error value, where, for example... Figure 1 As shown, the DA output generates filament current through the filament board. This filament current is converted into tube current (i.e., the MA value sent by the workstation) under the KV voltage of the high-voltage generator tube. This tube current flows through the sampling resistor and is input to the filament board along with the DA output. The MA feedback value is the measured MA value of the sampling resistor.

[0035] Step S2: If the MA error value is within 0.1 times the workstation's transmitted MA value, the MA value is correct and valid, and MA calibration is not required. If the MA error value is greater than 0.1 times the workstation's transmitted MA value but less than 0.3 times, an integral separation PID control algorithm is used to correct the MA until the MA error value is within 0.1 times the workstation's transmitted MA value. If the MA error value is greater than 0.3 times the workstation's transmitted MA value, an alarm message is sent to the workstation, indicating an exposure anomaly, requiring recalibration of all dose data.

[0036] Among them, such as Figure 3 As shown, in the integral separation PID control algorithm, the threshold value is set to 0.15 times the MA value sent by the workstation. When the error between the MA value sent by the workstation and the MA feedback value is greater than the threshold, PD control is used to avoid excessive adjustment of MA and generating unnecessary dose radiation. When the error between the MA value sent by the workstation and the MA feedback value is less than or equal to the threshold, PID control is used to ensure the accuracy of MA adjustment.

[0037] The integral separation PID control algorithm can be expressed as:

[0038]

[0039] In the formula, error(k) is the current MA error value;

[0040] j is the number of integrations, and error(j) is the MA error value of the j-th integration.

[0041] k i The integral coefficient;

[0042] k d These are the differential coefficients.

[0043] In the formula, u(k) is the adjusted MA error value; T is the sampling time, which can be 20us; β is the switching coefficient of the integral term. When |error(k)|≤ threshold, β=1; when |error(k)|> threshold, β=0.

[0044] kp is the proportional coefficient, which is set to 0.8 during the process; k i The integral coefficient is set to 0.15 during the process; k d This is the differential coefficient, which is set to 1.15 during the process.

[0045] Table 1. Error after adjustment of integral separation PID control algorithm

[0046]

[0047]

[0048] Step S3: If the first frame exposure ends before the PID adjustment correction MA is completed, the exposure is increased once for a set short time, such as 3ms, to ensure the accuracy of the PID algorithm's MA correction. Completing the MA adjustment correction can mean that the MA error value is adjusted to be less than or equal to 0.1 times the MA value sent by the workstation.

[0049] After analyzing and summarizing patterns from multiple experiments, it was found that when MA is relatively small, although the integral separation PID adjustment of MA takes a relatively long time, based on experience, data below 1MA results in significant system noise during high-KV exposure, leading to a longer adjustment time. Therefore, as mentioned above, if the PID adjustment to correct MA is not completed during the first frame of exposure, due to system noise, a short exposure pulse (approximately 1ms) is added to the X-ray to increase the accuracy of the integral separation PID adjustment. However, because the MA value is very small, the exposure time is very short, and the exposure dose is also relatively small. When MA is relatively large, because the PID adjustment time is shorter, it can be completed within the first frame of X-ray exposure time, finding a suitable MA value (the minimum X-ray excitation time per frame for the G-arm is 10ms). Therefore, the PID adjustment of MA can be completed within the exposure time.

[0050] Figure 4 This is an X-ray exposure timing diagram. (For example...) Figure 4 As shown, the solid line represents the exposure timing waveform of a normal X-ray exposure. If the integral separation adjustment is not completed after the first exposure, a short exposure is added before the next frame exposure, as shown below. Figure 4 As shown by the dashed line.

[0051] like Figure 5 The image shows the waveform of the MA feedback value. The horizontal axis represents time in milliseconds (ms), and the vertical axis represents the MA feedback value. When the workstation sends 1 MA, the MA feedback value is 0.7 MA (below 1 MA, the PID adjustment time is long). Through the integral separation PID control algorithm, the MA value stabilizes in about 7 ms, which meets the error requirement (MA error value is within 0.1 times the MA value sent by the workstation). The theory and practice are consistent.

[0052] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications are all within the protection scope of the claims of the present invention.

Claims

1. A method for controlling the exposure dose of an X-ray machine, characterized in that, include: In the Nth frame of exposure, after the X-ray is emitted, the MA feedback value is detected and compared with the MA value sent by the workstation to obtain the MA error value, where N is greater than or equal to 1. If the MA error value is less than or equal to 0.1 times the MA value issued by the workstation, then MA calibration will not be performed; If the MA error value is greater than 0.1 times the MA value sent by the workstation but less than 0.3 times the MA value sent by the workstation, the integral separation PID control algorithm is used to correct the MA. If the MA error value is greater than or equal to 0.3 times the MA value sent by the workstation, an alarm message is sent to the workstation. If the exposure of the Nth frame ends and the integral separation PID control algorithm has not completed the MA value correction, then the exposure is increased once by a set time so that the integral separation PID control algorithm can complete the MA value correction.

2. The X-ray machine exposure dose control method according to claim 1, characterized in that, In the integral separation PID control algorithm described above The threshold is set to 0.15 times the MA value issued by the workstation. When the MA error value is greater than the threshold, PD control is used; when the MA error value is less than or equal to the threshold, PID control is used.

3. The X-ray machine exposure dose control method according to claim 2, characterized in that, The formula for the integral separation PID control algorithm is expressed as follows: In the formula, error(k) is the current MA error value; j is the number of integrations, and error(j) is the MA error value of the j-th integration. k i The integral coefficient; k d These are differential coefficients. u(k) is the adjusted MA error value; T is the sampling time. The term is the switching coefficient of the integral term, when |error(k)| ≤ threshold. 1; When |error(k)| > threshold, 0; kp is the proportional coefficient; ki is the integral coefficient; kd is the differential coefficient.

4. The X-ray machine exposure dose control method according to claim 1, characterized in that, The Nth frame is the 1st frame.

5. The X-ray machine exposure dose control method according to claim 1, characterized in that, The description of detecting the MA feedback value after the X-ray is emitted and comparing it with the MA value sent by the workstation refers to detecting the MA feedback value 1ms after the X-ray is emitted and comparing it with the MA value sent by the workstation.

6. The X-ray machine exposure dose control method according to claim 1, characterized in that, The set time is 3ms.

7. An electronic device, characterized in that, The device includes a processor and a memory connected thereto, the memory storing an X-ray machine exposure dose control program. When the processor runs the X-ray machine exposure dose control program, it executes the X-ray machine exposure dose control method according to any one of claims 1 to 6.

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