A filament current calibration method and system for CT equipment

Abstract

The present invention provides a filament current calibration method and system for a CT device. The filament current calibration method includes the following steps: exposing at a first sampling point with a default filament current and a preset MA value to obtain a first target MA value; determining a default filament current and an ideal MA value based on a comparison result between the first target MA value and the preset MA value; fitting a nonlinear curve based on the default filament current and the ideal MA value; selecting a test MA value and a test filament current on the nonlinear curve, exposing to obtain an actual MA value, and replacing the test MA value; repeatedly performing the above operations until multiple sets of test filament currents and actual MA values ​​are obtained; correcting the nonlinear curve based on the test filament current and the actual MA value, and interpolating to obtain a corresponding relationship between the filament current and the MA value; and storing the above data in a filament current database. The above technical solution can reduce the number of word exposures during filament current calibration and improve the calibration quality of the filament current.

Description

Technical Field

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

[0002] Computed tomography (CT) uses a precise X-ray beam to penetrate the human body, where it is received by highly sensitive detectors. The X-ray beam's absorption by different tissues is then used to determine the specific details of the body part being examined. The X-ray tube's tube current (MA) determines the amount of X-ray radiation emitted, and this is influenced by the temperature of the filament. Therefore, controlling the filament current is crucial, as it affects the amount of X-ray radiation emitted.

[0003] Existing algorithms use a binary search method to iterate and approximate the desired filament current. However, under certain conditions, when the range of filament currents that meet the requirements is small, the number of iterations can be very high, and even the correct result cannot be accurately found. Furthermore, because existing algorithms use linear interpolation to obtain filament current values ​​at uncalibrated points, this requires a large number of scan points, and the interpolated results are not ideal.

[0004] Therefore, a new method for obtaining and calibrating the filament current is needed, which can obtain accurate filament current values ​​based on a small amount of exposure and sampling. Summary of the Invention

[0005] In order to overcome the above technical defects, the purpose of the present invention is to provide a filament current calibration method and system for CT equipment, which can reduce the number of word exposures during filament current calibration and improve the calibration quality of the filament current.

[0006] The present invention discloses a filament current calibration method for a CT device, comprising the following steps:

[0007] Obtain the tube current interval and take multiple sampling points within the tube current interval;

[0008] Expose at a first sampling point with a default filament current and a preset MA value to obtain a first MA curve, and extract a first target MA value when the first MA curve is first stabilized;

[0009] Determining at least two sets of default filament currents and their corresponding ideal MA values ​​based on a comparison result of the first target MA value and the preset MA value;

[0010] Fitting a nonlinear curve based on at least two sets of default filament currents and their corresponding ideal MA values;

[0011] Selecting a test MA value and its corresponding test filament current on the nonlinear curve, exposing the filament current based on the test MA value to obtain an actual MA value, and replacing the test MA value with the actual MA value;

[0012] Repeat the above operation until multiple sets of test filament currents and their corresponding actual MA values ​​are obtained;

[0013] Correcting the nonlinear curve based on multiple sets of test filament currents and their corresponding actual MA values, and interpolating on the corrected nonlinear curve to obtain at least one set of corresponding relationships between the filament currents and the MA values;

[0014] At least two sets of default filament currents and their corresponding ideal MA values, multiple sets of test filament currents and their corresponding actual MA values, and their corresponding relationships are stored in a filament current database.

[0015] Preferably, the step of exposing at a first sampling point with a default filament current and a preset MA value to obtain a first MA curve, and extracting a first target MA value when the first MA curve is first stabilized includes:

[0016] At the first sampling point, exposure is performed with a default filament current and a preset MA value, and a first MA curve during exposure is extracted;

[0017] The MA value corresponding to the first occurrence of a slope close to 0 in the first MA curve is used as a first target MA value, wherein the duration of the MA value corresponding to the first occurrence of a slope close to 0 is greater than a time threshold.

[0018] Preferably, based on the comparison result of the first target MA value and the preset MA value, the step of determining at least two sets of default filament currents and their corresponding ideal MA values ​​comprises:

[0019] Compare the first target MA value with the preset MA value,

[0020] When the offset of the preset MA value from the first target MA value is less than a preset offset, the preset MA value is recorded as the first ideal MA value, and the above steps are repeated at the second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values;

[0021] When the offset of the preset MA value from the first target MA value is greater than or equal to the preset offset, the preset MA value is modified to the first target MA value, and the above steps are repeated until the offset is less than the preset offset. The above steps are then repeated at the second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values.

[0022] Preferably, the step of fitting a nonlinear curve based on at least two sets of default filament currents and their corresponding ideal MA values ​​comprises:

[0023] A rectangular coordinate system is recommended with the MA value as the horizontal axis and the filament current as the vertical axis. Substitute at least two sets of default filament currents and their corresponding ideal MA values ​​into the rectangular coordinate system.

[0024] A nonlinear curve is fitted based on a logarithmic function or an exponential function, wherein points corresponding to at least two sets of default filament currents and their corresponding ideal MA values ​​are located within the nonlinear curve.

[0025] Preferably, the preset offset is -15% to 15%.

[0026] The present invention also discloses a filament current calibration system for CT equipment, comprising:

[0027] The sampling module obtains the tube current interval and takes multiple sampling points within the tube current interval;

[0028] a processing module that exposes at a first sampling point with a default filament current and a preset MA value to obtain a first MA curve, and extracts a first target MA value when the first MA curve is first stabilized;

[0029] The processing module determines at least two sets of default filament currents and their corresponding ideal MA values ​​based on a comparison result between the first target MA value and the preset MA value;

[0030] The processing module fits a nonlinear curve based on at least two sets of default filament currents and their corresponding ideal MA values;

[0031] The processing module selects a test MA value and its corresponding test filament current on the nonlinear curve, obtains an actual MA value based on the test filament current exposure, and replaces the test MA value with the actual MA value;

[0032] The processing module repeatedly performs the above operations until multiple sets of test filament currents and their corresponding actual MA values ​​are obtained;

[0033] The processing module corrects the nonlinear curve based on the multiple sets of test filament currents and their corresponding actual MA values, and interpolates on the corrected nonlinear curve to obtain at least one set of corresponding relationships between the filament currents and the MA values;

[0034] The processing module stores at least two sets of default filament currents and their corresponding ideal MA values, multiple sets of test filament currents and their corresponding actual MA values, and corresponding relationships in a filament current database.

[0035] Preferably, the processing module exposes at a first sampling point with a default filament current and a preset MA value, and extracts a first MA curve during exposure;

[0036] The processing module sets the MA value corresponding to the first occurrence of a slope close to 0 in the first MA curve as a first target MA value, wherein the duration of the MA value corresponding to the first occurrence of a slope close to 0 is greater than a time threshold.

[0037] Preferably, when the offset of the preset MA value from the first target MA value is less than a preset offset, the processing module records the preset MA value as the first ideal MA value, and repeats the above steps at the second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values;

[0038] When the offset of the preset MA value from the first target MA value is greater than or equal to the preset offset, the processing module modifies the preset MA value to the first target MA value and repeats the above steps until the offset is less than the preset offset. Then, the above steps are repeated at the second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values.

[0039] Preferably, the processing module recommends a rectangular coordinate system with the MA value as the horizontal axis and the filament current as the vertical axis, and substitutes at least two sets of default filament currents and their corresponding ideal MA values ​​into the rectangular coordinate system;

[0040] The processing module fits a nonlinear curve based on a logarithmic function or an exponential function, wherein points corresponding to at least two sets of default filament currents and their corresponding ideal MA values ​​are located within the nonlinear curve.

[0041] Compared with the existing technology, the above technical solution has the following beneficial effects:

[0042] 1. Reduce the number of scanning points required for filament current calibration to reduce the workload required for calibration;

[0043] 2. Use the high-voltage PLD controller to control the MA's control characteristics to determine the filament current results, reducing the number of hardware equipment coordination times;

[0044] 3. The LM nonlinear least squares method is used to fit the filament emission characteristic curve to obtain the filament current value at the unscanned point, and the filament current value is quite close to the actual expected value. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic flow chart of a filament current calibration method according to a preferred embodiment of the present invention;

[0046] Figure 2a To comply with the relationship between the filament current value and the MA value in a preferred embodiment of the present invention, the first target MA value in this embodiment has a large deviation from the preset MA value;

[0047] Figure 2bTo comply with the relationship between the filament current value and the MA value in a preferred embodiment of the present invention, in this embodiment, the first target MA value has a smaller deviation from the preset MA value. DETAILED DESCRIPTION

[0048] The advantages of the present invention are further described below with reference to the accompanying drawings and specific embodiments.

[0049] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

[0050] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless the context clearly indicates 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.

[0051] 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, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining."

[0052] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying 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 therefore cannot be understood as limiting the present invention.

[0053] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal communication between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0054] In the following description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention and have no specific meaning. Therefore, "module" and "component" can be used interchangeably.

[0055] See Figure 1 , shows a filament current calibration method for a CT device according to a preferred embodiment of the present invention. In this embodiment, the calibration method includes the following steps:

[0056] S100: Obtaining a tube current interval and taking multiple sampling points within the tube current interval;

[0057] The tube current (MA) has a fluctuation range. This fluctuation range is used as the sampling interval. Combined with the curve characteristics of the MA, multiple sampling points can be found within the interval. It can be understood that each sampling point has a corresponding filament current value and MA value, thereby generating different X-ray radiation doses.

[0058] S200: exposing at a first sampling point with a default filament current and a preset MA value to obtain a first MA curve, and extracting a first target MA value when the first MA curve is first stabilized;

[0059] After exposure, the control characteristics of MA by the high-voltage PLD controller can be used to determine the MA value corresponding to the current filament current. Specifically, when performing scanning point acquisition, after the first exposure (the filament current during exposure is based on the default value, and the preset MA value to which MA finally stabilizes is preset in the PLD controller), the first MA curve reflected in each time domain can be read. From the first MA curve, it can be seen that since MA and filament current are generally adjusted by a PID controller, according to the characteristics of the PID curve, the first MA curve (or all MA curves) can be divided into two periods: an adjustment period and a stable period. The criterion for judging the quality of the filament current is generally how long it takes for MA to enter the stable period, that is, the shorter the time occupied by the adjustment period, the better. In some cases, when the preset MA value deviates from the MA value corresponding to the filament current, the following will appear: Figure 2a As shown in the waveform, the first MA curve was stable for a period of time at a certain MA value, but then dropped to the preset MA value; if the preset MA value and the MA value corresponding to the filament current have basically no deviation, the following will appear: Figure 2bIn the waveform shown, the first MA curve stabilizes at a certain MA value and then remains stable at that value. Therefore, it can be understood that to minimize the adjustment period, the simplest approach is to achieve the desired result during the first controller adjustment and enter the stabilization period directly. Therefore, the target MA value can be deduced from the curve, and ultimately the target filament current value. In other words, in this step, regardless of whether the first MA curve continues to decline, remains stable, or reverses its upward trend after the initial plateau, the MA value at the initial plateau is used as the first target MA value.

[0060] S300: Determining at least two sets of default filament currents and their corresponding ideal MA values ​​based on a comparison result of the first target MA value and the preset MA value;

[0061] The first target MA value is compared to the preset MA value. If they closely match, the preset MA value is considered to match the MA value corresponding to the current default filament current and is the ideal MA value. If they do not match, the first target MA value is used as the new preset MA value, and the aforementioned steps are repeated to obtain the MA value that best matches the default filament current. The filament current and MA value that have a corresponding relationship will be used as the default filament current and its corresponding ideal MA value.

[0062] S400: Fitting a nonlinear curve based on at least two sets of default filament currents and their corresponding ideal MA values;

[0063] Considering that the correspondence between all filament currents and MA values ​​within their respective intervals exhibits a certain functional relationship (nonlinearity), a nonlinear curve can be fitted based on at least two sets of default filament currents and their corresponding ideal MA values. It is understood that the accuracy of the nonlinear curve is not a consideration during this fitting; it is sufficient to ensure that at least two sets of default filament currents and their corresponding ideal MA values ​​fall within the nonlinear curve.

[0064] S500: selecting a test MA value and its corresponding test filament current on the nonlinear curve, exposing the test filament current to obtain an actual MA value, and replacing the test MA value with the actual MA value;

[0065] Once the nonlinear curve is established, a random MA value is first selected. The corresponding test filament current is then found on the nonlinear curve. Using this test filament current as the standard exposure, the MA curve at that point is extracted (this can be referred to as the second MA curve). The value at which the MA curve finally stabilizes is determined as the actual MA value corresponding to the test filament current. Due to the correspondence between the test filament current and the actual MA value, the original test MA value is replaced, thereby correcting the point on the nonlinear curve.

[0066] S600: Repeat the above operation until multiple sets of test filament currents and their corresponding actual MA values ​​are obtained;

[0067] Repeating the above steps will gradually correct the nonlinear curve. It's understandable that, due to the functional relationship between filament current and MA value, a complete and accurate nonlinear curve can be fitted even with multiple sets (e.g., three or five) of filament current and MA values. Therefore, the re-exposure step in the above steps can be limited to a very small number of times.

[0068] S700: Correcting a nonlinear curve based on multiple sets of test filament currents and their corresponding actual MA values, and interpolating on the corrected nonlinear curve to obtain at least one set of corresponding relationships between filament currents and MA values;

[0069] After the nonlinear curve is corrected, the corrected nonlinear curve can be continuously interpolated (for example, an MA value is assigned) to obtain the corresponding filament current, and the filament current value is obtained through nonlinear interpolation.

[0070] S800: Storing at least two sets of default filament currents and their corresponding ideal MA values, multiple sets of test filament currents and their corresponding actual MA values, and their corresponding relationships in a filament current database.

[0071] Through the above configuration, the scanning points or sampling points of the filament calibration are reduced in the entire calibration process, the number of word exposures during the filament calibration is also reduced, and the filament current value finally stored in the database has a certain accuracy.

[0072] In a preferred embodiment, step S200 includes:

[0073] S210: Expose at a first sampling point with a default filament current and a preset MA value, and extract a first MA curve during exposure;

[0074] S220: The MA value corresponding to the first occurrence of a slope close to 0 in the first MA curve is set as a first target MA value, wherein the duration of the MA value corresponding to the first occurrence of a slope close to 0 is greater than a time threshold.

[0075] In this embodiment, the sampling criteria for the first stable first MA value is that the slope of its MA value in the first MA curve should be 0, or very close to 0, and the time of occurrence should not be instantaneous, but should be maintained for at least a certain time (for example, 10ms).

[0076] Furthermore, step S300 includes:

[0077] S310: Compare the first target MA value with the preset MA value,

[0078] S320: When the offset of the preset MA value from the first target MA value is less than a preset offset, recording the preset MA value as the first ideal MA value, and repeating the above steps at the second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values;

[0079] When the offset of the preset MA value from the first target MA value is less than a preset offset, it is reflected in the first MA curve that after the MA value drops, it will not stay at a certain MA value and then drop or rise again, but will gradually fall back to a steady state after reaching the pulse value (such as Figure 2b ), or even if it rises or falls again, the amount of rise or fall is extremely small and almost horizontal in the first MA curve. At this time, it means that the preset MA value basically corresponds to the current filament current. Therefore, the above steps can be repeated at the second sampling point to obtain the default filament current (the default filament current value can be used for the first two samplings) and the ideal MA value that match each other.

[0080] S320′: When the offset of the preset MA value from the first target MA value is greater than or equal to the preset offset, modify the preset MA value to the first target MA value, and repeat the above steps until the offset is less than the preset offset, and repeat the above steps at the second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values.

[0081] When the offset of the preset MA value from the first target MA value is greater than or equal to a preset offset, it is reflected in the first MA curve. After the MA value drops, it will briefly stay at a certain MA value. Since the MA value when stable is not equal to the preset MA value, it will be adjusted downward based on the preset MA value. Reflected in the first MA curve, the waveform will drop or rise again, that is, after reaching the pulse value, it will first fall back to a short-term steady state, and then fall back to a long-term steady state (such as Figure 2a (as shown), this means the preset MA value doesn't correspond to the current filament current. Therefore, the preset MA value can be modified to the first target MA value, ultimately achieving a stable state. Repeat the above steps for a second exposure (either at the first or second sampling point) to determine whether the offset is less than the preset offset. The final result must satisfy the offset requirement. Once this state is reached, repeat the above steps at the second sampling point to obtain the default filament current (the default filament current value can be used for the first two samplings) and the ideal MA value, which match each other.

[0082] In any of the above embodiments, the preset offset may be -15% to 15%, or may be freely adjusted according to working conditions and accuracy requirements.

[0083] The present invention also discloses a filament current calibration system for CT equipment, comprising: a sampling module for acquiring a tube current interval and taking a plurality of sampling points within the tube current interval; a processing module for exposing at a first sampling point with a default filament current and a preset MA value to obtain a first MA curve, and extracting a first target MA value when the first MA curve is first stabilized; the processing module determines at least two groups of default filament currents and their corresponding ideal MA values ​​based on a comparison result of the first target MA value and the preset MA value; the processing module fits a nonlinear curve based on the at least two groups of default filament currents and their corresponding ideal MA values; the processing module selects a first target MA value on the nonlinear curve; and the processing module selects a first target MA value on the nonlinear curve. A test MA value and its corresponding test filament current are exposed based on the test filament current to obtain an actual MA value, and the actual MA value replaces the test MA value; the processing module repeatedly performs the above operation until multiple sets of test filament currents and their corresponding actual MA values ​​are obtained; the processing module corrects the nonlinear curve based on the multiple sets of test filament currents and their corresponding actual MA values, and interpolates on the corrected nonlinear curve to obtain at least one set of corresponding relationships between filament currents and MA values; the processing module stores at least two sets of default filament currents and their corresponding ideal MA values, multiple sets of test filament currents and their corresponding actual MA values, and the corresponding relationships in a filament current database.

[0084] Preferably, the processing module exposes at a first sampling point with a default filament current and a preset MA value, and extracts a first MA curve during exposure; the processing module takes the MA value corresponding to the first time a slope close to 0 appears in the first MA curve as a first target MA value, wherein the time for which the MA value corresponding to the first time a slope close to 0 appears is maintained is greater than a time threshold.

[0085] Preferably, when the offset of the preset MA value from the first target MA value is less than a preset offset, the processing module records the preset MA value as the first ideal MA value and repeats the above steps at a second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values. When the offset of the preset MA value from the first target MA value is greater than or equal to the preset offset, the processing module modifies the preset MA value to the first target MA value and repeats the above steps until the offset is less than the preset offset, at which point the above steps are repeated at the second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values.

[0086] Preferably, the processing module proposes a rectangular coordinate system with the MA value as the horizontal axis and the filament current as the vertical axis, and substitutes at least two sets of default filament currents and their corresponding ideal MA values ​​into the rectangular coordinate system; the processing module fits a nonlinear curve based on a logarithmic function or an exponential function, wherein the points corresponding to the at least two sets of default filament currents and their corresponding ideal MA values ​​are located within the nonlinear curve.

[0087] It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technician familiar with the field may use the technical content disclosed above to change or modify it into an equivalent effective embodiment. However, any modification or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A filament current calibration method for a CT device, characterized in that: The following steps are involved: Obtaining a tube current interval, and taking a plurality of sampling points within the tube current interval; Expose at a first sampling point under a default filament current and a preset MA value to obtain a first MA curve, and extract a first target MA value when the first MA curve is first stabilized. Determining the first target MA value when the first MA curve is first stabilized includes: if the first MA curve remains stable after the first stabilization, directly using the stable value as the first target MA value; if the first MA curve drops or rises again to the preset MA value after the first stabilization, using the MA value when the first stabilization occurs as the first target MA value, and recording that the maintenance time of the MA value must be greater than a time threshold; Determining at least two sets of default filament currents and their corresponding ideal MA values ​​based on a comparison result of the first target MA value and the preset MA value; Fitting a nonlinear curve based on at least two sets of default filament currents and their corresponding ideal MA values; Selecting a test MA value and its corresponding test filament current on the nonlinear curve, exposing the test filament current to obtain an actual MA value, and replacing the test MA value with the actual MA value; Repeat the above operation until multiple sets of test filament currents and their corresponding actual MA values ​​are obtained; Correcting the nonlinear curve based on multiple sets of test filament currents and their corresponding actual MA values, and interpolating on the corrected nonlinear curve to obtain at least one set of corresponding relationships between filament currents and MA values; The at least two groups of default filament currents and their corresponding ideal MA values, the multiple groups of test filament currents and their corresponding actual MA values, and the corresponding relationships are stored in a filament current database.

2. The filament current calibration method according to claim 1, wherein: The steps of exposing at a first sampling point with a default filament current and a preset MA value to obtain a first MA curve, and extracting a first target MA value when the first MA curve is first stabilized include: At the first sampling point, exposure is performed with a default filament current and a preset MA value, and a first MA curve during exposure is extracted; The MA value corresponding to the first occurrence of a slope close to 0 in the first MA curve is used as a first target MA value, wherein the duration of the MA value corresponding to the first occurrence of a slope close to 0 is greater than a time threshold.

3. The filament current calibration method according to claim 1, wherein: The step of determining at least two sets of default filament currents and their corresponding ideal MA values ​​based on a comparison result of the first target MA value and the preset MA value includes: Compare the first target MA value with the preset MA value, When the offset of the preset MA value from the first target MA value is less than a preset offset, recording the preset MA value as a first ideal MA value, and repeating the above steps at a second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values; When the offset of the preset MA value from the first target MA value is greater than or equal to the preset offset, the preset MA value is modified to the first target MA value, and the above steps are repeated until the offset is less than the preset offset. The above steps are then repeated at the second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values.

4. The filament current calibration method according to claim 3, wherein: The step of fitting a nonlinear curve based on at least two sets of default filament currents and their corresponding ideal MA values ​​comprises: A rectangular coordinate system is recommended with the MA value as the horizontal axis and the filament current as the vertical axis. Substitute at least two sets of default filament currents and their corresponding ideal MA values ​​into the rectangular coordinate system. A nonlinear curve is fitted based on a logarithmic function or an exponential function, wherein points corresponding to at least two sets of default filament currents and their corresponding ideal MA values ​​are located within the nonlinear curve.

5. The filament current calibration method according to claim 3, wherein: The default offset is -15%~15%.

6. A filament current calibration system for a CT device, characterized in that: include: A sampling module, which obtains a current interval of the tube and takes a plurality of sampling points within the current interval of the tube; A processing module exposes at a first sampling point under a default filament current and a preset MA value to obtain a first MA curve, and extracts a first target MA value when the first MA curve is first stabilized. Determining the first target MA value when the first MA curve is first stabilized includes: if the first MA curve remains stable after the first stabilization, directly using the stable value as the first target MA value; if the first MA curve decreases or increases again to the preset MA value after the first stabilization, using the MA value when the first stabilization occurs as the first target MA value, and recording that the maintenance time of the MA value must be greater than a time threshold; The processing module determines at least two sets of default filament currents and their corresponding ideal MA values ​​based on a comparison result between the first target MA value and the preset MA value; The processing module fits a nonlinear curve based on at least two sets of default filament currents and their corresponding ideal MA values; The processing module selects a test MA value and its corresponding test filament current on the nonlinear curve, obtains an actual MA value based on the test filament current exposure, and replaces the test MA value with the actual MA value; The processing module repeatedly performs the above operations until multiple sets of test filament currents and their corresponding actual MA values ​​are obtained; The processing module corrects the nonlinear curve based on the multiple test filament currents and their corresponding actual MA values, and interpolates on the corrected nonlinear curve to obtain at least one set of corresponding relationships between the filament currents and the MA values; The processing module stores the at least two sets of default filament currents and their corresponding ideal MA values, multiple sets of test filament currents and their corresponding actual MA values, and the corresponding relationships in a filament current database.

7. The filament current calibration system according to claim 6, wherein: The processing module exposes at a first sampling point with a default filament current and a preset MA value, and extracts a first MA curve during exposure; The processing module uses the MA value corresponding to the first occurrence of a slope close to 0 in the first MA curve as a first target MA value, wherein the duration of the MA value corresponding to the first occurrence of a slope close to 0 is greater than a time threshold.

8. The filament current calibration system according to claim 6, wherein: When the offset of the preset MA value from the first target MA value is less than a preset offset, the processing module records the preset MA value as a first ideal MA value, and repeats the above steps at a second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values; When the offset of the preset MA value from the first target MA value is greater than or equal to the preset offset, the processing module modifies the preset MA value to the first target MA value and repeats the above steps until the offset is less than the preset offset. Then, the above steps are repeated at the second sampling point to obtain at least two sets of default filament currents and their corresponding ideal MA values.

9. The filament current calibration system according to claim 8, wherein: The processing module proposes a rectangular coordinate system with the MA value as the horizontal axis and the filament current as the vertical axis, and substitutes at least two sets of default filament currents and their corresponding ideal MA values ​​into the rectangular coordinate system; The processing module fits a nonlinear curve based on a logarithmic function or an exponential function, wherein points corresponding to at least two sets of default filament currents and their corresponding ideal MA values ​​are located within the nonlinear curve.

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