A control method for X-ray tube filaments suitable for dual-energy exposure

Abstract

This invention discloses a control method for the filament of an X-ray tube suitable for dual-energy exposure, comprising the following steps: performing a first exposure, wherein the filament current of the X-ray tube during the first exposure is FL1; after the first exposure, turning off the high-voltage output, determining and setting the rise and fall current FL0 of the X-ray tube filament, the output time t of FL0, and the filament current FL2 for the second exposure; after the X-ray tube filament is loaded with FL2 and held for t, and after the X-ray tube filament is loaded with FL2 and held for a period of time, performing the second exposure; when FL2 > FL1, FL0 > FL1 and FL2; when FL2 < FL1, FL0 < FL1 and FL2. The control method of this invention can reduce the interval time of dual-energy exposure, thereby reducing motion artifacts, and can effectively suppress overshoot or undershoot of the X-ray tube current during the second exposure, making the X-ray dosage more precise.

Description

Technical Field

[0001] This invention belongs to the field of X-ray dual-energy exposure technology, specifically relating to a control method for X-ray tube filaments suitable for dual-energy exposure. Background Technology

[0002] X-ray imaging systems employ dual-energy exposure technology, utilizing the different penetrating power of low-energy and high-energy rays to capture two images. These images are then decomposed by an algorithm into images containing only soft tissue and images containing only hard tissue. When a high-voltage generator drives the X-ray tube to perform two dual-energy exposures within a short period, motion artifacts inevitably occur due to the time interval between the two exposures caused by heartbeat, respiration, and muscle movement. Therefore, minimizing the interval between the two exposures can reduce motion artifacts.

[0003] However, in actual control, due to the nonlinearity and hysteresis of the filament temperature control within the X-ray tube, if the interval between two exposures is too short, the filament temperature may be too high or too low at the start of the second exposure, leading to overshoot or undershoot of the X-ray tube current, thus resulting in inaccurate X-ray dosage. Therefore, while it is necessary to minimize the time interval between two exposures in dual-energy exposure, the interval must also be controlled to avoid being too short. Addressing this issue by employing techniques such as dual X-ray tubes or dual-layer detectors would increase hardware costs. Summary of the Invention

[0004] In view of this, in order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a control method for the filament of an X-ray tube suitable for dual-energy exposure, which shortens the time between two exposures while avoiding overshoot or undershoot of the X-ray tube current during the second exposure.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a method for controlling the filament of an X-ray tube suitable for dual-energy exposure, comprising the following steps:

[0007] The first exposure is performed, and the filament current of the X-ray tube during the first exposure is FL1;

[0008] After the first exposure, the high voltage output is turned off. The rising and falling current FL0 of the X-ray tube filament, the output time t of the rising and falling current FL0, and the filament current FL2 of the X-ray tube during the second exposure are determined and set. The rising and falling current FL0 is used to heat up or cool down the X-ray tube filament.

[0009] After the X-ray tube filament is subjected to a rising and falling current FL0 and continuously output for a time t, the X-ray tube filament is subjected to a filament current FL2 and continuously output for a period of time before the second exposure is performed.

[0010] When FL2 > FL1, FL0 > FL1 and FL0 > FL2; when FL2 < FL1, FL0 < FL1 and FL0 < FL2.

[0011] Specifically, based on the exposure principle of X-ray tubes, when the interval between two exposures is short, the reason for current overshoot or undershoot in the second exposure is that the filament heating or cooling time is insufficient when the high voltage is turned on for the second exposure, and it hasn't had time to reach the temperature required for the second exposure. Therefore, the current in the second exposure will initially deviate. In this invention, by adding a short period of excessive heating or cooling, the filament temperature is brought closer to the target temperature (the temperature required for the second exposure, i.e., T3) in advance. Once the filament temperature is close to the target temperature, the filament current is output according to the second exposure's filament current within the remaining time range. This ensures that the target temperature is reached when the high voltage is turned on for the second exposure, avoiding filament current overshoot or undershoot during the second exposure. Based on this, the value of FL0 is adjusted by a certain proportion based on the value of FL2. If the filament needs to be heated from the first exposure to the second exposure, FL0 is used to increase FL2 by a certain proportion to ensure that the filament is overheated for a period of time before the filament current FL2 is applied. If the filament needs to be cooled from the first exposure to the second exposure, FL0 is used to decrease FL2 by a certain proportion to ensure that the filament is overcooled for a period of time before the filament current FL2 is applied.

[0012] According to some preferred embodiments of the invention, the rise / fall current FL0 is less than or equal to the maximum permissible current of the X-ray tube filament.

[0013] According to some preferred embodiments of the present invention, let FL2-FL1=ΔFL, where ΔFL≠0. When ΔFL is greater than 0, the rising / falling current FL0 and the output time t of the rising / falling current FL0 are both positively correlated with ΔFL; when ΔFL is less than 0, the rising / falling current FL0 and the output time t of the rising / falling current FL0 are both positively correlated with ΔFL. The output time t of the rising and falling current FL0 is negatively correlated with... The correlation is positive. The dual-energy exposure of this invention is aimed at X-ray tubes used in medical applications, wherein when ΔFL is greater than 0, it indicates that the X-ray tube filament needs to be heated; when ΔFL is less than 0, it indicates that the X-ray tube filament needs to be cooled.

[0014] According to some preferred embodiments of the present invention, the method for determining the rise and fall current FL0 of the X-ray tube filament and the output time t of the rise and fall current FL0 is as follows:

[0015] N calibration points are determined based on the type and accuracy requirements of the X-ray tube. A first calibration curve and a second calibration curve are plotted based on the N calibration points. The value of N increases with the increase of accuracy.

[0016] Then, based on ΔFL, determine one or two adjacent calibration points on the first calibration curve and the second calibration curve respectively, and obtain the rising and falling current FL0 and the output time t.

[0017] Preferably, in this invention, the ordinate of each of the N calibration points is determined through multiple experiments. The specific method is as follows:

[0018] First, based on the maximum difference in filament current corresponding to the type of X-ray tube (which determines the tube's power) in the X-ray tube parameter calibration table, and combined with the actual accuracy requirements, determine N values. These N values ​​are the abscissas of each of the N calibration points. Then, starting from the first calibration point, based on the abscissa ΔFL1 of the current calibration point, select multiple sets of first and second exposure parameters that meet the conditions (the absolute value of the difference between FL1 and FL2 corresponding to the two exposure parameters is equal to the abscissa of the first calibration point) and perform dual-energy exposure. Based on experience, set the rise and fall currents FL0 and their output time t for each set of experiments. After completing the experiment, based on the results of multiple sets of experiments (whether the accuracy meets the requirements, whether the X-ray tube current has overshoot or undershoot), determine whether the set multiple rise and fall currents FL0 and their output time t meet the requirements. Retain the two exposure parameters that meet the requirements. Based on the first and second exposure parameters of each set of experiments that meet the requirements, determine the multiple relationship between FL0 and the corresponding FL2 (e.g., FL01 = n × FL2) and the duration t of FL0. Then, determine the two ordinates corresponding to the abscissa ΔFL1 of the first calibration point. When the ordinate is n × FL2, this calibration point is the first calibration point on the first calibration curve; when the ordinate is the set t, this calibration point is the first calibration point on the second calibration curve. Then, determine the ordinates of the remaining calibration points in the same way. This allows you to determine N calibration points on the first and second calibration curves respectively. Furthermore, the abscissa of each of the N calibration points on the first and second calibration curves is the same; the difference lies in the corresponding ordinate. The ordinate of the calibration point in the first calibration curve is represented by its multiple relationship with FL2, rather than by a fixed value. This allows FL0 to be calculated based on the corresponding FL2 in each actual working process, ensuring that the set FL0 is more accurate.

[0019] Preferably, the accuracy requirement refers to the percentage error between the set rise / fall current FL0 and its output time t and the corresponding parameters actually output during the dual-energy exposure process. The smaller the required percentage error, i.e., the higher the accuracy, the more calibration points are needed when determining the calibration points, i.e., the larger N is. In addition, when the accuracy requirement is higher, the difference between the abscissas of any two adjacent calibration points among the N calibration points is also smaller, to ensure more accurate calibration results.

[0020] According to some preferred embodiments of the present invention, the first calibration curve is the rise / fall current FL0. x Regarding the difference in filament current ΔFL x The relationship curve diagram, the second calibration curve is the output time t x Regarding the difference in filament current ΔFL x The relationship curve is given, where N is a positive integer greater than or equal to 2, and x is a positive integer greater than or equal to 1 and less than or equal to N.

[0021] According to some preferred embodiments of the invention, when Less than and Greater than At that time, based on ΔFL, two adjacent calibration points on the first calibration curve and the second calibration curve are determined, including the following steps:

[0022] Determine ΔFL on the X-axis of the first calibration curve and the second calibration curve respectively. x =The position of ΔFL, and respectively on their respective X-axis by ΔFL x Draw a line x=ΔFL at point =ΔFL. x Based on the intersection points of the straight line with the first calibration curve and the second calibration curve, determine the two adjacent calibration points of ΔFL on the first calibration curve and the two adjacent calibration points on the second calibration curve.

[0023] According to some preferred embodiments of the present invention, the rise / fall current FL0 is calculated by the following formula:

[0024]

[0025] In the formula, and These are the ordinates of the nth and (n-1)th calibration points on the first calibration curve, respectively. and These are the absolute values ​​of the abscissas of the nth and (n-1)th calibration points in the first calibration curve, respectively.

[0026] According to some preferred embodiments of the present invention, the output time t is calculated by the following formula:

[0027]

[0028] In the formula, and These are the ordinates of the nth and (n-1)th calibration points in the second calibration curve, respectively. and These are the absolute values ​​of the abscissas of the nth and (n-1)th calibration points in the second calibration curve, respectively.

[0029] According to some preferred embodiments of the invention, 2≤n≤N, And the (n-1)th calibration point and the nth calibration point are two adjacent calibration points corresponding to ΔFL on the first calibration curve and / or the second calibration curve.

[0030] According to some preferred embodiments of the invention, when Less than ,or, Greater than At that time, a calibration point adjacent to it on the first calibration curve and the second calibration curve is determined according to ΔFL.

[0031] According to some preferred embodiments of the invention, when Less than At that time, ΔFL is the first calibration point when an adjacent calibration point on the first calibration curve and the second calibration curve are both the first calibration point, the rising and falling current FL0 is the ordinate of the first calibration point on the first calibration curve, and the output time t is the ordinate of the first calibration point on the second calibration curve.

[0032] when Greater than At that time, ΔFL is the Nth calibration point, which is an adjacent calibration point on both the first and second calibration curves. The rising and falling current FL0 is the ordinate of the Nth calibration point on the first calibration curve, and the output time t is the ordinate of the Nth calibration point on the second calibration curve.

[0033] According to some preferred embodiments of the present invention, in the first calibration curve and the second calibration curve, the absolute values ​​of the abscissas of the N calibration points gradually increase from the first calibration point to the Nth calibration point, and the absolute values ​​of the ordinates of the N calibration points gradually increase or decrease from the first calibration point to the Nth calibration point. Specifically, for the case FL2 > FL1, that is, when ΔFL is greater than 0, in the first calibration curve and the second calibration curve, the absolute values ​​of the abscissas of the N calibration points gradually increase from the first calibration point to the Nth calibration point, and the absolute values ​​of the ordinates of the N calibration points gradually increase from the first calibration point to the Nth calibration point. When FL2 < FL1, i.e. ΔFL is less than 0, in the first and second calibration curves, the absolute values ​​of the abscissas of the N calibration points gradually increase from the first calibration point to the Nth calibration point. In the first calibration curve, the absolute values ​​of the ordinates of the N calibration points gradually decrease from the first calibration point to the Nth calibration point. In the second calibration curve, the absolute values ​​of the ordinates of the N calibration points gradually increase from the first calibration point to the Nth calibration point.

[0034] According to some preferred embodiments of the present invention, the step prior to the first exposure step further includes the following steps:

[0035] Determine and set the parameters for the first and second exposures. When the high-voltage generator receives the control signal for the first exposure, calculate the filament current FL1 required for the X-ray tube during the first exposure. Set the filament current FL1 and simultaneously drive the rotor of the X-ray tube to start rotating until the X-ray tube filament is preheated with the filament current FL1 and the rotor is accelerated, and then perform the first exposure.

[0036] According to some preferred embodiments of the present invention, the first exposure parameters include the X-ray tube voltage U1 and the X-ray tube current I1, and the second exposure parameters include the X-ray tube voltage U2 and the X-ray tube current I2; the filament current FL1 is obtained by fitting the X-ray tube type, the X-ray tube voltage U1, and the X-ray tube current I1 into the X-ray tube parameter calibration table, and the filament current FL2 is obtained by fitting the X-ray tube type, the X-ray tube voltage U2, and the X-ray tube current I2 into the X-ray tube parameter calibration table. In some embodiments of the present invention, the calculation methods of FL1 and FL2 are conventional techniques in the art. The X-ray tube parameter calibration table is calculated by the following method (taking a voltage of 40kV as an example): At 40kV, the filament current of the X-ray tube is increased in increments of 20mA from the standby current of 2.5A until 5A (the maximum allowable current of the filament). All filament currents and corresponding X-ray tube currents during the exposure process are recorded, and then linear fitting is performed to obtain the filament currents corresponding to the X-ray tube in the range of 10mA to 1000mA. The filament currents of each R20 priority number current are stored to obtain the parameter calibration table at 40kV. The parameter calibration tables for voltages of 50kV, 60kV, 70kV, 80kV, 90kV, 100kV, 110kV and 125kV are obtained respectively according to the aforementioned method, and finally the total X-ray tube parameter calibration table is obtained.

[0037] Preferably, in some embodiments of the present invention, the dual-energy exposure mode can be either high-energy exposure followed by low-energy exposure, or low-energy exposure followed by high-energy exposure. Specifically, for the high-energy exposure followed by low-energy exposure mode, the X-ray tube voltage U1 is 110-150kV, the X-ray tube current I1 is 100-630mA, the X-ray tube voltage U2 is 60-90kV, and the X-ray tube current I2 is 20-800mA. For the low-energy exposure followed by high-energy exposure mode, the X-ray tube voltage U1 is 60-90kV, the X-ray tube current I1 is 20-800mA, the X-ray tube voltage U2 is 110-150kV, and the X-ray tube current I2 is 100-630mA.

[0038] According to some preferred embodiments of the present invention, the temperature of the X-ray tube filament at the end of the first exposure is T1, the temperature of the X-ray tube filament after being loaded with a rising and falling current FL0 and continuously output for a time t is T2, the temperature required for the X-ray tube filament during the second exposure is T3, and the filament current FL1 is used to raise the temperature of the X-ray tube filament to T1 for the first exposure.

[0039] According to some preferred embodiments of the present invention, when FL2 > FL1, T1 is less than T2, T2 is less than T3, and the X-ray tube filament is subjected to a rising and falling current FL0 and continuously output for a time t to raise the temperature of the X-ray tube filament from T1 to T2.

[0040] According to some preferred embodiments of the present invention, when FL2 < FL1, T1 is greater than T2 and T3, T2 is greater than T3, and the X-ray tube filament is loaded with a rising and falling current FL0 and continuously output for a time t, so that the temperature of the X-ray tube filament drops from T1 to T2.

[0041] Compared with the prior art, the advantages of the present invention are as follows: The control method of the X-ray tube filament for dual-energy exposure of the present invention, by setting an output time t of rising and falling current FL0 between the first and second exposures, is used for short-term overheating or cooling of the X-ray tube filament, ensuring that the filament has sufficient time to heat or cool before the second exposure, and that this output time t is neither too long nor too short. Without increasing hardware costs, the dual-energy exposure time interval can be shortened to reduce motion artifacts, while effectively suppressing X-ray tube current overshoot or undershoot during the second exposure, making the X-ray dose more accurate, which is beneficial to enhancing X-ray imaging quality and reducing unnecessary radiation doses received by patients. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart illustrating the control method for X-ray tube filaments applicable to dual-energy exposure according to the present invention.

[0044] Figure 2 This is a schematic diagram illustrating the principle of dual-energy exposure control in Embodiment 1 of the present invention;

[0045] Figure 3 This is a schematic diagram illustrating the principle of dual-energy exposure control in Embodiment 2 of the present invention;

[0046] Figure 4 This is a schematic diagram illustrating the principle of dual-energy exposure control in Comparative Example 1 of the present invention;

[0047] Figure 5 This is a schematic diagram illustrating the principle of dual-energy exposure control in Comparative Example 2 of the present invention;

[0048] Figure 6 This is the first calibration curve diagram in Embodiment 1 of the present invention;

[0049] Figure 7 This is the second calibration curve diagram in Embodiment 1 of the present invention;

[0050] Figure 8 This is the first calibration curve diagram in Embodiment 2 of the present invention;

[0051] Figure 9 This is the second calibration curve diagram in Embodiment 2 of the present invention. Detailed Implementation

[0052] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention. Example 1

[0053] like Figure 1 As shown, this embodiment provides a control method for the filament of an X-ray tube suitable for dual-energy exposure. The X-ray tube model is Canon E7869X, and the high-voltage generator has a power of 80kW. In this embodiment, the dual-energy exposure mode is high-energy exposure followed by low-energy exposure. By consulting the X-ray tube parameter calibration table and combining multiple experiments, the first and second calibration curves in this embodiment are obtained as shown below. Figure 6 and Figure 7 As shown, the specific control method includes the following steps:

[0054] Step 1: Determine and set the parameters for the first and second exposures, ensuring that both parameters are within the current and voltage range of the high-voltage generator. The parameters for the first exposure include the X-ray tube voltage U1, the X-ray tube current I1, and the first exposure time. The parameters for the second exposure include the X-ray tube voltage U2, the X-ray tube current I2, and the second exposure time. In this embodiment, the X-ray tube voltage U1 is 130kV, the X-ray tube current I1 is 180mA, the first exposure time is 50ms, the X-ray tube voltage U2 is 80kV, the X-ray tube current I2 is 250mA, and the second exposure time is 50ms.

[0055] Step 2: When the high-voltage generator receives the first exposure control signal, it fits the X-ray tube voltage of 130kV and the X-ray tube current of 180mA from Step 1 into the X-ray tube parameter calibration table to calculate the required X-ray tube filament current FL1 for the first exposure as 3999mA. The filament current FL1 is then set, and the rotor of the X-ray tube is driven to start rotating until the X-ray tube filament is preheated to T1 by applying the filament current FL1 and the rotor accelerates. The high-voltage generator then generates high voltage and outputs it to the X-ray tube at 130kV for the first exposure. At this time, the tube current is 180mA. After the high-voltage output time reaches 50ms, the high-voltage output is turned off, and the first exposure ends.

[0056] Step 3: Based on the X-ray tube voltage of 80kV and X-ray tube current of 250mA from Step 1, fit the parameters in the X-ray tube parameter calibration table to calculate the required X-ray tube filament current FL2 for the second exposure as 4136mA. Further calculation yields ΔFL = FL2 - FL1 = 4136mA - 3999mA = 137mA. Within the range of 100mA to 200mA, according to... Figure 6 and Figure 7 As shown in the first and second calibration curves, in this embodiment, the two adjacent calibration points of ΔFL on the first and second calibration curves are the first calibration point and the second calibration point.

[0057] Therefore, the rise and fall current FL0 of the X-ray tube filament is calculated using the following formula:

[0058] ;

[0059] The first calibration point on the first calibration curve has an abscissa of 100mA and an ordinate of 1.1×FL2, and the second calibration point on the first calibration curve has an abscissa of 200mA and an ordinate of 1.15×FL2. Thus, FL0 is calculated to be 4626mA.

[0060] The output time t is calculated using the following formula:

[0061] ;

[0062] The first calibration point on the second calibration curve has an abscissa of 100mA and an ordinate of 60ms, and the second calibration point on the second calibration curve has an abscissa of 200mA and an ordinate of 65ms. Therefore, t is calculated to be 61.85ms.

[0063] Step 4: Set the X-ray tube filament rise / fall current FL0 to 4626mA and its output time t to 61.85ms. Then set the filament current FL2 for the second exposure to 4136mA. Apply a rise / fall current of 4626mA to the X-ray tube filament to continuously heat it for 61.85ms until the filament temperature reaches T2. Then apply a filament current of 4136mA to preheat the filament until the temperature reaches T3. When the high-voltage generator receives the second exposure control signal, it turns on and generates high voltage, outputting 80kV to the X-ray tube for the second exposure. At this time, the tube current is 250mA. After the high-voltage output time reaches 50ms, the high-voltage output is turned off, and the second exposure ends. Then set the tube filament current to the standby current (2500mA) to enter standby mode.

[0064] In this embodiment, dual-energy exposure is performed according to... Figure 2 The control principle shown is to precisely set a rising and falling current FL0 (4626mA) for a duration of t (61.85ms) between the first and second exposures for short-term overheating of the X-ray tube filament, which can effectively solve the problem of insufficient X-ray tube current during the second exposure.

[0065] Example 2

[0066] like Figure 1 As shown, this embodiment provides a control method for the filament of an X-ray tube suitable for dual-energy exposure. The X-ray tube model is Canon E7869X, and the high-voltage generator has a power of 80kW. In this embodiment, the dual-energy exposure mode is low-energy exposure followed by high-energy exposure. By consulting the X-ray tube parameter calibration table and combining multiple experiments, the first and second calibration curves in this embodiment are obtained as shown below. Figure 8 and Figure 9 As shown, the specific control method includes the following steps:

[0067] Step 1: Determine and set the parameters for the first and second exposures, ensuring that both parameters are within the current and voltage range of the high-voltage generator. The parameters for the first exposure include the X-ray tube voltage U1, the X-ray tube current I1, and the first exposure time. The parameters for the second exposure include the X-ray tube voltage U2, the X-ray tube current I2, and the second exposure time. In this embodiment, the X-ray tube voltage U1 is 65kV, the X-ray tube current I1 is 200mA, the first exposure time is 50ms, the X-ray tube voltage U2 is 130kV, the X-ray tube current I2 is 125mA, and the second exposure time is 50ms.

[0068] Step 2: When the high-voltage generator receives the first exposure control signal, it fits the X-ray tube voltage of 65kV and the X-ray tube current of 200mA from Step 1 into the X-ray tube parameter calibration table to calculate the required X-ray tube filament current FL1 for the first exposure as 4235mA. The filament current FL1 is then set, and the rotor of the X-ray tube is driven to start rotating until the X-ray tube filament is preheated by the filament current FL1 to reach the filament temperature T1 and the rotor acceleration is complete. The high-voltage generator generates high voltage and outputs it to the X-ray tube at 65kV for the first exposure. At this time, the tube current is 200mA. After the high-voltage output time reaches 50ms, the high-voltage output is turned off, and the first exposure ends.

[0069] Step 3: Based on the X-ray tube voltage of 130kV and current of 125mA from Step 1, fit the parameters in the X-ray tube parameter calibration table to calculate the required X-ray tube filament current FL2 for the second exposure as 4003mA. Further calculation yields ΔFL = FL2 - FL1 = 4003mA - 4235mA = -232mA. Within the range of -200mA to -300mA, according to... Figure 8 and Figure 9 As shown in the first and second calibration curves, in this embodiment, the two adjacent calibration points of ΔFL on the first and second calibration curves are both the second and third calibration points.

[0070] Therefore, the rise and fall current FL0 of the X-ray tube filament is calculated using the following formula:

[0071] ;

[0072] The second calibration point on the first calibration curve has an abscissa of -200mA and an ordinate of 0.85×FL2, and the third calibration point on the first calibration curve has an abscissa of -300mA and an ordinate of 0.8×FL2. Thus, FL0 is calculated to be 3338.5mA.

[0073] The output time t is calculated using the following formula:

[0074] ;

[0075] The second calibration point on the second calibration curve has an abscissa of -200mA and an ordinate of 55ms, and the third calibration point on the second calibration curve has an abscissa of -300mA and an ordinate of 60ms. Therefore, t is calculated to be 56.6ms.

[0076] Step 4: Set the X-ray tube filament rise / fall current FL0 to 3338.5mA and the output time t of the rise / fall current FL0 to 56.6ms. Then set the filament current FL2 of the tube during the second exposure to 4003mA, so that the X-ray tube filament is subjected to a rise / fall current of 3338.5mA to continuously cool for 56.6ms until the filament temperature reaches T2. Then apply a filament current of 4003mA to make the filament temperature reach T3. When the high voltage generator receives the control signal for the second exposure, the high voltage generator turns on and generates high voltage, outputting a voltage of 130kV to the X-ray tube for the second exposure. At this time, the tube current is 125mA. When the high voltage output time reaches 50ms, the high voltage output is turned off, and the second exposure ends. Then set the current of the X-ray tube filament to the standby current (2500mA) and enter standby mode.

[0077] In this embodiment, dual-energy exposure is performed according to... Figure 3 The control principle is as shown. By precisely setting a rise and fall current FL0 (3338.5mA) for a duration of t (56.6ms) between the first and second exposures, a short-term supercooling of the X-ray tube filament is used, which can effectively solve the problem of X-ray tube current overshoot during the second exposure.

[0078] Comparative Example 1

[0079] The process is basically the same as in Example 1, except that: in step (3), the rise and fall current FL0 and output time t of the X-ray tube filament are not calculated, and in step (4), the rise and fall current FL0 and output time t of the X-ray tube filament are not set; instead, the filament current FL2 is used directly for preheating until the filament temperature reaches T3. The control principle of dual-energy exposure in Comparative Example 1 is as follows: Figure 4 As shown.

[0080] Comparative Example 2

[0081] The process is basically the same as in Example 2, except that: in step (3), the rise and fall current FL0 and output time t of the X-ray tube filament are not calculated, and in step (4), the rise and fall current FL0 and output time t of the X-ray tube filament are not set; instead, the filament current FL2 is used directly for cooling until the filament temperature reaches T3. The control principle of dual-energy exposure in Comparative Example 2 is as follows: Figure 5 As shown.

[0082] Depend on Figure 2 and Figure 4A comparison reveals that in Comparative Example 1, when preheating is performed directly with filament current FL2 before the second exposure, the filament temperature of the X-ray tube does not reach T3 when the high-voltage generator receives the second exposure signal and begins the second exposure; instead, it is lower than T3. This means the filament temperature is too low at the start of the second exposure, leading to insufficient X-ray tube current. In Embodiment 1 of this invention, a rising and falling current FL0 with a continuous output time t is set between the first and second exposures to overheat the filament and bring its temperature closer to the target temperature T3 in advance. Therefore, when preheating with filament current FL2, the filament temperature can be quickly heated to the target temperature T3, ensuring that the filament temperature has reached T3 before the high-voltage generator receives the second exposure signal and begins the second exposure.

[0083] Depend on Figure 3 and Figure 5 A comparison reveals that in Comparative Example 2, when cooling is performed directly with filament current FL2 before the second exposure, the filament temperature of the X-ray tube does not reach T3 but is higher than T3 when the high-voltage generator receives the second exposure signal and begins the second exposure. This means the filament temperature is too high at the start of the second exposure, leading to X-ray tube current overshoot. In Embodiment 2 of this invention, a continuous output current FL0 with a duration of t is provided between the first and second exposures to overcool the filament, bringing its temperature closer to the target temperature T3 earlier. Therefore, when further cooling is performed with filament current FL2, the filament temperature quickly reaches the target temperature T3, ensuring that the filament temperature reaches T3 before the high-voltage generator receives the second exposure signal and begins the second exposure.

[0084] The present invention provides a control method for X-ray tube filaments suitable for dual-energy exposure. Without increasing hardware costs, it precisely sets a rising and falling current FL0 with a continuous output time of t between the first and second exposures. This current is used for short-term overheating or cooling of the X-ray tube filament, which shortens the dual-energy exposure time interval to reduce motion artifacts. At the same time, it effectively suppresses X-ray tube current overshoot or undershoot during the second exposure, making the X-ray dose more accurate. This is beneficial for improving X-ray imaging quality and reducing unnecessary radiation doses to patients.

[0085] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for controlling the filament of an X-ray tube suitable for dual-energy exposure, characterized in that: Includes the following steps: The first exposure is performed, and the filament current of the X-ray tube during the first exposure is FL1; After the first exposure, the high voltage output is turned off. The rising and falling current FL0 of the X-ray tube filament, the output time t of the rising and falling current FL0, and the filament current FL2 of the X-ray tube during the second exposure are determined and set. The rising and falling current FL0 is used to heat up or cool down the X-ray tube filament. After the X-ray tube filament is subjected to a rising and falling current FL0 and continuously output for a time t, the X-ray tube filament is subjected to a filament current FL2 and continuously output for a period of time before the second exposure is performed. When FL2 > FL1, FL0 > FL1 and FL0 > FL2; when FL2 < FL1, FL0 < FL1 and FL0 < FL2, let FL2 - FL1 = ΔFL, where ΔFL ≠ 0. When ΔFL is greater than 0, the rising / falling current FL0 and its output time t are both positively correlated with ΔFL; when ΔFL is less than 0, the rising / falling current FL0 and its output time t are both positively correlated with ΔFL. The output time t of the rising and falling current FL0 is negatively correlated with... Positive correlation; The method for determining the rise and fall current FL0 of the X-ray tube filament and the output time t of the rise and fall current FL0 is as follows: N calibration points are determined based on the type and accuracy requirements of the X-ray tube. A first calibration curve and a second calibration curve are plotted based on the N calibration points. The value of N increases with the increase of accuracy. Then, based on ΔFL, determine one or two adjacent calibration points on the first calibration curve and the second calibration curve respectively, and obtain the rising and falling current FL0 and the output time t; The first calibration curve is the rise / fall current FL0 x Regarding the difference in filament current ΔFL x The relationship curve diagram, the second calibration curve is the output time t x Regarding the difference in filament current ΔFL x The relationship curve is given, where N is a positive integer greater than or equal to 2, and x is a positive integer greater than or equal to 1 and less than or equal to N.

2. The control method according to claim 1, characterized in that: The rise and fall current FL0 is less than or equal to the maximum allowable current of the X-ray tube filament.

3. The control method according to claim 1, characterized in that: when Less than and Greater than At that time, based on ΔFL, two adjacent calibration points on the first calibration curve and the second calibration curve are determined, including the following steps: Determine ΔFL on the X-axis of the first calibration curve and the second calibration curve respectively. x =The position of ΔFL, and respectively on their respective X-axis by ΔFL x Draw a straight line x=ΔFL at x=ΔFL. Based on the intersection points of the straight line with the first calibration curve and the second calibration curve, determine the two adjacent calibration points of ΔFL on the first calibration curve and the two adjacent calibration points on the second calibration curve.

4. The control method according to claim 3, characterized in that: The rise / fall current FL0 is calculated using the following formula: ； In the formula, and These are the ordinates of the nth and (n-1)th calibration points on the first calibration curve, respectively. and These are the absolute values ​​of the abscissas of the nth and (n-1)th calibration points in the first calibration curve, respectively.

5. The control method according to claim 3, characterized in that: The output time t is calculated using the following formula: ； In the formula, and These are the ordinates of the nth and (n-1)th calibration points in the second calibration curve, respectively. and These are the absolute values ​​of the abscissas of the nth and (n-1)th calibration points in the second calibration curve, respectively.

6. The control method according to claim 4 or 5, characterized in that: 2≤n≤N, ≤ ≤ And the (n-1)th calibration point and the nth calibration point are two adjacent calibration points corresponding to ΔFL on the first calibration curve and / or the second calibration curve.

7. The control method according to claim 1, characterized in that: when Less than ,or, Greater than At that time, a calibration point adjacent to it on the first calibration curve and the second calibration curve is determined according to ΔFL.

8. The control method according to claim 7, characterized in that: when Less than At that time, ΔFL is the first calibration point when an adjacent calibration point on the first calibration curve and the second calibration curve are both the first calibration point, the rising and falling current FL0 is the ordinate of the first calibration point on the first calibration curve, and the output time t is the ordinate of the first calibration point on the second calibration curve. when Greater than At that time, ΔFL is the Nth calibration point, which is an adjacent calibration point on both the first and second calibration curves. The rising and falling current FL0 is the ordinate of the Nth calibration point on the first calibration curve, and the output time t is the ordinate of the Nth calibration point on the second calibration curve.

9. The control method according to claim 1, characterized in that: In the first calibration curve and the second calibration curve, the absolute values ​​of the abscissas of the N calibration points gradually increase from the first calibration point to the Nth calibration point, and the absolute values ​​of the ordinates of the N calibration points gradually increase or decrease from the first calibration point to the Nth calibration point.

10. The control method according to claim 1, characterized in that: The following steps are included before the first exposure step: Determine and set the parameters for the first and second exposures. When the high-voltage generator receives the control signal for the first exposure, calculate the filament current FL1 required for the X-ray tube during the first exposure. Set the filament current FL1 and simultaneously drive the rotor of the X-ray tube to start rotating until the X-ray tube filament is preheated with the filament current FL1 and the rotor is accelerated, and then perform the first exposure.

11. The control method according to claim 10, characterized in that: The first exposure parameters include the X-ray tube voltage U1 and the X-ray tube current I1, and the second exposure parameters include the X-ray tube voltage U2 and the X-ray tube current I2; the filament current FL1 is obtained by fitting the X-ray tube type, X-ray tube voltage U1 and X-ray tube current I1 into the X-ray tube parameter calibration table, and the filament current FL2 is obtained by fitting the X-ray tube type, X-ray tube voltage U2 and X-ray tube current I2 into the X-ray tube parameter calibration table.

12. The control method according to claim 1, characterized in that: The temperature of the X-ray tube filament at the end of the first exposure is T1. The temperature of the X-ray tube filament after applying the rising and falling current FL0 and continuously outputting it for time t is T2. The temperature required for the X-ray tube filament to perform the second exposure is T3. The filament current FL1 is used to raise the temperature of the X-ray tube filament to T1 for the first exposure.

13. The control method according to claim 12, characterized in that: When FL2 > FL1, T1 is less than T2, and T2 is less than T3, the X-ray tube filament is loaded with a rising and falling current FL0 and continuously output for a time t to raise the temperature of the X-ray tube filament from T1 to T2.

14. The control method according to claim 12, characterized in that: When FL2 < FL1, T1 is greater than T2 and T3, and T2 is greater than T3. The X-ray tube filament is loaded with a rising and falling current FL0 and continuously output for a time t, so that the temperature of the X-ray tube filament drops from T1 to T2.

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