RU2776469C1 - Dynamic collimation of emission for non-destructive analysis of test objects - Google Patents

Abstract

FIELD: imaging.

SUBSTANCE: use: generation of tomographic data of a test object. The substance of the invention consists in the fact that, for each corresponding rotary position of the first phase from a set of rotary positions of the first phase, the visualisation system can generate a corresponding image of the first phase. Based on the identified area of interest in the corresponding image of the first phase, the visualisation system can determine the positions of collimator plates for the corresponding rotary position of the first phase. For each corresponding rotary position of the second phase from a set of rotary positions of the second phase, based on the positions of collimator plates for the rotary positions of the first phase, the visualisation system can determine the positions of collimator plates for the corresponding rotary position of the second phase . The visualisation system can generate the corresponding image of the second phase in a second sequence of images at a time when the test object is in the corresponding rotary position of the second phase, and at a time when the collimator plates are in the positions of collimator plates for the corresponding rotary position of the second phase. Based on the second sequence of images, the visualisation system can calculate the tomographic data for part of the test object.

EFFECT: increase in the quality of tomographic images.

20 cl, 17 dwg

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority of U.S. Patent Application No. 16/129,404 entitled "DYNAMIC RADIATION COLLIMATION FOR NON-DESTRUCTIVE ANALYSIS OF TEST OBJECTS" filed September 12, 2018, in full the content of which is incorporated into this application by reference.

FIELD OF TECHNOLOGY

[0002] This disclosure relates to digital radiography and computed tomography.

BACKGROUND OF THE INVENTION

[0003] X-ray digital radiography (digital radiography - DR) is a widely used non-invasive and non-destructive imaging technology using digital x-ray detectors such as flat panel detectors, charge-coupled device (CCD) cameras, or cameras based on a complementary metal-oxide-semiconductor (CMOS) structure, or linear diode arrays (LDA). X-ray computed tomography (CT) is a procedure that uses computer-processed x-ray radiographic images or sinograms obtained from different viewing angles to create three-dimensional (3D) data and two-dimensional (2D) images of an object. A tomographic image of an object is an image of a conceptually two-dimensional "slice" of an object that can be generated from radiographic images or a sinogram. The computing device may use tomographic images, radiographic images, or synograms of the object to generate three-dimensional data for the object, such as a three-dimensional model of the object. X-ray CT can be used for industrial purposes for non-destructive evaluation of objects.

SUMMARY OF THE INVENTION

[0004] In one example, this disclosure describes a method for generating tomographic data of a test object, the method comprising: for each corresponding first phase rotation position from a set of two or more first phase rotation positions: generating, by an imaging system, a corresponding a first phase image in the first sequence of images, wherein the corresponding first phase image is generated while the test object is in the corresponding rotational position of the first phase; identifying, by means of a visualization system, a region of interest (ROI) in the corresponding first phase image, the ROI corresponding to a portion of the test object being evaluated; and determining, by means of the imaging system, based on the identified ROI in the corresponding first phase image, the positions of the collimator plates for the corresponding rotational position of the first phase, wherein the radiation is emitted by the radiation generator and passes through the aperture of the collimator, the collimator is located between the radiation generator and the radiation detector, the test object is located between the radiation generator and the radiation detector, and the collimator contains a plurality of collimator plates that are movable with the ability to change the size and shape of the collimator aperture; for each corresponding second phase rotation position from a set of two or more second phase rotation positions: determining, by means of the imaging system, based on the positions of the collimator plates for the first phase rotation positions, the positions of the collimator plates for the corresponding second phase rotation position; and generating, by means of the imaging system, a corresponding second phase image in the second sequence of images, wherein the corresponding second phase image is an X-ray pattern generated based on the radiation patterns detected by the radiation detector at the time when the test object is in the corresponding rotational position of the second phase and at that the time when the collimator plates are in the positions of the collimator plates for the corresponding rotational position of the second phase; and calculating, by means of the imaging system, based on the second sequence of images, tomographic data for a portion of the test object being evaluated.

[0005] In another example, this disclosure describes an imaging system comprising: a radiation generator; radiation detector; collimator, moreover, the radiation emitted by the radiation generator passes through the collimator aperture, the collimator is located between the radiation generator and the radiation detector, the test object is located between the radiation generator and the radiation detector, and the collimator contains a plurality of collimator plates that are movable with the ability to change the size and shape of the collimator aperture ; and a processing system configured: for each respective first phase rotation position from a set of two or more first phase rotation positions: to generate a corresponding first phase image in the first sequence of images, wherein the corresponding first phase image is generated while the test object is in the corresponding rotary position of the first phase; identify a region of interest (ROI) in the corresponding first phase image, the ROI corresponding to a portion of the test object being evaluated; and determine, based on the identified ROI in the corresponding first phase image, the positions of the collimator plates for the corresponding rotational position of the first phase; for each corresponding second phase rotation position from a set of two or more second phase rotation positions: determine, based on the collimator plate positions for the first phase rotation positions, the collimator plate positions for the corresponding second phase rotation position; and generating a corresponding image of the second phase in the second sequence of images, wherein the corresponding image of the second phase is an X-ray pattern generated based on the radiation patterns detected by the radiation detector at the time when the test object is in the corresponding rotational position of the second phase and at the time when the collimator plates are in the positions of the collimator plates for the corresponding rotational position of the second phase; and calculate, based on the second sequence of images, tomographic data for a portion of the evaluated test object.

[0006] In another example, this disclosure describes a non-transitory computer-readable storage medium having instructions stored thereon that, when executed, causes one or more processors, for each corresponding first phase rotation position, from a set of two or more rotation positions first phase: generate a corresponding first phase image in the first sequence of images, wherein the corresponding first phase image is generated while the test object is at the corresponding rotational position of the first phase; identify a region of interest (ROI) in the corresponding first phase image, the ROI corresponding to a portion of the test object being evaluated; and determine, based on the identified ROI in the corresponding first phase image, the positions of the collimator plates for the corresponding rotational position of the first phase, wherein the radiation is emitted by the radiation generator and passes through the aperture of the collimator, the collimator is located between the radiation generator and the radiation detector, the test object is located between the radiation generator and a radiation detector, and the collimator contains a plurality of collimator plates that are movable with the ability to change the size and shape of the collimator aperture; for each corresponding second phase rotation position from a set of two or more second phase rotation positions: determine, based on the collimator plate positions for the first phase rotation positions, the collimator plate positions for the corresponding second phase rotation position; and generating a corresponding image of the second phase in the second sequence of images, wherein the corresponding image of the second phase is an X-ray pattern generated based on the radiation patterns detected by the radiation detector at the time when the test object is in the corresponding rotational position of the second phase and at the time when the collimator plates are in the positions of the collimator plates for the corresponding rotational position of the second phase; and calculate, based on the second sequence of images, tomographic data for a portion of the evaluated test object.

[0007] Details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a schematic drawing of an exemplary imaging system in accordance with one or more of the technologies of this disclosure.

[0009] FIG. 2A is a conceptual drawing of an exemplary imaging system when a test object is in a first rotational position during a second phase of scanning, in accordance with one or more of the technologies of this disclosure.

[0010] FIG. 2B is a conceptual drawing of exemplary collimator plate positions when the test object is in the first pivot position shown in FIG. 2A.

[0011] FIG. 2C is a conceptual drawing of an exemplary imaging system when a test object is in a second rotational position during a second phase of scanning, in accordance with one or more of the technologies of this disclosure.

[0012] FIG. 2D is a conceptual drawing of exemplary collimator plate positions when the test object is in the second pivot position shown in FIG. 2C.

[0013] FIG. 3A shows a first exemplary test object in a first pivot position.

[0014] FIG. 3B shows the test object of FIG. 3A in a second pivot position different from the first pivot position.

[0015] FIG. 4A shows an exemplary X-ray diffraction pattern of a test object in the absence of collimation.

[0016] FIG. 4B shows an exemplary radiograph of the test object of FIG. 4A in the case of standard, non-dynamic collimated computed tomography (CT) in the 0-degree rotational position.

[0017] FIG. 4C shows an exemplary radiograph of the test object of FIG. 4A-4B in the case of dynamic CT collimation at 0-degree rotational position according to one or more of the technologies of this disclosure.

[0018] FIG. 4D shows an exemplary radiograph of the test object of FIG. 4A-4C in the absence of collimation in the 90 degree rotation.

[0019] FIG. 4E shows an exemplary radiograph of the test object of FIG. 4A-4D for standard, non-dynamic CT collimation in a 90 degree rotation.

[0020] FIG. 4F shows an exemplary radiograph of the test object of FIG. 4A-4E in the case of dynamic CT collimation in a 90 degree rotational position according to one or more of the technologies of this disclosure.

[0021] FIG. 5 is a flowchart showing a first exemplary operation of an imaging system in accordance with one or more of the technologies of this disclosure.

[0022] FIG. 6 is a flowchart showing a second exemplary operation of an imaging system in accordance with one or more of the technologies of this disclosure.

[0023] FIG. 7 is a schematic drawing of an exemplary imaging system in accordance with one or more of the technologies of this disclosure.

[0024] FIG. 8 is a schematic drawing of an exemplary imaging system in accordance with one or more of the technologies of this disclosure.

DETAILED DESCRIPTION

[0025] In general, this disclosure relates to dynamic collimation in computed tomography. In a typical x-ray imaging system, the x-ray imaging system includes a radiation detector and a radiation generator. The radiation detector detects the X-rays generated by the radiation generator and outputs electrical signals corresponding to the structure of the detected X-rays. The test object to be evaluated is placed between the radiation detector and the radiation generator. The test object attenuates the X-rays in a characteristic manner, resulting in an X-ray pattern being detected by a radiation detector. The processing system of an x-ray imaging system generates an image, such as a radiograph, based on electrical signals output from a radiation detector.

[0026] By rotating the test object, the x-ray imaging system can generate a set of radiographs for various rotational positions of the test object, or a sinogram of the object. The processing system may generate computed tomography (CT) data based on the set of radiographs or sinograms thus generated. Thus, an x-ray imaging system can be used for x-ray radiography and CT. X-ray radiography and CT are methods for non-invasive or non-destructive acquisition of two-dimensional (2D) and three-dimensional (3D) data in medical imaging and non-destructive evaluation (NDE).

[0027] One of the problems associated with x-ray imaging systems of the type described above is that x-rays that do not pass directly through the test object may scatter from the test object being evaluated and various parts of the x-ray imaging system, and may be reflected on part of the radiation detector, relevant areas of interest. For example, x-rays can be reflected from the walls of a chamber that contains a test object and a radiation detector. This can lead to a decrease in contrast in the resulting radiographs. Reduced contrast can make it difficult to accurately interpret radiographs and CT datasets, and can make it difficult to calculate high-quality tomographic data for a test subject.

[0028] Thus, when performing digital radiography and CT, it should be understood that beam collimation can be used to improve image contrast and reduce imaging artifacts due to reduced stray radiation. Collimation is typically applied to the radiation cone, limiting the radiation cone to the outer geometry of the test object or to a particular region of interest in the test object. Typical system collimators provide a means to provide static, non-dynamic collimation when performing CT scans. The collimation is set once to provide a hole size that will align with the maximum area of interest (AOI) size of the test object that is projected onto the radiation detector. During a CT scan of an asymmetric test object, the test object is rotated in front of a static collimated X-ray beam, and non-optimal collimation may occur in all areas of the test object where the ROI dimensions are smaller than the aforementioned maximum AOI size.

[0029] According to the technology of this disclosure, the collimator is located between the radiation generator and the radiation detector. For example, in some examples, the collimator may be located between the radiation generator and the test object. In some examples, the collimator is located between the radiation detector and the test object. The collimator may include one or more plates of X-ray shielding material such as lead or tungsten. X-rays emitted by the radiation generator can pass through the gap between the plates of the collimator. This gap may be referred to as the collimator aperture. The collimator can block or attenuate x-rays that do not pass through the collimator aperture. According to the technology of this disclosure, the size of the aperture can be changed based on the contour of the test object or the region of interest (ROI) of the test object as the object rotates through various rotational positions. Thus, the collimator reduces the amount of radiation to the amount of radiation necessary to visualize the test object or the ROI of the test object. This reduction in radiation can reduce the amount of scattered x-rays that can reach the radiation detector, whereby contrast is potentially increased in parts of the x-rays that correspond to the test object. This may improve the quality of the resulting CT data based on radiographs. Although this disclosure often refers to x-rays, other types of radiation may be used instead of x-rays, such as gamma rays.

[0030] Thus, in one example of this disclosure, the imaging system may perform a first scanning phase and a second scanning phase. During the first phase of the scan, the imaging system uses a sequence of dynamic or static images to identify the ROI in the images and uses the ROI to determine the positions of the collimator plates for a set of rotational positions (for example, every 1 degree of rotation through 360 degrees). During the second phase of the scan, the imaging system may generate images while the collimator plates are in certain collimator plate positions for the rotational positions. In some examples, the imaging system may complete the first phase of the scan before beginning the second phase of the scan. In some examples, the imaging system alternates between the first scan phase and the second scan phase such that the first and second scan phases can be completed in a single turn. In some examples, the imaging system may remember the positions of the collimator plates, determined based on the ROI in the first phase images, as a command and control program for use in performing the second phase of the scan without having to repeat the first phase of the scan for each individual test object.

[0031] More specifically, in some examples, the imaging system may generate a first sequence of two or more images during a first scanning phase for a test object. Accordingly, this disclosure may refer to images in the first sequence of images as first phase images. The first sequence of images may be a sequence of radiographs or other types of images. Each image in the first sequence of images may correspond to a different rotational position of the test object in the set of rotational positions of the first phase. The set of pivot positions of the first phase may be a plurality of pivot positions. Thus, for each corresponding rotation position from the set of rotation positions of the first phase, a given image in the first sequence of images corresponds to the corresponding rotation position of the first phase.

[0032] Additionally, in this example, for each corresponding first phase rotational position, the imaging system may identify a region of interest (ROI) in the first phase image corresponding to the corresponding first phase rotational position. ROI corresponds to a part of the test object, for example, a specific part of the test object, or the entire test object to be evaluated. The imaging system also determines, based on the identified ROI in the first phase image corresponding to the corresponding rotational position of the first phase, the positions of the collimator plates for the corresponding rotational position of the first phase. In this example, radiation is emitted by a radiation generator and passes through the collimator aperture. The collimator is located between the radiation generator and the radiation detector. The test object is also located between the radiation generator and the radiation detector. The collimator includes a plurality of collimator plates that are movable with the ability to change the size and shape of the collimator aperture. In some examples, the imaging system may independently move each of the collimator plates.

[0033] Additionally, in this example, after determining the collimator plate positions for the first phase rotation positions, the imaging system may determine, based on the collimator plate positions for the first phase rotation positions, the collimator plate positions for the set of second phase rotation positions. The pivot positions of the second phase may be the same as or different from the pivot positions of the first phase. For each corresponding second phase rotation position, the imaging system may generate a corresponding second phase image in the second image sequence. The imaging system can generate a corresponding image of the second phase in the form of a radiograph based on the radiation patterns detected by the radiation detector at the time when the test object is in the corresponding rotational position of the second phase and at the time when the collimator plates are at the positions of the collimator plates for the corresponding rotational position second phase. The radiation pattern is a spatial pattern of greater or lesser intensity of radiation detected by a radiation detector. Each corresponding second phase image in the second sequence of images may be a radiograph. In this example, the imaging system may calculate, based on the second image sequence, tomographic data of a portion of the test object being evaluated.

[0034] In this disclosure, ordinal terms such as "first", "second", "third", etc., are not necessarily indicative of positions in some order, but rather can be used simply to distinguish between different instances of the same and the same subject. The examples provided in this disclosure may be used together, separately, or in various combinations.

[0035] FIG. 1 is a schematic drawing of an exemplary imaging system 10 in accordance with one or more of the technologies of this disclosure. As shown in FIG. 1, imaging system 10 may include a radiation generator 12 and a radiation detector 14. Although not shown in the example of FIG. 1, imaging system 10 may include one or more additional radiation generators and/or one or more additional radiation detectors. For example, the imaging system 10 may include a minifocus/conventional high energy tube as the first radiation generator and a microfocus tube as the second radiation generator. In some examples, imaging system 10 may include a flat panel detector as the first radiation detector, and may also include one or more linear diode array detectors. The radiation generator 12 can emit an x-ray beam 15 . Therefore, in some instances, this disclosure may refer to radiation generator 12 or similar devices as "radiation sources". In some examples, the x-ray beam 15 is cone shaped. In other examples, the x-ray beam 15 is fan-shaped. In some examples, the radiation generator 12 generates x-rays in the energy range from 20 keV to 600 keV. In other examples, radiation generator 12 generates x-rays in other energy ranges.

[0036] The radiation detector 14 detects X-rays generated by the radiation generator 12 and outputs electrical signals corresponding to the structure of the detected X-rays. In some examples, radiation detector 14 is a two-dimensional (2D) x-ray detector, such as a flat panel detector (FPD). In other examples, radiation detector 14 may comprise a two-dimensional array of radiation sensitive elements such as photodiodes. In some examples, the imaging system 10 includes a lens-associated scintillation detector or other type of X-ray detector instead of or in addition to the FPD. The FPD may include a layer of a scintillation material such as cesium iodide deposited on amorphous silicon on a glass detector array. In some examples, the FPD pixel size may range from about 25 microns to about 400 microns. In other examples, the pixel size of the FPD or other detector may be different and the pixel shape may be either square or non-isotropic. Additionally, the surface of the radiation detector 14 may be flat, curved, or may have other geometric shapes to align with particular x-ray beam configurations.

[0037] In other examples, the radiation detector 14 is a linear detector, such as a linear diode array (LDA) x-ray detector. The LDA X-ray detector includes a one-dimensional array of photodiodes. Each of the photodiodes corresponds to a different pixel. For example, the ratio between photodiodes and pixels can be one to one. In other examples, the pixel size of the radiation detector 14 ranges from about 25 microns to about 1000 microns. In other examples, the size of the pixels of the radiation detector 14 may be different, and the shape of the pixel may be either square or non-isotropic. Additionally, the surface of the radiation detector 14 may be flat, curved, or may have other geometric shapes to align with particular x-ray beam configurations.

[0038] In the example of FIG. 1, the radiation detector 14 is mounted on the detector carriage 16. Detector carriage 16 is mounted on frame 18. In some examples, detector carriage 16 is movable in z-dimension 20 relative to frame 18. In another example, detector carriage 16 is movable in y-dimension (right into the page shown in Fig. 1, or from it) or in the x-dimension 22 relative to the frame 18. Thus, in the example of Fig. 1, the detector carriage 16 can move the radiation detector 14 in a vertical direction, a horizontal direction, or in a direction towards or away from the radiation generator 12. In some examples, the radiation generator 12 is mounted on a carriage configured to move the radiation generator 12 in one or more x, y, or z dimensions. The x, y, or z dimensions can have any orientation in real space.

[0039] The radiation detector 14 can be aligned in y-dimension and z-dimension 20 with the radiation generator 12 using the radiation detector 14. In the example of FIG. 1 x-measurement 22 is parallel to the axis 24 (i.e., the x-ray beam axis) between the radiation generator 12 and the radiation detector 14 when the radiation detector 14 is in position to detect the x-ray beam generated by the radiation generator 12. Additionally, although the example of FIG. 1 shows the radiation generator 12 and the radiation detector 14 mounted on the same frame, the radiation generator 12 and the radiation detector 14 may in other examples be mounted on separate frames. Additionally, separate frames may be mounted on a carriage providing x-dimensional movement of either the radiation detector or the radiation generator, or both. It should be understood that the discussion of x-rays in this disclosure may, in some instances, be applicable to other forms of radiation such as gamma rays, neutron beams, and visible light.

[0040] In the example of FIG. 1, the imaging system 10 includes a processing system 30. Processing system 30 may include a computing system. Exemplary types of computing systems may include personal computers, server computers, mainframes, compact laptops, special purpose computers, and so on. As shown in the example of FIG. 1, the processing system 30 may include one or more processors 31. Each of the processors 31 may include one or more digital signal processors (digital signal processor (DSP), general purpose microprocessors, application specific integrated circuits (ASIC) , field-programmable gate array (FPGA) arrays, or other equivalent integrated or discrete logic circuits. For ease of explanation, this disclosure may describe the actions performed by one or more processors 31 as those performed by the processing system 30. The processing system 30, and hence the processors 31, is operatively coupled to the various components of the imaging system 10 such that the processors 31 are configured to provide electrical signals to and receive electrical signals from such components. Such electrical signals may be commands, image data, state data, and so on. Although this disclosure describes electrical signals, and the example of FIG. 1 shows a cable connecting the processing system 30 to a component in the imaging system 10, such signals may be optical signals and/or wirelessly transmitted signals. In some examples, the processing system 30 may receive data (eg, commands) from and send data (eg, commands) to various components of the rendering system 10 via a communications network such as the Internet or a local area network.

[0041] When the radiation detector 14 detects the pattern of X-rays emitted by the radiation generator 12, the radiation detector 14 can output electrical signals corresponding to the pattern of the X-rays. The processing system 30 may interpret the electrical signals to generate one or more radiographs.

[0042] The imaging system 10 may include one or more manipulator mechanisms configured to move the object relative to the radiation generator 12 and the radiation detector 14. In some examples, one or more processors 31 of the processing system 30 provide signals to move the test object relative to the radiation generator 12 and the radiation detector 14. For example, in the example of FIG. 1, an object can be installed (or, otherwise, positioned) on a platform 26 located between the radiation generator 12 and the radiation detector 14. In the example of FIG. 1, the platform 26 is mounted on the platform handling mechanism 28. Platform manipulation mechanism 28 may move platform 26 (and thus an object mounted on platform 26) parallel to the z-dimension 20. Additionally, in some examples, platform manipulation mechanism 28 may move platform 26 (and thus an object mounted on platform 26) parallel to a y-dimension that is mutually orthogonal to x-dimension 22 and z-dimension 20. Thus, in the example of FIG. 1 The y-dimension is oriented straight in and out of the page. In some examples, the platform manipulation mechanism 28 can simultaneously move the platform 26 (and thus the object placed on the platform 26) in the z-dimension 20 and the y-dimension. Additionally, in some examples, the platform manipulation mechanism 28 may tilt the platform 26.

[0043] Additionally, in some examples, the platform manipulation mechanism 28 rotates the platform 26 with the axis of rotation parallel to the z-dimension 20 (ie, perpendicular to the X-ray beam axis 24). Thus, platform 26 can be configured to carry and rotate an object. As a result, the imaging system 10 can acquire images, such as radiographs, at different projection angles (ie, rotational positions) as the test object rotates in the X-ray beam generated by the radiation generator 12. In some examples, the imaging system 10 acquires images at various rotation angles and processes those images to collect those images into 3D data for the test object, such as a 3D model of the test object. Additionally, in some examples, the platform manipulation mechanism 28 rotates the platform 26 while simultaneously moving the platform 26 linearly in the z-dimension 20.

[0044] As shown in the example of FIG. 1, the imaging system 10 may include a collimator 40 positioned between the radiation generator 12 and the radiation detector 14. The aperture 42 of the collimator 40 allows the reduced x-ray beam to pass through the collimator 40 on its way to the radiation detector 14. As described herein, processing system 30 may dynamically adjust the size and shape of aperture 42 as the profile of the test object rotated on platform 26 changes. In some examples, imaging system 10 includes a system for moving collimator 40 as a unit.

[0045] According to the techniques of this disclosure, when dynamic collimation is applied throughout the CT scan, optimal collimation can be provided throughout the scan by creating dynamic collimation that follows the outer geometry of the test object or a particular region of interest in the test object. This improved collimation may improve the sensitivity of the scan to contrast, which may provide an improvement in the visualization of subtle features and discontinuities in a test object, such as a product sample. When creating a dynamic collimation system, the outer perimeter of the test object can be identified using a software tool to identify the edge of the test object using the pixel values of the image when the test object is rotated. The software can then automatically create a corresponding positional program that associates the positions of the collimator plates with each rotational position of the platform 26. For example, in some examples, the program contains data that converts a set of positions of the collimator plates into a set of rotational positions of the platform. In some examples, this program can be created manually by simultaneously capturing collimation positions and platform rotation positions and writing them into a command and control program. In some examples, processing system 30 may generate a program by capturing a sample of collimator plate positions and pivot positions, calculating desired intermediate collimator plate positions for intermediate pivot positions, and writing the intermediate collimator plate positions and intermediate pivot positions to a command and control program. In some examples, processing system 30 generates a program by capturing a sample of collimator plate positions and rotational positions. Additionally, in this example, processing system 30 may determine one or more intermediate collimator plate positions for intermediate pivot positions and may also receive indications of user input for additional combinations of intermediate collimator plate positions and pivot positions. In this example, the processing system 30 may include definable and inputable intermediate collimator plate positions and rotational positions in the program.

[0046] To perform dynamic collimation, the imaging system 10 may perform a first scanning phase and a second scanning phase. The imaging system 10 may perform the first scanning phase and the second scanning phase sequentially or interleaved. In the first scanning phase, the processing system 30 may identify the outer perimeter of the test object or part of the test object and use the identified outer perimeter to determine collimator plate positions for the rotational positions used in the second scanning phase. Processing system 30 may generate a first sequence of images during a first scanning phase for a test object. This disclosure may refer to images in the first sequence of images as first phase images. The first image sequence includes a plurality of images. In some examples, processing system 30 may generate first phase images based on radiation patterns detected by radiation detector 14. In some examples, first phase images are not used when generating CT data for the test object. In some examples, the processing system 30 may generate first phase images based on signals from a camera separate from radiation detector 14, and the first phase images may be visible light based images. Each first phase image may correspond to a different rotational position of the first phase of the test object in the set of first phase rotational positions. For example, the set of first phase rotation positions may include positions where the test object is rotated 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°. In another example, the rotational positions of the first phase may include one position for each degree of 360° rotation. During the first phase of the scan, the collimator plates of the collimator 40 may be in the same positions when the test object is in each of the rotational positions of the first phase. In other words, in some examples, the collimator plates of the collimator 40 do not move during the first phase of the scan.

[0047] For each corresponding first phase rotation position from the set of first phase rotation positions, the processing system 30 may automatically identify the ROI in the first phase image corresponding to the corresponding first phase rotation position. In one example, processing system 30 may identify an ROI in a first phase image using an algorithm that starts with a bounding box that has a size equal to that of the first phase image. In this example, the processing system 30 may gradually reduce the bounding box on the left side by periodically checking whether the left border of the bounding box crosses the edge of the first phase image. An edge is a point where a break occurs in pixel values, usually corresponding to the actual edge of the test object or structure in the test object. After edge detection, processing system 30 may move the left border back to the left by a few pixels (eg, 10 pixels) to provide a so-called "air gap" around the test object on the left side. Processing system 30 may then stop the process of adjusting the left side of the bounding box. In this example, the processing system 30 may repeat this process for one or more of the right, top, and bottom edges of the bounding box. In some examples, processing system 30 may move the edges of the bounding box independently, or may move two or more edges of the bounding box at the same time. The resulting bounding box delineates the ROI in the first phase image.

[0048] In some examples, the ROI in the image is less than the part of the image corresponding to the test object. For example, the test object may include a part, such as a weld or a valve, to be evaluated. In this example, the processing system 30 can identify areas in the first phase images that correspond to this part. In some examples, in order to identify regions in first phase images that correspond to that part, a machine learning model may first be trained to recognize that part in other first phase images of the same test object. In such examples, the processing system 30 may then apply a machine learning model to identify regions in the first phase images corresponding to that portion. Alternatively or additionally, the processing system 30 may receive indications of a user input that identifies an area in the first phase image that corresponds to that portion. In these examples, the processing system 30 may determine how the ROI should be modified based on user input, known dimensions of that part, known information about the position of that part in the test object, the distance to the radiation detector 14 from the collimator 40, and the distance to the radiation generator 12 from the collimator 40. In some examples, the processing system 30 may identify the ROI based on a Computer Assisted Design (CAD) model of this part, combined with a model of the imaging system 10, which also models the radiation cone, the radiation detector 14, the collimator plates 44 and intersection of the radiation cone with the ROI and corresponding plate positions. This model can be used to program collimation positions independently of other methods.

[0049] In some examples, the imaging system 10 may perform a first phase of scanning as part of a test object evaluation process. For example, the imaging system 10 may use the first phase images to generate tomographic data used to actually evaluate the test object. In such examples, the imaging system 10 may use the first phase images to generate ROI data indicative of the ROI. As described below, the imaging system 10 may then use the generated ROI data in a control program to control the positions of the collimator plates 44 during evaluation of other test objects of the same type. Thus, in such examples, the imaging system 10 may not perform the first scanning phase again for each test object of the same type.

[0050] As mentioned above, radiation is emitted by radiation generator 12 and passes through aperture 42 of collimator 40. In the example of FIG. 1, the collimator 40 is located between the radiation generator 12 and the test object. Additionally, in the example of FIG. 1, the test object is located between the collimator 40 and the radiation detector 14. The collimator 40 includes a plurality of collimator plates 44A, 44B that are movable to change the size and shape of the aperture 42 of the collimator 40. For each respective first phase rotational position, the processing system 30 may determine, based on the identified ROI in the first phase image, for the corresponding rotational position the first phase, the position of the collimator plates for the corresponding rotational position of the first phase. For example, the processing system 30 may determine the positions of the collimator plates for the corresponding first phase rotational position based on the size and position of the identified ROI in the first phase image corresponding to the corresponding first phase rotational position, and also based on the distance to the collimator 40 from the radiation detector 14 and the distance to collimator 40 from the radiation generator 12. In some examples, processing system 30 may determine the positions of the collimator plates using, in part, a look-up table or formula that maps the width of the ROI to the width of the gap between horizontally moving collimator plates; and a lookup table that matches the height of the ROI to the height of the gap between the vertical moving collimator plates. Additionally, the processing system 30 may determine the positions of the collimator plates using, in part, a look-up table or formula that maps the top (or bottom) edge of the ROI to the position of the top (or bottom) collimator plate; the processing system 30 may also use a lookup table or formula that maps the left (or right) edge of the ROI to the position of the left (or right) collimator plate. Based on the gap widths and the positions of the upper (or lower) and left (or right) collimator plates, the processing system 30 can determine the positions of all four collimator plates of the collimator 40 for the respective rotational position. In this example, a lookup table or formula may be determined based on factors such as the distance to the collimator 40 from the radiation detector 14 and the distance to the collimator 40 from the radiation generator 12.

[0051] Thus, as part of identifying the ROI in the first phase image corresponding to a particular rotational position of the first phase, the processing system 30 may identify locations in the first phase image that correspond to the edges of a portion (e.g., area or entire) of the test object being evaluated. For example, the processing system 30 may perform a process that identifies pixels that correspond to the edges of a portion of the test object. Additionally, processing system 30 may define a rectangular bounding box that contains the identified locations. Additionally, as part of determining the positions of the collimator plates for the first phase rotation position, the processing system 30 may determine the positions of the collimator plates for the first phase rotation position such that the projection of the aperture edges of the collimator 40 onto the radiation detector 14 conforms to a certain rectangular bounding box. The projection of the edges can be considered a silhouette of the edges projected onto the radiation detector 14 . For example, this silhouette may be formed by beams from the radiation generator 12 that touch the edges and continue in straight lines towards the radiation detector 14. The bounding box corresponding to an edge projection can be the smallest bounding box that contains that projection, with an optional air gap on one or more sides. In another example, processing system 30 may use a machine learning model that is configured to identify bounding boxes around an ROI in images such as radiographs.

[0052] Additionally, the processing system 30 may determine the positions of the collimator plates for a set of two or more rotational positions of the second phase. The pivot positions of the second phase may be the same as the pivot positions of the first phase, or may be different from the pivot positions of the first phase. Thus, in some examples, the second phase pivot positions include more or fewer pivot positions than the set of first phase pivot positions. In some examples, the second phase pivot position set includes one or more pivot positions that are not present in the first phase pivot position set. In instances where the second phase rotation positions are the same as the first phase rotation positions, the processing system 30 may simply determine that the collimator plate positions for the second phase rotation positions are the same as the collimator plate positions for the first phase rotation positions.

[0053] In instances where the second phase rotation position is not present in the first phase rotation position set, processing system 30 may use one or more formulas to determine collimator plate positions for the second phase rotation position. For example, if the second phase pivot position is halfway between two first phase pivot positions, processing system 30 may determine that the collimator plate positions for the second phase pivot position are midway between the collimator plate positions for the two first phase pivot positions. In some examples, the processing system 30 may use a non-linear approach to determine the positions of the collimator plates for the rotational positions of the second phase. For example, in such examples, the processing system 30 may calculate the collimator plate positions for the second phase pivot position based on the arc between the collimator plate positions used for the two first phase pivot positions.

[0054] Additionally, in the second phase of scanning the test object, the imaging system 10 may generate a second sequence of images based on the radiation patterns detected by the radiation detector 14. This disclosure may refer to images in the second sequence of images as second phase images. The second image sequence may include more, less, or the same number of images as the first image sequence. Each corresponding second phase image may be a radiograph and may correspond to a different rotational position in the set of second phase rotational positions. In other words, for each corresponding second phase rotation position from the set of second phase rotation positions, the imaging system 10 may generate a corresponding second phase image in the second image sequence. The corresponding second phase image can be generated based on the radiation patterns detected by the radiation detector 14 at the time when the test object is in the corresponding rotational position of the second phase and at the time when the collimator plates 44 are in the positions of the collimator plates for the corresponding rotational position of the second phase . As part of generating the second sequence of images, the processing system 30 may control the positions of the collimator plates 44 such that the collimator plates 44 have the collimator plate positions determined for the rotational positions of the second phase.

[0055] Since the shape and position of the ROI may change when the test object is rotated, the shape and position of the aperture 42 of the collimator 40 may change during the second scanning phase when the test object is rotated. Thus, the portion of the radiation detector 14 that is shadowed by the collimator 40 may vary for each of the second phase rotational positions, especially if the test object is asymmetric about the rotational axis for the first and second sets of rotational positions. As a result, the usable image data area in each of the second phase images may change. The useful image data area in the second phase image corresponds to the area of the radiation detector 14 not in the shadow of the collimator 40 when the second phase image was generated. The useful image area may include the entire detector area or a sub-region of the detector area that corresponds to the ROI. In some examples, the processing system 30 may replace second phase image pixels that are outside the usable area (ie, in the collimated area) of the second phase image with a replacement pixel. For example, the processing system 30 may replace the collimated area of the second phase image with white or black pixels. In some examples, processing system 30 may apply image size cropping to reduce storage size to potentially improve data transfer and reduce recovery time. The processing system 30 may use software to provide the pixel positions of the ROI changing detector of the cropped ROI radiographs.

[0056] In some examples, imaging system 10 generates each of the first phase images before generating any of the second phase images. For example, in this example, the imaging system 10 may generate first phase images as the test object rotates through the first complete rotation, and may generate second phase images as the test object rotates through the second complete rotation. In other examples, imaging system 10 may generate first phase images and second phase images in an interleaved manner. Thus, in some such examples, imaging system 10 may generate all first phase images and all second phase images in a single rotation of the test object. For example, the imaging system 10 may generate an image of the first phase while the test object is in the first rotation position, determine the positions of the collimator plates for the first rotation position, set the collimator plates to certain positions of the collimator plates for the first rotation position, generate an image of the second phase at while the test object is at the first rotation position, and then rotate the test object to the next rotation position. In this example, the imaging system 10 may repeat these steps for the next rotational position (i.e., generate a first phase image while the test object is in the second rotational position, determine the positions of the collimator plates for the second rotational position, set the collimator plates to certain collimator plate positions for the second rotation position, generate a second phase image while the test object is in the second rotation position, and then rotate the test object to the next rotation position).

[0057] In this example, the processing system 30 may calculate, based on the second image sequence, tomographic data for a portion of the test object being evaluated. Processing system 30 may compute tomographic data according to any known techniques for computing tomographic data based on a sequence of radiographs known in the art.

[0058] FIG. 2A is a conceptual drawing of an exemplary imaging system 10 when the test object 200 is in the first pivot position during the second phase of scanning, in accordance with one or more of the technologies of this disclosure. In the example of FIG. 2A, the collimator 40 collimates the full x-ray beam 15. Additionally, in the example of FIG. 2A, collimator plates 44A, 44B are positioned such that aperture 42 is wide enough to allow the outer edges of the collimated X-ray beam 202 that passes through aperture 42 to pass through a relatively small area (i.e., "air gap") near the outer edges of the test probe. object 200.

[0059] FIG. 2B is a conceptual drawing of exemplary positions of the collimator plates 40 when the test object 200 is in the first rotational position shown in FIG. 2A. Fig. 2B is a perspective view of the center emission point of the full X-ray beam 15 of FIG. 2A. In the example of FIG. 2B, collimator 40 has four collimator plates 44A, 44B, 44C, and 44D (collectively, "collimator plates 44"). Collimator plates 44C and 44D are not shown in the example of FIG. 2A due to the perspective of FIG. 2A. In the example of FIG. 2B, the collimator plates 44A and 44B are oriented vertically and the collimator plates 44C and 44D are oriented horizontally. Additionally, in the example of FIG. 2B, the collimator plates 44C and 44D are closer to the radiation generator 12 than the collimator plates 44A and 44B. Therefore, in the example of FIG. 2A, collimator plates 44A and 44B are partially obscured by collimator plates 44C and 44D.

[0060] The collimator plates 44 are arranged such that an air gap 204 occurs along one or more sides of the test object 200. The air gap 204 may allow X-rays passing through the aperture 42 of the collimator 40 to reach the radiation detector 14 without passing through the test object 200 In some examples, there is no air gap on all sides of the test object 200.

[0061] FIG. 2C is a conceptual drawing of an exemplary imaging system when a test object is in a second rotational position during a second phase of scanning, in accordance with one or more of the technologies of this disclosure. In the example of FIG. 2C, the test object 200 is rotated 90° from the first rotational position of the test object 200 shown in FIG. 2A. In other examples, test object 200 may be rotated to other angles. Thus, the narrowest edge of the test object 200 faces the radiation generator 12. Accordingly, the collimator plates 44A, 44B changed their position to reduce the size of the aperture 42, whereby the collimated X-ray beam 202 narrowed.

[0062] FIG. 2D is a conceptual drawing of exemplary positions of collimator plates 40 when test object 200 is in the second rotational position shown in FIG. 2C. Fig. 2D is an image from the same perspective as in FIG. 2B. Since the test object 200 has rotated, the narrower face of the test object 200 faces the radiation generator 12. As shown in the example of FIG. 2D, the collimator plates 44C and 44D remain in the same positions, but the processing system 30 has moved the collimator plates 44A and 44B closer together.

[0063] FIG. 3A shows a first exemplary test object 300 in a first pivot position. Fig. 3B shows the test object 300 of FIG. 3A in a second pivot position different from the first pivot position. Fig. 3A and FIG. 3B shows an example of a test object that has an asymmetric geometry where dynamic collimation may be useful when performing CT scans. In the example of FIG. 3A, ROI 302 corresponds to a portion of test object 300 that is smaller than test object 300. In the example of FIG. 3B, ROI 304 corresponds to the same portion of test object 300. As shown in FIG. 3A and 3B, the size and shape of the ROI may change from image to image as test object 300 is rotated.

[0064] FIG. 4A shows an exemplary radiograph 500 of test object 502 in the absence of collimation. In FIG. 4A, FIG. 4B and FIG. 4C, the test object may be the test object 300 shown in FIG. 3A and FIG. 3B. Fig. 4B shows an exemplary X-ray diffraction pattern 504 of the test object 502 of FIG. 4A in the case of a standard, non-dynamic CT collimation in a 0-degree rotational position. In other words, the X-ray pattern 504 is generated when the collimator plates did not change position based on the rotational position of the test object 502. Thus, while the positions of the collimator plates used in the X-ray pattern 504 may be optimal at this 0-degree rotational position, when the test object object 502 is rotated 90°, there is considerable space when test object 502 is in the 90 degree rotation position shown in FIG. 4E. Fig. 4C shows an exemplary x-ray 506 of the test object 502 of FIG. 4A-4B in the case of dynamic CT collimation at 0-degree rotational position according to one or more of the technologies of this disclosure. The radiographs of Fig. 4B and FIG. 4C are the same due to collimator plate positions corresponding to standard, non-dynamic collimation technologies based on the widest part of the test object at any rotational position of the test object. As shown in FIG. 4A-4C, the use of the collimation results in X-rays 504 and 506 resulted in better image contrast and better definition of the radiographic edge of the test object than in X-ray 500.

[0065] FIG. 4D shows an exemplary radiograph 508 of the test object 502 of FIG. 4A-4C in the absence of collimation in the 90 degree rotation. Fig. 4E shows an exemplary x-ray of the test object 502 of FIG. 4A-4D for standard, non-dynamic CT collimation in a 90 degree rotation. Fig. 4F shows an exemplary radiograph of the test object 502 of FIG. 4A-4E in the case of dynamic CT collimation in a 90 degree rotational position according to one or more of the technologies of this disclosure. The 90 degree rotation position is 90 degrees from the rotation position of the test object 502 shown in FIG. 4A-4C. In the example of FIG. 4F, the collimation was continuously adjusted from a 0-degree position with a maximum aperture to a 90-degree minimum position with an aperture slightly larger than the smallest projected region of interest.

[0066] Because conventional, non-dynamic collimation technologies do not adjust collimator plate positions based on the rotational position of test object 502, the collimator plate positions are the same in FIG. 4B and FIG. 4E despite the excellent rotational position of the test object 502. However, according to the dynamic collimation techniques of this disclosure, the position of the collimator plates changes based on the rotational position of the test object 502 in the radiograph 512. As can be seen in FIG. 4D, 4E, and 4F, the image contrast and radiographic edge sharpness of the test object in the radiograph 510 is greater than that of the radiograph 508. However, the image contrast and radiographic edge sharpness of the test object in the radiograph 512 is still greater than that in the radiograph 510 due to dynamically changing positions of the collimator plates. Additionally, the brightness of the ROI in radiographs 508 and 510 may be greater and the edges of the test object 502 may begin to "blur" in radiograph 510 compared to the case when dynamic collimation is used in generating radiograph 512 despite applying the same exposure parameters. The reduced brightness level of radiograph 512 and the increase in image contrast and sharpness of the radiographic edge of the test object are directly related to the reduction in scatter radiation when dynamic collimation is applied.

[0067] FIG. 5 is a flowchart showing a first exemplary operation of the imaging system 10 in accordance with one or more of the technologies of this disclosure. In other examples, more, fewer, or different actions may be performed according to the techniques of this disclosure compared to FIG. 5; or the actions may be performed in other orders or in parallel.

[0068] In the example of FIG. 5, an imaging system (eg, imaging system 10 of FIG. 1, imaging system 700 of FIG. 7, imaging system 800 of FIG. 8) may perform a first scanning phase for a test object (eg, test object 200, 300, 502). During the first phase of the scan, the imaging system 10 may, for each corresponding first phase rotation position from a set of two or more first phase rotation positions, generate (602) a corresponding first phase image in the first image sequence. The corresponding first phase image is generated while the test object is in the corresponding rotational position of the first phase. In some examples, each image in the first sequence of images is a radiograph. In some examples, instead of radiographs, the first sequence of images may include visible light photographs captured by auxiliary optical imaging components of imaging system 10. Each image in the first sequence of images may correspond to a different rotational position of the test object in the set of rotational positions of the first phase.

[0069] Additionally, in the example of FIG. 7, for each corresponding first phase rotation position from the set of first phase rotation positions, the imaging system may identify (604) an ROI (eg, ROI 302, 304 (FIG. 3)) in the corresponding first phase image. This ROI corresponds to a portion of the test item being evaluated. For example, the ROI may correspond to part of the test object or the entire test object. In some examples, processing system 30 automatically identifies the ROI, as described elsewhere in this disclosure. For example, processing system 30 may identify ROIs by tracking edges in images.

[0070] Optional. for each corresponding first phase rotation position from the set of first phase rotation positions, the imaging system may determine (606), based on the identified ROI in the corresponding first phase image, the collimator plate positions for the corresponding first phase rotation position. The imaging system may determine the positions of the collimator plates for the corresponding rotational position of the first phase according to any of the examples described elsewhere in this disclosure. Radiation is emitted by a radiation generator (eg, radiation generator 12) and passes through the aperture of a collimator (eg, collimator 40). The collimator is located between the radiation generator and the radiation detector. For example, the collimator may be located between the radiation generator and the test object. The test object can be placed between the collimator and the radiation detector. The collimator includes a plurality of collimator plates (eg, collimator plates 44) that are movable to change the size and shape of the collimator aperture.

[0071] Additionally, in the example of FIG. 5, for each corresponding second phase rotation position in the set of two or more second phase rotation positions, the imaging system may determine (608), based on the collimator plate positions for the first phase rotation positions, the collimator plate positions for the corresponding second phase rotation position. In some examples, the set of rotation positions of the first phase and the set of rotation positions of the second phase consist of the same rotation positions. In other examples, the second phase pivot position set includes more, fewer pivot positions, or different pivot positions compared to the first phase pivot position set. In some examples, the test object is asymmetrical about the pivot axis for the first phase pivot positions and the second phase pivot positions. Thus, it may be necessary to change the positions of the collimator plates as the test object is rotated.

[0072] When the corresponding rotation position of the second phase is the same as the rotation position of the first phase in the set of rotation positions of the first phase, the imaging system may determine that the positions of the collimator plates for the corresponding rotation position of the second phase are the same as the positions of the collimator plates for the rotation position of the first phase. When the corresponding second phase rotation position is different from any first phase rotation position in the first phase rotation position set, the imaging system may determine the collimator plate positions for the corresponding second phase rotation position based on the collimator plate positions for the two or more first phase rotation positions, as described. elsewhere in this disclosure.

[0073] The imaging system may generate (610) a corresponding second phase image in the second image sequence. The corresponding image of the second phase is generated based on the radiation patterns detected by the radiation detector (for example, the radiation detector 14) at the time when the test object is in the corresponding rotational position of the second phase and at the time when the collimator plates are in the positions of the collimator plates for the corresponding rotational position of the second phase. The corresponding image of the second phase may be a radiograph. As part of generating the image of the second phase, the imaging system may control the positions of the collimator plates based on the positions of the collimator plates for the corresponding rotational position of the second phase. To physically control the collimator plates, the processing system of the imaging system (eg, the processing system 30) can directly or indirectly send signals to motors that drive the collimator plates. As mentioned above, in some examples, the radiation detector may include an LDA-based X-ray detector. In such examples, the collimator may be required to include only two collimator plates movable in a direction perpendicular to the longitudinal axis of the LDA x-ray detector.

[0074] Next, the imaging system may calculate (614), based on the second image sequence, tomographic data for a portion of the test object being evaluated. The imaging system may compute tomographic data according to any of the well-known techniques for computing tomographic data based on a sequence of radiographs or sinograms known in the art, such as, but not limited to, filtered back projection (FBP) techniques, iterative recovery techniques (iterative reconstruction - IR) and Fourier reconstruction technologies.

[0075] Additionally, the examples provided above refer to a collimator (eg, collimator 40) having a single aperture. However, in some examples, the collimator may have two or more apertures in a system with a single radiation generator 12 and a single radiation detector 14. In such a system, each of the apertures can be used to simultaneously evaluate a different test object. The processing system 30 can independently adjust the sizes and shapes of each of the apertures. In such examples, the processing system 30 may be configured to independently change the positions of each of the collimator plates. In another embodiment, two or more collimator plates may be linked to move together.

[0076] In some examples, an imaging system (eg, imaging system 10, 700, 800) may perform the actions of FIG. 5 automatically for one or more test objects without human intervention. In some such examples, the pipeline mechanism may automatically load test objects into the rendering system. Additionally, in some instances where multiple test objects of the same type are to be evaluated, the rendering system may perform the first phase (i.e., actions (602), (604), and (606)) on one of the test objects (e.g., the first emerging test object) to determine (608) the positions of the collimator plates for the rotational positions of the first phase and to determine the positions of the collimator plates for the rotational positions of the second phase. In such examples, the imaging system may reuse the collimator plate position information for second phase rotation positions to generate second phase images of other test objects without repeating steps (602), (604), (606), and (608) for other test objects. . In some examples, the test object in question may be the same physical test object, or two different physical test objects of the same type (eg, with the same shape, dimensions, composition, etc.).

[0077] FIG. 6 is a flowchart showing a second exemplary operation of an imaging system in accordance with one or more of the technologies of this disclosure. In contrast to the exemplary operation of FIG. 5, operation of FIG. 6 can generate images used to compute tomographic data in a single phase. In some examples, each of the images is a radiograph.

[0078] Specifically, in the example of FIG. 6, the imaging system 10 may generate (650) the current image. When the current image is the first occurring image in the set of images used to compute tomographic data, the imaging system 10 may generate the current image at the time the test object is at the first occurring rotational position in the rotational position set. In some examples, imaging system 10 may generate the first emerging image at a time when the collimator aperture is at its widest configuration.

[0079] Next, the imaging system 10 may identify (652) the ROI in the current image. As before, the ROI may correspond to a portion of the test object being evaluated, for example, a portion of the test object, or the entire test object being evaluated. In some examples, the edges of the ROI in the current image correspond to the outer edges of the test object shown in the current image, with an air gap of a few pixels on one or more sides. In some examples, the imaging system 10 automatically identifies the ROI as described in the examples provided elsewhere in this disclosure. In some examples, instead of using the current image to identify the ROI in the current image, the imaging system 10 may use information (eg, test object dimensions) in the CAD file for the test object to determine the ROI.

[0080] In one example, after determining the ROI in the first emerging image, the imaging system 10 may determine the positions of the collimator plates corresponding to the ROI in the first emerging image. In this example, the imaging system 10 may then change the positions of the collimator plates in accordance with the determined positions of the collimator plates. Additionally, in this example, the imaging system 10 may then reconstruct the image for the first rotational position that occurs. In this example, imaging system 10 may use this reconstructed image when computing a tomographic model of a portion of the test object.

[0081] In the example of FIG. 6, the imaging system 10 may then determine (654), based on the identified ROI in the image, the positions of the collimator plates for the next rotation position in the set of rotation positions. In some examples, to determine the positions of the collimator plates for the next rotational position, the imaging system 10 may determine the expected ROI for the next rotational position. The imaging system 10 may determine the expected ROI for the next rotational position based on the size of the air gap in the current image. For example, for each side of the bounding box that defines the ROI (or sides in a subset of the sides of the bounding box), if the air gap is less than a first threshold size (e.g., less than a given number of pixels), then the rendering system 10 moves that side outward relative to the test object. Conversely, if the air gap is larger than the second threshold size (eg, larger than a given number of pixels), then the rendering system 10 moves that side inward relative to the test object. The first and second threshold sizes may be the same or different numbers. Also, in some examples, there may be different first and second thresholds for different sides of the bounding box. In some examples, the amount by which the imaging system 10 moves the side out or in can be a fixed number. In some examples, imaging system 10 may determine the amount by which imaging system 10 moves a side out or in based on the difference in air gap size on that side in the previous two images. In some examples, the imaging system 10 may determine the amount by which the imaging system 10 moves the side out or in based on predetermined data indicative of the dimensions of the test object and how many degrees of rotation fall between the current rotation position and the next rotation position. After determining the ROI for the next pivot position, imaging system 10 may determine the collimator plate positions for the next pivot position based on a mathematical relationship between the collimator plate positions and the location and size of the ROI for the next pivot position in the same manner as described elsewhere in this disclosure.

[0082] Next, the imaging system 10 may rotate (656) the test object to the next rotation position in the rotation position set, change the collimator plate positions to the collimator plate positions for the next rotation position, and generate a new current image. Additionally, the imaging system 10 may determine if there are (658) any additional rotational positions in the set of rotational positions. In response to determining that additional rotational positions in the rotational position set exist (Yes branch of action 658), the imaging system 10 may repeat actions (652) - (658) with respect to the new current image. Otherwise, in response to determining that no additional rotation positions exist in the rotation position set (No branch of action 658), the imaging system 10 may compute (660), based on the images, a tomographic model of the portion of the test object being evaluated. The imaging system 10 may compute the tomographic model as described elsewhere in this disclosure.

[0083] FIG. 7 is a schematic drawing of an exemplary imaging system 700 in accordance with one or more of the technologies of this disclosure. In most respects, imaging system 700 is similar to imaging system 10 (FIG. 1). Thus, the parts numbered in FIG. 7 with the same reference numerals as the parts in FIG. 1 have the same functions and can be implemented in the same way as these parts in FIG. one.

[0084] In some examples, the test object itself may scatter x-rays that have passed through the aperture 42 of the collimator 40. The x-rays scattered in the test object may, in turn, be reflected or scattered from other areas of the object or components of the imaging system 700 before hit the detector 14 radiation. Thus, X-rays scattered from the test object can reduce the contrast in any resulting radiograph.

[0085] Accordingly, in the example of FIG. 7, imaging system 700 is provided with a second collimator 702 that is located on the detector side of test object 704 with collimator 702. Collimator 702 may be synchronized with tube side collimator 40 or may be moved and controlled independently of tube side collimator 40. Collimator 702 has a plurality of collimator plates including collimator plates 710A, 710B. Other collimator plates of collimator 702 are not shown in the example of FIG. 7 due to the perspective of FIG. 7. In some examples, the imaging system 700 may include a system for moving the collimator 702 as a unit. This may be useful because, in some instances, it may be preferable to keep the collimator 702 as close to the test object 704 as possible while rotating the test object 704.

[0086] The auxiliary collimation shown in FIG. 7 can reduce the scattered radiation 706 initiated by the test object 704 that terminates in the region of interest on the radiation detector 14. This assisted dynamic collimation can further improve the image contrast and radiographic edge sharpness of the test object by reducing this secondary scattering from the test object. Since collimator 702 is synchronized with collimator 40, changes in the size, shape, and position of aperture 42 result in corresponding changes in size, shape, and position of aperture 708 of collimator 702. For example, if aperture 42 becomes wider horizontally, then aperture 708 also becomes wider horizontally. . In some examples, processing system 30 may determine the angle θ such that tg(θ) is equal to ½ of the width (or height) of aperture 42 divided by the distance from aperture 42 to radiation generator 12. In this example, processing system 30 may determine the width (or height) of aperture 708 as 2*tg(θ)*(distance from aperture 42 to radiation generator 12). In other examples, processing system 30 may control the positions of the collimator plates of collimator 702 independently of the positions of the collimator plates of collimator 40.

[0087] Thus, the collimator referred to in FIG. 5 may be considered the first collimator, the positions of the collimator plates for the corresponding rotational position of the second phase may be considered the first positions of the collimator plates for the corresponding rotational position of the second phase. Additionally, continuing with FIG. 5, the imaging system 700 may, for a corresponding second phase rotation position from a set of second phase rotation positions, determine, based on the collimator plate positions for the first phase rotation positions, second collimator plate positions for the corresponding second phase rotation position. For example, the imaging system 700 may determine the second positions of the collimator plates for the corresponding rotational position of the second phase, as described in the previous paragraph. Additionally, continuing with FIG. 5, the imaging system 700 may generate a corresponding second phase image based on the radiation patterns detected by the radiation detector 14 while the test object is in the corresponding rotational position of the second phase at the time when the collimator plates of the first collimator (i.e., the collimator 40) are at the first collimator plate positions for the corresponding second phase rotation position and while the second collimator plates 710 (i.e., collimator 702) are at the second collimator plate positions for the corresponding second phase rotation position.

[0088] FIG. 8 is a schematic drawing of an exemplary imaging system 800 in accordance with one or more of the technologies of this disclosure. In most respects, imaging system 800 is similar to imaging system 10 (FIG. 1) and imaging system 700 (FIG. 7). Thus, the parts numbered in FIG. 8 with the same reference numerals as the parts in FIG. 1 and FIG. 7 have the same functions and can be implemented in the same way as those parts in FIG. 1 and FIG. 7.

[0089] In the example of FIG. 8, the imaging system 800 is provided with a collimator 802, which is located on the detector side of the test object 704 with the collimator 802. In other words, the collimator 802 is located between the test object 704 and the radiation detector 14. However, imaging system 800 does not include a collimator, such as collimator 40 located between test object 704 and radiation generator 12. Like collimator 702, collimator 802 has a plurality of collimator plates including collimator plates 810A, 810B. Other collimator plates of collimator 802 are not shown in the example of FIG. 8 from the perspective of FIG. 8. In some examples, imaging system 800 may include a system for moving collimator 802 as a unit. This can be useful because in some examples it may be preferable to keep the collimator 802 as close to the test object 704 as possible. The collimator 802 can provide similar benefits as described above with respect to the collimator 702 in FIG. 7.

[0090] Although the technologies of this disclosure have been described with reference to x-rays, the technologies of this disclosure can also be applied to electromagnetic radiation at other wavelengths, such as visible light, microwaves, ultraviolet radiation, radio waves, infrared radiation, gamma rays. radiation, or other types of electromagnetic radiation.

[0091] The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses. Various components, modules, or blocks are described in this disclosure to emphasize the functional aspects of devices capable of implementing the disclosed technologies, but do not necessarily require implementation by different hardware blocks. Rather, as described above, the various blocks may be combined in some hardware block, or provided by a set of cooperating hardware blocks, including one or more of the processors described above, along with suitable software and/or firmware.

[0092] In one or more examples, the specific functions described may be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, the functions may be stored or transmitted as one or more instructions or code on a computer-readable storage medium and executed by a hardware processing unit. Computer-readable storage media may include computer-readable storage media that corresponds to a tangible medium, such as storage media, or communication media, including any medium that enables the transfer of a computer program from one place to another, for example, according to some communication protocol. Thus, computer-readable storage media can generally correspond to (1) tangible computer-readable storage media that is non-transitional, or (2) a communication medium such as a signal or carrier wave. Storage media can be any suitable media that can be accessed by one or more computers or one or more processors to retrieve instructions, code, and/or data structures for implementing the technologies described in this disclosure. The computer program product may include a computer-readable storage medium.

[0093] By way of example, and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage device, magnetic disk storage device, or other magnetic storage devices, flash memory, or any other medium that can be used to store program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable storage medium. For example, if commands are sent from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared technology, radio technology , and microwave technology, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared technology, radio technology, and microwave technology should be included in the media definition. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transient media, but are instead directed to non-transitory, tangible data storage media. The discs (disk and disc) used herein include a compact disc (CD), a laser disc, an optical disc, a digital versatile disc (DVD), a floppy disc, and a Blu-ray disc, wherein discs with the English spelling "disk" usually reproduce data magnetically, while discs with the English spelling "disc" reproduce data optically using lasers. Combinations of the above should also be included within the scope of computer-readable storage media.

[0094] Instructions can be executed by one or more processors, such as one or more digital signal processors (digital signal processor - DSP), general purpose microprocessors, application specific integrated circuits (ASIC), arrays of programmable logic gates (field -programmable gate array - FPGA) or other equivalent integrated or discrete logic circuits. Accordingly, the term "processor" as used herein may refer to any of the aforementioned structures, or to any other structure suitable for implementing the technologies described here. Additionally, in some aspects, the functionality described herein may be provided in dedicated hardware and/or software modules. Also, specific parts of these technologies may be implemented in one or more circuits or logic elements.

[0095] Various examples have been described above. These and other examples are within the scope of the following claims.

Claims (86)

1. A method for generating tomographic data of a test object, the method comprising the steps of: for each corresponding rotational position of the first scanning phase from a set of two or more rotational positions of the first scanning phase: generating, by means of the imaging system, a corresponding first scanning phase image in the first sequence of images, wherein the corresponding first scanning phase image is generated while the test object is in the corresponding rotational position of the first scanning phase; identifying, by means of the imaging system, a region of interest (ROI) in the corresponding image of the first scanning phase, the ROI corresponding to a portion of the test object being evaluated; and determine, by means of the imaging system, on the basis of the identified ROI in the corresponding image of the first scanning phase, the positions of the collimator plates for the corresponding rotational position of the first scanning phase, wherein the radiation is emitted by the radiation generator and passes through the aperture of the collimator, the collimator is located between the radiation generator and the radiation detector, the test object located between the radiation generator and the radiation detector, and the collimator contains a plurality of collimator plates that are movable with the ability to change the size and shape of the collimator aperture; for each corresponding rotational position of the second scanning phase from a set of two or more rotational positions of the second scanning phase: determining, by means of the imaging system, based on the positions of the collimator plates for the rotational positions of the first scanning phase, the positions of the collimator plates for the corresponding rotational position of the second scanning phase; and generating, by means of the imaging system, a corresponding image of the second scanning phase in the second sequence of images, wherein the corresponding image of the second scanning phase is a radiograph generated based on the radiation patterns detected by the radiation detector at the time when the test object is in the corresponding rotational position of the second scanning phase, and while the collimator plates are at the positions of the collimator plates for the corresponding rotational position of the second scanning phase; and calculating, by means of the imaging system, based on the second sequence of images, tomographic data for a portion of the test object being evaluated. 2. The method according to claim 1, in which: the collimator is located between the radiation generator and the test object, and the test object is located between the collimator and the radiation detector, or the collimator is located between the radiation detector and the test object, and the test object is located between the collimator and the radiation generator. 3. The method of claim 1, wherein the set of rotational positions of the first scanning phase and the set of rotational positions of the second scanning phase consist of the same rotational positions. 4. The method according to claim 1, in which: the step of identifying the ROI in the corresponding image of the first scanning phase comprises the steps of: identifying, by means of the imaging system, locations in the corresponding image of the first scanning phase that correspond to the edges of a part of the test object being evaluated; and defining, by means of the rendering system, a rectangular bounding box that contains the identified locations, and the step of determining the positions of the collimator plates for the corresponding rotational position of the first scanning phase comprises the step of determining, by means of the imaging system, the positions of the collimator plates for the corresponding rotational position of the first scanning phase in such a way that the projection of the edges of the collimator aperture on the radiation detector corresponds to a certain rectangular bounding box. 5. The method according to claim. 1, in which the step of determining the positions of the collimator plates for the corresponding rotational position of the second scanning phase comprises the steps of: based on the corresponding rotational position of the second scanning phase being the same as the rotational position of the first scanning phase in the set of rotational positions of the first scanning phase, it is determined by the imaging system that the positions of the collimator plates for the corresponding rotational position of the second scanning phase are the same as the positions collimator plates for the rotary position of the first scanning phase; and based on the corresponding rotational position of the second scanning phase, which is different from any rotational position of the first scanning phase in the set of rotational positions of the first scanning phase, the positions of the collimator plates for the corresponding rotational position of the second scanning phase are determined, by means of the imaging system, based on the positions of the collimator plates for two or more rotary positions of the first phase of scanning. 6. The method of claim. 1, in which the test object is asymmetric about the axis of rotation for the rotational positions of the first phase of scanning and the rotational positions of the second phase of scanning. 7. The method according to claim 1, in which: collimator is the first collimator, the positions of the collimator plates for the corresponding rotational position of the second scanning phase are the first positions of the collimator plates for the corresponding rotational position of the second scanning phase, the first collimator is located between the test object and the radiation generator, the second collimator is located between the test object and the radiation detector, the method further comprising the step of, for each corresponding rotational position of the second scanning phase from the set of rotational positions of the second scanning phase, determining, by means of the imaging system, based on the positions of the collimator plates for the rotational positions of the first scanning phase, the second positions of the collimator plates for the respective rotational positions of the second phase of scanning; and the step of generating the corresponding image of the second scanning phase comprises the step of generating the corresponding image of the second scanning phase based on the radiation patterns detected by the radiation detector at the time when the test object is in the corresponding rotational position of the second scanning phase at the time when the collimator plates of the first collimator are in the first positions of the collimator plates for the corresponding rotational position of the second scanning phase, and while the collimator plates of the second collimator are in the second positions of the collimator plates for the corresponding rotational position of the second scanning phase. 8. The method of claim 1, wherein each corresponding image in the first image sequence is a radiograph. 9. An imaging system, comprising: radiation generator; radiation detector; collimator, moreover, the radiation emitted by the radiation generator passes through the collimator aperture, while the collimator is located between the radiation generator and the radiation detector, the test object is located between the radiation generator and the radiation detector, and the collimator contains a plurality of collimator plates that are movable with the ability to change the size and shape collimator apertures; and a processing system configured to: for each corresponding rotational position of the first scanning phase from a set of two or more rotational positions of the first scanning phase: generate a corresponding image of the first phase of scanning in the first sequence of images, and the corresponding image of the first phase of scanning is generated at the time when the test object is in the corresponding rotational position of the first phase of scanning; to identify a region of interest (ROI) in the corresponding image of the first phase of scanning, and ROI corresponds to a part of the evaluated test object; and determine, based on the identified ROI in the corresponding image of the first scanning phase, the positions of the collimator plates for the corresponding rotational position of the first scanning phase; for each corresponding rotational position of the second scanning phase from a set of two or more rotational positions of the second scanning phase: determine, based on the positions of the collimator plates for the rotational positions of the first scanning phase, the positions of the collimator plates for the corresponding rotational position of the second scanning phase; and generate a corresponding image of the second scan phase in the second sequence of images, wherein the corresponding second scan phase image is an X-ray pattern generated based on the radiation patterns detected by the radiation detector at the time when the test object is in the corresponding rotational position of the second scan phase and at the time when the collimator plates are in the positions of the collimator plates for the corresponding rotational position of the second scanning phase; and calculate, based on the second sequence of images, tomographic data for a portion of the evaluated test object. 10. The imaging system of claim. 9, in which the collimator is located between the radiation generator and the test object and the test object is located between the collimator and the radiation detector. 11. The imaging system of claim. 9, in which the collimator is located between the radiation detector and the test object and the test object is located between the collimator and the radiation generator. 12. The imaging system of claim 9, wherein the set of rotational positions of the first scanning phase and the set of rotational positions of the second scanning phase consist of the same rotational positions. 13. The visualization system according to claim 9, in which: the processing system is designed in such a way that, as part of the step of identifying the ROI in the corresponding image of the first scanning phase, the processing system: identifies locations in the corresponding image of the first scanning phase that correspond to the edges of a portion of the test object being evaluated; and defines a rectangular bounding box that contains the identified locations, and the processing system is designed in such a way that, as part of the step of determining the positions of the collimator plates for the corresponding rotational position of the first scanning phase, the processing system determines the positions of the collimator plates for the corresponding rotational position of the first scanning phase in such a way that the projection of the edges of the collimator aperture onto the radiation detector corresponds to a certain rectangular bounding box. 14. The imaging system of claim. 9, wherein the processing system is configured such that, as part of the step of determining the positions of the collimator plates for the corresponding rotational position of the second scanning phase, the processing system: based on the corresponding rotational position of the second scanning phase being the same as the rotational position of the first scanning phase in the set of rotational positions of the first scanning phase, determines that the positions of the collimator plates for the corresponding rotational position of the second scanning phase are the same as the positions of the collimator plates for the rotational positions of the first phase of scanning; and based on a corresponding rotational position of the second scanning phase, which is different from any rotational position of the first scanning phase in the set of rotational positions of the first scanning phase, determines the positions of the collimator plates for the corresponding rotational position of the second scanning phase, based on the positions of the collimator plates for two or more rotational positions of the first phase scanning. 15. The visualization system according to claim 9, in which collimator is the first collimator, the positions of the collimator plates for the corresponding rotational position of the second scanning phase are the first positions of the collimator plates for the corresponding rotational position of the second scanning phase, the first collimator is located between the test object and the radiation generator, the second collimator is located between the test object and the radiation detector, the processing system is further configured to, for each corresponding rotational position of the second scanning phase from the set of rotational positions of the second scanning phase, determine, based on the positions of the collimator plates for the rotational positions of the first scanning phase, the second positions of the collimator plates for the corresponding rotational position of the second scanning phase, and the processing system is configured to generate a corresponding image of the second scanning phase based on the radiation structures detected by the radiation detector at the time when the test object is in the corresponding rotational position of the second scanning phase, while the collimator plates of the first collimator are in the first positions of the collimator plates for the corresponding rotational position of the second scanning phase, and while the collimator plates of the second collimator are in the second positions of the collimator plates for the corresponding rotational position of the second scanning phase. 16. The imaging system of claim 9, wherein each corresponding image in the first sequence of images is a visible light based image. 17. A non-transitory computer-readable storage medium having instructions stored thereon which, when executed, causes one or more processors to: for each corresponding rotational position of the first scanning phase from a set of two or more rotational positions of the first scanning phase: generate a corresponding image of the first phase of scanning in the first sequence of images, and the corresponding image of the first phase of scanning is generated at the time when the test object is in the corresponding rotational position of the first phase of scanning; to identify a region of interest (ROI) in the corresponding image of the first phase of scanning, and ROI corresponds to a part of the evaluated test object; and determine, based on the identified ROI in the corresponding image of the first scan phase, the positions of the collimator plates for the corresponding rotational position of the first scan phase, and the radiation is emitted by the radiation generator and passes through the aperture of the collimator, while the collimator is located between the radiation generator and the radiation detector, the test object is located between a radiation generator and a radiation detector, and the collimator contains a plurality of collimator plates that are movable with the ability to change the size and shape of the collimator aperture; for each corresponding rotational position of the second scanning phase from a set of two or more rotational positions of the second scanning phase: determine, based on the positions of the collimator plates for the rotational positions of the first scanning phase, the positions of the collimator plates for the corresponding rotational position of the second scanning phase; and generate a corresponding image of the second scan phase in the second sequence of images, wherein the corresponding second scan phase image is an X-ray pattern generated based on the radiation patterns detected by the radiation detector at the time when the test object is in the corresponding rotational position of the second scan phase, and at the time, when the collimator plates are in the positions of the collimator plates for the corresponding rotational position of the second scanning phase; and calculate, based on the second sequence of images, tomographic data for a portion of the evaluated test object. 18. The non-transitory computer-readable storage medium of claim 17, wherein: as part of the step of causing one or more processors to identify the ROI in the corresponding image of the first scan phase, executing the instructions causes one or more processors to: identify locations in the corresponding image of the first scanning phase that correspond to the edges of a portion of the test object being evaluated; and define a rectangular bounding box that contains the identified locations, and as part of the step of causing one or more processors to determine the positions of the collimator plates for the corresponding rotational position of the first scan phase, the execution of the instructions causes one or more processors to determine the positions of the collimator plates for the corresponding rotational position of the first scan phase so that the projection of the edges of the collimator aperture on the radiation detector corresponded to a certain rectangular bounding box. 19. The non-transitory computer-readable storage medium of claim 17, wherein, as part of causing one or more processors to determine collimator plate positions for a corresponding rotational position of the first scan phase, executing the instructions causes one or more processors to: based on the corresponding rotational position of the second scanning phase being the same as the rotational position of the first scanning phase in the set of rotational positions of the first scanning phase, determine that the positions of the collimator plates for the corresponding rotational position of the second scanning phase are the same as the positions of the collimator plates for the rotational positions of the first phase of scanning; and based on a corresponding rotational position of the second scanning phase, which is different from any rotational position of the first scanning phase in the set of rotational positions of the first scanning phase, determine the positions of the collimator plates for the corresponding rotational position of the second scanning phase, based on the positions of the collimator plates for two or more rotational positions of the first phase scanning. 20. The visualization system according to claim 15, in which: collimator is the first collimator, the positions of the collimator plates for the corresponding rotational position of the second scanning phase are the first positions of the collimator plates for the corresponding rotational position of the second scanning phase, the first collimator is located between the test object and the radiation generator, the second collimator is located between the test object and the radiation detector, wherein the execution of the instructions further causes one or more processors to determine, for each respective second scan phase rotation position from the set of second scan phase rotation positions, based on the collimator plate positions for the first scan phase rotation positions, the second collimator plate positions for the respective second scan phase rotation position , and the execution of the commands causes one or more processors to generate the corresponding image of the second scan phase based on the radiation patterns detected by the radiation detector at the time when the test object is in the corresponding rotational position of the second scan phase at the time when the collimator plates of the first collimator are in the first positions of the collimator plates for the corresponding rotational position of the second scanning phase, and while the collimator plates of the second collimator are in the second positions of the collimator plates for the corresponding rotational position of the second scanning phase.

Images