Image fusion using acquisition techniques

Abstract

A first radiographic image of a workpiece is acquired in a digital radiography (DR) detector using a low energy exposure level below a saturation level of the DR detector. A second radiographic image of the workpiece is acquired using a high exposure level above a known saturation level of the DR detector. The acquired first and second radiographic images of the workpiece are composited to form a final image.

Description

Technical Field

[0001] The subject matter disclosed in this paper relates to a radiographic imaging system and method that can be used for nondestructive testing (NDT) applications, specifically a method for acquiring and synthesizing radiographic images during nondestructive testing. Background Technology

[0002] When using X-ray imaging systems to inspect thick metal components such as steel castings, the inspection process presents challenges to the imaging system. First, high exposure levels of kilovolts (kV) and milliampere-seconds (mAs) are required to penetrate the thick areas of the casting, generating a sufficiently high signal level on the X-ray imaging receiver or digital ray (DR) detector for observation and inspection. Inhomogeneity in casting thickness can cause excessive X-ray beams to penetrate thinner areas of the casting and irradiate the detector. If the casting does not completely cover the DR detector's imaging receiver, direct exposure areas will appear on the detector's imaging surface. The imaging receiver may saturate, resulting in artifacts in subsequent image acquisition and potentially obscuring the current image being inspected.

[0003] A trade-off needs to be struck: on the one hand, high X-ray exposure energy is required to penetrate thick areas of the metal casting; on the other hand, low X-ray exposure energy is needed to clearly image thinner areas, while simultaneously avoiding detector saturation and achieving a good signal-to-noise ratio (SNR). In practical applications, image frame averaging and / or image frame accumulation are used to alleviate these problems. In one example, the DR detector acquires each exposure (hereinafter referred to as E...). n The X-ray energy of each image frame, or the maximum X-ray energy level acquired (hereinafter referred to as E). max Below the detector's known saturation level (hereinafter referred to as E) sat After acquiring several image frames (hereinafter referred to as N), the average value is calculated. This produces a new averaged image. Since averaging is equivalent to using a higher exposure level, the SNR of this averaged image is improved. In another example, multiple captured image frames N can be summed (…). This produces a new image with improved SNR. The SNR of this new image is improved by a factor of N squared (). ).

[0004] The above discussion provides only general background information and is not intended to help determine the scope of the subject matter for which protection is sought. Summary of the Invention

[0005] A first ray image of the workpiece is acquired on a digital ray (DR) detector using a low-energy exposure level below the saturation level of the DR detector. A second ray image of the workpiece is acquired using a high-exposure level above the known saturation level of the DR detector. The acquired first and second ray images of the workpiece are then combined (e.g., added) to form a final image. A beneficial effect achievable through practice using some of the disclosed embodiments is that any saturated regions in the acquired second image are not represented in the final image.

[0006] In some embodiments, a first X-ray image of the workpiece is acquired using an X-ray source set to a low exposure level. A second X-ray image of the workpiece is acquired using an X-ray source set to a high exposure level above the low exposure level. The acquired first and second X-ray images of the workpiece are then combined to form a final image.

[0007] In some embodiments, a first set of X-ray images of the workpiece is acquired using a DR detector with a known saturation level and an X-ray source set to a first exposure energy level. This first exposure energy level will not cause pixel saturation within the DR detector. A second set of X-ray images of the workpiece is acquired using the same DR detector and an X-ray source set to a second exposure level. The second exposure level is at least twice the first exposure energy level. The acquired first and second set of X-ray images of the workpiece are then combined to form a final image.

[0008] The above overview is not intended to describe individual embodiments where components are not interchangeable. In fact, many components associated with a particular embodiment can be used in combination with, or even interchanged with, components of other described embodiments. Various changes and modifications can be made within the scope of this disclosure without departing from its spirit, and this disclosure encompasses all such modifications.

[0009] The summary portion of this disclosure is merely a brief overview of the subject matter disclosed herein based on one or more exemplary embodiments and is not intended to interpret the claims or limit the scope of this disclosure. The scope of this disclosure is defined only by the appended claims. The summary introduces a series of exemplary concepts in a simplified form, which will be further illustrated in the detailed description below. The summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help determine the scope of the claimed subject matter. The claimed subject matter is not limited to embodiments capable of addressing any or all of the deficiencies mentioned in the background art. Attached Figure Description

[0010] To facilitate understanding of the features of this disclosure, reference can be made to certain embodiments for detailed description, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings only illustrate certain embodiments of this disclosure and should not be considered as limiting the scope of this disclosure. The scope of this disclosure covers other equally effective embodiments. The following drawings are not drawn strictly according to relative dimensions, angular relationships, relative positions, or temporal relationships, nor are they drawn according to combinations of interchangeable, alternative, or necessary implementation methods. The following drawings generally emphasize features of certain embodiments of this disclosure. In the various drawings, the same reference numerals always denote the same parts. Therefore, for a further understanding of this disclosure, reference can be made to the following detailed description section in conjunction with the accompanying drawings.

[0011] Figure 1 A schematic perspective view of an exemplary digital X-ray imaging system; Figure 2 This is a schematic diagram of a two-dimensional imaging pixel array in a DR detector; Figure 3 A perspective view of an exemplary DR detector; Figure 4 This is a cross-sectional view of an exemplary DR detector; Figures 5A to 5D A series of ray images of an object are shown: the left image is an underexposed image of the object with a high noise level; the middle image is an overexposed image of the object with saturation in areas of thinness; the right image is a fused or composite image of the object, which uses the left and middle images to improve the dynamic range of the composite image in terms of material thickness discrimination. Figure 6 Another set of examples with different X-ray energy exposure levels is shown, from left to right: fused image, underexposed image, and overexposed image. Detailed Implementation

[0012] Figure 1This is a perspective view of a digital radiography (DR) imaging system 10. According to some embodiments, the DR imaging system 10 may include a DR detector 40, an X-ray source 14, and a control console. The DR detector 40 is generally arc-shaped or flat; in this figure, it is shown as a flat embodiment, and the housing is omitted for ease of description. The X-ray source 14 is configured to generate radiation energy (X-ray radiation). The control console includes a digital monitor 26 (or electronic display) and a processing system 34. The electronic display 26 is configured to display images 24 acquired by the DR detector 40. The processing system 34 is used to control the operation of the DR imaging system 10. The DR detector 40 may include a two-dimensional array 12 composed of detector units 22 (imaging pixels or photoelectric sensors). The detector units are arranged in electrically addressable rows and columns. During radiation detection, the DR detector 40 is able to receive X-rays 16 emitted by the X-ray source 14 that penetrate an object 18. The object 18 is, for example, a metal workpiece component. Figure 1 As shown, the X-ray imaging system 10 can use an X-ray source 14. This X-ray source 14 emits collimated X-rays 16 (e.g., an X-ray beam), which are directed to irradiate and pass through a pre-defined workpiece 18, so that the emitted X-rays 16 are incident on the imaging area of ​​the DR detector 40, i.e., the imaging pixel array 12. The X-ray beam 16 can be attenuated to different degrees on multiple beams depending on the structure of the metal object 18 (e.g., thickness differences). The attenuated X-rays are detected by the pixel array 12 composed of imaging pixels 22. The curved or flat DR detector 40 can be positioned as perpendicular as possible to the central beam of the multiple beams 16 emitted by the X-ray source 14. In an embodiment with a curved array, the X-ray source 14 can be centrally located, such that most or all of the imaging pixels 22 are positioned perpendicular to the X-rays incident on the centrally located X-ray source 14. The array 12 composed of the individual imaging pixels 22 can be electrically addressed (scanned) according to the row and column positions. As used herein, the terms "column" and "row" refer to the vertical and horizontal arrangement of the photoelectric sensor units 22, respectively. For ease of description, it is assumed that rows extend horizontally and columns extend vertically. However, the orientation of rows and columns is arbitrary and does not limit the scope of protection of any embodiment disclosed herein. Each individual imaging pixel 22 can be scanned by the readout circuits 28 and 30 described herein to determine the stored voltage level within the pixel generated by the energy level of the incident X-ray beam. The voltage level stored within each imaging pixel 22 can be read out via circuits 28 and 30 and electronically stored as a digital value. It is well known that an analog-to-digital (A / D) converter can be used to convert the stored voltage level within each pixel 22 into a digital value. The larger the value, the more X-ray energy absorbed by a single imaging pixel 22 during the imaging process of the object 18.

[0013] In some exemplary embodiments, rows within the imaging pixel array 12 may be scanned row-by-row or multiple rows synchronously by the electronic scanning circuit 28, so that exposure data from the array 12 can be transmitted to the electronic readout circuit 30. Each imaging pixel 22 may independently store charge or voltage. This charge or voltage is proportional to the intensity or energy level of the attenuated radiation or X-rays received and absorbed by the pixel 22. Therefore, after each imaging pixel is read out via circuits 28 and 30, it can provide information defining the pixel of the radiation image 24, such as the brightness level or the energy value absorbed by the pixel 22. This information may be digitally decoded by the readout circuit 30 (e.g., using an analog-to-digital converter) and transmitted to the digital monitor 26, where it is ultimately displayed for user viewing. The electronic bias circuit 32 may be electrically connected to the two-dimensional detector array 12 to provide a bias voltage to each imaging pixel 22.

[0014] The bias circuit 32, scanning circuit 28, and readout circuit 30 can each communicate with the control processing unit 34 via a wired connection cable 33. Alternatively, the DR detector 40 and the control processing unit 34 can be equipped with a wireless transmitter and receiver to wirelessly transmit X-ray image data to the control processing unit 34. The control processing unit 34 may include a processor and electronic memory (not shown) and can control the operation of the X-ray imaging system 10 as described herein, including, for example, controlling circuits 28, 30, and 32 using preset program instructions, and storing and processing image data. The control processing unit 34 can also be used during X-ray exposure to control the startup of the X-ray source 14, control the current magnitude (mAs) of the X-ray tube, thereby controlling the X-ray flux in the X-ray beam 16, and / or control the X-ray tube voltage (kVp), thereby controlling the X-ray energy level in the X-ray beam 16. Some or all of the functions of the control processing unit 34 can be integrated into the onboard processing system 36 of the detector 40. The onboard processing system 36 may include a processor and electronic memory for controlling the operation of the DR detector 40 in the manner described herein, including controlling circuits 28, 30, and 32 using program instructions and storing and processing image data. This function is similar to that of the independent control processing system 34. The image processing system can perform the image acquisition and image arrangement related functions described herein. The image processing system 36 may be onboard on the detector 40 and control image transmission, image processing, and image correction. Alternatively, the control processing unit 34 may receive raw image data from the detector 40, perform image processing and storage, or store unprocessed raw image data in local memory or remotely accessible memory.

[0015] In a direct detection embodiment of the DR detector 40, each imaging pixel 22 may include an X-ray-sensitive sensing element. That is, the sensing element absorbs X-rays and generates charge carriers and voltage proportional to the amount of absorbed X-ray energy. A switching element may be configured to selectively activate to read out the charge level of the corresponding imaging pixel 22. In an indirect detection embodiment of the DR detector 40, each imaging pixel 22 may include a visible spectrum-sensitive sensing element and a switching element. The sensing element absorbs light and generates charge carriers proportional to the amount of absorbed light energy. The switching element may be selectively activated to read out the charge level of the corresponding sensing element. A scintillator, or wavelength converter, may be arranged above the imaging pixel array 12 to convert incident X-ray energy into visible light energy. Therefore, in the embodiments disclosed herein, it needs to be explained that the DR detector 40 (or...) Figure 3 DR detector 300 in Figure 4 The DR detector 400 in the DR detector may include an indirect or direct DR detector.

[0016] Examples of sensing elements used in the sensing array 12 include various photoelectric conversion devices (e.g., photoelectric sensors), such as photodiodes (PN diodes or PIN diodes), photocontrolled MIS (Metal-Insulator-Semiconductor) capacitors, phototransistors, or photoconductors. Examples of switching elements used for signal readout include amorphous silicon thin-film transistors (TFTs), oxide TFTs, MOS (Metal-Oxide-Semiconductor) transistors, bipolar transistors, and other PN junction elements.

[0017] Figure 2 This is a partial schematic diagram 240 of a two-dimensional array 12 used for the DR detector 40. The operation of the optical sensor unit array 212 is consistent with that of the optical sensor array 12 described above. The optical sensor unit array 212 may include several hydrogenated amorphous silicon (a Si:H)n i A p-type photodiode 270 and a thin-film transistor (TFT) 271. The TFT is formed as a field-effect transistor (FET), each having a gate (G), source (S), and drain (D) terminal. In embodiments of the DR detector 40 disclosed herein, such as a multilayer DR detector (… Figure 4The two-dimensional array 12 of the optical sensor unit (400) can be formed within the device layer. This device layer is adjacent to the adjacent layer of the DR detector structure. The adjacent layer may include a rigid glass layer, a flexible polyimide layer, or a functional layer containing carbon fibers and without an adjacent rigid layer. Multiple gate drive circuits 228 can be electrically connected to multiple gate lines 283. The gate lines 283 can control the voltage applied to the gate of the thin-film transistor 271. Multiple readout circuits 230 can be electrically connected to data lines 284. Multiple bias lines 285 can be electrically connected to a bias line bus or a variable bias reference voltage line 232. The reference voltage line 232 can control the voltage applied to the photodiode 270. A charge amplifier 286 can be electrically connected to the data lines 284 to receive signals transmitted by the data lines. The output of the charge amplifier 286 can be electrically connected to a multiplexer 287 (e.g., an analog multiplexer) and then connected to an analog-to-digital converter (ADC) 288. The output of the charge amplifier 286 can also be directly connected to an analog-to-digital converter, thereby continuously outputting digital X-ray image data at the desired rate. In some embodiments, Figure 2 The schematic diagram may represent a portion of the DR detector 40, such as an indirect flat panel, curved panel, or flexible panel imager based on a-Si:H.

[0018] Incident X-rays or X-ray photons 16 can be converted into optical photons or light rays by a scintillator. When the light rays illuminate an a-Si:H nip photodiode 270, they can be converted into electron-hole pairs or charges. In some embodiments, the exemplary detector unit 222 is equivalently referred to herein as a pixel. This detector unit may include a photodiode 270. The anode of the photodiode 270 is electrically connected to a bias line 285, and the cathode is electrically connected to the drain (D) of a thin-film transistor 271. A bias reference voltage line 232 controls the bias voltage of the photodiode 270 within each detector unit 222. The charge capacity of each photodiode 270 can be a function of the bias voltage and capacitance. Typically, a reverse bias voltage, such as a negative voltage, can be applied to the bias line 285 to create an electric field and depletion region across the PN junction of each photodiode 270, thereby improving the collection efficiency of the photodiode 270 for the charge generated by the incident light rays. The image signal generated by the light sensor array 212 can be integrated by photodiodes, during which the corresponding thin-film transistors 271 can remain in an off state. For example, the gate drive circuit 228 can maintain the gate line 283 at a negative voltage, keeping the corresponding thin-film transistors 271 in an off state. The TFTs 271 can be switched to the on state row by row by the gate drive circuit 228 to complete the signal readout of the light sensor array 212. When a row of pixels 22 is switched to the on state (e.g., by applying a positive voltage to the corresponding gate line 283), the charge collected by the photodiodes in these pixels can be transferred along the data line 284 and integrated by the external charge amplifier circuit 286. The row can then be switched back to the off state. This process is repeated row by row until the signal readout of the entire light sensor array 212 is completed. The integrated signal output can be transmitted from the external charge amplifier 286 to the analog-to-digital converter (ADC) 288 via a parallel-to-serial converter (such as a multiplexer 287). The charge amplifier circuit 286, the multiplexer 287, and the analog-to-digital converter 288 can together form the readout circuit 230.

[0019] The digital image information can then be processed by processing system 34 to generate digital image 24. Digital image 24 can then be digitally stored, or displayed instantly on monitor 26, or retrieved later from a digital electronic memory containing the stored image for display. (Reference available) Figure 2 The flat panel DR detector 40 of the described imaging array 212 can achieve both single imaging (e.g., static radiographic imaging) and continuous imaging (e.g., fluoroscopic imaging).

[0020] Figure 3This is a perspective view of a generally rectangular, flat, portable wireless DR detector 300 in the related art. The DR detector 300 corresponds to one embodiment of the DR detector 40 disclosed herein. The DR detector 300 may include a flexible substrate to allow the DR detector to acquire X-ray images in a curved orientation, such as when the DR detector 300 is locally positioned around a pipe. The flexible substrate may be fabricated to a permanently curved shape or remain flexible throughout its entire lifespan, providing two-dimensional or three-dimensional adjustable curvature as needed. The DR detector 300 may include a housing portion 314 with similar flexibility. The housing portion 314 may surround a multi-layer structure including a flexible photosensitive sensor array portion 22 of the DR detector 300. The housing portion 314 of the DR detector 300 may include a continuous rigid or flexible X-ray blocking material, which may be used herein as equivalent to a radiation blocking material, and may surround the internal space of the DR detector 300. The housing portion 314 may include four flexible sides 318. Four flexible sidewalls 318 extend between the top side 321 and the bottom side 322, and are arranged to be approximately orthogonal to the top side 321 and the bottom side 322. The bottom side 322 may be continuous with the four sidewalls and is disposed opposite to the top side 321 of the DR detector 300. The top side 321 includes a top cover 312, which is attached to the housing portion 314. The top cover 312 cooperates with the housing portion 314 to substantially enclose the multilayer structure within the internal space of the DR detector 300. The top cover 312 may be attached to the housing 314 to form a sealed structure between the two. The top cover 312 may be made of a material that is permeable to X-rays 16 without causing significant attenuation, i.e., an X-ray-transparent material (the term may be used interchangeably with radiation-permeable material herein), such as carbon fiber plastics, polymer materials, or other plastic-based materials.

[0021] refer to Figure 4 , Figure 4 The DR detector 300 is shown in schematic form. Figure 3An exemplary cross-sectional view along section 4-4 of the exemplary embodiment of the DR detector 400. For spatial reference, one main surface of the DR detector 400 may be referred to as the top side 451, and the second main surface as the bottom side 452. A multilayer structure may be arranged within an internal space 450 enclosed by the housing 314 and the top cover 312. The multilayer structure may include a flexible, curved, or flat scintillator layer 404. This scintillator layer 404 is arranged above a curved or flat two-dimensional imaging sensor array 12. The two-dimensional imaging sensor array 12 is schematically shown as device layer 402. The scintillator layer 404 may be arranged directly below (e.g., directly connected to) the generally flat top cover 312. The imaging array 402 may be arranged directly below the scintillator layer 404. Alternatively, a flexible layer 406 may be positioned as part of the multilayer structure between the scintillator layer 404 and the top cover 312 to achieve curvature adjustment of the multilayer structure and / or provide cushioning and damping. The flexible layer 406 can be selected to provide a certain amount of flexible support for both the top cover 312 and the scintillator layer 404, and may include a foam rubber-like material. The aforementioned layers constituting the multi-layer structure can each be generally shaped into a rectangle, defined by orthogonally arranged sides, and arranged parallel to the inner side of the side 318 of the outer shell 314, as detailed in [reference needed]. Figure 3 .

[0022] In some embodiments, a substrate 420 may be disposed below an imaging array 402. The substrate 420 may be, for example, a rigid glass layer or a flexible substrate comprising polyimide or carbon fiber. The photosensitive array 402 may be formed on this flexible substrate to achieve adjustable array curvature. The substrate may constitute another layer in a multilayer structure. A radiation blocking shielding layer 418 may be disposed below the substrate 420 as an X-ray blocking layer to help prevent scattering of X-rays passing through the substrate 420, while also blocking X-rays reflected from other surfaces within the internal space 450. The readout electronics include a scanning circuit 28, a readout circuit 30, a bias circuit 32, and a processing system 36 (all referenced in the original text). Figure 1 The readout electronics can be formed adjacent to the imaging array 402, or, as shown, arranged as an integrated circuit (IC) below the frame support member 416 and electrically connected to printed circuit boards 424 and 425. The imaging array 402 can be electrically connected to the readout electronics 424 (integrated circuit) via a flexible connector 428. The flexible connector 428 may include multiple hermetically sealed flexible conductors, i.e., chip-on-film (COF) connectors.

[0023] X-ray flux can pass through the X-ray-permeable top panel cover 312 in the direction shown by the exemplary X-ray beam 16 and irradiate the scintillator layer 404. The high-energy X-rays 16 (i.e., photons) excite the scintillator layer 404, causing it to emit low-energy photons, forming visible light. The visible light can then be received by the light sensor of the imaging array 402. The frame support member 416 connects the multi-layer structure to the housing 314 and also acts as a buffer, achieving a cushioning effect by arranging an elastic pad (not shown) between the frame support beam 422 and the housing 314. Fasteners 410 can be used to attach the top cover 312 to the housing 314 and form a seal at the area 430 where the top cover 312 contacts the housing 314. In some embodiments, an external bumper strip 412 can be attached along the side 318 of the DR detector 400 to provide additional cushioning.

[0024] refer to Figures 5A to 5D The radiographic images of the steel castings shown are easier to obtain with appropriate sensitivity (signal-to-noise ratio) in areas where the workpiece thickness is smaller. For example... Figures 5A to 5D As shown in each image, the left image is underexposed or underexposed, resulting in higher noise levels; the middle image is overexposed, leading to saturation in areas with thinner workpieces. The right image is created by fusing or merging the left and middle images to increase the dynamic range of the composite image in terms of material thickness resolution. Figure 6 The left side shows a composite image of a metal casting. This composite image is obtained by combining an underexposed image of the same metal casting in the middle with an overexposed image of the same metal casting on the right. In some embodiments, the image compositing operation may include overlaying the images.

[0025] When a minimum SNR threshold must be met to ensure the quality of radiation detection images, recommended exposure process settings need to be provided to the operator. For example, the single-frame exposure level (En) in milliampere-seconds (mAs) and the minimum number of frames (N) can be specified. min This parameter can be determined by acquiring a pre-scan image. The pre-scan image is a preliminary exposure image and can be used as a sample image of the metal casting to be inspected. Typically, the exposure energy level can be controlled so that the detector's imaging pixels do not reach saturation, i.e., the exposure energy level is maintained below the saturation energy level. <E satThe operator can then select two or more regions of interest (ROIs) to calculate the signal-to-noise ratio (or, interchangeably, CNR: contrast-to-noise ratio). The pre-scanned image can be displayed on a monitor. The window width and level of the pre-scanned image can be adjusted (to adjust contrast and brightness), or the image processing can be controlled by the system operator. The operator can use cursor tools, for example, to place two or more rectangular cursors on the displayed pre-scanned image of the metal workpiece, each corresponding to one of the two or more ROIs within the pre-scanned image. The image regions selected by the operator can be stored in the image processing system for the calculation operations described herein.

[0026] In one example, the number of image frames (M) required to achieve the desired signal-to-noise ratio can be calculated using the following formula:

[0027] In the formula: The desired signal-to-noise ratio, as determined by radiation inspectors; Both parameters are for the region of interest; M is rounded up to the nearest positive integer.

[0028] In another example, assuming each acquired image frame uses the same exposure process settings as the pre-scanned image, the SNR can be determined by calculating the signal difference between two regions of interest (ROIs) selected by the operator in the image, and then dividing it by the noise level of either of the two selected regions, or by dividing it by the average noise level of either of the two selected regions. To determine the signal difference, the average pixel intensity of each ROI selected by the operator must first be calculated, i.e., the average signal intensity of all pixels within each ROI is obtained, and then the difference between the two sets of calculated average pixel intensities is calculated. In some embodiments, the 16-bit digital X-ray detector can output a value between 0 and 65535 for each pixel within the ROI. The noise level of each ROI can be determined by calculating the standard deviation of the pixel intensity of all pixels within that ROI, or by calculating its average pixel intensity, or by using other suitable measures of central tendency.

[0029] A graphical user interface (GUI) can be provided for X-ray imaging systems for operator use. This interface can automatically calculate the required number of frames using operator-selected calculation methods, automatically set the system's energy acquisition level, and automatically acquire the calculated number of image frames at a given energy level. Image frame averaging and / or cumulative processing are not without limitations. For example, when the current image signal level is below the known noise floor (E) of the DR detector... minWhen the signal level is low, regardless of how many frames are exposed, averaged, and / or accumulated at the current signal level, the composite signal of all exposed images may not be able to achieve the minimum signal-to-noise ratio requirement. One way to solve this problem is to increase the exposure power level (mAs) so that the X-ray energy signal received by the DR detector is higher than the noise floor (E) of the detector. min This can cause an abnormal operating condition that leads to saturation of the image receiver in the DR detector. To overcome this problem, the operator can acquire two sets of images. The first set of images can be obtained by performing frame averaging and / or accumulation processing on multiple frames, or it can consist of only a single frame. The first set of images is acquired at a lower exposure level, below the known saturation level (E) of the DR detector. max This will not cause saturation of the image receiver (i.e., the imaging pixels of the DR detector). Based on the DR detector used, it can be determined that this type of detector generally operates at 90% of the maximum pixel intensity of 65535 (E). max When the image density reaches 58982, the image enters a saturated state. The second set of images is similar in form to the first set and can undergo frame averaging and / or accumulation processing, or a single frame image can be used directly. The second set of images is acquired at a very high exposure level (exposure level of 2 times or more than that of the first set of images), which can cause pixel saturation of the DR detector. Subsequently, the second set of images acquired at a high exposure level can be combined with the first set of images acquired under low exposure conditions where the pixels are not saturated to produce the final image. The final image can be viewed and inspected by the operator.

[0030] In one example, for unsaturated pixels in both the low-exposure level (Group 1) and high-exposure level (Group 2) images, a scaling factor (sf) can be calculated based on the ratio of the pixel values ​​of the two groups of images. This scaling factor represents the ratio of the actual exposure applied to the low-exposure image to the high-exposure image, for example, a ratio of 0.5. In the region where neither the low-exposure pixel value (vl) nor the high-exposure pixel value (vh) is saturated, the final image pixel value (vf) can be calculated using the following formula: In a high-exposure image, the pixel saturation region can have its final image pixel value (vf) set as follows: This processing flow can reduce the number of images to be viewed to a single image, optimizing the workflow. This hybrid approach can be performed with operator assistance or automatically by software. Therefore, the method may include the following steps: acquiring one or more X-ray images of the workpiece using a DR detector with a known saturation level and an X-ray source set to a first exposure energy level that will not cause pixel saturation in the DR detector; and acquiring one or more X-ray images of the workpiece using the DR detector and an X-ray source set to a second exposure energy level. This second exposure energy level is at least twice the first exposure energy level. The final step is: using the formula... Determine the pixel values ​​of the final image. If multiple images are acquired at both the first and second exposure energy levels, a preferred measure of central tendency (e.g., average pixel intensity) can be used to determine the image noise level corresponding to each exposure energy level. Then, the formula can be applied to each group of averaged images.

[0031] Those skilled in the art will understand that the various embodiments of this disclosure can be implemented as systems, methods, or computer program products. Therefore, aspects of this disclosure can take the form of entirely hardware embodiments, entirely software embodiments (including firmware, resident software, microcode, etc.), or embodiments combining software and hardware aspects; all of these types are collectively referred to herein as "services," "circuits," "circuit systems," "modules," and / or "systems." Furthermore, aspects of this disclosure can take the form of computer program products carried on one or more computer-readable media, on which computer-readable program code is mounted.

[0032] Any combination of one or more computer-readable media may be used. A computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium may be, for example, but not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any suitable combination thereof. Further specific examples of computer-readable storage media (not an exhaustive list) may include: electrical connection lines having one or more wires, portable computer floppy disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, and any suitable combination thereof. In the context of this document, a computer-readable storage medium may be any tangible medium capable of containing or storing a program that is available for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0033] Program code and / or executable instructions carried on a computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, fiber optic cable, radio frequency, or any suitable combination thereof.

[0034] The computer program code used to perform the operations of this disclosure may be written in any combination of one or more programming languages, including object-oriented programming languages ​​and conventional procedural programming languages. This program code may run entirely on the user's computer (device), or partially on the user's computer as a standalone software package, or partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may establish a connection with the user's computer through various networks, including local area networks (LANs) or wide area networks (WANs), and may also establish a communication connection with a cloud server.

[0035] This written specification discloses the invention by way of examples, including the best mode of implementation, and enables those skilled in the art to practice the invention, including making and using any device or system, and performing any of the methods described herein. The patentable scope of this disclosure is defined by the claims and may include other embodiments readily conceived by those skilled in the art. Such other embodiments shall fall within the scope of the claims if they have structural elements that are identical to the literal description of the claims, or include equivalent structural elements that are not substantially different from the literal description of the claims.

Claims

1. A method, characterized in that, include: A first X-ray image of a workpiece is acquired using a digital ray (DR) detector and an X-ray source set to a low exposure level, wherein the low exposure level is preset to be below the known saturation level of the DR detector; A second X-ray image of the workpiece is acquired using the X-ray source set to a high exposure level, wherein the high exposure level is preset to be higher than the known saturation level of the DR detector; and The first and second ray images of the workpiece that have been acquired are combined to form the final image.

2. The method according to claim 1, characterized in that, The step of acquiring the first X-ray image includes: acquiring a preset number of low-exposure X-ray images of the workpiece; The step of acquiring the second X-ray image includes: acquiring a preset number of high-exposure X-ray images of the workpiece; and The synthesis steps include: The preset number of low-exposure ray images are averaged. The preset number of high-exposure ray images are averaged; and The averaged low-exposure ray image and the averaged high-exposure ray image are combined to form the final image.

3. The method according to claim 2, characterized in that, Also includes: Use formula Determine the preset number of low-exposure ray images.

4. The method according to claim 1, characterized in that, Any saturated region in the acquired second image will not appear saturated in the final image.

5. A method, characterized in that, include: The first X-ray image of the workpiece is acquired using an X-ray source set to a low exposure level. A second X-ray image of the workpiece is acquired using an X-ray source set to a high exposure level, wherein the high exposure level is higher than the low exposure level; as well as The first ray image of the workpiece and the second ray image of the workpiece are combined to form the final image.

6. The method according to claim 5, characterized in that, The steps for acquiring the first ray image of the workpiece include: Multiple X-ray images of the workpiece are acquired using an X-ray source set to the low exposure level.

7. The method according to claim 6, characterized in that, The steps for acquiring the second X-ray image of the workpiece include: Multiple X-ray images of the workpiece are acquired using an X-ray source set to the high exposure level.

8. The method according to claim 6, characterized in that, The synthesis step includes: superimposing multiple X-ray images of the workpiece acquired using an X-ray source set to the low exposure level.

9. The method according to claim 7, characterized in that, The synthesis steps include: Multiple X-ray images of the workpiece acquired using an X-ray source set to the low exposure level are superimposed on each other; and Multiple X-ray images of the workpiece acquired using an X-ray source set to the high exposure level are superimposed on each other.

10. The method according to claim 6, characterized in that, The synthesis steps include: Multiple X-ray images of the workpiece acquired using an X-ray source set to the low exposure level are averaged.

11. The method according to claim 7, characterized in that, The synthesis steps include: Averaging multiple X-ray images of the workpiece acquired using an X-ray source set to the low exposure level; and Multiple X-ray images of the workpiece acquired using an X-ray source set to the high exposure level are averaged.

12. A method, characterized in that, include: A first set of X-ray images of a workpiece is acquired using a DR detector with a known saturation level and an X-ray source set to a first exposure energy level, wherein the first exposure energy level will not cause the pixels in the DR detector to saturate. Using the DR detector and the X-ray source set to a second exposure level, a second set of X-ray images of the workpiece is acquired, wherein the second exposure level is at least twice the first exposure energy level; and The first set of X-ray images and the second set of X-ray images of the acquired workpiece are combined to form the final image.

13. The method according to claim 12, characterized in that, Also includes: The X-ray source is configured to not produce saturated exposure energy levels in the pixels of the selected region of interest within the DR detector.

14. The method according to claim 13, characterized in that, The synthesis step includes: superimposing the first set of X-ray images and the second set of X-ray images of the workpiece.

15. The method according to claim 13, characterized in that, The synthesis steps include: Within the selected region of interest, the pixel values ​​of the first and second sets of ray images of the workpiece are averaged; and The average pixel values ​​of the first group of ray images are superimposed with the average pixel values ​​of the second group of ray images.

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