Method, Controller, X-ray Device, Control Program and Storage Medium for Setting Filament Requirements in an X-ray Device

Abstract

The present disclosure provides a method for setting a filament requirement in an X-ray device. The X-ray device has a filament, and a heating current flowing through the filament allows thermionic emission of electrons from the filament. The X-ray device has a target arranged to be able to generate X-rays based on electrons emitted from the filament. The X-ray device has a detector arranged to be able to detect the X-rays generated by the target to form an X-ray image. The X-ray device has a controller configured to perform a measurement operation of the X-ray device. The measurement operation measures a parameter of the X-ray device. The controller is configured to be able to set the filament requirement of the filament. The filament requirement is related to the current flowing through the filament. The method includes changing the filament requirement between a first value corresponding to a lower filament current and a second value corresponding to a higher filament current. The method includes measuring the parameter at a series of values of the filament requirement between the first value and the second value. The method includes detecting an inflection point in the measured parameter. The method includes determining the filament requirement corresponding to the detected inflection point in the parameter. The method includes setting the filament requirement for the X-ray device based on the determined filament requirement corresponding to the detected inflection point in the parameter.

Description

Technical Field

[0001] The present invention relates to a method for setting a filament requirement in an X-ray device, a controller for an X-ray device, an X-ray device, a control program for an X-ray device, and a non-transitory storage medium including embodiments implementing these methods. Background Art

[0002] In an X-ray device, a filament is heated by a heating current to allow thermionic emission of electrons from the filament. These electrons are accelerated under an accelerating voltage to strike a target including elements with a relatively high atomic number (high Z), thereby generating an X-ray beam from the target. Such an X-ray beam can be directed to a sample of interest, and the transmitted X-rays are detected by a detector to form, for example, an image. Since different materials attenuate X-rays to different degrees, such images can be used to illustrate the structure of the sample.

[0003] Generally, in an X-ray device, it is desirable to obtain a high-quality image. One of the parameters affecting the quality of the obtained image is the temperature of the filament, because this determines the number of electrons generated at the filament by thermionic emission. However, it is difficult for a user to correctly set the filament temperature to obtain a suitable image quality.

[0004] Generally, the filament in an X-ray device is heated by passing a current through the filament, thereby heating the filament by resistive heating. The current supplied to the filament or a quantity related thereto is generally referred to as the filament requirement.

[0005] Generally, a user needs a high skill level to appropriately set the filament requirement. The process is labor-intensive and typically requires a high level of understanding of the X-ray device and the physics behind it. This limits the usability of X-ray systems and makes the development of highly automated or turn-key X-ray systems difficult.

[0006] Therefore, there is a need for an improved method for setting the filament requirement in an X-ray device, and an improved X-ray device and its components capable of implementing such a method.

[0007] In particular, there is a need for an X-ray device having one or more of lower complexity for the user, a higher degree of automation, a longer and more reliable filament life, a greater degree of assurance of correct operation of the device, and a more reliable image quality, especially an X-ray device that can simultaneously meet one or more of these requirements. Summary of the Invention

[0008] According to a first aspect of the present invention, a method of setting a filament requirement in an X-ray device is provided. The X-ray device has a filament, and a heating current flowing through the filament allows thermionic emission of electrons from the filament. The X-ray device has a target arranged to be able to generate X-rays based on the electrons emitted from the filament. The X-ray device has a detector arranged to be able to detect the X-rays generated by the target to form an X-ray image. The X-ray device has a controller configured to be able to perform a measurement operation of the X-ray device. The measurement operation measures a parameter of the X-ray device. The controller is configured to be able to set the filament requirement of the filament. The filament requirement is related to the current flowing through the filament. The method includes changing the filament requirement between a first value corresponding to a lower filament current and a second value corresponding to a higher filament current. The method includes measuring the parameter at a series of values of the filament requirement between the first value and the second value. The method includes detecting an inflection point in the measured parameter. The method includes determining the filament requirement corresponding to the detected inflection point in the parameter. The method includes setting the filament requirement for the X-ray device based on the determined filament requirement corresponding to the detected inflection point in the parameter.

[0009] The controller may be configured to be able to determine the parameter based on the detection of X-rays by the detector.

[0010] The parameter may be an objective measure of image quality.

[0011] The parameter may be related to one of sharpness, noise, dynamic range, resolution, or contrast of an X-ray image derived from the X-rays received by the detector.

[0012] The parameter may be related to the contrast-to-noise ratio of an X-ray image derived from the X-rays received by the detector.

[0013] The parameter may be related to the intensity of the X-rays received by the detector.

[0014] The parameter may be a measure of the contrast-to-noise value in an X-ray image derived from the X-rays received by the detector.

[0015] The parameter may be related to the beam current between the filament and the target, the electron beam spot size on the target, or the electron beam spot intensity on the target.

[0016] The step of setting the filament requirement may include setting a filament requirement equal to the filament requirement corresponding to the identified inflection point.

[0017] The step of setting the filament requirement may include setting a filament requirement that is lower than the filament requirement corresponding to the identified inflection point by a predetermined ratio or absolute amount.

[0018] The step of setting the filament requirement may include setting a filament requirement that is higher than the filament requirement corresponding to the identified inflection point by a predetermined ratio or absolute amount.

[0019] The identification of the inflection point may include determining the slope of the measured parameter with respect to the filament demand. The step of identifying the inflection point may include selecting a filament demand value as the inflection point value based on the determined curvature.

[0020] The identification of the inflection point may include determining the value of the following filament demand between the first value and the second value: at which value, the slope of the determined measured parameter decreases to a set percentage of the maximum slope of the measured parameter.

[0021] The determined point is the first such determined value in sequence between the first value and the second value.

[0022] The filament demand may represent a set filament operating current.

[0023] The filament demand may represent a set filament operating voltage.

[0024] The method may be repeated at intervals during the service life of the filament.

[0025] The interval may be a predetermined interval based on the clock time elapsed since the previous repetition of the method of the first aspect.

[0026] The interval may be a predetermined interval based on the operating time elapsed since the previous repetition of the method of the first aspect.

[0027] The method may further include a process of calculating the remaining life of the filament based on a set filament demand.

[0028] The process of calculating the remaining life of the filament may include comparing the set filament demand with a predetermined representation that correlates the set filament demand with the filament life. The process of calculating the remaining life of the filament may include determining the remaining life of the filament based on this comparison.

[0029] For each repetition or subset of repetitions of the set filament demand, record the set filament demand and the cumulative operating time of the filament. The process of calculating the remaining life of the filament may include comparing the representation of the set filament demand according to the cumulative operating time with a predetermined representation of the expected set filament demand with respect to the operating time. The process of calculating the remaining life of the filament may include determining the filament life based on this comparison.

[0030] The predetermined representation of the set filament demand with respect to the remaining life of the filament may be an analytical representation.

[0031] The predetermined representation of the set filament demand with respect to the remaining life of the filament may be a curve or a set of values.

[0032] The predetermined representation of the set filament demand with respect to the remaining life of the filament may be determined theoretically.

[0033] A predetermined representation of the set filament demand relative to the remaining life of the filament can be determined empirically.

[0034] The predetermined representation can be established based on information that correlates the set filament demand with the remaining life of the filament based on a series of received values for filament demand and filament life.

[0035] The predetermined representation can be established based on previously recorded values of the set filament demand and the cumulative operating time of the filament pre-installed in the X-ray device.

[0036] After a change in the beam current between the filament and the target or the potential between the filament and the target, the filament demand can be changed to a different filament demand.

[0037] The filament demand can be changed to a different filament demand by repeating the steps of changing, detecting, determining, and setting of the first aspect.

[0038] The filament demand can be changed to a different filament demand based on a predetermined relationship between the filament demand, the beam current, and the potential.

[0039] The predetermined relationship can be a relationship between the filament demand and one of the beam current and the potential, with a ratio associated with the other of the beam current and the potential.

[0040] The predetermined relationship can be determined by defining a mapping of the filament demand for each pair of beam current and potential.

[0041] According to a second aspect of the present invention, there is provided a controller for an X-ray device. The controller includes a data processing device configured to enable the X-ray device to perform the method according to the first aspect.

[0042] According to a third aspect of the present invention, there is provided an X-ray device including the controller according to the second aspect.

[0043] According to a fourth aspect of the present invention, there is provided a control program for an X-ray device. The control program includes machine-readable instructions that, when executed, cause the X-ray device to perform the method according to the first aspect.

[0044] According to a fifth aspect of the present invention, there is provided a non-transitory storage medium storing the control program according to the fourth aspect.

[0045] By applying the present invention according to any one of the first to fifth aspects or their embodiments and implementations, improvements can be obtained in setting the filament requirements in an X-ray device, as well as improvements in filament life and in predicting the remaining life of the filament. These improvements will be apparent to those skilled in the art in view of the following exemplary, illustrative, and non-limiting description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] For a better understanding of the present invention and to show how it may be implemented, reference will be made only by way of example to the accompanying drawings, in which:

[0047] Figure 1 A schematic diagram of an X-ray device implementing the present invention is shown;

[0048] Figure 2 A schematic diagram of a controller of an X-ray device for implementing the present invention is shown;

[0049] Figure 3 The relationship between parameter P and filament demand I is shown in schematic form, with the variation of parameter P with filament demand I from an initial value to a final value shown on the left axis, and the variation of the slope or first derivative of parameter P with filament demand I corresponding to the respective variation shown on the right axis; f from an initial value to a final value, and the variation of the slope or first derivative of parameter P with filament demand I corresponding to the respective variation shown on the right axis; f from an initial value to a final value shown on the left axis, and the variation of the slope or first derivative of parameter P with filament demand I corresponding to the respective variation shown on the right axis; f corresponding variation;

[0050] Figure 4A The potential at the filament in a state corresponding to Figure 3 the state I shown is shown;

[0051] Figure 4B The potential at the filament in a state corresponding to Figure 3 the state II shown is shown;

[0052] Figure 4C The potential at the filament in a state corresponding to Figure 3 the state III shown is shown;

[0053] Figure 5A A flowchart showing the steps of a setting method as an embodiment of the present invention is shown;

[0054] Figure 5B A flowchart showing the steps of a setting method as a variant of an embodiment of the present invention is shown;

[0055] Figure 6 The relationship between parameter P and filament demand I at a series of time points during the service life of the filament is shown; f is shown;

[0056] Figure 7The relationship between suitable filament requirements and filament operating time is shown in the form of a curve;

[0057] Figure 8 A flowchart showing the steps of an estimation method for filament life as an embodiment of the present invention is shown;

[0058] Figure 9 The beam voltage V between the filament and, for example, the anode is shown B and the beam current I between the filament and, for example, the anode B and the relationship between the suitable filament requirement I f is shown; and

[0059] Figure 10 The curve of the parameter P and the filament requirement I are shown f and the relationship between the parameter P and the filament requirement I f and the first derivative and higher-order derivatives of the parameter P with respect to the filament requirement I and the filament requirement I f are shown. Detailed Description of the Invention

[0060] Figure 1 The configuration of an X-ray device in which the present invention can be implemented is shown. The X-ray device 100 has an X-ray generator 110 that emits an X-ray beam B towards an X-ray detector 130 X

[0061] The X-ray device 100 further includes a sample stage 120 that is arranged to support a sample S to be observed in the path of the X-ray beam B from the X-ray generator 110 to the X-ray detector 130 X

[0062] The X-ray detector 130 is arranged to be able to generate image data D based on the X-rays of the X-ray beam B that has passed through the sample S received at the X-ray detector 130 X and make the image data D IMG available for further processing. The image represented by the image data D IMG can reveal details of the internal structure and composition of the sample S. IMG

[0063] ​​​The X-ray generator 110 is provided with a filament 111, which is formed of a metal that is relatively easy to undergo thermionic emission, such as tungsten. As an alternative, a composite filament can be used, such as a filament coated with a material that is relatively easy to undergo thermionic emission, such as tungsten, by a metal having a relatively high resistance, such as nichrome. Also known and available are doped filaments that contain a small percentage of another material, such as a filament formed of tungsten and approximately 2% thorium. Such filaments can exhibit improved thermionic emission characteristics. The filament 111 is set to a negative potential to facilitate the thermionic emission of electrons. This negative potential is typically selected by the user of the X-ray device according to the desired X-ray emission spectrum and intensity, and can be set, for example, to -160 keV.

[0064] Arranged around the filament 111 and extending slightly behind the filament 111 is a grid 112, sometimes referred to as a Wehnelt, which provides a local negative potential around the filament to repel the electrons emitted by the filament to form an electron beam B that travels away from the filament. e The form of the grid well-known to those skilled in the art is also used as a converging electrostatic lens to converge the emitted electrons into a beam.

[0065] Another function provided by the grid 112 is to regulate the electron beam current from the filament 111 as the temperature of the filament 111 changes, so that the number of free electrons emitted by the filament 111 changes. For a given filament temperature, the potential of the grid 112 relative to the potential of the filament 111 controls the equipotential lines near the tip of the filament 111. If the grid 112 becomes more negative, the equipotential lines rise towards the tip of the filament, such that fewer of the free electrons generated at the filament tip are accelerated to form the electron beam B. e Therefore, when the filament temperature changes, by appropriately controlling the potential of the grid 112 relative to the potential of the filament 111, the electron beam current from the filament 111 can be set to a defined value, called the beam current set point. The potential of the grid can vary, for example, by approximately 1% of the potential of the filament 111. For example, if the potential of the filament 111 is set to -160 keV, the potential of the grid 112 can be adjusted to be at the same or relatively more negative potential as the filament 111. As described below, this adjustment can be automatically performed based on the desired electron beam current.

[0066] Oppositely arranged to the filament 111 is a target 113, which includes an X-ray generating material, such as tungsten, rhodium, or molybdenum, such that the electron beam B incident on the target 113 e causes the emission of an X-ray beam B from the target 113. X The choice of the target material can affect the X-ray emission spectrum. The target 113 can be grounded, or can be connected to a potential different from ground, such as a positive potential, to attract and accelerate the electrons of the electron beam B e towards it.

[0067] Also disposed between the filament 111 and the target 113 is the anode 117. In some embodiments, the anode 117 may be grounded or may be at an adjustable potential to provide further control of the flux and energy of the electrons of the electron beam between the filament 111 and the anode 117. The anode 117 has a disk shape with a through hole in the center and is sized to allow the electron beam to pass through.

[0068] Between the filament 111 and the target 113, on the target side of the anode 117, a focusing coil 114 is also disposed. The current I in the focusing coil 114 l can be adjusted to control the focusing of the electron beam B e impinging on the target 113. The focusing coil 114 has the form of a cylindrical coil and is sized to allow the electron beam B e to pass through.

[0069] The filament 111, the grid 112, the anode 117, the target 113, and the focusing coil 114 are all contained within an enclosure 115, which is sealable to support a vacuum inside. The enclosure 115 can thus be brought to relatively vacuum conditions to allow the electron beam B e to be freely transmitted from the filament 111 to the target 113. Forming part of the enclosure 115 is a window 116, which can be formed of a material that is relatively transmissive to X-rays but relatively opaque to electrons, such as beryllium. The window 116 allows the beam B X to pass through the enclosure 115.

[0070] The entire X-ray device 100 is typically provided with an X-ray-impervious enclosure (not shown), which is used to prevent X-ray leakage outside the X-ray device.

[0071] By passing a current I, which can be an alternating current or can be a direct current, f through the filament, the filament 111 is heated. As described above, to facilitate thermionic emission of electrons from the filament, the filament is set at a relatively negative potential V f . Also as described above, to control the electron emission from the heated filament 111, the grid 112 is set at a negative potential V g , which is typically more negative than the potential V f of the filament. In one embodiment, the target 113 is set at ground potential, but in other embodiments, for example to facilitate electron acceleration onto the target 113, the target 113 can be set at a target potential V t .

[0072] Appropriate electrical connections are provided through the enclosure 115 to connect the various elements of the X-ray generator 110 to the corresponding power supplies to provide the necessary current and potential.

[0073] The current of the focusing coil 114 is set to the focusing current I l .

[0074] Each electrical connection to the X-ray generator 110 is connected to a suitable power supply, such as Figure 2 shown Figure 2 illustrates the power supply and control means of the X-ray apparatus 100.

[0075] For example, the X-ray apparatus is provided with a filament potential power supply 140 that supplies the potential V f to the filament 111. The X-ray apparatus 100 is also provided with a filament current source 150 that supplies the filament current I f through the filament 111. The X-ray apparatus 100 is provided with a grid potential power supply 160 that supplies the grid potential V g to the grid 112. The X-ray apparatus is also provided with an anode potential power supply 165 that supplies the anode potential V a to the anode 117. The X-ray apparatus 100 is also provided with a focusing coil current source 170 that supplies the focusing current I l to the focusing coil 114. The X-ray apparatus 100 is also provided with a target potential power supply 180 that supplies the target potential V t .

[0076] Each of the filament potential power supply 140, the filament current source 150, the grid potential power supply 160, the anode potential power supply 165, the focusing coil current source 170, and the target potential power supply 180 can be provided as discrete units, or can be integrated in an overall power supply section. In one variant, the filament current source 150 and the filament potential power supply 140 can be provided by a common filament current and potential power supply.

[0077] In the disclosed configuration, the filament potential power supply 140, the filament current source 150, the grid potential power supply 160, and the anode potential power supply 165 form part of the overall high voltage generator HVG.

[0078] In the disclosed configuration, the focusing coil current source 170 and the target potential power supply 180 that supplies the target potential V t to the target 113 form part of the overall gun control unit GCU (gun control unit).

[0079] In the disclosed configuration, the gun control unit GCU sends and receives control and status signals from the controller 190 via the control signal C1. The gun control unit GCU has an auxiliary control link C2 for sending control and status signals to the high-voltage generator HVG. Such a signal can be an analog signal, such as an analog potential that varies within a defined range for defining an analog quantity, or such a signal can be a digital signal, such as a digital potential corresponding to a high or low digital value for defining a digital quantity. A combination of analog control signals or digital control signals can also be implemented without limitation.

[0080] In the disclosed configuration, the controller 190 indirectly controls the high-voltage generator HVG, i.e., via the gun control unit GCU as an intermediate. The gun control unit GCU can relay signals to or from the high-voltage generator HVG on behalf of the controller 190, or it can itself implement control functions that could otherwise be performed by the controller 190. The exact distribution of control functions can vary.

[0081] Each of the filament potential power supply 140, the grid potential power supply 160, the focusing coil current source 170, and the target potential power supply 180 is shown as providing its appropriate potential with respect to the ground potential. However, in a variant arrangement, some of the various potential power supplies can be configured to provide the potential assigned to them with respect to one of the other potentials in the system without limitation. In particular, the target potential V t and the anode potential V a can be directly grounded. In some configurations, the current in the focusing coil 114 can be controlled by a potential power supply instead of a current source. In the present embodiment, a DC power supply is used.

[0082] In this configuration, the various power supplies described above are controlled by the controller 190, as Figure 2 shown, the controller 190 includes a central processing unit CPU connected to a memory MEM, an instruction storage INS, an input / output unit IO, a storage controller STC, and a user interface controller UIC.

[0083] Each of the memory MEM, the instruction storage INS, the user interface controller UIC, the storage controller STC, and the input / output unit IO is connected to the central processing unit CPU such that the central processing unit CPU can control and mediate the various functions of the listed elements of the controller 190.

[0084] For example, the instruction storage INS can store machine-readable instructions that determine the operation of the controller 190. The memory MEM can store data values associated with the operation of the controller 190, including parameter values related to the control of the X-ray device and the acquired image data related to the acquired X-ray images. The input / output unit IO can send and receive data between the controller 190 and the elements of the exposure device that are under the control of the controller 190, such elements being, for example, the filament potential power supply 140, the filament current source 150, the grid potential power supply 160, the anode potential power supply 165, the focusing coil current source 170, and the target potential power supply 180, as well as other aspects of the device, without particular limitation. The user interface controller UIC allows the controller 190 to output the user interface output data D UIO to a user interface output unit, such as a display or discrete output elements, such as the visual and auditory elements of a control panel, and to read the user interface input data D from a user interface input unit, which can be, for example, a peripheral device such as a keyboard and / or a mouse, but can also be an interactive input element formed as part of the control panel UII .

[0085] In this configuration, the controller 190 also controls the reading of the image data D from Figure 1 the X-ray detector 130 as shown, IMG as well as the processing of such data. Alternatively, the reading of the data D from the X-ray detector 130 IMG can be performed by a separate image acquisition system or can be arranged in a hybrid configuration in which the controller 190 acquires the image data D from the X-ray detector 130 IMG and then transfers it to another unit for further processing.

[0086] In this configuration, the controller 190 is provided with a storage controller STC that allows the storage data D, which can include the acquired image data D IMG , to be written to an external storage device, such as a hard disk drive or a storage area network. STO Although in this configuration the controller 190 is arranged to be able to control all the material aspects and functions of the X-ray device 100 based on instructions provided by the user via the user interface controller UIC or based on instructions retrieved from the instruction storage INS or a combination of both, the present disclosure relates in one aspect to the use of the controller 190 in the setting of the filament demand, which here corresponds to the setting of the filament current I to be passed through the filament 111.

[0087] The method will be explained with reference to the flowchart of f , and also with reference to the curve of Figure 5A and the schematic diagram of the potential at the filament as shown in Figure 3 and Figures 4A to 4C .

[0088] First, in step S110, the controller establishes the initial settings of the X-ray device 100, such as the filament potential V f , the grid potential V g , the focusing current I l , the anode potential V a and the target potential V t , while maintaining the filament demand I f at a low value I o , such as a zero or initial value that is insufficient to establish a large amount of thermionic emission. Thus, in this state, there is no electron beam current B e or it can be ignored.

[0089] In this embodiment, the filament demand is equivalent to the filament current. In other embodiments, the filament demand can be a quantity related to the filament current, such as the voltage across the filament, or can be any parameter related to the filament current or filament voltage through a scaling and / or offset relationship.

[0090] Some or all of the values of the various potentials V s , V f , V g , V l , V t and the current I l can be set according to predetermined values stored in the memory MEM, such as the last used value or default value, or can be received from a user input device, such as a console or control panel, through the user interface controller UIC according to the expected function of the device. In some embodiments, these values can be directly specified by the user; in other embodiments, these values can be determined by the controller 190 based on required performance parameters, such as the desired beam current I B and the desired beam acceleration potential V B . For example, in a turnkey or highly automated system, these values can be determined based on the user's selection of the imaging operation to be performed.

[0091] Generally, once thermionic emission is established by heating the filament with a sufficient filament current I f at the filament 111 to generate free electrons, these potentials should be able to allow an electron beam to be established between the filament 111 and the anode 117 and ultimately reach the target 113.

[0092] This corresponds to Figure 4A the situation shown, where the grid and the filament are at the same potential and the dashed equipotential lines are on the surfaces of the filament and the grid 112.

[0093] Next, in step S120, the controller 190 changes the filament demand from the previously set value towards a second value If Increases. The second value may represent the maximum acceptable filament current and may similarly be retrieved from the memory MEM or set according to data received by the user interface controller UIC. The second value does not need to be known in advance, and increasing the filament demand without knowing a specific upper limit value is also considered as increasing the filament demand towards the upper limit value.

[0094] As the filament demand increases towards the initial imaging filament demand I i increases, the filament 111 becomes hot enough to generate free electrons. This still corresponds to Figure 4A the situation shown, where the grid and the filament are at the same potential and the dashed equipotential lines are on the surfaces of the filament and the grid 112.

[0095] Finally, the desired beam current is obtained between the filament 111 and the anode 117, which is typically maintained for the correct operation of the X-ray device 100. This may be referred to as the beam current set point and may be determined by the current supplied to the filament.

[0096] When the filament demand reaches the initial imaging filament demand I i , the beam current B e reaches the beam current set point corresponding to the state II shown in Figure 3 , and may also be referred to Figure 4B . In Figure 4B , the grid 112 has a lower potential than the filament 111. Figure 4B The equipotential line represented by the dashed line in Figure 4B is at the filament potential. Electrons emitted below this line will not be accelerated towards the anode 117 and thus not towards the target 113, but electrons emitted above this line will be accelerated towards the anode 117 and thus towards the target 113. It is noted in e that the region of the filament for emitting electrons to form the electron beam B e is large, the electron beam B

[0097] is very divergent and most of the emitted electrons are lost at the anode 117 rather than reaching the target 113 through the anode 117. f According to the well-known Richardson equation, if the filament demand I g is further increased, the free electrons generated by the filament 111 will also increase. The proportion of electrons accelerated towards the target is regulated by the grid potential V Figure 4C . As shown in g a state where the grid potential V Figure 4B is more negative than the state shown in e , the dashed equipotential line is again at the filament potential and electrons emitted below this line are not accelerated towards the anode. The region of the filament for emitting electrons to form the electron beam B Figure 4Bin the region, so the gate potential V g is more negative, the divergence of the electron beam B e is smaller. Therefore, a smaller proportion of the emitted electrons are lost at the anode 117, and a larger proportion of the emitted electrons reach the target 113 through the anode 117.

[0098] To maintain the beam current setpoint at a predetermined level, as the filament demand further increases, the potential V of the gate 112 is gradually adjusted g to maintain the beam current I B at the beam current setpoint. For example, such adjustment can be implemented by means of a feedback loop implemented by the controller 190, the high voltage generator HVG or the gun control unit GCU.

[0099] Therefore, appropriately adjusting the gate potential as described above allows the beam current I to be maintained at the setpoint during the entire adjustment of the filament demand I f . Moreover, as the filament demand I B increases, due to the adjustment of the gate potential V f , the region where the filament emits electrons to form the electron beam B g becomes smaller, the divergence of the electron beam B e becomes smaller, and a larger proportion of the emitted electrons reach the target 113 through the anode 117. e

[0100] Once the beam current B e reaches the beam current setpoint corresponding to Figure 3 the state II shown, also refer to Figure 4B , in step S130, the controller 190 further increases the filament demand from the first value corresponding to the initial imaging current I i towards the second value corresponding to a higher filament current, and the controller acquires the imaging data D IMG from the X-ray detector 130 and obtains a parameter P related to the image quality of the image formed on the X-ray detector 130 based on the image data D IMG .

[0101] For example, the parameter P can be intensity, contrast noise value, sharpness value, noise value, resolution value, dynamic range value or contrast value. The determination of these values is known to those skilled in the art. For example, the resolution can be measured by performing a Fourier transform on an image of an edge, a pinhole or a JIMA pattern, for example by a fast Fourier transform (FFT) algorithm. The resolution measurement value can be selected as the spatial frequency corresponding to a specific modulation transfer function (MTF) value, for example 50% value. This parameter can be based on the imaging data D IMG ​The average value of the entire image represented, or it may be based on the average value of a predetermined region of the image. The region of the image can be received from a user input device, such as a console or a control panel, via a user interface controller UIC according to a user's command.

[0102] During such a measurement, a test object can be arranged to replace the sample S to provide a reference object for determining the image quality. Such a reference object can be manually placed by the user or can be automatically arranged at the position of the sample, for example, arranged by a sliding mechanism, a robotic arm, or other positioning mechanisms. Such a test object can be a pinhole, an edge, a pair of spheres, or a figure providing a test pattern, such as JIMA-C006-R:2006 provided by JIMA (Japan Inspection Instrument Manufacturers Association).

[0103] As described above, during this process, the potential V of the gate 112 is gradually adjusted g to keep the beam current I B at the beam current set point.

[0104] Step S130 is repeated until at least two measured values of the parameter P are obtained. Each parameter P is associated with a corresponding value of the filament demand I f and is stored in the memory MRM. More than two such measured values can be obtained in step S130. Thus, multiple measured values are obtained from a series of measurements.

[0105] Next, based on a series of measured values of the parameter P, the controller 190 detects an inflection point in the measured parameters. In one definition, an inflection point of a parameter can be considered as a point where the curvature (second derivative or convexity) of the parameter has a local absolute maximum. Hereinafter, the inflection point is associated with a local negative maximum, that is, the minimum value in the curvature of the measured parameter. Therefore, in step S140, the controller 190 determines the curvature of the parameter P with respect to the filament demand I f and identifies the inflection point in the filament demand values based on the curvature. For example, the identification can be performed by identifying a point where the curvature of the parameter has a local absolute maximum, such as a local negative maximum or a minimum.

[0106] The controller 190 can determine the curvature of the measured parameter based on the slope of the rate of change (first derivative), that is, the second derivative of the parameter P with respect to the filament demand I f This second derivative can be determined by fitting a curve, such as a quadratic curve, to the collected measured values of the parameter P and calculating the second derivative of the curve. This second derivative can also be directly calculated from the measured values collected by numerical methods.

[0107] The curve can be fitted to the acquired measured values in a window of a predetermined size. The controller can be configured to smooth the data associated with parameter P by a smoothing algorithm, such as a Savitzky-Golay filter, before determining the curvature of parameter P. Alternatively, relatively few points can be measured and the curve can be generated by interpolation, such as by means of spline interpolation.

[0108] Next, in step S150, the process of increasing the parameter in step S130 and the process of determining the curvature in S140 are repeated, and the local maximum of the curvature is detected by comparing the previously determined value of the curvature of parameter P with the filament demand.

[0109] In Figure 3 the value of parameter P is as shown by the solid line A in Figure 3 and the value of the slope of the curve is as shown by the dashed line B, which can be understood as the derivative of parameter P with respect to the filament demand I f Thus, the inflection point in the filament demand I f can be identified as the value I at which the slope of the curve becomes the absolute (negative) maximum or alternatively the minimum when k .

[0110] The local maximum can be identified as the highest curvature value after the slope maximum, which is determined within a window that also includes the subsequently acquired curvature values below the local maximum. The window can include all values acquired since step S150, or can include a more limited set of values, such as a predetermined number of most recent values. Step S160 can continue until a second value (maximum) of the filament demand I f is reached, or can continue only until the local maximum of the curvature is determined, or until a defined state thereafter. For example, step S160 can continue until the slope (first derivative) of the curve is less than a predetermined percentage, such as 10% or 5% of the maximum slope of the curve, or can continue for a predetermined number of data points.

[0111] In an alternative method, the inflection point value can be determined by an approximation method as the point at which the slope of parameter P reaches a predetermined percentage of the slope maximum after the slope maximum in the slope. For example, the inflection point value can be determined as the point at which the slope of parameter P drops to a value, such as between 25% and 5% of the maximum slope, such as 25%, 20%, 15%, 10% or 5%.

[0112] In one embodiment, while measuring the slope of parameter P, the filament demand is increased, and the point at which parameter P drops to the first percentage, such as 10%, of the maximum slope is identified. Once this point is identified, interpolation, such as spline interpolation, can be applied to generate a curve, and the slope of this curve can be calculated with a higher resolution. Based on the generated curve, the point at which the slope drops to the second percentage, such as 25%, of the maximum slope is identified and determined as the inflection point value.

[0113] Compared with the second derivative, this method can provide a computational advantage in terms of the ease of calculating the slope or the first derivative. This method is shown in Figure 5B the exemplary flowchart of.

[0114] In another alternative method, the inflection point value can be determined by the reverse process, where the filament demand is set to a relatively higher filament demand than the value stored in the memory MEM of the controller 190 or the value input by the user. This demand can correspond to the previously determined inflection point value. Then, instead of gradually increasing the filament demand as described above to find the inflection point, the filament demand is gradually decreased while measuring parameter P. The inflection point of the curvature can be detected by a process corresponding to the above method, or by comparing the previously determined curvature value of parameter P with the filament demand. For example, when parameter P decreases to a predetermined percentage or absolute value of the highest point of parameter P, or when the slope of parameter P increases to a predetermined value, the inflection point can be determined.

[0115] In yet another alternative method, higher-order derivatives of parameter P with respect to the filament demand that are higher than the first derivative or slope and the second derivative or curvature can be used to identify the inflection point in parameter P. For example, as shown in Figure 10 the third derivative of parameter P can exhibit a first maximum, minimum, and second maximum. As needed, an approximate value of the inflection point in parameter P can be identified based on the first minimum, the position between the second maximum, the first minimum and the second maximum, the weighted average of the first minimum and the second maximum, or the offset or percentage of the selected maximum or minimum value. In addition, using the fourth-order or higher-order derivatives, a specific percentage or fraction of the selected maximum or minimum slope or the minimum / maximum slope position of the third derivative can be selected as the approximate value of the inflection point. Instead of the maximum or minimum value, the zero crossing of the relevant derivative can be used as the basis for approximating the inflection point position.

[0116] In another alternative method, the tangent intersection of the curve of parameter P with respect to the filament demand can be used to identify the approximate inflection point. For example, the tangent with the steepest slope and the tangent at the maximum filament demand value can be identified. The filament demand value at the intersection of these two tangents can be determined as the approximate value of the inflection point.

[0117] In yet another alternative method, the inflection point can be identified as the location corresponding to a specific percentage of the maximum value in parameter P.

[0118] In addition, other methods for identifying the inflection point in parameter P can be applied without limitation. It should be noted that, in principle, any characteristic of the curve of parameter P with respect to the filament demand can be used as a basis for establishing an approximate inflection point value, as long as such a characteristic can be repeatedly identified.

[0119] Next, in step S160, based on the detected inflection point, the inflection point value I of the filament demand k is set to the value of the filament demand I existing at the identified inflection point in parameter P. f Based on the determined inflection point value I of the filament demand k , the filament demand setpoint I s is established. For example, the filament demand setpoint I s can be established as the following filament demand value: the value corresponding to the same value as the inflection point of the filament demand. Alternatively, the filament demand setpoint I s can be established as the following filament demand value: the value corresponding to a value lower than the inflection point of the filament demand by the offset d shown Figure 3 (I k ).

[0120] Alternatively still, the filament demand setpoint I s can be established as the following filament demand value: the value corresponding to a value proportionally lower than the inflection point value of the filament demand. In addition, alternatively, the filament demand value corresponds to a value proportionally or absolutely higher than the inflection point value of the filament demand. If the filament demand is set lower than the inflection point, the image quality will tend to decrease, but the filament life will tend to increase. If the filament demand is set higher than the inflection point, the image quality will tend to improve, but the filament life will tend to decrease.

[0121] In step S170, the filament demand I f is set to the value of the filament demand setpoint I s , and the X-ray device can be put into operation to study the sample S. Among them, for a manually placed reference object used to determine parameter P, the object can be removed before introducing the sample S. In the case where the reference object has been automatically introduced, the reference object can be automatically withdrawn from the path of the X-ray beam B X .

[0122] In step S180, the image data D IMG is acquired and stored for further analysis.

[0123] Therefore, when implementing the above process for setting the filament demand, the controller 190 causes the filament demand I f to change from the value I 0Increase until the filament demand I f The inflection point in k is identified. When the inflection point value I k is identified, the controller calculates the set value of the filament demand I s based on the newly identified value I

[0124] In other configurations, a predetermined absolute or proportional offset d can alternatively or additionally be used to calculate the set filament demand I k based on the identified inflection point of the filament demand I s .

[0125] If the filament demand further increases beyond the inflection point I k , then the point in Figure 3 and Figure 4C where the III state shown is reached, where the maximum space charge caused by the free electrons emitted by the filament 111 is reached, corresponding to the maximum number of emitted electrons per unit area. If the filament demand further increases to the situation in the IV state shown in Figure 3 , the filament will become overheated, although Figure 4C the equipotential lines shown as dashed lines in

[0126] will further move upward along the filament, thus providing a smaller filament area for emitting electrons. However, since the maximum space charge has been reached, it is impossible to further improve the image quality. Therefore, from the III state to the IV state, the parameter P will not increase further. In this case, the filament 111 will become overheated, and thus the service life of the filament will be significantly shortened. Figure 4C Therefore, by implementing the above techniques, it is possible to avoid approaching, reaching, or exceeding the III point in

[0127] during the process of setting the filament demand and avoid filament overheating. Operating the filament at a high temperature is related to a shortened service life of the filament during operation. Therefore, by following the disclosed techniques, the life of the filament can be increased. k .

[0128] The advantage of this variant is that if the inflection point is found at a relatively low value of the filament demand, the filament demand does not need to increase significantly above this point to obtain the filament demand set value I s , thus avoiding the filament temperature rising to an excessive value, even for a short period of time.

[0129] However, in practice, it may be necessary to overshoot the filament demand inflection point I k by a certain amount to confirm the filament demand I fThere is a local maximum in the curvature. In particular, the double inflection point phenomenon has been observed, especially if the X-ray device 100 is misaligned. As the filament demand increases, the parameter P may not increase temporarily. To avoid this, the technique may temporarily overshoot the inflection point. Therefore, the characteristics of the parameter P after the inflection point consistent with a correctly aligned system can be confirmed by the expected characteristics of the parameter P after the inflection point. This involves temporarily operating the filament at a temperature higher than necessary to confirm that the correct inflection point has been identified. This overshoot can last for a very limited time to minimize the impact on the filament life.

[0130] In an alternative technique, the controller 190 can vary the filament demand within a predetermined range of filament demand values in order to identify the inflection point within these values. In other words, before identifying the filament inflection point, the filament demand can vary throughout the predetermined range, for example from Figure 3 I as shown 0 to I max . This technique may have the advantage of ensuring a more definite identification of the inflection point. In some embodiments, the values of I 0 to I max can be set based on the range in which the expected inflection point lies. In some embodiments, such a range can be determined based on one or more previously identified inflection points.

[0131] It should be noted that the above description is given for the filament demand represented by the filament current I f . However, based on the potential applied by the filament current source 150 across the two ends of the filament 111 to heat the filament 111, the same procedure can be applied with equivalent effect. In other words, the filament power supply can equivalently be a constant current source or a constant voltage source.

[0132] Although the above techniques can be used to establish the filament demand for an X-ray machine, which can be maintained throughout the operation of the X-ray machine, in some cases it may be advantageous to repeat the method at regular intervals.

[0133] In particular, as the filament ages during operation, the filament typically deteriorates. Among other factors, this deterioration may be due to local evaporation causing the filament to become thinner. Therefore, the resistance of the filament generally increases during its service life. This deterioration process may accelerate until the hot spot melts or breaks, resulting in filament failure. Therefore, for a given filament demand value, over time, the power dissipated in the filament and consequently the temperature of the filament will increase according to Ohm's heating law.

[0134] If the filament demand is set only once, after some time the filament will operate in an inappropriate thermal state. However, this is usually not noticed by the user because above Figure 3After the filament demand shown in the medium state III, the image quality will not increase any further.

[0135] By repeating the above technique after the machine has been operating for a period of time, new filament demand values can be identified while avoiding operating the X-ray device for an extended period of time in the case of overheating of the filament.

[0136] In particular, compared to the technique of setting a single filament demand for all beam currents and beam potentials, a filament life enhancement of two times or more can be obtained.

[0137] Such an operating cycle can be selected such that the filament temperature or filament demand required to maintain a defined filament temperature is expected to have changed by at least a certain ratio, for example, a ratio between 20% and 1%, such as 20%, 10%, 5% or 1%.

[0138] In some cases, the technique can be repeated based on the clock time elapsed since the last setting of the filament demand. For example, the technique can be repeated at least twice a day, at least once a day, at least twice a week, at least once a week, at least once every two weeks, or at least once a month. In this case, the controller 190 can compare the current clock time with the last setting time of the filament demand and can automatically execute the technique if a predetermined time has elapsed.

[0139] Such automatic execution can be conditional on, for example, the restart of the X-ray device 100 or can be conditional on, for example, the completion of a measurement operation or a sequence of measurement operations of the X-ray device 100. Such automatic execution can provide the user of the X-ray device 100 with the option to postpone or omit the repetition of the setting technique, for example, by notifying the user through the user interface controller UIC to a user output device, such as a console or a control panel or a display screen, that the repetition of the technique has been scheduled, and then receiving a command to postpone, omit, or initiate the repetition from a user input device, such as a console or a control panel, through the user interface controller UIC.

[0140] Regardless of whether the technique is repeated automatically or manually by the user, the controller 190 can notify the user that the technique should be repeated by providing a notification to a user output device, such as a console or a control panel or a display screen, through the user interface controller UIC. The notification can be a warning that the automatic execution is scheduled, for example, that the automatic execution will occur after the next measurement is completed or after a notified time period has elapsed, or can be an invitation to the user to initiate the execution of the technique. Such initiation can be performed by receiving a command from a user input device, such as a console or a control panel, through the user interface controller UIC.

[0141] Alternatively, since the filament requirements were previously set, the technique can be repeated based on the elapsed operating time of the X-ray device, e.g., the elapsed time during which current was supplied to the filament. In this case, the controller 190 can record the amount of time since the previous filament requirements were set and can compare this amount of time with a predetermined maximum amount of time for the execution of the technique. In this case, if the predetermined time as described above is exceeded, the controller 190 can automatically execute the technique or can invite the user to start the execution of the technique again as described above.

[0142] Alternatively, after the X-ray device 100 has been turned on a predetermined number of times, the technique can be repeated each time the X-ray device is turned on. In this case, the controller 190 can count the number of times the X-ray device has been turned on since the previous filament requirements were set and can compare the number of times with a predetermined maximum number of times for the execution of the technique. In this case, if the predetermined maximum number of times as described above is exceeded, the controller 190 can automatically execute the technique or can invite the user to start the execution of the technique again as described above.

[0143] Alternatively, the technique can be started on demand according to a user request. Again, such a start can be made by receiving a command via the user interface controller UIC from a user input device, e.g., a console or a control panel.

[0144] In addition, obtaining the filament inflection point according to the above-disclosed technique can be used to estimate the remaining service life of the filament in the X-ray device.

[0145] In particular, for a given filament type, in terms of shape, structure, and composition, there is a clear relationship between the service life of the filament at a specific filament requirement and the inflection point detected in the curve of the parameter P with respect to the filament requirement I f of the curve.

[0146] The service life of the filament is hereby defined as the filament operating time from the first operation of the filament to the failure of the filament. The filament operating time is defined as the time during which the filament is heated according to the filament requirement.

[0147] Generally, when the filament deteriorates due to heating and ion back-bombardment of the filament material, and the filament becomes thinner so that the increased heating caused by the thinning of the filament leads to melting and breakage of the filament, the filament fails. As the filament becomes thinner, the deterioration process of the filament tends to accelerate. Then the remaining life of the filament at a specific time is defined as the operating time assuming a constant filament requirement from that specific time until the failure of the filament.

[0148] For example, as Figure 6 shown, when the filament remains in operation, a specific type of filament exhibits an offset in the characteristic curve of the parameter P with respect to the filament requirement I f of the curve. Refer toFigure 6 , curve α represents a new filament, curve β represents a filament that has been operated for a certain period of time, and curve γ represents a filament that has been operated for a longer period of time. From Figure 6 it can be seen that the identified inflection point value I associated with curve α α is greater than the identified inflection point value I associated with curve β β , and the identified inflection point value I associated with curve β β is greater than the identified inflection point value I associated with curve γ γ . That is, for a given filament, the identified inflection point value I k decreases as the operating time of the filament elapses.

[0149] In addition, for a given filament, the identified inflection point value I k decreases in a predictable relationship with the operating time of the filament, which depends on the type of filament. This predictable relationship can be used to determine the remaining life of the filament.

[0150] For example, the determined filament demand I s or the determined inflection point value I k can be compared with the known relationship between the set filament demand and the elapsed filament operating time for any specific filament or filament type to determine the expected remaining time to failure, i.e., the remaining life of the filament. The elapsed operating time can be the operating time elapsed since the first operation of the filament.

[0151] For example, the flowchart shown in reference Figure 8 illustrates the determination of the remaining life of the filament.

[0152] A specific type of filament exhibits a characteristic curve C, which defines the filament inflection point I determined in the above-disclosed technology k and the relationship with the elapsed filament operating time T 0 . Such a curve can have the form of curve C shown in Figure 7 . Since under constant conditions, after the filament has been operated for a certain period of time, at Figure 7 shown as T in 1 , a specific type of filament exhibits a characteristic failure time T f , characteristic filament life, so the inflection point of the filament demand has a certain characteristic value I 1 . The characteristic curve C can be specific to the configuration of the x-ray device 100 and can be specific to an instance of the x-ray device 100. Based on the known characteristic curve C and the inflection point T of the filament demand 1 , the predicted remaining failure time of the filament, i.e., the remaining life of the filament, can be established as T f - T 1 .

[0153] Thus, in the first step S210, the inflection point of the filament demand is identified and the set value of the filament demand is determined. Step S210 can be performed by, for example, steps S110 to S150 described previously.

[0154] In the second step S220, the filament demand of the device 100 is set to the obtained set value of the filament demand, and the X-ray device 100 is placed in an operating state based on this filament demand. The setting of the obtained value can be performed by, for example, step S180 described previously. The set filament demand value can be regarded as the filament demand I described previously 1 .

[0155] In the third step S230, next, the filament operates at this filament demand. For example, one or more X-ray images of one or more samples S can be acquired using the set filament demand value. During this step, the controller 190 measures the operating time elapsed since the setting of the filament demand.

[0156] After the filament has been operated for a specific further length of time, for example until time T 2 , if the inflection point T of the filament demand k is subsequently determined, the inflection point of the filament demand will be reduced to the value I 2 . As described above, this is because the filament has become thinner and requires a smaller current to maintain a specific temperature in the filament, thereby maintaining a specific space charge density around the filament, thereby maintaining the electron flux in the electron beam B e . Based on the known curve C and the determined inflection point I of the filament demand 2 , the new remaining time to failure can be established as T f -T 2 .

[0157] Figure 7 The relationship shown in B applies to specific values of the operating parameters of the X-ray device, such as the filament demand, the beam current I between the filament 111 and the anode 117 B and the beam potential V

[0158] Thus, in the fourth step S240, the identification of the filament inflection point is repeated. For example, step S240 can be performed by repeating steps S110 to S150 described previously. A new value of the filament demand is obtained as the filament demand I described previously 2 .

[0159] Then, in the fifth step S250, the controller 190 takes I 1 , I 2 and the operating time T elapsed between step S230 and step S240 2 -T 1Compare with curve C and determine a new remaining time to failure T based on the comparison f- T 2 .

[0160] Finally, in the sixth step S260, the controller makes information about the remaining time to failure T f -T 2 available, for example, by storing information about the remaining time to failure in a memory for reading or by reporting information about the remaining time to failure to a user interface output unit by means of a user interface controller UIC so that the user can record the information. This information can be a value, for example, the value of the remaining time to failure, or it can be information about a state, such as a warning flag or warning indicator for low filament remaining life. In one embodiment, the controller can notify the supplier that the filament life is low, so that an electronic order can be placed for replacing the filament. Such notification can be carried out via a network, such as the Internet or a GPRS or GSM mobile network, according to a well-known messaging protocol, such as SMS or email.

[0161] It is noted that for a given filament type, the shape of curve C basically does not change. Therefore, in order to predict the remaining life of the filament, a set of such curves C can be stored under different conditions, and a suitable curve can be selected for relevant cases including a specific filament life.

[0162] Alternatively, a single curve can be stored and then scaled according to the operating parameters of the X-ray device. For example, such a curve can be defined by an analytical formula, such as an algebraic formula, or can be generated based on interpolation of specific values of the curve. These values can be obtained theoretically in advance or can be obtained from a study of the life characteristics of a given type of filament under different conditions.

[0163] In one implementation, curve C can be stored as a representative in the memory MRY of the controller 190. Such a representative can be updated periodically, for example, by loading data representing the representative from an external storage device into the memory MRY via a storage controller STC.

[0164] Alternatively, the controller 190 can measure and store the operating time of the filament for each repetition of the filament demand setting technique disclosed above, and can update the representative periodically based on the characteristics of the inflection point of the filament demand with respect to the operating time.

[0165] Such update can include recording the values of the filament demand relative to the service life, and optionally, interpolating these values to estimate the expected filament demand associated with intermediate values of the operating time between the times when the inflection points of the filament demand are identified. Alternatively, the update can include based on the determined inflection point I k and the cumulative operating time T0 Based on the measured value, adjust the coefficients in the analytical representation of curve C stored in memory MRY.

[0166] In addition, since the appropriate filament demand can be predicted based on the cumulative operating time T of the filament 0 at the inflection point I of the determined filament demand, after initially setting the filament demand k the filament demand can then vary according to Figure 7 curve C in based on the appropriate filament demand inflection point I k predicted value. This can provide an alternative or additional mechanism for setting the filament demand after an initial filament demand has been determined, rather than performing an additional repetition of the inflection point I k setting technique of the filament demand disclosed above.

[0167] In addition, if it is found that the identified inflection point I k is inconsistent with curve C, for example by comparing the inflection point I identified at a specific operating time k with the expected inflection point based on curve C and finding an inconsistency, the identification of the inflection point can be repeated, for example until a consistent value is determined. If it is confirmed after one or more repetitions that the identified inflection point is inconsistent with curve C, this may indicate a failure. Therefore, in such a case, the user can be notified of the failure situation, for example, by outputting a notification to a user output device, such as a console or a control panel or a display screen, through a user interface controller UIC. Alternatively, the failure situation can be notified to a management system, a management department, a user, or a service system, a service department, or a service engineer. Such notification can be carried out according to a well-known messaging protocol, such as SMS or email, through a network, such as the Internet or a GPRS or GSM mobile network.

[0168] Curve C can be pre-determined or can be determined empirically based on previous measurements of the identified inflection point I k relative to the elapsed filament operating time. For example, the parameters of the algebraic representation of curve C can be updated based on one or more previous measurements, or curve C can be constructed over time based on one or more previous measurements. Estimation techniques, such as maximum likelihood estimation techniques, can be used to update curve C based on the history of previous measurements. Machine learning techniques can also be used to determine and / or update curve C based on the history of previous measurements. Such a curve can be stored locally and associated with a specific device 100, or can be replicated or shared with other devices 100 having the same configuration. In some embodiments, the measured values from multiple devices 100 or the curves from multiple devices 100 can be combined to obtain a corresponding curve by any of the above techniques.

[0169] In addition, as Figure 9As shown by the exemplary mapping, the beam current value I measured between the filament and the anode B , the beam potential V between the filament and the anode B and the filament requirements are in a corresponding relationship. This relationship can be expressed as Figure 9 the mapping shown, a set of values in a look-up table, a 3d surface, a set of curves or an analytical relationship between quantities. For any desired situation, the existence of this relationship can again be used to determine a suitable value of the filament requirements based on the representation of the relationship between the filament requirements, the beam current, and the potential. For example, given a filament requirement value and a set of beam current values I B and beam potential V B , if it is desired to adjust one or both of the beam current value I B and beam potential V B , it is not necessary to re-determine the suitable filament requirement value. Instead, Figure 9 the relationship illustrated in can be used to determine a suitable new filament requirement value for the adjusted quantity. After such a determination, the new filament requirement value can be set and the device can be placed in an operating state for new measurements under the new conditions of the beam current value I B and / or beam potential V B .

[0170] Advantageously, Figure 9 the mapping is scaled according to the filament requirements. That is, after re-determining the suitable filament requirements by the techniques disclosed above, the filament requirement values associated with each set of beam potential and beam current can be directly determined. Such a new determination can be, for example, the result of the long-term operation of the X-ray device 100. Based on the new determination, a new relationship, such as a new mapping, can be determined by correcting each value in the mapping by a correction factor determined based on the difference between the previous suitable filament requirements and the newly determined filament requirements. Such a correction factor can be a proportional scaling such that each value in the mapping is adjusted by the same correction factor applied to each value, such as a scaling constant.

[0171] By implementing the disclosed techniques, the user can obtain suitable filament requirements without professional knowledge.

[0172] For example, if the user sets the filament requirements under conditions corresponding to low current and low potential, the suitable filament requirements may typically also be low. If the device 100 is then adjusted to operate at higher beam current and beam potential, the image quality will deteriorate.

[0173] Conversely, if the filament requirement is set by the user under conditions corresponding to high beam current and high beam potential, the appropriate filament requirement may typically also be high. If the device 100 is then adjusted to operate at lower beam current and beam potential, the image quality may not typically improve. However, the filament requirement may be too high. Operating at an inappropriate high filament requirement typically results in a shorter filament life compared to operating at an appropriate filament requirement.

[0174] Therefore, by implementing the disclosed techniques, compared to an inappropriate setting of the filament requirement, an appropriate image quality can be ensured while allowing an increase in filament life.

[0175] It should be noted that in the above, reference was made to parameters determined by the controller 190 using the detector 130 based on the measured image quality. However, other quantities related to the image quality but not based on any measurements using the detector 130 can also be used as parameters for determining the inflection point of the filament requirement. Here, the correlation with the image quality can refer to a quantity that behaves relative to the image quality in the same manner as the filament requirement, and can more particularly refer to a quantity that has a proportional or substantially proportional relationship with the image quality.

[0176] For example, the controller 190 can be configured to be able to measure the electron beam current from the filament 111 to the target 113. This is directly related to the intensity of the X-rays generated by the target 113 and thus to the image quality determined by the detector 130. Such a measurement can be made by measuring the current provided by the target potential power supply 180, which can be reported by the target potential power supply 180 through the input / output unit IO. For example, such a measurement can be performed by placing a resistor between the target and the target potential power supply 180 and measuring the voltage drop across the resistor using a voltmeter.

[0177] In addition, any other parameter related to the image quality at the X-ray detector 130, such as any parameter related to the intensity or flux of the X-rays emitted by the target 113, can equivalently be used as the parameter P for setting the filament requirement I f of.

[0178] As a further example, the electron beam spot size on the target or the electron beam spot intensity on the target is also related to the intensity or flux of the X-rays emitted by the target and can thus be used as a parameter. For example, such a parameter can be detected as follows: by placing a layer of scintillator on the target 113 or temporarily replacing the target 113 to intersect with the electron beam emitted by the filament 111 and observing the scintillator, for example, observing the scintillator using a charge-coupled device (CCD). Alternatively, the X-ray intensity from the target 113 can be observed using a scintillator arranged to cover the window 116 and again observed using a CCD.

[0179] In the above description, reference was made to as Figure 1The controller 190 implemented using a central processing unit CPU and auxiliary components MEM, INS, IO, UIC, and STC is shown. However, such a controller can also be implemented using discrete electronic devices, programmable logic controllers, general industrial controllers, or suitable instructions loaded on a general-purpose data processing device with a suitable configuration, such as a workstation, personal computer, or laptop computer.

[0180] Such a controller can also be provided in a hybrid configuration, including dedicated control electronics under the control of off-the-shelf computer hardware. The controller 190 can be located in a single location or can have discrete components networked together. In particular, the controller 190 can control multiple such X-ray devices 100 as a common controller, or multiple such controllers 190 can be controllers via a common user interface, such as a network terminal or a keyboard-video-mouse switch.

[0181] However, as will be directly understood by those skilled in the art, the basic functions described above will remain unchanged.

[0182] Accordingly, the present disclosure also includes a controller for an X-ray device configured to perform the techniques disclosed herein; a control program for an X-ray device including machine-readable instructions that, when executed, cause the X-ray device to perform the techniques disclosed herein; and a non-transitory storage medium storing such a program in machine-readable form.

[0183] Furthermore, it will be apparent to those skilled in the art that the inventive concept can be implemented in alternative and equivalent modes in various situations applicable to specific requirements without limitation. In particular, the configurations of the X-ray device and the controller shown and described herein are entirely exemplary, and the present technology can be generally applied to any form of X-ray device without limitation.

[0184] Therefore, the scope of the claimed invention is determined solely by the appended claims.

Claims

1. A method for setting the filament requirement in an X-ray device, wherein, the X-ray device has: a filament, a heating current flowing through the filament allowing thermionic emission of electrons from the filament, a target arranged to be able to generate X-rays according to the electrons emitted from the filament, a detector arranged to be able to detect the X-rays generated by the target to form an X-ray image, and a controller, wherein the controller is configured to be able to: perform a measurement operation of the X-ray device to measure parameters of the X-ray device; and set a filament requirement for the filament, the filament requirement being related to the current flowing through the filament, the method comprising: changing the filament requirement between a first value corresponding to a lower filament current and a second value corresponding to a higher filament current; measuring the parameters at a series of values of the filament requirement between the first value and the second value; detecting an inflection point in the measured parameters; determining the filament requirement corresponding to the detected inflection point in the parameters; setting the filament requirement for the X-ray device based on the determined filament requirement corresponding to the detected inflection point in the parameters; wherein the controller is configured to be able to measure the parameters based on the detection of X-rays by the detector, or the parameters are related to the beam current between the filament and the target, the electron beam spot size on the target, or the electron beam spot intensity on the target.

2. The method according to claim 1, wherein, the parameter is an objective measurement value of the image quality.

3. The method according to claim 2, wherein, the parameter is related to one of the sharpness, noise, dynamic range, resolution, or contrast of the X-ray image derived from the X-rays received by the detector.

4. The method according to claim 1, wherein, the parameter is related to the contrast-to-noise ratio of the X-ray image derived from the X-rays received by the detector.

5. The method according to claim 1, wherein, the parameter is related to the intensity of the X-rays received by the detector.

6. The method according to claim 1, wherein, the parameter is a measured value of the contrast-noise value in the X-ray image derived from the X-rays received by the detector.

7. The method according to claim 1, wherein, the step of setting the filament requirement includes setting a filament requirement equal to or at a predetermined ratio or absolute amount lower than the filament requirement corresponding to the identified inflection point.

8. The method according to claim 1, wherein, the step of setting the filament requirement includes setting a filament requirement at a predetermined ratio or absolute amount higher than the filament requirement corresponding to the identified inflection point.

9. The method according to claim 1, wherein, the identification of the inflection point includes determining the slope of the measured parameter with respect to the filament requirement and selecting a value of the filament requirement as the value of the inflection point based on the determined slope.

10. The method according to claim 9, wherein, the identification of the inflection point includes determining the value of the filament requirement between the first value and the second value at which the determined slope of the measured parameter decreases to a set percentage of the maximum slope of the measured parameter.

11. The method according to claim 10, wherein, the determined value is the first such determined value in sequence between the first value and the second value.

12. The method according to claim 1, wherein, the filament demand represents a set filament operating current.

13. The method according to claim 1, wherein, the filament demand represents a set filament operating voltage.

14. The method according to claim 1, wherein, the method is repeated at intervals during the service life of the filament.

15. The method according to claim 14, wherein, the interval is a predetermined interval based on the clock time elapsed since the last repetition of the method according to claim 1.

16. The method according to claim 15, wherein, the interval is a predetermined interval based on the operating time elapsed since the last repetition of the method according to claim 1.

17. The method according to claim 14, 15 or 16, wherein, the method further includes: a process of calculating the remaining life of the filament based on the set filament demand.

18. The method according to claim 17, wherein, the process of calculating the remaining life of the filament includes: comparing the set filament demand with a predetermined representation associating the set filament demand with the filament life, and determining the remaining life of the filament according to the comparison.

19. The method according to claim 17, wherein, for each repetition or subset of repetitions of the set filament demand, the set filament demand and the cumulative operating time of the filament are recorded, and wherein the process of calculating the remaining life of the filament includes: comparing the representation of the set filament demand relative to the cumulative operating time with a predetermined representation of the expected set filament demand relative to the operating time, and determining the remaining life of the filament according to the comparison.

20. The method according to claim 18 or 19, wherein, the predetermined representation of the set filament demand relative to the remaining life of the filament is an analytical representation.

21. The method according to claim 18 or 19, wherein, the predetermined representation of the set filament demand relative to the remaining life of the filament is a curve or a set of values.

22. The method according to claim 18 or 19, wherein, the predetermined representation of the set filament demand relative to the remaining life of the filament is determined theoretically.

23. The method according to claim 18 or 19, wherein, the predetermined representation of the set filament demand relative to the remaining life of the filament is determined empirically.

24. The method according to claim 23, wherein, the predetermined representation is established based on the following information received: information associating the set filament demand with the remaining life of the filament for a series of values of the filament demand and the filament life.

25. The method according to claim 24, wherein, the predetermined representation is established based on the previously recorded values of the set filament demand and the cumulative operating time of the filament pre-installed in the X-ray device.

26. The method according to claim 1, wherein, after the beam current between the filament and the target or the potential between the filament and the target is changed, the filament demand is changed to a different filament demand.

27. The method according to claim 26, wherein, the filament requirement is changed to a different filament requirement by repeating the steps of changing, detecting, determining, and setting of claim 1.

28. The method according to claim 27, wherein, the filament requirement is changed to a different filament requirement based on a predetermined relationship among the filament requirement, the beam current, and the potential.

29. The method according to claim 28, wherein, the predetermined relationship is a relationship between the filament requirement and one of the beam current and the potential, and a ratio is associated with the other of the beam current and the potential.

30. The method according to claim 28, wherein, the predetermined relationship is determined by a mapping that defines the filament requirement for each pair of the beam current and the potential.

31. A controller for an X-ray device, wherein, the controller includes a data processing device configured to enable the X-ray device to perform the method according to any one of claims 1 to 3.

32. An X-ray device including the controller according to claim 31.

33. A control program product for an X-ray device, wherein, the control program product includes machine-readable instructions that, when executed, cause the X-ray device to perform the method according to any one of claims 1 to 30.

34. A non-transitory storage medium storing the control program product according to claim 33.

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