Rapid industrial computed tomography for large objects

Abstract

Systems and methods for non-destructive testing by computed tomography are provided. The system can include a stationary radiation source, a stage, and a plurality of stationary radiation detectors. The source can be configured to emit a penetrating radiation beam having a three-dimensional geometry from a focal point and direct the beam into a path that is incident on a target. The stationary radiation source can be positioned relative to the plurality of stationary radiation detectors and the stage such that a first plurality of beam segment paths are defined between the focal point and respective sensing faces of the plurality of radiation detectors and at least one second beam segment path is defined between the focal point and a predetermined gap.

Description

Background Technology

[0001] Non-destructive testing (NDT) is a class of analytical techniques that can be used to examine a target without causing damage to determine whether the target meets required specifications. NDT has been widely adopted in industries that employ structures that are not easily removed from their surrounding environment, such as aerospace, power generation, oil and gas transportation or refining, and shipping.

[0002] Computed tomography (CT) is an example of NDT technology. In some implementations, CT can provide quantitative images of material density as a function of the geometry of a cross-section passing through the target. These cross-sectional images can be combined to obtain a corresponding 3D representation of the target. Summary of the Invention

[0003] In some cases, a CT system may include a radiation source that generates penetrating radiation (e.g., X-rays), a rotatable stage, and a detector. During the examination, a target is mounted on the stage, and the radiation source generates and directs radiation along a path that passes through the target at a predetermined angle (e.g., relative to a reference angle) and is incident on the detector; this is referred to as a CT projection. As the radiation travels through the target, a portion of the radiation intensity (energy per unit time and per unit stereo angle) may be lost due to absorption and / or scattering, resulting in a decrease in the intensity of the transmitted radiation compared to the amount incident on the target. Therefore, the intensity of the radiation detected by the detector after passing through the target can be a function of the length of the path the radiation traveled and the material through which the radiation passed (e.g., material composition, material density, etc.). After the detector measures the radiation intensity at a first angle relative to the position of a first CT projection, the stage can be rotated to a second angle. The second angle can be characterized relative to a reference angle, or the first CT measurement can be used as a reference angle, and the measurement process can be repeated to characterize a second CT projection at the second angle. This CT measurement and rotation sequence can be repeated until enough CT projections have been acquired to sample the target volume of the desired size, up to and including the entire target; this is known as a CT scan. The detector transmits the radiation intensity-location data acquired by the detector during the CT scan to a computing device. The computing device can then combine the intensity-location data based on the target's rotation angle, the direction of the radiation beam, and the selected reconstruction method to provide a three-dimensional characterization of the examined target volume. However, in some cases, the target and / or its projection onto the detector may be larger than the detector itself (e.g., targets such as aircraft wings, turbine blades, etc.).

[0004] While techniques have been developed to increase the measurement area of ​​detectors, these solutions may have problems. On one hand, the detector and / or target (e.g., stage) can be moved to increase the effective size of the detector. However, moving the detector and / or target can increase the time required to complete a CT scan. When CT equipment is in high demand, extended scan times may be undesirable. On the other hand, detectors with larger dimensions can be used. However, larger detectors may be more expensive than their smaller counterparts.

[0005] Generally, improved systems and methods for CT examinations are provided that overcome one or more of these limitations. Such systems and methods can employ at least two detectors simultaneously to expand the CT measurement area for examining large targets and / or targets presenting large projections. This approach can help save time when larger detectors are unavailable, or when available larger detectors are too expensive or unsuitable for the penetrating radiation employed (e.g., unable to measure at least a portion of the energy of the penetrating radiation). There is no delay caused by moving a single detector or target to expand the measurement area, thus saving time. The measurement area can be further expanded by employing additional detectors simultaneously (e.g., three or more detectors). In some embodiments, penetrating radiation can be emitted in one dimension (e.g., a line or point), two dimensions (e.g., a sector), or three dimensions (e.g., a cone). Detectors can be positioned in various locations depending on the geometry of the penetrating radiation (e.g., the opening cone angle of three-dimensional penetrating radiation).

[0006] In one embodiment, a system is provided that may include a stage, a plurality of static radiation detectors, and a static radiation source. The stage may be configured to hold a target thereon and rotate the target about an axis of rotation. Each of the plurality of static radiation detectors may include a sensing surface configured to acquire a measurement of penetrating radiation incident thereon as a function of position. The sensing surfaces of adjacent radiation detectors may be separated by a predetermined gap. The static radiation source may be configured to emit a penetrating radiation beam from a focal point. The plurality of static radiation detectors and the radiation source may be positioned relative to the stage and configured to emit beams such that first plurality of beam segment paths may be defined between the focal point of the plurality of radiation detectors and a corresponding sensing surface, and at least one second beam segment path may be defined between the focal point and the predetermined gap.

[0007] In another embodiment, multiple radiation detectors may be positioned relative to the target and the radiation source such that a first plurality of beam segment paths extend through more than half of the cross-sectional area of ​​the target in a predetermined measurement plane.

[0008] In another embodiment, multiple radiation detectors may be positioned relative to the target and the radiation source such that the central axis of the respective beam path in the first plurality of beam path may be offset from the axis of rotation.

[0009] In another embodiment, the first beam segment path in the first plurality of beam segment paths may be a straight cone, and the second beam segment path in the first plurality of beam segment paths may be an oblique cone.

[0010] In another embodiment, the sensing surfaces of at least two of the plurality of radiation detectors may be coplanar.

[0011] In another embodiment, the first sensing surface of a first radiation detector among a plurality of radiation detectors may be aligned with a first detector plane, and the second sensing surface of a second radiation detector among a plurality of radiation detectors may be aligned with a second detector plane. The first detector plane and the second detector plane may be substantially parallel and laterally offset from each other by a predetermined offset distance.

[0012] In another embodiment, a first surface normal extending from the centroid of the sensing surface of at least one of the plurality of radiation detectors may be oriented at a predetermined non-zero angle to a second surface normal extending from a plane containing the focal point of the radiation source.

[0013] In another embodiment, the plurality of radiation detectors may include a first radiation detector and a second radiation detector. A first surface normal extending from a first sensing surface may be parallel to a first radial vector extending from the focal point to the centroid of the first sensing surface, and a second surface normal extending from a second sensing surface may be parallel to a second radial vector extending from the focal point to the centroid of the second sensing surface.

[0014] In another implementation, the length of the first radial vector may be equal to the length of the second radial vector.

[0015] In another implementation, the length of the first radial vector may be different from the length of the second radial vector.

[0016] In another embodiment, a method for non-destructive testing via computed tomography is provided. The method may include emitting a penetrating radiation beam from a focal point of a stationary radiation source. The method may further include guiding the emitted radiation beam into a beam path extending from the focal point, passing through a portion of a target, and incident on respective sensing surfaces of a plurality of stationary radiation detectors. The plurality of stationary radiation detectors may be positioned relative to the stationary radiation source and the target such that the emitted radiation beam defines a first plurality of beam segment paths extending between the focal points and sensing surfaces of the plurality of stationary radiation detectors and at least one second beam segment path extending between the focal point and a predetermined gap. The method may further include each of the plurality of stationary radiation detectors outputting a corresponding signal, the corresponding signal including data characterizing the intensity of the penetrating radiation incident on its sensing surface, the intensity of which is a function of position.

[0017] In another embodiment, multiple radiation detectors may be positioned relative to the target and the radiation source such that the central axis of the respective beam path in the first plurality of beam path may be offset from the axis of rotation.

[0018] In another embodiment, the first plurality of beam path can penetrate more than half of the cross-sectional area of ​​the target within the predetermined measurement plane.

[0019] In another embodiment, after a single rotation of the target, the first plurality of beam path paths can penetrate through the entire cross-sectional area of ​​the target within a predetermined measurement plane.

[0020] In another embodiment, the first beam segment path in the first plurality of beam segment paths may be a straight cone, and the second beam segment path in the first plurality of beam segment paths may be an oblique cone.

[0021] In another embodiment, the sensing surfaces of at least two of the plurality of radiation detectors may be coplanar.

[0022] In another embodiment, the first sensing surface of a first radiation detector among a plurality of radiation detectors may be aligned with a first detector plane, and the second sensing surface of a second radiation detector among a plurality of radiation detectors may be aligned with a second detector plane. The first detector plane and the second detector plane may be parallel and laterally offset from each other by a predetermined offset distance.

[0023] In another embodiment, a first surface normal extending from the centroid of the sensing surface of at least one of the plurality of radiation detectors may be oriented at a predetermined non-zero angle to a second surface normal extending from a plane containing the focal point of the radiation source.

[0024] In another embodiment, the plurality of radiation detectors may include a first radiation detector and a second radiation detector. A first surface normal extending from a first sensing surface may be parallel to a first radial vector extending from the focal point to the centroid of the first sensing surface, and a second surface normal extending from a second sensing surface may be parallel to a second radial vector extending from the focal point to the centroid of the second sensing surface.

[0025] In another implementation, the length of the first radial vector may be equal to the length of the second radial vector.

[0026] In another implementation, the length of the first radial vector may be different from the length of the second radial vector. Attached Figure Description

[0027] These and other features will be more readily understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0028] Figure 1 This is an illustration of an exemplary embodiment of an operating environment including a computed tomography (CT) system, which includes a radiation source configured to emit a penetrating radiation beam for examining a target and multiple radiation detectors configured to detect the penetrating radiation after it has passed through the target.

[0029] Figure 2 It is shown Figure 1 The illustration shows another exemplary embodiment of a CT system, which includes three radiation detectors configured to detect penetrating radiation after it has passed through a target;

[0030] Figure 3 It is shown Figure 1 The illustration shows another exemplary embodiment of a CT system, which includes two radiation detectors positioned in different planes relative to each other;

[0031] Figure 4 It is shown Figure 1 The illustration shows another exemplary embodiment of a CT system, which includes a radiation detector positioned at a non-zero angle relative to a radiation source;

[0032] Figure 5 It is shown Figure 1 The illustration shows another exemplary embodiment of a CT system, which includes a plurality of radiation detectors oriented such that the normal vector of each sensing surface is substantially parallel to a radius vector extending from the focal point of the radiation source.

[0033] Figure 6 It is shown Figure 1The illustration shows another exemplary embodiment of a CT system, which includes three radiation detectors having corresponding sensing surfaces focally positioned at a common radius r relative to the radiation source;

[0034] Figure 7 It is shown Figure 5 The illustration shows another exemplary embodiment of a CT system, which includes three radiation detectors having corresponding sensing surfaces focally positioned relative to a radiation source at different radii r1, r2, and r3; and

[0035] Figure 8 This is a flowchart illustrating an exemplary implementation of a method for performing a CT examination on a target using two or more detectors.

[0036] It should be noted that the accompanying drawings are not necessarily drawn to scale. The drawings are intended only to depict typical aspects of the subject matter disclosed herein and should not be considered as limiting the scope of this disclosure. Detailed Implementation

[0037] Computed tomography (CT) is an example of a non-destructive testing technique that provides quantitative images of the material density of a slice or cross-section of a target object using a radiation beam, such as X-rays. These images (e.g., cross-sections) can be combined to obtain a corresponding three-dimensional representation of the target. However, existing techniques for performing CT can present problems when the target object or its projection is larger than the detector. In one approach, the detector and / or the target can be moved to expand the measurement area. However, this movement can prolong the time required to complete a CT scan, which is undesirable when the CT system is under high demand. On the other hand, purchasing a relatively large detector can be prohibitively expensive. Therefore, improved systems and methods for CT examinations have been provided. Such systems and methods can employ at least two detectors simultaneously to expand the CT measurement area for examining large targets. Furthermore, the detectors can be arranged relative to the radiation source such that the entire cross-section of the target can be measured during a single rotation of the target. This approach can be useful for saving time if no larger detector is available or if the available larger detectors are too expensive or unsuitable for the penetrating radiation employed. It is not necessary to move a single detector to expand the measurement area, thus saving time.

[0038] This paper discusses embodiments of sensing systems and corresponding methods for non-destructive inspection of targets such as industrial parts via computed tomography. However, the embodiments disclosed herein can be used without limitation to image any target object via computed tomography.

[0039] Figure 1An exemplary embodiment of an operating environment including a computed tomography (CT) system 100 configured to perform a non-destructive test on a target 102 is shown. The CT system 100 may include a radiation source 104, a stage 106, a plurality of radiation detectors 110, a controller 112, and an output device 114. One or more power supplies (not shown) may be configured to provide power to the CT system 100. The stage 106 may be positioned between the radiation source 104 and the plurality of detectors 110, and may be configured to hold the target 102 thereon and rotate the target 102 about a rotation axis T. The radiation source 104 may be configured to emit a radiation beam 108 (e.g., penetrating radiation) from a focal point 116 and guide the radiation beam 108 incident on the target 102 for imaging the target 102. The plurality of detectors 110 may include corresponding sensing surfaces 110f configured to detect portions of the radiation beam 108 incident on them after it has passed through the target 102.

[0040] In use, radiation source 104 can be configured to emit a radiation beam 108 from focus 116 in a predetermined geometry (e.g., two-dimensional or three-dimensional geometry) in response to a command signal 118s received from controller 112. As detailed below, multiple detectors 110 can be positioned relative to radiation source 104 and to each other in various ways. Figure 1 In one embodiment, system 100 includes two detectors 110a, 110b separated by a gap 124. Due to the presence of the gap 124, first plurality of beam segments of radiation beam 108 follow corresponding first beam paths incident on the plurality of detectors 110. For example, first beam segment 108a of radiation beam 108 follows a first path extending through a first portion 102a of target 102 and incident on the first detector 110a. Similarly, second beam segment 108b of radiation beam 108 follows a beam path extending through a second portion of target 102 and incident on the second detector 110b. Additionally, at least one second beam segment path 109 is defined between the focal point 116 and the predetermined gap 124 (e.g., defined by the relative edges of adjacent detectors among the plurality of detectors 110).

[0041] Advantageously, by employing two or more radiation detectors 110 simultaneously during the CT examination (e.g., in parallel operation), multiple portions of the target 102 (e.g., 102a, 102b) can be examined concurrently. Other portions of the target 102 can also be examined by rotating the target 102. In this way, CT examinations of large targets and / or target projections can be performed faster than alternative methods employing the movement of a single radiation detector.

[0042] Implementations of target 102 can be any structure and / or material suitable for inspection using radiation beam 108. For example, target 102 may allow the transmission of radiation beam 108 with sufficient radiation intensity (electromagnetic energy per unit time per unit stereo beam angle) for detection by multiple detectors 110. Examples of target structures may include castings, vehicle components (e.g., automobiles, aircraft, ships, etc.). Examples of materials forming target 102 may include metals, metal alloys, ceramics, polymers, stone, and composites thereof. Although target 102 is shown herein as having a circular cross-section (e.g., perpendicular to the axis of rotation T), it will be understood that implementations of the target may have any desired cross-sectional area.

[0043] The stage 106 may be configured to secure the target 102 thereto via a fixing mechanism (not shown). The fixing mechanism may be incorporated into and / or deployed in combination with the stage 106. Examples of the fixing mechanism may include adhesives, clamps, belts, threaded connections (e.g., screws, bolts), etc. The stage 106 may be further configured to selectively rotate the target 102 to a desired rotation angle about the axis of rotation T in response to a command received from the controller 112 (e.g., command signal 118s).

[0044] Implementations of radiation source 104 can be any device capable of generating a penetrating radiation beam and directing the penetrating radiation beam through a selected cross-section of target 102. Examples of penetrating radiation may have energies up to about 15 MeV (e.g., about 100 eV to about 15 MeV).

[0045] In some embodiments, controller 112 may communicate with radiation source 104 and stage 106 to control characteristics of radiation beam 108 (e.g., frequency, amplitude, intensity, geometry, etc.) and rotation of stage 106 relative to target 102 (e.g., in response to operator input). Controller 112 may be any computing device employing a general-purpose or special-purpose processor. In either case, controller 112 may also include a memory (not shown) for storing instructions relating to the control of radiation beam 108 and rotation of target 102.

[0046] In some embodiments, the radiation beam 108 may have a two-dimensional or three-dimensional geometry. Examples of a two-dimensional geometry may include a fan-shaped beam. Examples of a three-dimensional geometry may include a conical geometry (e.g., a straight cone, an oblique cone, and combinations thereof). In either case, such as Figure 1 As shown, the radiation beam 108 can extend from the focal point 116 to multiple detectors 110 and has a beam angle α. oFor example, the beam path 108a incident on the first detector 110a may have a beam angle α1 and it may extend about the central axis A1. The second beam path 108b incident on the second detector 110b may have a beam angle α2 and it may extend about the central axis A2. Generally, the central axis of the radiation beam may be a line segment extending from the focal point 116 to the center (e.g., geometric center or centroid) of the sensing surface 110f of the corresponding radiation detector (e.g., 110a or 110b).

[0047] In some embodiments, multiple detectors 110 and beam angles α1, α2 may be selected such that the central axis (e.g., A1, A2) of each of the beam segment paths 108a, 108b is offset from the rotation axis T of the target 102. For example, the central axes A1 and A2 of the beam segment paths 108a, 108b may extend along corresponding lines that do not intersect the rotation axis T. Generally, if the central axis of any of the first plurality of beam segment paths intersects the rotation axis T, the reconstruction quality may be strongly distorted in these regions, particularly the quantitative values.

[0048] As further shown, adjacent beam segment paths in the first plurality of beam segment paths (e.g., 108a, 108b) are separated by a first gap G1 within the entirety of the target 102, which increases with distance from the focal point 116. That is, the first beam segment paths 108a, 108b are divergent. Furthermore, at least one beam segment path in the first beam segment path (e.g., 108b) is separated from a portion of the outer surface of the target 102 by a second gap G2. Therefore, each beam segment path in beam segment paths 108a, 108b does not overlap and different cross-sections of the target 102 (e.g., 102a, 102b) can be inspected.

[0049] Each of the plurality of radiation detectors 110 can be configured to detect the flux density, also known as intensity, of transmitted radiation incident on its sensing surface 110f, which is a function of position within the sensing surface 110f. Examples of radiation detectors 110 may include gas ionization detectors, scintillation counter detectors, photostimulated phosphor plates, photographic films, semiconductor detectors (e.g., electrocoupling devices or CCDs), etc. In some embodiments, the sensing surface 110f of each of the plurality of detectors 110 may have a predetermined geometry. Figure 1 As shown, each of the plurality of radiation detectors 110 may include a generally planar sensing surface 110f. However, in an alternative embodiment, the geometry of the sensing surface of one or more of the plurality of radiation detectors may be independently selected to be different from that of the other radiation detectors.

[0050] Each of the plurality of radiation detectors 110 may also be configured to output a detection signal 120s, which includes data characterizing the radiation intensity as a function of the position incident on the sensing surface 110f. The controller 112 may store instructions, based on the corresponding detection signals 120s received from the plurality of detectors 110 and an understanding of the emission intensity of the radiation beam 108 (e.g., before transmission through the target 102), for determining a quantitative mapping of the material density or related quantities at each location within the examined cross-section of the target 102.

[0051] In response to a command received from controller 112 (not shown), stage 106 can rotate target 102 about rotation axis T relative to a reference angle by a predetermined angle. Therefore, first plurality of beam path paths 108a, 108b can transmit through different cross-sections (e.g., 102a, 102b) of target 102 for detection by plurality of detectors 110. The process of emitting radiation beam 108 through radiation source 104, detecting radiation beam 108 incident on plurality of detectors 110 after transmission through target 102, and the rotation of target 102 by stage 106 can be repeated multiple times as needed to examine the desired volume of target 102.

[0052] In some embodiments, the positions of the radiation beams 108, the plurality of radiation detectors 110, and the rotation of the target 102 can be configured to facilitate the transmission of the plurality of radiation beams 108 through a cross-section representing the entire volume of the target 102 within one rotation of the target 102 about the rotation axis T. In one aspect, the angle α can be selected. o This allows beam 108 to cover each of the plurality of detectors 110. Alternatively, gap 124 can be selected such that the first plurality of beam segment paths 108a, 108b extend through more than half of the cross-sectional region of the target 102, which lies within a predetermined measurement plane. As shown, the predetermined measurement plane is the xz plane, where the axis of rotation extends parallel to the y-direction. In other words, by selecting gap 109 such that the Fourier slice theorem is satisfied in the cross-sectional region (e.g., the xz plane) of the target 102 in both the case of a two-dimensional fan-shaped beam and for the case of a three-dimensional (conical) beam, the target 102 can be examined in a single rotation. Those skilled in the art will understand that the requirement of the Fourier slice theorem is derived from a theoretical perspective. In practice, the condition can be weakened as the quality and approximation decrease. Furthermore, the Fourier slice theorem criterion can be weakened for non-analytical reconstruction methods (e.g., iterative methods).

[0053] The memory of controller 112 may also store instructions related to reconstructing the volume of target 102 according to one or more reconstruction techniques based on the target's rotation angle and corresponding detection signals received from multiple detectors. Examples of reconstruction techniques may include iterative and analytical algorithms. Cross sections may be analyzed individually and then combined to form the target's three-dimensional volume, or the cross sections may be rearranged / combined into a rotation dataset. In some embodiments, such datasets may be incomplete with respect to the Tuy-Smith sufficient condition. Specifically, iterative algorithms may be configured to process incomplete datasets. In an alternative embodiment not shown, multiple radiation detectors may be configured to transmit detection signals to an alternative computing device other than the controller for reconstruction of the target cross sections and / or target volume, as described above.

[0054] The controller 112 or alternative computing device may also be configured to transmit one or more output signals 122s, including data characterizing the cross-section of the examined target and / or the reconstructed target volume, to the output device 114. For example, the controller 112 may output material density or a related quantity as a function of position. In some embodiments, the output device may be a display and / or a data storage device.

[0055] In some embodiments, the radiation source 104 and the plurality of detectors 110 may be stationary. That is, the radiation source 104 and the plurality of detectors 110 may exhibit near-immobility during CT examination (e.g., remaining in a fixed position relative to the axis of rotation T of the target 102 and / or to each other), but may be moved prior to performing the CT examination to set the desired scan geometry. Advantageously, as described above, when combined with the configuration of the radiation beam 108 and the position of the plurality of detectors 110, the stationary plurality of detectors 110 allows the entire volume of the target 102 to be examined. Since the plurality of detectors 110 and / or the radiation source 104 are not moved during the CT examination process, the examination time for large targets or large target projections can be reduced.

[0056] Figures 1 to 7 Various configurations for positioning each of the plurality of radiation detectors 110 relative to each other and the radiation source 104 are further illustrated. In one embodiment, the sensing surface 110f of each of the plurality of detectors 110 may be parallel to each other. Figure 1 As shown, the first radiation detector 110a and the second radiation detector 110b may each include a planar sensing surface 110f. Each of the first sensing surface and the second sensing surface 110f may be substantially coplanar and aligned with a common plane 124.

[0057] This coplanar arrangement of multiple radiation detectors 110 can be maintained by adding additional radiation detectors. For example, Figure 2Another operating environment including a CT examination system 200 is shown, which has multiple radiation detectors 110 in the form of multiple radiation detectors 210. As shown, the multiple radiation detectors 210 include a first radiation detector 210a and a second radiation detector 210b, and also include a third radiation detector 210c. Each of the first radiation detector 210a, the second radiation detector 210b, and the third radiation detector 210c may include a corresponding sensing surface 210f, which is configured to detect portions of the radiation beam 208 incident thereon (e.g., portions of the radiation beam 208 along beam-following paths 208a, 208b, 208c respectively and having beam angles α1, α2, α3, α4, α5, α6, α7, α8 ... 2、 (Part of α3). The first radiation detector 210a, the second radiation detector 210b, and the third radiation detector 210c can be positioned such that they are each aligned with the common plane 224 and thus substantially coplanar with each other.

[0058] In some embodiments, any two or more radiation detectors of a plurality of radiation detectors 110 may be considered substantially coplanar when the angle between the surface normals of their respective sensing surfaces 110f is less than a predetermined first angular tolerance and the distance separating the planes containing the respective sensing surfaces 110f is less than a predetermined linear tolerance.

[0059] In an alternative embodiment, one or more of the plurality of radiation detectors 110 may be substantially parallel to each other, but offset in one or more predetermined directions. For example, Figure 3 Another operating environment including a CT examination system 300 is shown, which includes multiple radiation detectors 110 in the form of multiple radiation detectors 310. As shown, the multiple radiation detectors 310 include a first radiation detector 310a and a second radiation detector 310b having corresponding sensing surfaces 310f, these sensing surfaces being configured to detect portions of a radiation beam 308 thereon (e.g., portions of the radiation beam 308 along beam-following paths 308a, 308b and having beam angles α1, α2, respectively). The sensing surface 310f of the first radiation detector 310a is aligned with a first plane 324a, and the sensing surface 310f of the second radiation detector 310b is aligned with a second plane 324b. The first plane 324a and the second plane 324b are generally parallel but not coplanar. Instead, the first plane 324a and the second plane 324b are separated from each other in the x-direction by an offset distance D greater than a predetermined linear tolerance. In some implementations, the minimum offset distance D can be the minimum offset distance D in which the plurality of radiation detectors 110 do not contact the target 102 during rotation, and the maximum offset distance D can be the maximum offset distance D that enables the detection of quantum energy reaching a given one of the plurality of radiation detectors 110.

[0060] In another embodiment, at least one of the plurality of radiation detectors 110 may be oriented relative to the radiation source 104 at a predetermined non-zero angle β. Such orientation allows for better use of the angle segment and radiation. For example, Figure 4 Another operating environment including a CT examination system 400 is shown, which includes multiple radiation detectors 110 in the form of multiple radiation detectors 410. As shown, the multiple radiation detectors 410 include a first radiation detector 410a and a second radiation detector 410b having corresponding sensing surfaces 410f, these sensing surfaces being configured to detect portions of a radiation beam 408 incident thereon (e.g., portions of the radiation beam 408 along beam-following paths 408a, 408b and having beam angles γ1, γ2, respectively). Figure 4 As shown, angle β can be determined as the angle between the surface normal N of the sensing surface 410f of the first radiation detector 410a and the surface normal N of the sensing surface 410f of the first radiation detector 410a. D and the surface normal N for the predetermined plane 424 containing the focal point 116 F between.

[0061] In another embodiment, at least one of the plurality of radiation detectors 110 may be positioned relative to a radius vector R extending from the focal point 116 of the radiation source 104. For example, Figure 5 Another operating environment including a CT examination system 500 is shown, which includes a plurality of radiation detectors 110 in the form of a plurality of radiation detectors 510. As shown, the plurality of radiation detectors 510 includes a first radiation detector 510a and a second radiation detector 510b having corresponding sensing surfaces 510f. These sensing surfaces are configured to detect portions of a radiation beam 508 incident thereon (e.g., portions of the radiation beam 508 along beam-following paths 508a, 508b and having beam angles γ1, γ2, respectively). First surface normal N D1 Extending from the centroid C1 of the sensing surface 510f of the first radiation detector 510a, and the second surface normal N D2 Extending from the centroid C2 of the sensing surface 510f of the second radiation detector 510b. Further described are radial vectors R1 and R2 of length r extending from the focal point 116 to the respective centroids C1 and C2. In one aspect, at least the first radiation detector 510a can be positioned such that the first surface normal N... D1 The first surface normal ND1 is approximately parallel to the radius vector R1. Alternatively, both the first radiation detector 510a and the second radiation detector 510b can be positioned such that the first surface normal ND1 is approximately parallel to the first radius vector R1 and the second surface normal is approximately parallel to the radius vector R2. In some embodiments, any surface normal and radius vector can be considered parallel when the angle between them is less than a predetermined second angle tolerance.

[0062] In one embodiment, at least one radiation detector 110 may be positioned such that a predetermined position of the sensing surface 110f is located at a predetermined distance from the focal point 116. In some embodiments, the predetermined position may be the centroid of the sensing surface 110f, i.e., the arithmetic mean position of all points on the sensing surface 110f. In other embodiments, the predetermined distance may be a radial distance from the focal point 116. Figure 5 As shown in the embodiment, the sensing surface 510f of the first radiation detector 510a has a centroid C1, and the sensing surface 510f of the second radiation detector 510b has a centroid C2, and each of the centroids C1 and C2 is located at a common radial distance r. That is, the lengths of each of the radial vectors R1 and R2 are approximately equal.

[0063] In some implementations, radial vectors R1 and R2 can be considered approximately equal when the difference in their respective lengths is less than a predetermined linear tolerance.

[0064] This radial arrangement of multiple radiation detectors 510 can be maintained by adding additional radiation detectors. For example, Figure 6 Another operating environment including a CT examination system 600 is shown, which includes a plurality of radiation detectors 110 in the form of a plurality of radiation detectors 610. As shown, the plurality of radiation detectors 610 includes a first radiation detector 610a and a second radiation detector 610b, and also adds a third radiation detector 610c. Each of the first radiation detector 610a, the second radiation detector 610b, and the third radiation detector 610c may include a corresponding sensing surface 610f with centroids C1, C2, and C3, respectively. The sensing surface 610f may be configured to detect portions of the radiation beam 608 incident thereon (e.g., portions of the radiation beam 608 along the beam-following paths 608a, 608b, and 608c, respectively, and having beam angles γ1, γ2, and γ3). The third radial vector R3 is further shown to have the same radial length r as the first and second radial vectors. As shown in the figure, each of the first radiation detector 610a, the second radiation detector 610b, and the third radiation detector 610c can be positioned such that the centroids C1, C2, and C3 are located at a radial distance r.

[0065] In an alternative embodiment, one or more of the plurality of radiation detectors 610 may be positioned at different radial distances. Figure 7Another operating environment including a CT examination system 700 is shown, which includes each of a first radiation detector 610a, a second radiation detector 610b, and a third radiation detector 610c, and whose radial vectors R1, R2, and R3 have different radial lengths r1, r2, and r3, respectively, where r1 > r2 > r3. The first radiation detector 610a, the second radiation detector 610b, and the third radiation detector 610c can be positioned such that their respective centroids C1, C2, and C3 are located at radial distances r1, r2, and r3, respectively.

[0066] Figure 8 An embodiment of a method 800 for performing a CT scan is shown. As illustrated, method 800 may include operations 802 to 806 and... Figures 1 to 7 This will be discussed in the context below. However, it will be understood that implementations of this method may include more than […]. Figure 8 The number of operations shown may be more or fewer, and the one or more operations may differ from those shown. Figure 8 Execute in the order shown.

[0067] In operation 802, a beam 108 of penetrating radiation can be emitted from radiation source 104. As described above, radiation source 104 can be a stationary radiation source relative to target 102 and the plurality of detectors 110.

[0068] In operation 804, the emitted radiation beam can be directed into a beam path extending from the focal point 116 of the radiation source, through a portion of the target 102, and incident on a corresponding sensing surface (e.g., 110f) of a plurality of stationary radiation detectors (e.g., 110). The plurality of stationary radiation detectors can be positioned relative to the stationary radiation source and the target such that the emitted radiation beam is defined by a first plurality of beam segment paths extending between the focal points and sensing surfaces of the plurality of radiation detectors and at least one second beam segment path extending between the focal point and a predetermined gap.

[0069] In operation 806, each of the plurality of detectors may output a corresponding signal. For example, a corresponding sensing surface 110f of the plurality of radiation detectors 110 may measure the radiation intensity as a function of the position of the portion of the radiation beam 108 (e.g., 108a, 108b) that has penetrated through the target 102 and is incident upon it. Each of the plurality of radiation detectors 110 may be configured to output one or more signals that include data characterizing the intensity of the penetrating radiation incident on its sensing surface, the intensity of which is a function of position (e.g., detection signal 120s). That is, the plurality of stationary radiation detectors may be two-dimensional radiation detectors. In some embodiments, one or more detection signals 120s may be output to controller 112 for further analysis.

[0070] By way of non-limiting examples, exemplary technical effects of the methods, systems, and apparatus described herein include the ability to perform CT scans on large targets or targets exhibiting large target projections (e.g., targets or target projections greater than twice the width of the sensitive region of the respective radiation detectors among multiple radiation detectors). CT scans can be performed much faster than conventional stitching methods using a single virtual detector with sensitive and non-sensitive regions. Improved CT scan speed facilitates better utilization of expensive and limited examination resources (e.g., radiation shielding rooms, radiation sources, etc.). Furthermore, the improved CT scan speed is achieved without the need for motion equipment to move the detectors, compared to virtual detectors.

[0071] Certain exemplary embodiments are described to provide a comprehensive understanding of the principles of structure, function, manufacture, and use of the systems, apparatuses, and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. It will be understood by those skilled in the art that the systems, apparatuses, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments, and that the scope of the invention is defined only by the claims. Features shown or described in conjunction with one exemplary embodiment may be combined with features of other embodiments. Such modifications and variations are intended to be included within the scope of the invention. Furthermore, in this disclosure, similarly named components of embodiments generally have similar features, and therefore, within a specific embodiment, not every feature of every similarly named component is necessarily fully described.

[0072] The subject matter described herein may be implemented in analog electronic circuits, digital electronic circuits and / or computer software, firmware or hardware (including the structural means disclosed herein and their structural equivalents) or combinations thereof. The subject matter described herein may be implemented as one or more computer program products, such as those tangibly embodied in an information carrier (e.g., embodied in a machine-readable storage device) or embodied in a propagated signal, for execution by or control of the operation of a data processing device (e.g., a programmable processor, a computer, or multiple computers). A computer program (also referred to as a program, software, software application, or code) may be written in any form of programming language (including compiled or interpreted languages) and may be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for a computing environment. A computer program does not necessarily correspond to a file. A program may be stored as a portion of a file containing other programs or data, in a single file dedicated to the program under consideration, or in multiple co-located files (e.g., a file storing portions of one or more modules, subroutines, or code). Computer programs can be deployed to run on one computer or on multiple computers located at one site or distributed across multiple sites and interconnected by a communication network.

[0073] The processes and logical flows described in this specification, including the method steps of the subject matter herein, can be executed by one or more programmable processors that execute one or more computer programs to perform the functions of the subject matter herein by manipulating input data and generating output. These processes and logical flows can also be executed by special-purpose logic circuitry (e.g., FPGAs (Field-Programmable Gate Arrays) or ASICs (Application-Specific Integrated Circuits)), and the devices of the subject matter herein can be implemented as special-purpose logic circuitry (e.g., FPGAs or ASICs).

[0074] By way of example, processors suitable for executing computer programs include both general-purpose microprocessors and special-purpose microprocessors, as well as any one or more processors in any kind of digital computer. Generally, a processor receives instructions and data from read-only memory or random access memory, or both. The basic components of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include one or more mass storage devices (e.g., magnetic disks, magneto-optical disks, or optical disks) for storing data, or operatively coupled to receive data from or / and transfer data to one or more mass storage devices (e.g., magnetic disks, magneto-optical disks, or optical disks) for storing data. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including, for example, semiconductor memory devices (e.g., EPROM, EEPROM, and flash memory devices); magnetic disks (e.g., internal hard disks or removable magnetic disks); magneto-optical disks; and optical disks (e.g., CDs and DVDs). The processor and memory may be supplemented by or incorporated into special-purpose logic circuitry.

[0075] To provide interaction with the user, the subject matter described herein can be implemented on a computer having a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user, and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the computer. Other types of devices can also be used to provide interaction with the user. For example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback), and input from the user can be received in any form, including sound, speech, or tactile input.

[0076] The techniques described herein can be implemented using one or more modules. As used herein, the term "module" refers to computing software, firmware, hardware, and / or various combinations thereof. However, at a minimum, a module should not be construed as software not implemented on hardware, firmware, or documented on a non-transitory processor-readable storage medium (i.e., a module itself is not software). In practice, a "module" will be interpreted as always including at least some physical non-transitory hardware, such as a processor or part of a computer. Two different modules may share the same physical hardware (e.g., two different modules may use the same processor and network interface). Modules described herein can be combined, integrated, separated, and / or replicated to support a variety of applications. Additionally, instead of functions performed at a particular module, or functions described herein as performing at a particular module, functions may be performed at one or more other modules and / or by one or more other devices. Furthermore, modules may be implemented locally or remotely across multiple devices and / or other components relative to each other. Additionally, modules may be moved from one device and added to another device, and / or may be included in two devices.

[0077] The subject matter described herein can be implemented in a computing system that includes back-end components (e.g., a data server), middleware components (e.g., an application server), or front-end components (e.g., a client computer with a graphical user interface or web browser through which a user interacts with embodiments of the subject matter described herein), or any combination of such back-end, middleware, and front-end components. Components of the system can be interconnected via any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include local area networks (“LANs”) and wide area networks (“WANs”), such as the Internet.

[0078] As used herein throughout the specification and claims, approximate language may be used to modify any quantitative expression that may vary but does not result in a change in the essential function associated with it. Therefore, values ​​modified by one or more terms such as “about,” “approximately,” and “substantially” should not be limited to the specified precise value. In at least some cases, approximate language may correspond to the precision of the instrument used to measure the value. Scope limitations may be combined and / or interchanged herein and throughout the specification and claims, and unless otherwise indicated by context or language, such scopes are identified and include all subscopes contained therein.

[0079] Based on the above embodiments, those skilled in the art will understand other features and advantages of the present invention. Therefore, except as indicated in the appended claims, this application is not limited to the content specifically shown and described. All publications and references cited herein are expressly incorporated in their entirety by reference.

Claims

1. A computed tomography (CT) scanning system, comprising: A stage, configured to fix a target on it and rotate the target about an axis of rotation; Multiple static radiation detectors, each static radiation detector including a planar sensing surface configured to acquire a measurement of penetrating radiation incident thereon, the measurement of penetrating radiation being a function of position, wherein the sensing surfaces of adjacent static radiation detectors are separated by a predetermined gap. A stationary radiation source configured to emit a penetrating radiation beam from a focal point, wherein the plurality of stationary radiation detectors and the stationary radiation source are positioned relative to the stage and configured to emit the penetrating radiation beam, such that a first plurality of beam segment paths are defined between the focal point and respective sensing surfaces of the plurality of stationary radiation detectors, and at least one second beam segment path is defined between the focal point and the predetermined gap. and The controller includes a memory storing instructions related to reconstructing the volume of the target based on a rotation angle of the target and corresponding detection signals received from the plurality of static radiation detectors, according to one or more reconstruction techniques, the reconstruction techniques including an iterative algorithm that can be configured to handle incomplete datasets; In the plurality of static radiation detectors, the first sensing surface of the first static radiation detector is aligned with the first detector plane, and the second sensing surface of the second static radiation detector is aligned with the second detector plane. The first detector plane and the second detector plane are substantially parallel and laterally offset from each other by a predetermined offset distance. The minimum offset distance is the minimum offset distance at which the plurality of static radiation detectors do not contact the target during rotation, and the maximum offset distance is the maximum offset distance at which quantum energy reaching a given static radiation detector can be detected.

2. The computed tomography system of claim 1, wherein the plurality of radiation detectors are positioned relative to the target and the stationary radiation source such that the first plurality of beam segment paths extend through more than half of the cross-sectional area of ​​the target in a predetermined measurement plane.

3. The computed tomography system of claim 1, wherein the plurality of stationary radiation detectors are positioned relative to the target and the stationary radiation source such that the central axis of the corresponding beam path in the plurality of beam path paths is offset from the axis of rotation.

4. The computed tomography system according to claim 1, wherein the first beam segment path of the first plurality of beam segment paths is a straight cone, and the second beam segment path of the first plurality of beam segment paths is an oblique cone.

5. The computed tomography system of claim 1, wherein the sensing surfaces of at least two of the plurality of static radiation detectors are coplanar.

6. The computed tomography system of claim 1, wherein a first surface normal extending from the centroid of the sensing surface of at least one of the plurality of static radiation detectors is oriented at a predetermined non-zero angle to a second surface normal extending from the plane containing the focal point of the static radiation source.

7. The computed tomography system of claim 1, wherein the plurality of static radiation detectors includes a first static radiation detector and a second static radiation detector, wherein a first surface normal extending from the first sensing surface is parallel to a first radial vector extending from the focal point to the centroid of the first sensing surface, and a second surface normal extending from the second sensing surface is parallel to a second radial vector extending from the focal point to the centroid of the second sensing surface.

8. The computed tomography system of claim 7, wherein the length of the first radial vector is equal to the length of the second radial vector.

9. The computed tomography system of claim 7, wherein the length of the first radial vector is different from the length of the second radial vector.

10. A method for performing a computed tomography (CT) scan using a computed tomography system according to any one of claims 1 to 9, comprising: A penetrating radiation beam is emitted from the focal point of a stationary radiation source; The emitted penetrating radiation beam is guided through a portion of the target in a beam path extending from the focal point and incident on the respective sensing surfaces of a plurality of stationary radiation detectors, each of which has a planar sensing surface. The plurality of static radiation detectors are positioned relative to the static radiation source and the target such that the emitted penetrating radiation beam is defined by a first plurality of beam segment paths extending between the focal point and the sensing surfaces of the plurality of static radiation detectors and at least one second beam segment path extending between the focal point and the predetermined gap. as well as Each of the plurality of static radiation detectors outputs a corresponding signal, the corresponding signal including data characterizing the intensity of the penetrating radiation incident on the sensing surface of the static radiation detector, the intensity of the penetrating radiation being a function of position; In the plurality of static radiation detectors, the first sensing surface of the first static radiation detector is aligned with the first detector plane, and the second sensing surface of the second static radiation detector is aligned with the second detector plane. The first detector plane and the second detector plane are substantially parallel and laterally offset from each other by a predetermined offset distance. The minimum offset distance is the minimum offset distance at which the plurality of static radiation detectors do not contact the target during rotation, and the maximum offset distance is the maximum offset distance at which quantum energy reaching a given static radiation detector can be detected.

11. The method of claim 10, wherein the plurality of stationary radiation detectors are positioned relative to the target and the stationary radiation source such that the central axis of a corresponding beam segment path in the plurality of beam segment paths is offset from the axis of rotation.

12. The method of claim 10, wherein the first plurality of beam segment paths penetrate more than half of the cross-sectional area of ​​the target in the predetermined measurement plane.

13. The method of claim 10, wherein after a single rotation of the target, the first plurality of beam segments are transmitted through the entire cross-sectional area of ​​the target in a predetermined measurement plane.

14. The method of claim 10, wherein the first beam segment path of the first plurality of beam segment paths is a straight cone, and the second beam segment path of the first plurality of beam segment paths is an oblique cone.

15. The method of claim 10, wherein the sensing surfaces of at least two of the plurality of static radiation detectors are coplanar.

16. The method of claim 10, wherein a first surface normal extending from the centroid of the sensing surface of at least one of the plurality of static radiation detectors is oriented at a predetermined non-zero angle to a second surface normal extending from the plane containing the focal point of the static radiation source.

17. The method of claim 10, wherein the plurality of static radiation detectors comprises a first static radiation detector and a second static radiation detector, wherein a first surface normal extending from the first sensing surface is parallel to a first radial vector extending from the focal point to the centroid of the first sensing surface, and a second surface normal extending from the second sensing surface is parallel to a second radial vector extending from the focal point to the centroid of the second sensing surface.

18. The method of claim 17, wherein the length of the first radial vector is equal to the length of the second radial vector.

19. The method of claim 17, wherein the length of the first radial vector is different from the length of the second radial vector.

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