A method and system for controlling the filament current of a CT device

Abstract

The present invention provides a filament current control method and system for a CT device. The filament current control method includes the following steps: The host computer sends exposure parameters to the high-voltage control system; The high-voltage control system sends the exposure parameters to the high-voltage generator; An FPGA chip in the high-voltage control system is preset with a filament current threshold value, and the real-time filament current and real-time tube current are read in real time; When the FPGA chip detects that the real-time filament current reaches the filament current threshold value, the PWM control strategy is started, and a filament current control value is output to the high-voltage controller, so that the real-time filament current and real-time tube current decrease and then rise within the control period; The above steps are repeatedly executed until the real-time tube current stabilizes at the desired tube current, and the value of the decreased real-time filament current controlled by the PWM control strategy at this time is recorded as the stable filament current; Exit the PWM control strategy. After adopting the above technical solution, exposure can still be completed even under the condition of filament current error reporting.

Description

Technical Field

[0001] The present invention relates to the field of medical equipment, and in particular to a method and system for controlling the filament current of a CT device. Background Art

[0002] Currently, in a CT device, the high voltage and the tube exposure are basically matched, that is, the magnitude of the applied voltage is closely related to the exposure parameters. However, when a new exposure sequence appears, under certain special conditions, the exposure may fail. The reason is that the PID algorithm inside the high voltage controller maintains the filament current at the maximum filament current, resulting in a fault in the internal logic judgment of the high voltage and a failure of the high voltage exposure. In other words, since the high voltage internally judges overcurrent based on the fact that the filament current reaches the maximum value and continues continuously for 10 ms, when such conditions are reached, the high voltage reports an error.

[0003] Therefore, in the existing solutions, in order to solve the above problems, only the magnitude of the filament current can be continuously adjusted, and basically, it is impossible to avoid high voltage error reporting during actual use, and the problem still cannot be completely solved.

[0004] Therefore, a new method and system for controlling the filament current of a CT device are needed, so that the filament does not operate at the maximum current for a long time. Summary of the Invention

[0005] In order to overcome the above technical defects, the purpose of the present invention is to provide a method and system for controlling the filament current of a CT device, which can still complete the exposure even under the condition of filament current error reporting.

[0006] The present invention discloses a method for controlling the filament current of a CT device, including the following steps:

[0007] An upper computer connected to the high voltage control system of the CT device issues exposure parameters to the high voltage control system, where the exposure parameters at least include a preset filament current and an expected tube current;

[0008] The high voltage control system issues the exposure parameters to the high voltage generator and preheats the filament current to the preset filament current;

[0009] After the high voltage control system turns on the exposure signal to the high voltage generator, an FPGA chip in the high voltage control system presets a filament current threshold value, and reads the real-time filament current and the real-time tube current;

[0010] When the FPGA chip detects that the real-time filament current reaches the filament current threshold value, the FPGA chip starts a PWM control strategy to output a filament current control value to the high voltage controller, so that the real-time filament current and the real-time tube current decrease and then rise within a control period, where the filament current control value is less than the filament current threshold value;

[0011] Repeat the above steps until the real-time tube current stabilizes at the desired tube current, and record the value of the decreased real-time filament current after being controlled by the PWM control strategy at this time as the stable filament current;

[0012] Exit the PWM control strategy.

[0013] Preferably, the exposure parameters further include: a preset high voltage value;

[0014] The steps of the high-voltage control system sending the exposure parameters to the high-voltage generator and preheating the filament current to the preset filament current include:

[0015] The high-voltage control system detects the voltage value in real time, and when the voltage value reaches the preset high voltage value, it sends the exposure parameters to the high-voltage generator.

[0016] Preferably, when the FPGA chip detects that the real-time filament current reaches the filament current threshold, the FPGA chip starts the PWM control strategy to output a filament current control value to the high-voltage controller, so that the real-time filament current and the real-time tube current decrease and then rise within a control period, and the step that the filament current control value is less than the filament current threshold includes:

[0017] The FPGA chip starts the PWM control strategy and forms a filament current control value based on the following algorithm:

[0018]

[0019] Where FA ctrl is the filament current control value, FA max is the filament current threshold, t n is the control period, t set is the duty cycle duration, so that the duty ratio of the PWM control strategy is:

[0020] Preferably, when the FPGA chip detects that the real-time filament current reaches the filament current threshold, the FPGA chip starts the PWM control strategy to output a filament current control value to the high-voltage controller, so that the real-time filament current and the real-time tube current decrease and then rise within a control period, and the step that the filament current control value is less than the filament current threshold further includes:

[0021] The FPGA chip controls the real-time filament current to decrease to the filament current control value within the duty cycle duration and rise to the filament current threshold after the duty cycle duration;

[0022] The steps of repeating the above steps until the real-time tube current stabilizes at the desired tube current and recording the value of the decreased real-time filament current after being controlled by the PWM control strategy at this time as the stable filament current include:

[0023] In a subsequent control period, the FPGA chip controls the filament current to decrease to a subsequent filament current control value greater than the previous filament current control value within the duty cycle duration;

[0024] Repeat the above steps until the real-time tube current stabilizes at the desired tube current.

[0025] The present invention also discloses a filament current control system for a CT device. The filament current control system includes: a host computer and an FPGA chip. The FPGA chip includes a high-voltage control system and a PWM control module;

[0026] The host computer connected to the high-voltage control system of the CT device issues exposure parameters to the high-voltage control system, where the exposure parameters at least include a preset filament current and a desired tube current;

[0027] The high-voltage control system issues the exposure parameters to the high-voltage generator and preheats the filament current to the preset filament current;

[0028] After the high-voltage control system turns on the exposure signal to the high-voltage generator, there is a preset filament current threshold in the FPGA chip within the high-voltage control system, and the real-time filament current and the real-time tube current are read;

[0029] When the FPGA chip detects that the real-time filament current reaches the filament current threshold, the FPGA chip activates the PWM control strategy to output a filament current control value to the high-voltage controller, so that the real-time filament current and the real-time tube current decrease and then rise within a control period, where the filament current control value is less than the filament current threshold;

[0030] Repeat the above steps until the real-time tube current stabilizes at the desired tube current. The FPGA chip records the value of the decreased real-time filament current after being controlled by the PWM control strategy at this time as the stable filament current;

[0031] The FPGA chip exits the PWM control strategy.

[0032] Preferably, the exposure parameters further include: a preset high-voltage value;

[0033] The high-voltage control system detects the voltage value in real time. When the voltage value reaches the preset high-voltage value, it issues the exposure parameters to the high-voltage generator.

[0034] Preferably, when the FPGA chip activates the PWM control strategy, a filament current control value is formed based on the following algorithm:

[0035]

[0036] Where FA ctrl is the filament current control value, FA max is the filament current threshold, t n is the control period, tset is the duty cycle duration, such that the duty ratio of the PWM control strategy is:

[0037] Preferably, the FPGA chip controls the real-time filament current to drop to the filament current control value within the duty cycle duration and rise back to the filament current threshold after the duty cycle duration;

[0038] Repeatedly execute the above steps until the real-time tube current stabilizes at the desired tube current. The steps for the FPGA chip to record the value of the decreased real-time filament current after being controlled by the PWM control strategy at this time as the stable filament current include:

[0039] In the next control cycle, the FPGA chip controls the filament current to drop to a next filament current control value greater than the previous filament current control value within the duty cycle duration;

[0040] Repeatedly execute the above steps until the real-time tube current stabilizes at the desired tube current.

[0041] After adopting the above technical solution, compared with the prior art, it has the following beneficial effects:

[0042] On the premise of meeting the rising stable time of the tube current, the filament current is made not to exceed the threshold set inside the high voltage, so that the exposure can be carried out normally, and the fault of the high voltage reporting overcurrent of the filament current under certain conditions is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a schematic flow chart of the filament current control method according to a preferred embodiment of the present invention;

[0044] Figure 2 is a schematic diagram of the filament current and tube current of the PWM control logic according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0045] The advantages of the present invention will be further elaborated below in conjunction with the accompanying drawings and specific embodiments.

[0046] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0047] The terms used in this disclosure are for the purpose of describing particular embodiments only and are not intended to limit the disclosure. The singular forms "a", "said", and "the" used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0048] It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining".

[0049] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0050] In the description of the present invention, unless otherwise specified and defined, it should be noted that the terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, it may be a mechanical connection or an electrical connection, or it may be the communication inside two elements. It may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0051] In the subsequent description, the suffixes such as "module", "component", or "unit" used to represent elements are only for the convenience of describing the present invention and have no specific meaning in themselves. Therefore, "module" and "component" can be used interchangeably.

[0052] Referring to Figure 1 , a schematic flow diagram of a filament current control method according to a preferred embodiment of the present invention is shown. In this embodiment, the filament current control method includes the following steps:

[0053] S100: The host computer connected to the high-voltage control system of the CT device sends exposure parameters to the high-voltage control system, where the exposure parameters at least include a preset filament current and a desired tube current

[0054] Since in high-voltage exposure, the host computer sends the parameters under the scanning conditions to the exposure control system, and after the exposure control system reaches the condition for starting exposure, it turns on the high voltage to achieve exposure control. Therefore, the host computer first needs to send the exposure parameters to the high-voltage control system so that the high-voltage control system can control the exposure action. Among them, the exposure parameters should at least include, for example, the preset filament current (FA), the desired tube current (MA), or the grid value, etc.

[0055] S200: The high-voltage control system sends the exposure parameters to the high-voltage generator and preheats the filament current to the preset filament current

[0056] After receiving the above exposure parameters, the high-voltage control system sends them to the high-voltage generator and preset the filament current to the preset filament current based on the PID control algorithm, that is, gradually increase the value of the filament current to the preset filament current. It can be understood that the high-voltage control system can communicate with the high-voltage generator through the SPI communication interface to send control signals.

[0057] S300: After the high-voltage control system turns on the exposure signal to the high-voltage generator, a filament current threshold is preset in the FPGA chip in the high-voltage control system, and the real-time filament current and real-time tube current are read

[0058] After the high-voltage control system detects the set value for starting exposure (that is, the exposure condition is met), it will send an exposure start signal to the high-voltage generator, and the high-voltage generator generates high voltage to start the exposure action. At this time, a filament current threshold is preset in the FPGA chip in the high-voltage control system (or the high-voltage control system is integrated in the FPGA chip), and at the same time, the values of the real-time filament current and real-time tube current caused by the real-time exposure state are read. It can be understood that generally speaking, the high-voltage internal overcurrent judgment is based on the fact that after the filament current reaches the maximum value (that is, the above-mentioned filament current threshold), it continues continuously for 10 ms. When such conditions are met, the high-voltage reports an error. Therefore, it is necessary to control the real-time filament current not to exceed the filament current threshold for a long time.

[0059] S400: When the FPGA chip detects that the real-time filament current reaches the filament current threshold, the FPGA chip starts the PWM control strategy to output a filament current control value to the high-voltage controller, so that the real-time filament current and real-time tube current decrease and then rise within a control cycle, where the filament current control value is less than the filament current threshold

[0060] Once it is detected that the real-time filament current reaches the filament current threshold, within the above-mentioned long time (such as 10 ms), the FPGA chip will start a PWM control strategy and output a filament current control value to the high-voltage controller, that is, command the high-voltage controller to control the magnitude of the filament current to drop to the filament current control value. It should be noted that the drop time is only the duty cycle time within the PWM control strategy. After the duty cycle time has passed, it may still rise back to the filament current threshold. However, for the tube current, since the average filament current value within the controlled period decreases due to the PWM control strategy, the real-time tube current will also gradually drop (refer to Figure 2 ).

[0061] S500: Repeatedly execute the above steps until the real-time tube current stabilizes at the desired tube current, and record the value of the decreased real-time filament current after being controlled by the PWM control strategy at this time as the stable filament current

[0062] After repeatedly executing the above step S400, it is found that for the magnitude of the filament current control value and the duty cycle within the PWM control strategy, they will affect the magnitude of the real-time tube current. Once the magnitude of the real-time tube current basically drops back to the desired tube current during its operation (the tube current in mA will generally eventually enter a steady state), it is equivalent to that the filament current value should also be in a stable state at this time. Therefore, when the real-time tube current stabilizes at the desired tube current, the value of the decreased real-time filament current after being controlled by the PWM control strategy can be recorded as the stable filament current.

[0063] S600: Exit the PWM control strategy and the high voltage operates stably

[0064] And at this step, the value of the real-time filament current is less than the filament current threshold, and it will not cause parameters that prevent normal exposure.

[0065] In a preferred embodiment, the exposure parameters further include: a preset high voltage value KV;

[0066] The step S200 of the high-voltage control system sending the exposure parameters to the high-voltage generator and preheating the filament current to the preset filament current includes:

[0067] S200: The high-voltage control system detects the voltage value in real time. When the voltage value reaches the preset high voltage value, it sends the exposure parameters to the high-voltage generator. Thus, the start of the exposure is determined by the magnitude of the high voltage.

[0068] Further, step S400 includes:

[0069] S410: The FPGA chip starts the PWM control strategy and forms a filament current control value based on the following algorithm:

[0070]

[0071] where FA ctrl is the filament current control value, and FA max is the filament current threshold, t n is the control period, and t set is the duty cycle duration, such that the duty ratio of the PWM control strategy is:

[0072] Users can adjust the filament current control value and the duty ratio according to the working conditions. For example, when the filament current control value is small and the duty ratio is large, the safety control of the filament current can be improved (the real-time filament current will not exceed the filament current threshold), but it may take a longer time for the tube current to reach a steady state. On the contrary, if it is necessary to quickly determine the stable magnitude of the tube current, the filament current control value can be set larger, the duty ratio can be smaller, or other selections of the filament current control value and the duty ratio are also possible.

[0073] Furthermore, step S400 further includes:

[0074] S420: The FPGA chip controls the real-time filament current to drop to the filament current control value within the duty cycle duration and rise back to the filament current threshold after the duty cycle duration;

[0075] That is, within one control period, it is divided into two time periods. In the first time period, the real-time filament current drops to the filament current control value, and in the second time period, it rises back to the filament current threshold.

[0076] Repeatedly execute the above steps until the real-time tube current stabilizes at the desired tube current. Recording the value of the real-time filament current that has dropped after being controlled by the PWM control strategy at this time as the stable filament current, step S500 includes:

[0077] S510: In the subsequent control period, the FPGA chip controls the filament current to drop to a subsequent filament current control value that is greater than the previous filament current control value within the duty cycle duration;

[0078] When in the second control period, the magnitude of the duty ratio may not change (it can also be modified in some embodiments), but the drop value of the real-time filament current within this control period can be less than the filament current control value that the previous drop reached (refer to Figure 2 ), and gradually adjust the tube current.

[0079] S520: Repeatedly execute the above steps until the real-time tube current stabilizes at the desired tube current.

[0080] After repeatedly executing the above step S510, the real-time tube current finally reduces fluctuations and stabilizes at the desired tube current.

[0081] It is understandable that if it is found that the real-time tube current cannot reach a steady state eventually, the duty cycle can be increased or the filament current control value can be decreased to reduce the average filament current value within a control period, thereby reducing the average tube current value within a control period.

[0082] The present invention also discloses a filament current control system for a CT device. The filament current control system includes: a host computer and an FPGA chip. The FPGA chip includes a high-voltage control system and a PWM control module. The host computer connected to the high-voltage control system of the CT device issues exposure parameters to the high-voltage control system, where the exposure parameters at least include a preset filament current and an expected tube current. The high-voltage control system issues the exposure parameters to the high-voltage generator and preheats the filament current to the preset filament current. After the high-voltage control system turns on the exposure signal to the high-voltage generator, there is a preset filament current threshold in the FPGA chip within the high-voltage control system, and the real-time filament current and the real-time tube current are read. When the FPGA chip detects that the real-time filament current reaches the filament current threshold, the FPGA chip starts the PWM control strategy to output a filament current control value to the high-voltage controller, so that the real-time filament current and the real-time tube current decrease and then rise within a control period, where the filament current control value is less than the filament current threshold. The above steps are repeatedly executed until the real-time tube current stabilizes at the expected tube current. The FPGA chip records the value of the decreased real-time filament current after being controlled by the PWM control strategy at this time as the stable filament current. The FPGA chip exits the PWM control strategy.

[0083] Preferably, the exposure parameters further include: a preset high-voltage value. The high-voltage control system detects the voltage value in real time. When the voltage value reaches the preset high-voltage value, it issues the exposure parameters to the high-voltage generator.

[0084] Preferably, when the FPGA chip starts the PWM control strategy, a filament current control value is formed based on the following algorithm:

[0085]

[0086] where FA ctrl is the filament current control value, FA max is the filament current threshold, t n is the control period, t set is the duty cycle duration, so that the duty cycle of the PWM control strategy is:

[0087] Preferably, the FPGA chip controls the real-time filament current to decrease to the filament current control value within the duty cycle duration and then rise to the filament current threshold after the duty cycle duration. In the next control period, the FPGA chip controls the filament current to decrease to a next filament current control value greater than the previous filament current control value within the duty cycle duration. The above steps are repeatedly executed until the real-time tube current stabilizes at the expected tube current.

[0088] It should be noted that the embodiments of the present invention have better implementability and do not impose any form of limitation on the present invention. Any person skilled in the art may use the technical content disclosed above to modify or transform it into equivalent effective embodiments. However, as long as it does not depart from the content of the technical solution of the present invention, any modification, equivalent change, or modification made to the above embodiments based on the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for controlling the filament current of a CT device, characterized in that, Including the following steps: The host computer connected to the high-voltage control system of the CT device sends exposure parameters to the high-voltage control system, where the exposure parameters at least include a preset filament current and an expected tube current; The high-voltage control system sends the exposure parameters to the high-voltage generator and preheats the filament current to the preset filament current; After the high-voltage control system turns on the exposure signal to the high-voltage generator, there is a preset filament current threshold in the FPGA chip in the high-voltage control system, and the real-time filament current and real-time tube current are read; When the FPGA chip detects that the real-time filament current reaches the filament current threshold, the FPGA chip starts a PWM control strategy to output a filament current control value to the high-voltage control system, so that the real-time filament current and real-time tube current decrease and then rise within a control period, where the filament current control value is less than the filament current threshold; Repeatedly execute the above steps until the real-time tube current stabilizes at the expected tube current, and record the value of the decreased real-time filament current after being controlled by the PWM control strategy at this time as the stable filament current; Exit the PWM control strategy; Wherein When the FPGA chip detects that the real-time filament current reaches the filament current threshold, the FPGA chip starts a PWM control strategy to output a filament current control value to the high-voltage control system, so that the real-time filament current and real-time tube current decrease and then rise within a control period, where the filament current control value is less than the filament current threshold. The steps include: The FPGA chip starts a PWM control strategy and forms a filament current control value based on the following algorithm: where FA ctrl is the filament current control value, FA max is the filament current threshold, t n is the control period, t set is the duty cycle duration, such that the duty ratio of the PWM control strategy is:

2. The filament current control method according to claim 1, characterized in that The exposure parameters further include: a preset high-voltage value; The steps that the high-voltage control system sends the exposure parameters to the high-voltage generator and preheats the filament current to the preset filament current include: The high-voltage control system detects the voltage value in real time, and when the voltage value reaches the preset high-voltage value, it sends the exposure parameters to the high-voltage generator.

3. The filament current control method according to claim 1, characterized in that When the FPGA chip detects that the real-time filament current reaches the filament current threshold, the FPGA chip starts a PWM control strategy to output a filament current control value to the high-voltage control system, so that the real-time filament current and real-time tube current decrease and then rise within a control period, where the filament current control value is less than the filament current threshold. The steps further include: The FPGA chip controls the real-time filament current to decrease to the filament current control value within the duty cycle duration and then rise to the filament current threshold after the duty cycle duration; The steps of repeatedly executing the above steps until the real-time tube current stabilizes at the expected tube current and recording the value of the decreased real-time filament current after being controlled by the PWM control strategy at this time as the stable filament current include: In the next control period, the FPGA chip controls the filament current to decrease to a next filament current control value greater than the previous filament current control value within the duty cycle duration; Repeat the above steps until the real-time tube current stabilizes at the desired tube current.

4. A filament current control system for a CT device, characterized in that, The filament current control system includes: a host computer and an FPGA chip, and the FPGA chip includes a high-voltage control system and a PWM control module; The host computer connected to the high-voltage control system of the CT device sends exposure parameters to the high-voltage control system, where the exposure parameters at least include a preset filament current and a desired tube current; The high-voltage control system sends the exposure parameters to the high-voltage generator and preheats the filament current to the preset filament current; After the high-voltage control system turns on the exposure signal to the high-voltage generator, there is a preset filament current threshold in the FPGA chip within the high-voltage control system, and the real-time filament current and real-time tube current are read; When the FPGA chip detects that the real-time filament current reaches the filament current threshold, the FPGA chip starts a PWM control strategy to output a filament current control value to the high-voltage control system, so that the real-time filament current and real-time tube current decrease and then rise within a control period, where the filament current control value is less than the filament current threshold; Repeat the above steps until the real-time tube current stabilizes at the desired tube current, and the FPGA chip records the value of the decreased real-time filament current after being controlled by the PWM control strategy at this time as the stable filament current; The FPGA chip exits the PWM control strategy; where The FPGA chip starts a PWM control strategy and forms a filament current control value based on the following algorithm: Among them, FA ctrl is the filament current control value, FA max is the filament current threshold, t n is the control period, t set is the duty cycle duration, such that the duty ratio of the PWM control strategy is:

5. The filament current control system according to claim 4, characterized in that The exposure parameters further include: a preset high-voltage value; The high-voltage control system detects the voltage value in real time, and when the voltage value reaches the preset high-voltage value, it sends the exposure parameters to the high-voltage generator.

6. The filament current control system according to claim 4, characterized in that The FPGA chip controls the real-time filament current to decrease to the filament current control value within the duty cycle and rise to the filament current threshold after the duty cycle; In the next control period, the FPGA chip controls the filament current to decrease to a next filament current control value greater than the previous filament current control value within the duty cycle; Repeat the above steps until the real-time tube current stabilizes at the desired tube current.

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