On-detector scatter measurement device(s) for scatter suppression within x-ray imaging systems

Abstract

Systems and methods for measuring and correcting scatter within X-ray imaging systems are provided herein. In an aspect, an X-ray imaging system having at least one X-ray source configured to emit X-rays and a detector comprising a pixel array configured to detect X-rays emitted from the at least one X-ray source is provided. An on-detector scatter measurement (OSM) device comprising a plurality of attenuating elements may be positioned physically proximate to the detector such to generate a shadow pixel region on a subset of pixels within the pixel array of the detector when the X-rays are emitted from the X-ray source. An image processor in operable communication with the detector may generate a scatter-corrected image of an object positioned between the X-ray source and the detector. The scatter-corrected image may be generated based on the shadow pixel region generated by the OSM device.

Description

Docket No. 303.0140WOON-DETECTOR SCATTER MEASUREMENT DEVICE(S) FOR SCATTER SUPPRESSION WITHIN X-RAY IMAGING SYSTEMSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 788,243, titled ON-DETECTOR SCATTER MEASUREMENT DEVICE(S) FOR SCATTER SUPPRESSION WITHIN X-RAY IMAGING SYSTEMS, tiled on April 14, 2025, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] Aspects of the disclosure are related to the field of X-ray imaging detectors and systems, in particular to technology for measuring and correcting scatter within X-ray imaging systems, including both fixed and variable geometry X-ray imaging systems.BACKGROUND

[0003] X-ray imaging systems are imaging devices that utilize ionizing radiation to capture internal structures of an object or body. These systems are pervasive across numerous industries, including medical diagnostics (e.g., radiography and computed tomography), security screening (e.g., airport baggage scanners), and industrial inspection (e.g., nondestructive testing of welds and materials). At a high level, X-ray imaging systems comprise two primary components: an X-ray source and a detector. The source emits high-energy X-ray photons, typically generated by accelerating electrons toward a metal target within an X-ray tube. As the X-rays pass through an object, they are attenuated to varying degrees depending on the object's density and composition. The attenuated X-rays are then received by a detector, which may include scintillators and photodiodes or flat-panel sensors, that convert the incoming X-ray photons into electrical signals. The electrical signals are then processed to reconstruct digital images that reveal internal anatomical or structural details of the object being imaged.

[0004] A persistent technical challenge in X-ray imaging is the presence of scattered radiation. When X-ray photons interact with matter, a portion of them undergo Compton scattering, deviating from their original paths before reaching the detector. This scattered radiation introduces noise and reduces image contrast by contributing non-informative signal across the detector surface. The resulting degradation in image quality can obscure structural details, particularly in regions with subtle density variations. Scatter is especially problematic in large or dense objects and wide field-of-view imaging, where the probability of off-angleDocket No. 303.0140WOphoton interactions increases. Managing scatter remains an issue for X-ray imaging systems across clinical and industrial applications.

[0005] Accordingly, there is a need for improved technology to detect and correct scatter within X-ray imaging systems, in particular within variable configuration imaging systems.SUMMARY

[0006] Systems and methods for measuring and correcting scatter within a variable configuration X-ray imaging system are provided herein. In one aspect, an X-ray imaging system having at least one X-ray source and a detector is provided. The X-ray source may be configured to emit X-rays towards the detector, which in turn contains a pixel array configured to detect the emitted X-rays. The X-ray imaging system may also include an on-detector scatter measurement (OSM) device positioned physically proximate to the detector such to generate a shadow pixel region on a subset of pixels within the pixel array when X-rays are emitted by the X-ray source. The OSM device may contain one or more attenuating elements that are configured to cast the shadow pixel region on the pixel array. An image processor in operable communication with the detector may generate a scatter-corrected image of an object positioned between the X-ray source and the detector based on the shadow-pixel region generated by the OSM device.

[0007] In another aspect, a scatter correction engine is provided herein for measuring and correcting the scatter as detected by a pixel array of a detector. The scatter correction engine may measure scatter by generating one or more projection signal profiles corresponding to an OSM device positioned between an X-ray source and the detector. Each of the projection signal profiles may represent a projection signal response of a subset of pixels within the pixel array within a cross-sectional segment of a shadow pixel region cast by the OSM device onto the pixel array.

[0008] The scatter correction engine may also generate one or more object signal profiles corresponding to an object positioned between the X-ray source and the detector. Each of the object signal profiles may represent an object signal response of the subset of pixels within the cross-sectional segment. Using the object signal profiles and the projection signal profiles, the scatter correction engine may generate a residual scatter estimate and generate a scatter-corrected image using the object signal profile and the residual scatter estimate.

[0009] In yet another aspect, an X-ray detector system is provided. The X-ray detector system may include a detector having a pixel array and an OSM device positioned physically proximate to the detector. The OSM device may include multiple attenuating elementsDocket No. 303.0140WOcomposed of a material configured to reduce X-ray fluence by approximately 15% to 50%. The attenuating elements may be oriented as an array along a longitudinal axis extending between a first side of the detector and an opposing second side of the detector irrespective of pixel orientation of the pixel array underlying the plurality of attenuating elements and positioned at a predefined distance above the pixel array to create a shadow pixel region on a subset of pixels of the pixel array when exposed to an X-ray source.

[0010] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Technical Disclosure. It may be understood that this Overview is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Many aspects of the disclosure may be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. While several embodiments are described in connection with these drawings, the disclosure is not limited to the embodiments disclosed herein. On the contrary, the intent is to cover all alternatives, modifications, and equivalents.

[0012] Figure 1 illustrates an operational environment for providing an on-detector scatter measurement (OSM) device, according to an embodiment herein.

[0013] Figure 2 illustrates an example scatter correction engine, according to an embodiment provided herein.

[0014] Figure 3 illustrates a process for providing a scatter correction engine and its related functions, according to an embodiment herein.

[0015] Figure 4 illustrates an example embodiment of an OSM device positioned physically proximate to a detector, according to an embodiment herein.

[0016] Figure 5 illustrates a focused perspective of a region of the pixel array from Figure 4, according to an embodiment herein.

[0017] Figure 6A illustrates an example projection signal profile, according to an embodiment herein.

[0018] Figure 6B illustrates an example normalized signal profile, according to an embodiment herein.Docket No. 303.0140WO

[0019] Figure 7A illustrates an example object signal profile, according to an embodiment herein.

[0020] Figure 7B illustrates an example normalized object profile, according to an embodiment herein.

[0021] Figure 8 illustrates an example region of a pixel array containing multiple pixel neighborhoods, according to an embodiment herein.

[0022] Figure 9 illustrates an example OSM device having an array of attenuating elements, according to an embodiment herein.

[0023] Figure 10 illustrates an example OSM device having an array of discrete attenuating elements, according to an embodiment herein.

[0024] Figure 11 illustrates another example OSM device in which a grid is formed from a single cohesive attenuating element, according to an embodiment herein.

[0025] Figure 12 illustrates an example embodiment of an OSM device integrated into one or more layers of a detector, according to an embodiment herein.

[0026] Figure 13 illustrates another example in which an OSM device is formed as part of a detector, according to an embodiment herein.

[0027] Figure 14 shows an example client device suitable for providing a scatter correction engine and related functions, according to an embodiment herein.

[0028] Figures 15A-B illustrate an experimental result obtained using an OSM device in accordance with Experimental Example 1, according to an embodiment herein.

[0029] Figures 16A-B illustrate another experimental result obtained using an OSM device in accordance with Experimental Example 2, according to an embodiment herein.

[0030] Figures 17A-B illustrate another experimental result obtained using an OSM device in accordance with Experimental Example 3, according to an embodiment herein.

[0031] Figures 18A-B illustrate another experimental result obtained using an OSM device in accordance with Experimental Example 4, according to an embodiment herein.DETAILED DESCRIPTION

[0032] X-ray imaging systems are widely used tools for visualizing the internal structure of objects across medical, industrial, and security domains. These systems operate by emitting high-energy X-ray photons from a source, which pass through an object and are partially absorbed or attenuated depending on the material properties. The remaining photons are captured by a detector, which converts the received radiation into electrical signals to generate a digital image. A fundamental issue in this process is scatter — radiation that deviates from itsDocket No. 303.0140WOoriginal path after interacting with the object, primarily through Compton scattering. Unlike primary X-rays that travel directly from the source to the detector, scattered photons arrive at the detector from multiple angles and contribute to unwanted signal. This degrades image quality by reducing contrast and obscuring fine details, making scatter a consideration in system design and performance evaluation.

[0033] The presence of scatter in X-ray imaging has several detrimental effects on image quality, particularly in applications requiring accurate density differentiation. Scatter reduces image contrast by adding a non-uniform background signal to the detector, which can mask subtle differences in tissue or material density. This is especially problematic in diagnostic scenarios such as detecting fluid accumulation in the lungs, where clinicians rely on high-contrast images to distinguish between air-filled lung tissue and denser fluid regions. In such cases, scattered radiation can obscure the boundaries between normal and pathological areas, potentially leading to missed or inaccurate diagnoses. The inability to clearly visualize low-contrast features due to scatter-induced artifacts poses a limitation in both clinical intciprctation and quantitative image analysis.

[0034] To address scatter, some conventional approaches rely on algorithmic correction methods that use the acquired X-ray image of the object — either a 2-dimensional (2D) projection or a 3-dimensional (3D) reconstraction — as the sole input for estimating and correcting scatter. These methods employ computational models to simulate the scatter generation and detection process based on assumptions about the object’s geometry, material properties, and the imaging system’s configuration. By analyzing the image data, the model estimates the spatial distribution and intensity of scattered radiation reaching the detector. However, because these models do not incorporate independent measurements or real-time system parameters, they fail to fully capture the actual imaging conditions. Variations in patient anatomy, positioning, beam profile, and system geometry are often simplified or excluded. Consequently, the scatter estimation may be inaccurate, resulting in under- or over-correction that introduces residual artifacts, reduces contrast, and compromises overall image quality.

[0035] In addition to algorithmic correction methods, some conventional X-ray imaging systems employ antiscatter grids to reduce the amount of scattered radiation reaching the detector. These grids are placed directly in front of the X-ray detector and consist of a onedimensional (ID) or 2D array of radiopaque septa, or walls, designed to absorb off-angle, scattered X-rays while allowing primary X-rays to pass through. By physically blocking a portion of the scattered radiation, antiscatter grids can reduce scatter-induced degradation inDocket No. 303.0140WOimage quality. However, not all scattered photons are intercepted — some scatter is still transmitted through the grid, contaminating the image.

[0036] Despite their benefits, antiscatter grids present several limitations that complicate their use in advanced or variable geometry imaging configurations. For optimal performance, the grid walls must be precisely aligned — or “focused" — toward the X-ray source. In X-ray imaging systems where the X-ray source position varies relative to the detector, such as systems with distributed X-ray source arrays or variable source-to-detector distances, misalignment can occur. This misalignment reduces the transmission of primary X-rays through the grid, thereby degrading image quality. In multi-source systems, a 2D antiscatter grid can only be focused to one source location, making it incompatible with multiple simultaneously active sources. Although ID grids can be used in configurations where sources are distributed parallel to the grid septa, this restricts source placement to a linear arrangement and comes at the cost of reduced scatter suppression performance. Furthermore, antiscatter grids are typically optimized for a fixed sourcc-to-dctcctor distance, and deviations from this distance degrade grid efficiency. Lastly, while 2D grids provide superior scatter reduction, they are costly and complex to manufacture, limiting their feasibility in low-cost or portable X-ray imaging systems.

[0037] To address at least the above shortcomings of conventional approaches to managing scatter within X-ray imaging systems, the technology provided herein provides systems and methods for measuring and correcting scatter within X-ray imaging systems. In particular, an on-detector scatter measurement (OSM) device is provided herein for measuring scatter within variable configuration X-ray imaging systems. As will be described in greater detail below, the OSM device may include one or more attenuating elements position physically proximate to the detector. A flood projection may be generated using the OSM device to measure a baseline or projection signal intensity variation within a shadow pixel region cast by the attenuating elements. When an object is imaged by the X-ray imaging system, the projection signal intensity variation is then used to measure a residual scatter caused by the object. Using the measured residual scatter, a scatter-corrected image is generated by suppressing signal contributions attributable to the residual scatter in corresponding object image, thereby reducing image noise and improving the overall image quality and contrast.

[0038] Accurately measuring and correcting for residual scatter in X-ray imaging systems offers numerous technical benefits, particularly in systems with variable source and detector geometries. In such configurations, where the relative positions or distances between the X-ray source and detector may change, scatter behavior becomes increasingly complex and lessDocket No. 303.0140WOpredictable. The ability to directly measure residual scatter enables image correction that reflects the true scatter distribution under actual imaging conditions, rather than relying on assumptions or static models. This leads to more precise suppression of scatter-induced artifacts, resulting in improved image contrast, enhanced visibility of low-density structures, and more reliable quantitative analysis. Additionally, accurate scatter correction supports greater flexibility in system design — such as mobile, multi-angle, or tomosynthesis systems — by decoupling image quality from strict geometric constraints. This capability is particularly valuable in clinical and industrial settings where high-fidelity imaging must be maintained across a range of object sizes, shapes, and orientations. Accordingly, the OSM device and the related scatter-correction engine provide numerous technological improvements over current approaches to scatter suppression within X-ray imaging systems.

[0039] Turning now to Figure 1, Figure 1 illustrates an operational environment 100 for providing an on-detector scatter measurement (OSM) detector 110, according to an embodiment herein. In particular, the environment 100 illustrates an X-ray imaging system 102 containing an X-ray source 104 and a detector 106. The X-ray source 104 may be configured to emit X-rays 108 towards the detector 106, which responsively receives and converts the X-rays 108 to electrical signals. Although the illustrative example depicts the X-ray source 104 and the detector 106 as separate components of the X-ray imaging system 102, it should be appreciated that in some embodiments the X-ray source 104 and the detector 106 may be integrated into a single physical unit.

[0040] The X-ray source 104 may encompass a range of source configurations depending on the design and application of the X-ray imaging system 102. In some embodiments, the source 104 may be a conventional fixed-position X-ray tube that emits a fan or cone beam of X-rays 108, such as illustrated. In other embodiments, however, the source 104 may represent multiple discrete X-ray sources arranged in a linear or two-dimensional array, enabling rapid sequential or simultaneous image acquisition from different angles. Alternatively, the source 104 may be a single X-ray tube mounted on a mechanical actuator or robotic arm 112A, allowing its position and orientation to be varied relative to the detector 106 and object 114 being imaged, along one or more of the x-axis, y-axis, and / or the z-axis. This variablepositioning configuration supports flexible imaging geometries, such as tomosynthesis, C-arm rotation, or dynamic field-of-view adjustments, which are particularly useful in applications such as interventional radiology or industrial non-destructive evaluation.

[0041] As noted above, the source 104 is configured to emit X-rays 108 towards the detector 106. The detector 106 may be implemented using various detector technologies depending onDocket No. 303.0140WOthe design and application of the X-ray imaging system 102. In some embodiments, the detector 106 is a flat-panel detector containing a scintillator layer coupled to a photodiode array or a direct-conversion material such as amorphous selenium. Flat-panel detectors offer high spatial resolution and are commonly used in digital radiography and fluoroscopy. Alternatively, in other embodiments, the detector 106 may be a curved detector designed to conform to a specific imaging geometry, such as panoramic or intraoral dental imaging, where the curvature allows for improved coverage and more uniform focal distance across the field of view. Curved detectors can reduce geometric distortion and maintain consistent resolution and magnification, which is particularly advantageous in systems with a fixed source-detector arc or in compact designs with limited mechanical flexibility. Similar to the X-ray source 104, the detector 106 may be mounted to a mechanical actuator or robotic arm 112B that allows for positional variation along one or more of the x-axis, y-axis, and / or the z-axis. In some embodiments, the detector 106 may be a photon counting detector, a conventional multi -detector CT detector, or a multilayer X-ray detector.

[0042] The X-ray imaging system 102 is configured to generate image data of an object 114 by directing X-rays 108 toward the object 114, which is positioned between the X-ray source 104 and the detector 106. The object 114 may be any subject suitable for radiographic imaging, such as a human or animal patient in medical applications, a piece of luggage or cargo in security screening, or a manufactured component in industrial inspection. As the X-rays pass through the object, varying levels of attenuation occur depending on the material composition and density of internal structures. The detector 106 captures the transmitted X-rays and converts them into electrical signals, which are processed to produce an image representing the internal features of the object 114.

[0043] The source 104 may emit X-rays 108 across a range of energies, frequencies, wavelengths, and intensities, vary depending on the application and / or the object 114. For example, the photon energy of the emitted X-rays may range from approximately 20 keV to 150 keV for diagnostic imaging applications, with higher energies — extending into the megavolt (MeV) range — used in industrial inspection or therapeutic systems. These energy levels correspond to wavelengths in the range of approximately 0.01 to 0.1 nanometers, placing the emitted radiation within the high-frequency region of the electromagnetic spectmm. The intensity of the emitted X-rays, defined by photon flux or dose rate, can be adjusted by varying tube current (measured in milliamperes) and exposure duration. In some implementations, the source 104 may emit a polychromatic (broad-spectrum) beam, while in others, filtration or source design may enable emission of quasi-monochromatic beams to enhance image contrastDocket No. 303.0140WOor reduce dose. The ability to modulate these parameters allows the source to tailor imaging performance for different object types, sizes, and diagnostic or inspection requirements.

[0044] The detector 106 may be in operable communication with an image processor 116, which is configured to receive the electrical signals generated by the detector 106 in response to the detected X-rays. These electrical signals represent the spatial distribution of X-ray attenuation through the object 114. The image processor 116 processes this signal data to reconstruct an object image 118 that depicts internal features of the object 114. This processing may include analog-to-digital conversion, signal normalization, noise reduction, and image reconstruction algorithms, depending on whether the system is configured for 2D radiographic imaging or 3D volumetric imaging such as computed tomography. The resulting object image 118 can be used for visualization, analysis, or further processing, depending on the application of the X-ray imaging system 102.

[0045] The image processor 116 may be in operable communication with a client device 120 associated with a provider, such as a radiologist, technician, or system operator. The client device 120 is configured to receive the object image 118 generated by the image processor 116 and present it to the provider for review, analysis, or diagnostic interpretation. This communication may occur over wired or wireless networks and can support various data formats, including raw image data, processed image outputs, or annotated diagnostic overlays. The object image 118 may be displayed on a local or remote monitor, stored in an image archive, or integrated into a broader workflow system such as a picture archiving and communication system (PACS) in medical imaging or a quality assurance interface in industrial inspection environments.

[0046] The client device 120 may execute software applications that interface with the image processor 116 and / or the X-ray imaging system 102 to support visualization, interaction, and further processing of the object image 118. These applications may be installed natively, run as web-based interfaces within a browser, operate as mobile or streaming applications, or take any other suitable form. To facilitate communication with system components, the client device 120 may interface with application services associated with the X-ray imaging system 102 via various network configurations, including local area networks (LANs), wide area networks (WANs), the Internet, or combinations thereof. Examples of client devices 120 include personal computers, tablets, mobile phones, wearable devices, gaming consoles, Internet of Things (loT) devices, or any other suitable computing apparatus, such as the computing apparatus 1491 illustrated in Figure 14.Docket No. 303.0140WO

[0047] In some embodiments, the image processor 116 may operate in a cloud-based environment. In such configurations, the processing and service functionalities may be delivered by one or more server computers, which may be co-located or geographically distributed across multiple data centers. These servers may include web servers, application servers, virtual machines, or dedicated physical servers — any of which may be used individually or in combination to support image generation, processing, and communication. The cloud-based architecture facilitates scalability, remote accessibility, and centralized system management.

[0048] As illustrated, the object image 118 or other processed output may be presented to the provider via a user interface 124 of an application executing on the client device 120. This application may be associated with the image processor 116 and / or a scatter correction engine 122, as described in greater detail below. Through the user interface 124, the provider or technician can interact with the object image 118 — such as by adjusting visualization parameters, annotating regions of interest, comparing time-series images, or initiating additional image processing tasks. This interactive capability supports efficient diagnostic review and enhances the interpretability of the imaging data.

[0049] Scatter is a common phenomenon in X-ray imaging applications, including within the X-ray imaging system 102. As the X-ray source 104 emits X-rays 108 toward the object 114, a portion of the X-rays 108 interacts with matter in the object 114 rather than passing through directly to the detector 106. These interactions, primarily Compton scattering, cause a portion of the X-rays 118 to deflect from their original paths at various angles. Some of the scattered X-rays 108 ultimately reach the detector 106, arriving from off-axis directions unrelated to the intended line-of-sight path from the source 104. This scattered radiation introduces unintended signal across the detector, contributing background intensity that is unrelated to the actual internal structures of the object 114 being imaged.

[0050] In the resulting object image 118 presented to the provider or technician, scatter manifests as a degradation in image quality — most notably through reduced contrast, loss of detail, and overall image noise. This can impair diagnostic accuracy, particularly in scenarios that require subtle density discrimination. Following the above example, when evaluating a patient for fluid accumulation in the lungs, clear contrast between air-filled lung tissue and denser fluid regions is essential. Scatter can blur these differences, obscuring fluid boundaries and making it more difficult to detect early-stage pathology. As a result, uncorrected scatter may lead to misinterpretation or missed diagnoses, emphasizing the importance of identifying and mitigating scatter effects in the imaging process.Docket No. 303.0140WO

[0051] Accordingly, to detect and correct for scatter within the X-ray imaging system 102, the operational environment 100 includes a scatter correction engine 122. The scatter correction engine 122 may be in operable communication with the image processor 116 to receive imaging data and apply scatter correction algorithms. In some embodiments, the scatter correction engine 122 is integrated as a component of the image processor 116. In other embodiments, the scatter correction engine 122 is implemented as a separate processing unit, which may be hosted externally — for example, by a third-party system or in a cloud-based environment.

[0052] As will be described in greater detail below, when the image processor 116 receives the electrical signals from the detector 106, the scatter correction engine 122 is leveraged to measure scatter present during the X-ray event (e.g., a single instance of X-ray 108 emission from the source 104 towards the detector 106 during image acquisition). Using the measured scatter, the scatter correction engine 122 corrects an object image to generate a scatter-corrected image, which is subsequently provided to the client device 120 for display.

[0053] To measure the scatter present during an X-ray event, the X-ray imaging system 102 includes the OSM device 110. The OSM device 110 may be positioned at a location along an X-ray path between the X-ray source 104 and the detector 106. As will be described in greater detail below with respect to Figures 2-13, in some embodiments, the OSM device 110 is positioned physically proximate to the detector 106, such as mounted within a few millimeters of a surface of the detector 106 directed towards the source 104. In some embodiments, a flood projection or calibration image may be captured prior to positioning the object 114 between the source 104 and the detector 106. Using the flood projection and the subsequently generated object image 118, scatter present during the X-ray event with the object 114 can be measured and used to correct scatter present within the object image 118. In other words, the scatter correction engine 112 measures the scatter using the flood projection and a subsequently acquired object image, such as the object image 118, and then generates a scatter-corrected image using the measured scatter.

[0054] In alternative embodiments, the OSM device 110 may be positioned at other locations along the X-ray path between the X-ray source 104 and the detector 106. For example, the OSM device 110 may be positioned between the X-ray source 104 and the object 114, such that the OSM device is located closer to the X-ray source than to the detector. In such configurations, the attenuating elements of the OSM device may modulate the emitted X-ray beam prior to interaction with the object 114, such that corresponding intensity variations are propagated to the detector 106 and used to estimate scatter and generate scatter-correctedDocket No. 303.0140WOimages using techniques consistent with those described herein, including the processes illustrated in Figures 5-8.

[0055] In some implementations, positioning the OSM device closer to the X-ray source may increase sensitivity to variations in source position or system geometry. For example, small deviations in the position of the X-ray source 104 may result in amplified variations in projected shadow regions at the detector 106, which may impact the accuracy of scatter estimation. Accordingly, calibration, alignment, or compensation techniques may be employed in such embodiments to mitigate sensitivity to source positioning variations.

[0056] Leveraging the scatter correction engine 122 within the operational environment 100 provides several technical benefits and advantages that enhance the overall performance of the X-ray imaging system 102. By accurately measuring and correcting for scatter, the scatter correction engine 122 improves image contrast, reduces noise, and enhances the visibility of low-contrast structures within the object 114. This leads to more reliable diagnostic interpretation and quantitative analysis, particularly in applications where subtle differences in tissue or material density impact end-results or diagnosis. Integration of the scatter correction engine 122 also enables consistent image quality across a range of imaging conditions, including variable source-detector geometries, complex object shapes, and heterogeneous compositions. Additionally, in some embodiments, the scatter correction engine 122 reduces reliance on physical scatter mitigation hardware (e.g., anti-scatter grids), allowing for more compact, flexible, and cost-effective system designs. These advantages make the scatter correction engine 122 a key component for delivering high-fidelity imaging across clinical, industrial, and security applications.

[0057] Referring now to Figure 2, an example scatter correction engine 222 is provided, according to an embodiment herein. For ease of illustration, Figure 2 is described with respect to Figure 3, which provides a process 300 for providing a scatter correction engine and its related functions, such as the scatter correction engine 222, according to an embodiment herein. Although Figure 3 is described in relation to Figure 2, it should be appreciated that the process 300 illustrated in Figure 3 is equally applicable to other embodiments and components shown in the remaining figures. Additionally, Figures 2 and 3 are discussed in conjunction with Figures 4-8 for illustrative purposes. However, Figures 2 and 3 are not limited to the specific examples, components, or configurations depicted in Figures 4-8, and other variations are contemplated.

[0058] As illustrated, Figure 2 depicts a scatter correction engine 222, which may be the same as or functionally similar to the scatter correction engine 122. The scatter correctionDocket No. 303.0140WOengine 222 is in operable communication with a detector 206, which may likewise correspond to or share characteristics with the detector 106. Accordingly, the scatter correction engine 222 may be integrated into, or in operable communication with, an X-ray imaging system, such as the X-ray imaging system 102. As described above, in some embodiments, the scatter correction engine 222 may be incorporated into, or operate in conjunction with, an image processor 216, which may be the same or similar to the image processor 116, that is associated with the detector 206.

[0059] The scatter correction engine 222 may be leveraged by the X-ray imaging system to measure and correct for scatter during X-ray image acquisition. As such, the scatter correction engine 222 may measure scatter and / or generate a residual scatter estimate for the X-ray imaging system. As can be appreciated, scatter characteristics may vary depending on the configuration and / or application of the X-ray imaging system, the object being imaged, and a variety of other factors.

[0060] To measure scatter, the scatter correction engine 222 may generate a flood projection using an on-detector scatter measurement (OSM) device (305). In particular, the scatter correction engine 222 may include a flood projection generator 226 that generates the flood projection. As used herein, a flood projection refers to a calibration image that is generated by the X-ray imaging system without any object positioned between the source and the detector 206, object being a subject matter for diagnostic imaging or inspection. Instead, the flood projection is generated when an OSM device is positioned physically proximate to the detector 206. As will be described in greater detail in the following paragraphs, the when the flood projection is captured detector 206 provides electrical signals 207A to the scatter correction engine 222, which responsively generates the flood projection.

[0061] Referring now to Figure 4, an example embodiment 400 of an OSM device 410 positioned physically proximate to a detector 406 is illustrated, according to an embodiment herein. As shown, the OSM device 410 includes one or more attenuating elements 428 A-C. The attenuating elements 428A-C may be formed from material that attenuates X-rays 108 emitted from an X-ray source, such as the source 104. The attenuating elements 428 A-C may be formed from one or more materials selected based on X-ray attenuation properties, including high atomic number (high-Z) materials. Suitable materials include, for example, tungsten, lead, bismuth, tantalum, metal-infused polymers, glass fiber-reinforced materials, ceramic materials, and high-density metal alloys. In some embodiments, the material forming the attenuating elements may have a high density and high atomic number (high-Z) to enable a reduced physical size or diameter of the attenuating elements while still maintaining a high attenuationDocket No. 303.0140WOefficiency. This allows for more compact system integration without compromising performance. The selected material may be configured to reduce X-ray fluence by approximately 15% to 50%, depending on system design requirements, thereby minimizing radiation exposure and optimizing image quality through effective scatter reduction. In other embodiments, the material may reduce X-ray fluence by approximately 10% to 30%, by 20% to 40%, by 30% to 50%, or more than 50%.

[0062] As illustrated, the detector 206 may include a pixel array 430 composed of a plurality of pixels 432. During an X-ray event, the pixels 432 within the pixel array 430 are configured to receive or detect incident X-rays 108 emitted from the X-ray source 104. Each pixel 432 converts the received X-ray photons into corresponding electrical signals, such as the electrical signals 207 A, typically through a process involving a scintillator layer and a photodiode, or via direct conversion using a photoconductive material such as amorphous selenium. The electrical signals generated by the pixels 432 may be read out, processed, and used to generate a digital image representing the spatial distribution and intensity of the incident X-rays 108, as described herein.

[0063] Each of the pixels 432 may have characteristic dimensions, such as a width and height, which define the spatial resolution of the detector 206. In some cases, the pixels 432 may be square or rectangular in shape, with typical dimensions ranging from about 50-100 micrometers (mm) to 200-1000 mm per side. The specific pixel dimensions may vary depending on the intended application, with smaller pixels generally preferred for high-resolution imaging (e.g., mammography) and larger pixels suitable for applications requiring higher sensitivity or faster readout (e.g., chest radiography or industrial inspection).

[0064] The attenuating elements 428A-C may be elongated members having a cylindrical shape. As such, the attenuating elements 428A-C may have a circular cross-section profile having a diameter d and a length I. As will be described in greater detail below with respect to Figures 9-13, the attenuating elements 428A-C may have alternative configurations, orientations, and shapes. For example, in some embodiments, instead of a cylindrical shape having a circular cross-section profile, the attenuating elements 428 A-C may have a rectangular shape having a square or angular cross-section profile having a width and height, instead of a diameter, d. In other embodiments, instead of elongated members, the attenuating elements 428A-C may be spherical members or formed as part of a grid or mesh, as described below with respect to Figures 9-13.

[0065] In some embodiments, the attenuating elements 428A-C may have a diameter d (or a cross-sectional profile in the case of a rectangular, cubic, or non-circular shape), that isDocket No. 303.0140WOproportional to the characteristic dimensions of the pixels 432. For example, in certain implementations, the diameter d of the attenuating elements 428A-C may be equal to or greater than the characteristic dimension of a pixel 432, while in other embodiments, the diameter d may be equal to or less than the characteristic dimension of the pixel 432. The diameter d of the elements 428A-C may range from approximately 0.05 millimeters to 1.5 millimeters, depending on factors such as the desired spatial resolution, the pitch of the pixel array 430 and / or the intended imaging application. In general, the selection of the diameter d may be optimized to balance factors such as scatter measurement and object image quality, as described in greater detail below.

[0066] The attenuating elements 428A-C may also have a length I which may vary depending on the size and configuration of the detector 406, particularly the geometry of the pixel array 430. In the illustrated example, the length I of the attenuating elements 428 A-C corresponds to the lateral dimensions of the pixel array 430. Specifically, the attenuating elements 428 A-C extend from a first side 431 A to a second, opposing side 43 IB of the pixel array 430. As will be appreciated, the shape and layout of the pixel array 430 may vary based on the design of the detector 406. Although the illustrated detector 406 is a flat, square detector (i.e., with no curvature), the present disclosure is equally applicable to detectors having curved geometries or non-symmetrical shapes, including rectangular, circular, or irregular configurations. Accordingly, the length, shape, and configuration of the attenuating elements 428A-C may also vary based on the shape and configuration of the underlying detector 406 and / or the pixel array 430 to ensure proper alignment and functional integration.

[0067] The attenuating elements 428A-C of the OSM device 410 may be positioned physically proximate to the pixel array 430 of the detector 406. In particular, the attenuating elements 428 A-C may be positioned physically proximate to a surface 433 of the pixel array 430. The attenuating elements 428A-C may be positioned at a pitch p (not shown) above the surface 433 of the pixel array 430 such to not contact the detector 406. The pitch p refers to the distance between the surface 433 and the attenuating elements 428A-C. The surface 433 of the pixel array 430 may be defined by a surface of the detector 406 that faces the source 104 and is configured to receive incident X-rays 108 during transmission. The pitch p may be in the order of a few millimeters (mm) to several centimeters (cm) depending on the application. By increasing the pitch of the attenuating elements 428A-C, artifacts caused by the OSM device 410 may be reduced, primary X-ray transmission may be improved, and a more accurate scatter intensity estimation may be achieved. In some cases, the pitch / ? above the surface 433 of the detector 406 may range from approximately 0.1 mm to several centimeters (e.g., up to aboutDocket No. 303.0140WO2-3 cm), depending on the configuration and application. As will be described in greater detail below, the pitch p and / or diameter d of the attenuating elements 428A-C may be selected to cast a shadow on the pixel array 430 having a desirable cross-sectional dimension (e.g., 3-5 pixels within a cross-sectional segment of the shadow pixel region).

[0068] The attenuating elements 428A-C may be positioned and arranged in a onedimensional (ID) or two-dimensional (2D) linear array, as illustrated. For example, the OSM device 410 may include multiple attenuating elements 428 A-C that are spaced equidistantly from adjacent elements and aligned such that each attenuating element shares a common angular orientation, i.e., each element is parallel to its neighboring elements. The spacing between adjacent attenuating elements 428 A-C may be uniform or variable, depending on factors such as the resolution, pitch, and configuration of the pixel array 430 and / or the design parameters of the OSM device 410. In certain embodiments, the spacing .y may be selected to correspond to the pixel 432 pitch of the pixel array 430 to ensure modulation alignment with underlying pixels 432, as described in greater detail below. Alternatively, spacing, s may be optimized to minimize a number of attenuating elements 428A-C within the OSM device 410 while maintaining accuracy with measuring and correcting scatter within the X-ray imaging system. In an example, the spacing ,y may be 2-4 times the diameter d of the attenuating elements 428A-C. For instance, if the diameter of the attenuating elements 428A-C is 1 mm or less, then the spacing 5 between adjacent attenuating elements 428A-C may be 2-3 mm or more.

[0069] In some embodiments, the spacing, s, between adjacent attenuating elements 428A-C may vary depending on the imaging application, detector characteristics, and desired sampling of shadow pixel regions. For example, in 3D imaging systems where the detector 406 is a flat panel detector for interventional radiology or radiation therapy, the spacing, s, may be in a range of approximately 10-20 mm, while in other embodiments the spacing may be larger, such as approximately 50-60 mm. In some implementations, the spacing may be selected relative to the diameter (d) of the attenuating elements and / or the characteristic dimension of the detector pixels (e.g., pixels 432), for example being on the order of multiple times the element diameter to balance scatter sampling resolution and primary signal transmission.

[0070] In certain experimental implementations, the spacing, s, between adjacent attenuating elements may be approximately 2 cm (e.g., about 20 mm). Such spacing, in combination with attenuating element dimensions and detector pixel size, may be selected to produce shadow pixel regions with sufficient spatial sampling to enable accurate estimation of residual scatter while minimizing interference with primary image acquisition. More generally, the spacing may be selected based on a trade-off between spatial sampling density of scatterDocket No. 303.0140WOmeasurements and preservation of image quality, and may vary across different system configurations and use cases.

[0071] In some implementations, the dimensions and relative positioning of the attenuating elements may be selected based on the characteristic dimensions of the detector pixels. For example, the diameter (d) of the attenuating elements (e.g., elements 428A-428C) may be comparable to a characteristic dimension of the detector pixels (e.g., pixels 432), such as a width or pitch of the pixel array. In certain implementations, the diameter of the attenuating elements may be approximately equal to the pixel size, while in other implementations the diameter may be smaller than the pixel size, such as less than or equal to approximately 50% of the pixel dimension, while still enabling effective formation of shadow pixel regions for scatter measurement and correction.

[0072] In a representative experimental implementation, the attenuating elements were formed as rods having a diameter of approximately 300 microns, with adjacent elements spaced apart by a spacing (s) of approximately 2 cm, consistent with the arrangement illustrated in Figure 4. The detector pixel array had a pixel size of approximately 300 microns, such that the diameter of the attenuating elements was comparable to the characteristic pixel dimension. The attenuating elements were positioned above the detector surface at a pitch (p) of approximately 2-2.5 cm, as measured between the attenuating elements and the detector pixel array. This configuration was observed to produce suitable shadow pixel regions for scatter measurement while maintaining acceptable primary signal transmission.

[0073] In some embodiments, the attenuating elements 428A-C may be oriented such that their pitch is parallel to the surface of the pixel array 430, including configurations in which the surface 433 of the pixel array 430 is curved. In other embodiments, the pitch of the attenuating elements 428A-C may be non-uniform or may differ from the pitch of the pixel array 430. The relative orientation and pitch relationship between the attenuating elements 428A-C and the pixel array 430 may vary based on factors such as the optical path geometry, device form factor, or intended spatial resolution.

[0074] As noted above, a flood projection is generated using the OSM device 410 positioned physically proximate to the surface 433 of the pixel array 430. For ease of illustration, the following discussion focuses on a region 434 of the pixel array 430, however, it should be appreciated that the discussion applies to the entire pixel array 430. Referring now to Figure 5, a focused perspective 500 of the region 434 is illustrated, according to various embodiments herein. The region 434 depicts a subset of the pixels 432 from the pixel array 430. In particular, the region 434 illustrates the formation of a shadow pixel region 436 on the pixels 432.Docket No. 303.0140WO

[0075] As illustrated, when an X-ray source 504 (which may be identical or similar to the source 104) emits X-rays 508 toward a detector, such as detector 406, the attenuating element 428A may obstruct a portion of the X-rays 508 from reaching the pixel array 430. As a result, the attenuating element 428A casts a shadow onto the detector 406, thereby forming a shadow pixel region 536. The shadow pixel region 536 may include both shaded pixels 538 and unshaded pixels 540. As their names imply, the shaded pixels 538 correspond to pixels 432 that are at least partially covered by the shadow pixel region 536, while the unshaded pixels 540 correspond to pixels 432 that remain fully exposed to the X-rays and are not covered by the shadow.

[0076] The attenuating element 428A may have a defined diameter, length, and / or be positioned at a vertical pitch p above the pixel array 430 such that the resulting shadow pixel region 536 cast onto the detector 406 includes a cross-sectional segment 542 spanning a desired number of pixels 432. For example, in some embodiments, it may be desirable to have the cross-sectional segment 542 spanning 5-10 pixels 432, in particular, 3-5 pixels 432. The cross-sectional segment 542 may be defined as a segment of the shadow pixel region 536 that extends perpendicular to the lengthwise direction of the attenuating element 428A — i.e., orthogonal to the longitudinal axis of the attenuating element 428A — and intersects the underlying pixel array 530 along a single pixel 432 increment, as illustrated. The cross-sectional segment 542 captures a linear cross-section of the shadow pixel region 536 across the pixel array 430, and includes the shaded pixels 538 within the shadow pixel region 536, as well as the at least one unshaded pixel 540 at each lateral end.

[0077] Referring back to Figures 2-3, when the flood projection is captured with the OSM device 410 positioned physically proximate to the detector 206, the shadow pixel region 536 is generated on the pixel array 430. The pixels 432 on the detector 206 detect the X-rays and convert them into electrical signals 207A. As noted above, the electrical signals 207A may correspond to the signal intensity of a respective pixel 432 within the pixel array 430. Accordingly, the pixels 432 covered by the shadow pixel region 536 (e.g., the shaded pixels 538) may reflect the decrease in signal intensity due to the attenuating elements 428A-C of the OSM device 410.

[0078] In some embodiments, the flood projection generator 226 may generate projection signal profiles 244 based on the flood projection (310). Referring now to Figure 6A, an example projection signal profile 644 is illustrated, according to an embodiment herein. The projection signal profile 644, which may be the same or similar to the projection signal profiles 244, depicts the projection signal response 646 detected by the pixel array 430 during the floodDocket No. 303.0140WOprojection. In particular, the projection signal profile 644 illustrates the projection signal response 646 of the pixels 432 within the cross-sectional segment 542 of the shadow pixel region 236. For illustrative purposes, a representation 628 of the attenuating element 428A is provided on the projection signal profile 644 to show the relationship between the attenuating element 428A and a low point 641 in projection signal response 646. The low point 641 in projection signal response 646 may correspond to the shaded pixels 438 while high points 643 in the projection signal response 646 may correspond to the unshaded pixels 440.

[0079] In some embodiments, the shadow pixel region 536 may be partitioned into multiple cross-sectional segments 542, each corresponding to a pixel 432 increment along the length I of the attenuating element 428 A. As such, the flood projection generator 226 may generate a projection signal profile 644 for each cross-sectional segment 542 along the length I of the attenuating element 428A. Similar projection signal profiles 644 may also be generated along the length of a respective shadow pixel region 436 formed by the attenuating elements 428B and 428C.

[0080] Responsive to generating the projection signal profiles 244, the scatter correction engine 222 may determine a signal attenuation estimate for the OSM device 410 based on the flood projection (315). In particular, the scatter correction engine 222 may include a signal attenuation estimator 248 that generates an attenuation estimate 250 based on the flood projection. The attenuation estimate 250 represents a quantitative estimation of the degree to which each of the attenuating elements 428A-428C reduces or attenuates the signal intensity. In some embodiments, the attenuation estimate 250 may be generated per cross-sectional segment basis, such that a separate attenuation estimate 250 is produced for each cross-sectional segment 542 of the shadow pixel region 536.

[0081] In some embodiments, to generate the attenuation estimate 250, the signal attenuation estimator 248 may normalize the projection signal response 646 of the projection signal profile. Referring now to Figure 6B, a normalized signal profile 600 is illustrated according to an embodiment herein. The normalized signal profile 600 represents the projection signal profile 644 after normalization of the projection signal response 646 to produce a normalized projection response 650. The normalization may be performed relative to a baseline or predefined normalization constant to facilitate comparison across cross-sectional segments 542. In the illustrated example, the normalization constant is 1, thus the intensity signal 646 on the projection signal profile 644 is normalized to a scale of 1 to 2 from an original intensity of 50 to 100.Docket No. 303.0140WO

[0082] In some embodiments, a normalization map is generated based on the flood projection and / or the projection signal profiles 244. To generate the normalization map, the electrical signals 207A for each pixel 432 within a cross-sectional segment 542 may be normalized. The following is an example normalization equation that may be used to generate a normalization map, NM(z ):

[0083] NM(i,n = ^

[0084] where (z, j) correspond to the pixel coordinates of a pixel 432 within the cross-sectional segment 542 (such as described below with respect to Figure 8), C is a normalization constant, and F is the electrical signal 407 A or signal intensity detected of the respective pixel 432 during the flood projection. The normalization map may characterize and compensate for primary signal intensity reduction due to the attenuating elements 428A-C.

[0085] Referring now to Figures 2-3, once the attenuation estimate 250 is generated, the scatter correction engine 222 may capture an object image of an object positioned between the source 104 and the detector 206 (320). For example, at a time subsequent to creation of the flood projection, an object, such as the object 114, may be positioned between the source 104 and the detector 206 for an X-ray event. The electrical signals 208B corresponding to this X-ray event may be provided from the detector 206 to the scatter correction engine 222. Using the electrical signals 208B, an object image generator 252 may generate an object image. In some embodiments, instead of or in place of the object image, the scatter correction engine 222 may generate object signal profiles 254 (325). Similar to the projection signal profiles 244, the object signal profiles 254 may represent the signal intensities detected by pixels 432 within the cross-sectional segments 542.

[0086] Referring now to Figure 7A, an example object signal profile 754 is illustrated, according to an embodiment herein. The object signal profile 754, which may be the same or similar to the object signal profiles 254, may correspond to the same cross-sectional segment 542 used to generate the projection signal profile 644. As such, an object signal response 746 may correspond to the same pixels 432 that generated the projection signal response 646. Although the following is discussed with respect to a single cross-sectional segment 542, the scatter correction engine 222 may generate an object signal profile 754 for each or a subset of the cross-sectional segments 542 of any shadow pixel regions 536 created on the pixel array 430.

[0087] As noted above, when the object 114 is positioned between the source 104 and the detector 206, scatter occurs. As such, the object signal profile 754 may contain fluctuations inDocket No. 303.0140WOobject signal response 746 caused by scatter. That is, the reduction in object signal response 746 drop for pixels 432 within the cross-sectional segment 542 corresponds to scatter intensity. In the illustrated object signal profile 754, scatter is indicated by the dotted line 760.

[0088] In the illustrated example, when no object was present during the flood projection, the OSM device 410 caused a projection signal response 646 drop of 50 in pixel value between the high points 643 corresponding to the unshaded pixels 540 and the low point 641 corresponding to the shaded pixels 538, as illustrated in Figure 6A. However, when the object is present, the OSM device 410 only causes the object signal response 746 drop of 5 counts between a high point 743 corresponding to the unshaded pixels 540 and a low point 741 corresponding to the shaded pixels 538. Since there is an object positioned between the source 104 and the detector 406, the object may attenuate or absorb a portion of the X-rays 108. As such, only a portion of the X-rays 108 may reach the detector 406. This accounts for the decrease from 50 to 5 between the projection signal response 646 and the object signal response 746.

[0089] The OSM device 410, being the same in both the flood projection and the X-ray event, should cause the same or substantially similar decrease in signal intensity if no scatter is present. However, because some of the X-rays 108 deflect off the object during the X-ray event, scatter occurs. Because scatter often reaches the detector 408 at different angles than what the source 104 emits at it can be assumed that the scatter incident on region 434 to be approximately uniform, even though the OSM device 410 may partially attenuate scatter. Thus, pixels 432 within the region 434, including pixels within the shadow pixel region 536, may detect scatter, resulting in an increase in signal intensity. This increase in signal intensity due to scatter, also referred to herein as scatter intensity, results in the low point 741 of the object signal profile 754 being proportionally higher than the low point 641 on the projection signal profile 644.

[0090] In some embodiments, the scatter correction engine may generate a residual scatter estimate based on the object image and the flood projection (330). In particular, the scatter correction engine 222 may include a residual scatter estimator 256 that generates a residual scatter estimate 258. The residual scatter estimate 258 may be based on the object image and the flood projection, such as in some cases, being generated per cross-sectional segment basis, such that a separate residual scatter estimate 528 is produced for each cross-sectional segment 542 of the shadow pixel region 536. In some embodiments, as described below, the residual scatter estimate 258 includes a primary scatter intensity and a secondary scatter intensity.Docket No. 303.0140WO

[0091] To generate the residual scatter estimate 258, the residual scatter estimator 256 may initially normalize the object signal profile 754. Referring now to Figure 7B, an example normalized object profile 700 is illustrated according to an embodiment herein. The normalized object profile 700 may be generated using the object signal profile 754 and the normalized signal profile 600 from Figure 6B. A resulting normalized object response 750 may be generated.

[0092] To generate the normalized signal profile 600, the object signal response 746 corresponding to the object signal profile 754 may be multiplied by the normalized projection response 650 to create the normalized object response 750. As illustrated in Figure 6B, the normalized projection response 650 fluctuates across the cross-sectional segment 542, depending on whether the underlying pixel 432 corresponds to an unshaded pixel 540 or a shaded pixel 538, and whether the shaded pixel 538 is a completely covered or only partially covered by the shadow pixel region 536. In some embodiments, the normalization of the object signal response 746 may be performed on a per pixel basis, thus reflecting the fluctuations in normalized projection response 650, while in other embodiments, the normalized projection response 650 may be averaged or otherwise quantified into a single value representative of the cross-sectional segment 542.

[0093] In some embodiments, the object signal response 746, O(z',j) may be normalized to generate the normalized object response 750 (Onorm) using the following equation:

[0094] Onorm(i,f) = NM(i,j) x O(i )

[0095] where (z, j) correspond to the pixel coordinates of a pixel 432 within the cross-sectional segment 542 (such as described below with respect to Figure 8), NM(z' ) corresponds to the respective pixel 432 on the normalization map as computed above, and O(z ) is the electrical signal 407B or object signal response 746 detected of the respective pixel 432 during the X-ray event. The normalized object response 750 (Onorm) may exhibit hyperintense signals within the shadow pixel region 536. As such, an amplitude (Amp) of the normalized object response 750 is proportional to the scatter intensity.

[0096] Once the normalized object response 750 is calculated, the scatter correction engine 222 may leverage the amplitude of the normalized object response 750 to calculate a primary scatter intensity. The primary scatter intensity, as used herein, refers to an estimated scatter intensity for pixels 432 falling within the cross-sectional segments 542 of the shadow pixel region 536 formed by the OSM device 410. To calculate the primary scatter intensity, the scatter correction engine 222 may partition the cross-sectional segments 542 into pixelDocket No. 303.0140WOneighborhoods and compute the scatter intensity between shaded pixels 538 and unshaded pixels 540 using the normalized object response 750.

[0097] Referring now to Figure 8, an example region 834 of the pixel array 430 containing multiple pixel neighborhoods 862, according to various embodiments herein. The region 834 may include four cross-sectional segments 842A-D, each containing one or more shaded pixels 838A-L and one or more unshaded pixels 840A-H. As shown, the cross-sectional segment 842A contains the shaded pixels 838A-C and unshaded pixels 840A-B, the cross-sectional segment 842b contains the shaded pixels 838D-F and unshaded pixels 840C-D, the cross-sectional segment 842C contains the shaded pixels 838G-I and unshaded pixels 840E-F, and the cross-sectional segment 842D contains the shaded pixels 838J-L and unshaded pixels 840G-H.

[0098] As noted above, the scatter correction engine 222 may compute the normalized object response 750 for each of the cross-sectional segments 842A-D and determine a respective amplitude for each normalized object response 750. Using the amplitude of the normalized object response 750 for each cross-sectional segments 842A-D, the scatter correction engine 222 computes a scatter intensity for each pixel within the pixel array 430.

[0099] To compute the primary scatter intensity, the scatter correction engine 222 may partition the pixel array 430 — specifically, the pixels 432 within a cross-sectional segment of the shadow pixel region 536 — into pixel neighborhoods 862. Each pixel neighborhood 862 comprises a k-by-k group of adjacent pixels, where k may be, for example, 2, 3, or 5 (i.e., 2x2, 3x3, or 5x5 regions). The pixel neighborhood 862 may require that at least one pixel within the neighborhood 862 be a shaded pixel and at least one pixel be an unshaded pixel. The shaded pixel, such as pixel 838D, can be partially shaded, meaning that the pixel is only partially within the shadow pixel region 536 cast by the attenuating element 428A. Likewise, in an example (not illustrated), an unshaded pixel, such as 840C, may also be slightly within the shadow pixel region 536. Thus, at least one pixel is more shaded than the remaining pixels in neighborhood 862.

[0100] Then assuming that scatter is uniform within a respective neighborhood 862, the scatter correction engine 222 calculates the scatter intensity using the following equation:[ooioi] sGi, A) = .. . .T. . .

[0102] Where (ji, ji) and fe J2) are pixel coordinates of a shaded pixel and an unshaded pixel, respectively, within a given pixel neighborhood 862. For example, the scatter intensity for shaded pixel 838D having the pixel coordinates (12, ji may be computed using the aboveDocket No. 303.0140WOequation. Thus, the normalized projection response, NMshadedfe .7’2) is computed as described above, and then the normalized object response, NMunshaded( 12, ji) is computed for the adjacent unshaded pixel 840C. Using the calculated amplitude Ainpi / -, jb) of the normalized object response 750 for the cross-sectional segment 842B, the scatter intensity, S( / 2, jb), for the shaded pixel 838D is calculated. The above steps may be repeated for the majority or all of the pixels within the pixel neighborhood 862, and then for all of the pixel neighborhoods 862 within the pixel array 430. This scatter intensity calculated based on the pixel neighborhoods 862 is referred to herein as primary scatter intensity since it is reliably estimated based on primary signal attenuation observed by the shadow pixel regions 536 generated by the OSM device 410.

[0103] In some embodiments, the scatter correction engine 222 then estimates the scatter intensity for pixels 432 that fall outside of the pixel neighborhoods 862 (e.g., pixels that do not fall within a cross-sectional segment of the shadow pixel region 536), which is referred to herein as secondary scatter intensity. Since the primary scatter intensity can be directly estimated based on attenuation of the OSM device 410, the primary scatter intensity may serve as anchor points for estimating the secondary scatter intensity of pixels 432 falling outside or between of the shadow pixel regions 536.

[0104] To estimate the secondary scatter intensity for the pixels 432 that lie outside the shadow pixel regions 536, the scatter correction engine 222 may use one or more interpolation techniques. In some embodiments, the scatter correction engine 222 uses a spatial averaging interpolation technique, where the scatter intensity for each pixel 432 outside the pixel neighborhoods 862 is calculated as an average of nearby primary scatter intensity values. The accuracy and smoothness of spatial interpolation can be adjusted by varying the size of the averaging kernel. A large kernel uses scatter intensity values from a wider area, producing smoother but less localized estimates, which is useful when scatter changes gradually over space. A smaller kernel, on the other hand, focuses on a more localized neighborhood, capturing finer variations in scatter intensity but potentially being more sensitive to noise or outliers. By selecting an appropriate kernel size, the scatter correction engine 222 can estimate the secondary scatter intensity that blends smoothly with the primary scatter intensity estimates and provides continuous correction coverage across the entire pixel array 430.

[0105] It should be appreciated that other scatter estimation methods may be leveraged by the scatter correction engine 222 to estimate both the primary scatter intensity and the secondary scatter intensity using similar approaches. That is, the primary scatter intensity may be computed based on the projection signal response 646 and the object signal response 746.Docket No. 303.0140WOThe primary scater intensity may then be used to estimate the secondary scater intensity for pixels outside of the shadow pixel regions 536.

[0106] Responsive to estimating the primary scatter intensity and the secondary scatter intensity, the residual scater estimator 256 generates the residual scater estimate 258. The residual scater estimate 258 may then be used by the scatter correction engine 222 to generate a scatter-corrected object signals 266 (335). In particular, the scater correction engine 222 may include a scatter-corrected image generator 264 that corrects the object image based on the residual scatter estimate 258.

[0107] To generate the scatter-corrected object signals 266, the object signal responses of all pixels within the pixel array 430 (e.g., the electrical signals 208B) may be adjusted based on the residual scatter estimate 258 (340). For example, the primary scatter intensity values may be subtracted from the object signal response 746 and the secondary scatter intensity values may be subtracted from respective object signal responses for pixels falling outside of the shadow pixel regions 536. In an example, the following equation may be used to adjust for the residual scatter estimate 258:

[00108] Oadjusted(i,j) = OQi.n -

[0109] In some embodiments, the object signal responses may also be adjusted based on the projection signal responses 646 to remove any signal fluctuations or impacts due presence of the attenuation elements 428A-C (345). To adjust for the attenuation elements 428A-C within the object image, the projection signal responses 646 may be multiplied by the normalization map to remove the shadow pixel regions 536 from the object signal response 746. In an example, the following equation may be used to adjust for the projection signal responses 646:

[00110] Ofinal(t,f) = X Oadjusted(j-> J)

[0111] The scatter-corrected object signals 266, Ofmai, may then be used by an imaging processor, such as the image processor 116 to generate the scatter-corrected object signals 266. As illustrated, the scatter-corrected image generator 264 may be in operable communication with the image processor 216, which in turn may receive the scatter-corrected object signals 266 and generate a scatter-corrected image 268. The scatter-corrected image 268 may then be provided to a client device 220 for display to a provider, technician, or user.

[0112] Referring now to Figures 9-13, various configurations and arrangements of an OSM device are illustrated, in accordance with several embodiments described herein. As noted above, the OSM device may be constructed in either a one-dimensional (ID) array or a two-dimensional (2D) array format. Configurations of attenuating elements within these arrays canDocket No. 303.0140WOassume various geometric layouts, including but not limited to square, rectangular, or hexagonal patterns.

[0113] In preferred embodiments, the attenuating elements may exhibit spherical or cylindrical symmetry, as illustrated in the example embodiments described herein. Such symmetry ensures that the shadow pixel regions projected onto the detector by each attenuating element exhibit minimal variation as the relative position between the X-ray source and the X-ray detector changes. This geometric consistency helps preserve image uniformity across different source-detector configurations. The choice between a one-dimensional (ID) and a two-dimensional (2D) array format may depend on application-specific requirements and performance objectives. A 2D array offers the advantage of a greater number of attenuating elements, thereby enabling more discrete scatter intensity estimation points compared to a ID array. However, this configuration is more complex to fabricate and may introduce additional attenuation of primary X-rays, due to increased material obstruction, potentially reducing the intensity of unscattcrcd X-rays reaching the detector.

[0114] Ultimately, the design, configuration, and arrangement of the OSM device may be selected based on factors such as fabrication complexity, spatial resolution requirements, desired scatter sampling density, and acceptable levels of primary beam attenuation.

[0115] Figure 9 illustrates an example OSM device 910 having an array 970 of attenuating elements 928. As illustrated, the attenuating elements 928 are spherical members formed in a 2D array 970. Within the array 970, the attenuating elements 928 are spaced equidistantly from an adjacent spherical member along two orthogonal axes. In some cases, the attenuating elements 928 are arranged in the 2D regular array 970 having a uniform pitch along each of the two orthogonal axes such that the centers of the attenuating elements 928 define a plane parallel to a surface 933 of an underlying pixel array 930, which may be the same as the pixel surface 433 of the pixel array 430. It should be noted that in other embodiments, the attenuating elements 928 may be spaced non-equidistantly from an adjacent attenuation element 928.

[0116] Figure 10 illustrates an example OSM device 1010 comprising an array 1070 of discrete attenuating elements 1028A-G, according an embodiment herein. As shown, the array 1070 forms a grid-like arrangement of the attenuating elements 1028A-G. In the illustrated embodiment, upper-layer attenuating elements 1028D-G are positioned above underlying elements 1028A-C to construct the grid structure. In alternative embodiments, however, the grid may be implemented as a monolithic attenuating structure, such as the configuration depicted in Figure 11.Docket No. 303.0140WO

[0117] Figure 11 shows another example OSM device 1110, in which the grid is formed from a single integrated attenuating element 1128, according to an embodiment herein. Forming the grid as a single cohesive attenuating element 1128, rather than assembling it from multiple overlaid discrete elements as in Figure 10, may improve the uniformity of the shadow pixel regions cast onto the underlying pixel array 1130. This improved uniformity can enhance the consistency and accuracy of X-ray attenuation and scatter measurements across the pixel array 1130.

[0118] In some embodiments, the OSM device may be formed as part of the detector. The detector, such as the detector 106 may be composed of multiple layers, such as a substrate layer, a photoconductive layer, an electrode layer, and one or more intermediate dielectric or semiconductive layers. For example, the substrate layer may be composed of glass, silicon, or a flexible polymeric material, while the photoconductive layer may include amorphous selenium, cadmium telluride, or other X-ray sensitive materials. The electrode layer may include a transparent conductive oxide (TCO), such as indium tin oxide (ITO), or a metal such as aluminum or gold.

[0119] Referring now to Figure 12, an example embodiment 1200 illustrating an OSM device 1210 formed as part of a detector 1206 is illustrated, according to an embodiment herein. The detector 1206, which may be the same or similar to the detector 106 may be a dual or multilayer detector. As such, the detector 1206 includes at least one top layer 1272 and a pixel array layer 1230. An attenuating element 1228 of the OSM device 1210 may be formed between the pixel array layer 1230 and the top layer 1272. By integrating the OSM device 1210 between or within one or more of these layers 1230 and 1272, the attenuating element 1228 may only impact (e.g., cast a shadow on) the pixel array layer 1230, allowing for image acquisition by the top layer 1272 without primary X-ray reduction or image artifacts caused by the OSM device 1210. Integration of the OSM device within the multilayer detector 1206 may also reduce overall system complexity and facilitate compact detector designs.

[0120] Figure 13 illustrates another example embodiment 1300 illustrating an OSM device 1310 formed as part of a detector 1306, according to an embodiment herein. The detector 1306 may be the same or similar to the detector 1206 and as such contain a top layer 1372 and a pixel array layer 1330. The OSM device 1310 may be formed by a regular array of spherical members (e.g., attenuating elements) 1328. The OSM device 1310 may be integrated between the top layer 1372 and the pixel array layer 1330, and thereby be formed as part of the detector 1306.Docket No. 303.0140WO

[0121] In some embodiments, the OSM device may be positioned between the detector and an antiscatter grid, or above the antiscatter grid (e.g., between the antiscatter grid and the X-ray source). As described in U.S. Patent No. 11,224,389, entitled Radiation Transmission Grid Apparatus and Methods for X-Ray Imaging Detectors, which is hereby incorporated by reference in its entirety, an antiscatter grid may be employed to reduce scattered radiation. However, residual scatter may still be present, particularly in variable-geometry or adaptive X-ray imaging systems. Accordingly, in certain implementations, the OSM device may be used in conjunction with the antiscatter grid to detect and compensate for remaining scattered radiation, thereby improving image quality and system performance.

[0122] Referring to Figure 14, Figure 14 illustrates a computing apparatus 1491 that may be used for providing a scatter correction engine and related functions, as described herein. For example, the client devices 120 or 220, the image processor 116, or the scatter correction engine 122 or 222 may be or include the computing apparatus 1491. As illustrated, the computing apparatus 1491 includes a processing system 1492 that includes a microprocessor and other circuitry that retrieves and executes software 1495 from storage system 1493. The processing system 1492 may be implemented within a single processing device but may also be distributed across multiple processing devices or sub-systems that cooperate in executing program instructions. Examples of the processing system 1492 include general purpose central processing units, graphical processing units, application specific processors, and logic devices, as well as any other type of processing device, combinations, or variations thereof.

[0123] The storage system 1493 may comprise any computer-readable storage media or medium readable by processing system 1492 and capable of storing software 1495. The storage system 1493 may include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of infomiation, such as computer readable instructions, data structures, program modules, or other data. Examples of storage media include random access memory, read only memory, magnetic disks, optical disks, flash memory, virtual memory and non-virtual memory, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other suitable storage media. In no case is the computer readable storage media a propagated signal.

[0124] In addition to computer readable storage media, in some implementations the storage system 1493 may also include computer readable communication media over which at least some of the software 1495 may be communicated internally or externally. The storage system 1493 may be implemented as a single storage device but may also be implemented across multiple storage devices or sub-systems co-located or distributed relative to each other. TheDocket No. 303.0140WOstorage system 1493 may comprise additional elements, such as a controller capable of communicating with the processing system 1492 or possibly other systems.

[0125] The software 1495 (including scatter correction engine process 1496) may be implemented in program instructions and among other functions may, when executed by the processing system 1492, direct the processing system 1492 to operate as described with respect to the various operational scenarios, sequences, and processes illustrated herein. For example, the software 1495 may include program instructions for implementing a scatter correction engine and related functions, such as the process 300, as described herein.

[0126] The term “engine” as used herein includes a “component”, “module”, “system,” and the like is intended to refer to a computer-related entity, either software-executing general-purpose processor, hardware, firmware and a combination thereof. For example, an engine may be, but is not limited to being, a process running on a hardware processor, a hardware-based processor, an object, an executable, a thread of execution, a program, and / or a computer.

[0127] In particular, the program instructions may include various components or modules that cooperate or otherwise interact to carry out the various processes and operational scenarios described herein. The various components or modules may be embodied in compiled or interpreted instructions, or in some other variation or combination of instructions. The various components or modules may be executed in a synchronous or asynchronous manner, serially or in parallel, in a single threaded environment or multi-threaded, or in accordance with any other suitable execution paradigm, variation, or combination thereof. The software 1495 may include additional processes, programs, or components, such as operating system software, virtualization software, or other application software. The software 1495 may also comprise firmware or some other form of machine-readable processing instructions executable by the processing system 1492.

[0128] In general, the software 1495 may, when loaded into the processing system 1492 and executed, transform a suitable apparatus, system, or device (of which computing apparatus 1491 is representative) overall from a general-purpose computing system into a special-purpose computing system customized to generate features, functionality, and user experiences provided by the scatter correction engine. Indeed, encoding the software 1495 on the storage system 1493 may transform the physical structure of the storage system 1493. The specific transformation of the physical structure may depend on various factors in different implementations of this description. Examples of such factors may include, but are not limited to, the technology used to implement the storage media of the storage system 1493 and whetherDocket No. 303.0140WOthe computer- storage media are characterized as primary or secondary storage, as well as other factors.

[0129] For example, if the computer readable storage media are implemented as semiconductor-based memory, the software 1495 may transform the physical state of the semiconductor memory when the program instructions are encoded therein, such as by transforming the state of transistors, capacitors, or other discrete circuit elements constituting the semiconductor memory. A similar transformation may occur with respect to magnetic or optical media. Other transformations of physical media are possible without departing from the scope of the present description, with the foregoing examples provided only to facilitate the present discussion.

[0130] Communication interface system 1497 may include communication connections and devices that allow for communication with other computing systems (not shown) over communication networks (not shown). Examples of connections and devices that together allow for inter-system communication may include network interface cards, antennas, power amplifiers, RF circuitry, transceivers, and other communication circuitry. The connections and devices may communicate over communication media to exchange communications with other computing systems or networks of systems, such as metal, glass, air, or any other suitable communication media. The aforementioned media, connections, and devices are well known and need not be discussed at length here.

[0131] User interface system 1499 may include various components and devices that enable interaction between the user and the computing system. Examples of these components and devices may include display screens, touchscreens, keyboards, mice, trackpads, styluses, voice recognition microphones, and other input / output devices. The user interface system 1499 facilitates user commands and feedback through graphical user interfaces (GUIs), commandline interfaces (CLIs), or other interaction models. These interfaces may display information, receive user inputs, and provide visual, auditory, or tactile responses. The components and devices within the user interface system 1499 are designed to ensure seamless and intuitive user interaction, leveraging well-established technologies and practices that need not be elaborated upon here.

[0132] Communication between the computing apparatus 1491 and other computing systems (not shown), may occur over a communication network or networks and in accordance with various communication protocols, combinations of protocols, or variations thereof. Examples include intranets, internets, the Internet, local area networks, wide area networks, wireless networks, wired networks, virtual networks, software defined networks, data centerDocket No. 303.0140WObuses and backplanes, or any other type of network, combination of network, or variation thereof. The aforementioned communication networks and protocols are well known and need not be discussed at length here.

[0133] While some examples of methods and systems herein are described in terms of software executing on various machines, the methods and systems may also be implemented as specifically-configured hardware, such as field-programmable gate array (FPGA) specifically to execute the various methods according to this disclosure. For example, examples can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in a combination thereof. In one example, a device may include a processor or processors. The processor comprises a computer-readable medium, such as a random access memory (RAM) coupled to the processor. The processor executes computer-executable program instructions stored in memory, such as executing one or more computer programs. Such processors may comprise a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), field programmable gate arrays (FPGAs), and state machines. Such processors may further comprise programmable electronic devices such as PLCs, programmable interrupt controllers (PICs), programmable logic devices (PLDs), programmable read-only memories (PROMs), electronically programmable read-only memories (EPROMs or EEPROMs), or other similar devices.

[0134] Such processors may comprise, or may be in communication with, media, for example one or more non-transitory computer-readable media, which may store processorexecutable instructions that, when executed by the processor, can cause the processor to perform methods according to this disclosure as carried out, or assisted, by a processor. Examples of may include, but are not limited to, an electronic, optical, magnetic, or other storage device capable of providing a processor, such as the processor in a web server, with processor-executable instructions. Other examples of non-transitory computer- readable media include, but are not limited to, a floppy disk, CD-ROM, magnetic disk, memory chip, ROM, RAM, ASIC, configured processor, all optical media, all magnetic tape or other magnetic media, or any other medium from which a computer processor can read. The processor, and the processing, described may be in one or more structures, and may be dispersed through one or more stmctures. The processor may comprise code to carry out methods (or parts of methods) according to this disclosure.

[0135] Examples are described herein in the context of systems and methods for providing a scatter correction engine and related functions. Those of ordinary skill in the art will realize that the foregoing description is illustrative only and is not intended to be in any way limiting.Docket No. 303.0140WOReference is made in detail to implementations of examples as illustrated in the accompanying drawings. The same reference indicators will be used throughout the drawings and the following description to refer to the same or like items.

[0136] Additionally, the foregoing description of some examples has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Numerous modifications and adaptations thereof will be apparent to those skilled in the art without departing from the spirit and scope of the disclosure. In the interest of clarity, not all of the routine features of the examples described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer’s specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another.

[0137] Reference herein to an example or implementation means that a particular feature, structure, operation, or other characteristic described in connection with the example may be included in at least one implementation of the disclosure. The disclosure is not restricted to the particular examples or implementations described as such. The appearance of the phrases “in one example,” “in an example,” “in one implementation,” or “in an implementation,” or variations of the same in various places in the specification does not necessarily refer to the same example or implementation. Any particular feature, structure, operation, or other characteristic described in this specification in relation to one example or implementation may be combined with other features, structures, operations, or other characteristics described in respect of any other example or implementation.

[0138] Use herein of the word “or” is intended to cover inclusive and exclusive OR conditions. In other words, A or B or C includes any or all of the following alternative combinations as appropriate for a particular usage: A alone; B alone; C alone; A and B only; A and C only; B and C only; and A and B and C.EXPERIMENTAL RESULTS

[0139] The following experimental examples demonstrate implementation and performance of an OSM device consistent with the embodiments described herein. In particular, the OSM device utilized in the experiments is structurally and functionally similar to the device illustrated in Figure 4, including attenuating elements (e.g., elements 428A-428C) arranged relative to a detector pixel array (e.g., pixel array 430). The attenuating elements wereDocket No. 303.0140WOconfigured to cast shadow pixel regions on the detector in a manner consistent with the operational principles described above, thereby enabling measurement and correction of scatter using projection and object signal profiles.

[0140] In the experimental implementations, the attenuating elements were formed as elongated rods composed of tungsten. Each rod had a diameter of approximately 300 microns, and adjacent rods were spaced apart by a spacing (s) of approximately 2 cm, consistent with the spacing parameter described in connection with Figure 4. The detector pixel array had a pixel size of approximately 300 microns, such that the diameter of the attenuating elements was comparable to the characteristic dimension of the detector pixels (e.g., pixels 432). The attenuating elements were positioned above the detector surface at a pitch (p) of approximately 2-2.5 cm, as measured between the attenuating elements and the detector pixel array, consistent with the pitch parameter described in paragraph

[0060] . This configuration was selected to produce measurable shadow pixel regions while maintaining acceptable primary signal transmission and minimizing imaging artifacts.

[0141] The following examples illustrate imaging results obtained using the abovedescribed OSM device configuration across objects of varying size and composition.

[0142] Experimental Example 1

[0143] Figure 15A and Figure 15B illustrate an experimental result obtained using the OSM device described herein. In particular, Figure 15A shows a cone-beam computed tomography (CBCT) image 1500A acquired without use of the OSM device, while Figure 15B shows a corresponding CBCT image 1500B acquired with the OSM device implemented. The imaged object in this example is comparable in size to a human head. As shown in Figure 15 A, the image 1500A acquired without the OSM device exhibits substantial shading artifacts attributable to scatter. In contrast, the image 1500B shown in Figure 15B demonstrates that such shading artifacts are significantly reduced or removed when the OSM device is employed. The OSM device used in this experiment is consistent with, and structurally similar to, the embodiment illustrated in Figure 4, including the arrangement of attenuating elements configured to generate shadow pixel regions for scatter measurement and correction.

[0144] Experimental Example 2

[0145] Figure 16A and Figure 16B illustrate an additional experimental result obtained using the OSM device described herein. In particular, Figure 16A shows a CBCT image 1600A acquired without use of the OSM device, while Figure 16B shows a corresponding CBCT image 1600B acquired with the OSM device implemented. The imaged object in this example is comparable in size to a human pelvis. As shown in Figure 16A, the image 1600A acquiredDocket No. 303.0140WOwithout the OSM device exhibits substantial shading artifacts attributable to scatter. In contrast, the image 1600B shown in Figure 16B demonstrates that such shading artifacts are significantly reduced or removed when the OSM device is employed. The OSM device used in this experiment is consistent with, and structurally similar to, the embodiment illustrated in Figure 4, including the arrangement of attenuating elements configured to generate shadow pixel regions for scatter measurement and correction.

[0146] Experimental Example 3

[0147] Figure 17A and Figure 17B illustrate a further experimental result obtained using the OSM device described herein. In particular, Figure 17A shows a CBCT image 1700A acquired without use of the OSM device, while Figure 17B shows a corresponding CBCT image 1700B acquired with the OSM device implemented. The imaged object in this example is comparable in size to a human thorax. As shown in Figure 17A, the image 1700A acquired without the OSM device exhibits substantial shading artifacts attributable to scatter. In contrast, the image 1700B shown in Figure 17B demonstrates that such shading artifacts arc significantly reduced or removed when the OSM device is employed. The OSM device used in this experiment is consistent with, and structurally similar to, the embodiment illustrated in Figure 4, including the arrangement of attenuating elements configured to generate shadow pixel regions for scatter measurement and correction.

[0148] Experimental Example 4

[0149] Figure 18A and Figure 18B illustrate an additional experimental result obtained using the OSM device described herein. In particular, Figure 18A shows a CBCT image 1800A acquired without use of the OSM device, while Figure 18B shows a corresponding CBCT image 1800B acquired with the OSM device implemented. The imaged object in this example is comparable in size to a human pelvis. As shown in Figure 18A, the image 1800A acquired without the OSM device exhibits substantial shading artifacts attributable to scatter. In contrast, the image 1800B shown in Figure 18B demonstrates that such shading artifacts are significantly reduced or removed when the OSM device is employed. The OSM device used in this experiment is consistent with, and structurally similar to, the embodiment illustrated in Figure 4, including the arrangement of attenuating elements configured to generate shadow pixel regions for scatter measurement and correction.

[0150] Conclusion of Experimental Examples

[0151] The foregoing experimental examples demonstrate that implementation of the OSM device, as described herein, demonstrates that implementation of the OSM device can enable effective measurement and correction of scatter in X-ray imaging systems across objects ofDocket No. 303.0140WOvarying size and composition. In each example, use of the OSM device results in a substantial reduction of shading artifacts and an improvement in image uniformity relative to images acquired without the OSM device. These results are consistent with the operational principles described above, in which attenuating elements generate shadow pixel regions that facilitate estimation of residual scatter and subsequent correction of object signal responses. The demonstrated performance across multiple imaging scenarios indicates that the disclosed OSM device and associated methods are applicable to a range of imaging configurations and object types, including anatomically relevant scales.EXAMPLES

[0152] These illustrative examples are mentioned not to limit or define the scope of this disclosure, but rather to provide examples to aid understanding thereof. Illustrative examples are discussed above in the Detailed Description, which provides further description. Advantages offered by various examples may be further understood by examining this specification.

[0153] As used below, any reference to a series of examples is to be understood as a reference to each of those examples disjunctively (e.g., “Examples 1-4” is to be understood as “Examples 1, 2, 3, or 4”).

[0154] Example 1 is an X-ray imaging system comprising: at least one X-ray source configured to emit X-rays; a detector comprising a pixel array configured to detect X-rays emitted from the at least one X-ray source; an on-detector scatter measurement (OSM) device comprising a plurality of attenuating elements, wherein the OSM device is positioned physically proximate to the detector such to generate a shadow pixel region on a subset of pixels within the pixel array of the detector when the X-rays are emitted from the at least one X-ray source; and an image processor in operable communication with the detector to generate a scatter-corrected image of an object positioned between the at least one X-ray source and the detector, wherein the scatter-corrected image is generated based on the shadow pixel region generated by the OSM device.

[0155] Example 2 is the X-ray imaging system of any previous or subsequent Example, wherein to generate the scatter-corrected image based on the shadow pixel region generated by the OSM device, the image processor comprises a scatter correction engine, wherein the scatter correction engine is configured to: generate a residual scatter estimate based on the shadow pixel region; and generate the scatter-corrected image based on the residual scatter estimate.Docket No. 303.0140WO

[0156] Example 3 is the X-ray imaging system of any previous or subsequent Example, wherein the plurality of attenuating elements of the OSM device comprises a plurality of elongated members disposed at a predefined distance above a surface of the pixel array, wherein: each elongated member is oriented parallel to and spaced equidistantly from adjacent elongated members; and the plurality of elongated members are arranged in a regular linear array with a fixed pitch and a common angular orientation that is parallel to the surface of the pixel array.

[0157] Example 4 is the X-ray imaging system of any previous or subsequent Example, wherein the plurality of attenuating elements of the OSM device comprises a plurality of spherical members disposed at a predefined distance above a surface of the pixel array, wherein: the plurality of spherical members are spaced equidistantly from adjacent spherical members along two orthogonal axes; and the plurality of spherical members are arranged in a two-dimensional regular array with a uniform pitch along each of the two orthogonal axes such that the centers of the spherical members define a plane parallel to the surface of the pixel array.

[0158] Example 5 is the X-ray imaging system of any previous or subsequent Example, wherein: each pixel of the pixel array comprises a characteristic dimension corresponding to width, height, or both of the pixel; each attenuating element of the plurality of attenuating elements comprises a diameter that is equal to or greater than the characteristic dimension of the pixels in the pixel array; and the OSM device is disposed at a predefined distance above a surface of the pixel array such that the shadow pixel region cast on the subset of pixels within the pixel array comprises between three and five pixels along an axis orthogonal to a longitudinal axis of a respective attenuating element.

[0159] Example 6 is the X-ray imaging system of any previous or subsequent Example, wherein: the detector comprises a plurality of detector layers; and the plurality of attenuating elements of the OSM device are disposed in between one or more detector layers of the plurality of detector layers.

[0160] Example 7 is a method comprising: generating one or more projection signal profiles corresponding to an on-detector scatter measurement (OSM) device positioned between an X-ray source and a detector comprising a pixel array, wherein each projection signal profile represents a projection signal response of a subset of pixels within the pixel array within a cross-sectional segment of a shadow pixel region cast by the OSM device onto the pixel array when X-rays are emitted from the X-ray source; generating one or more object signal profiles corresponding to an object positioned between the X-ray source and the detector, wherein each object signal profile represents an object signal response of the subset of pixelsDocket No. 303.0140WOwithin the cross-sectional segment; generating a residual scatter estimate from the one or more projection signal profiles and the one or more object signal profiles; and generating a scatter-corrected image using the object signal profile and the residual scatter estimate.

[0161] Example 8 is the method of any previous or subsequent Example, wherein generating the one or more projection signal profiles corresponding to the OSM device positioned between the X-ray source and the detector comprises: emitting X-rays from the X-ray source towards the detector to cast a shadow onto the pixel array of the detector; identifying a plurality of shaded pixels that fall within a geometrically occluded region defined by the shadow of the OSM device on the pixel array, wherein the plurality of shaded pixels comprises the shadow pixel region; calculating the projection signal response for each shaded pixel within the plurality of shaded pixels forming the shadow pixel region, selecting a first subset of pixels within a first cross-sectional segment of the shadow pixel region; and aggregating the projection signal responses for the first subset of pixels within the cross-sectional segment to form a first projection signal profile, wherein the one or more projection signal profiles comprise the first projection signal profile.

[0162] Example 9 is the method of any previous or subsequent Example, wherein: the OSM device comprises an array of attenuating elements oriented along a longitudinal axis extending between a first side of the pixel array and an opposing second side of the pixel array; and the method further comprises: identifying a first subset of pixels that are positioned along an axis orthogonal to the longitudinal axis of the array of attenuating elements as within a first cross-sectional segment of the shadow pixel region; and generating the one or more projection signal profiles corresponding to the OSM device positioned between the X-ray source and the detector comprises: generating a first projection signal profile representing the projection signal response of the first subset of pixels within the first cross-sectional segment of the shadow pixel region, wherein the one or more projection signal profiles comprise the first projection signal profile.

[0163] Example 10 is the method of any previous or subsequent Example, wherein generating the residual scatter estimate from the one or more projection signal profiles and the one or more object signal profiles further comprises: generating a normalization map of the pixel array based on the one or more projection signal profiles; and generating the residual scatter estimate based on the normalization map.

[0164] Example 11 is the method of any previous or subsequent Example, wherein: generating the scatter-corrected image using the object signal profile and the residual scatter estimate further comprises: subtracting the projection signal responses of a plurality of shadedDocket No. 303.0140WOpixels within the shadow pixel region from the object signal responses of the respective plurality of shaded pixels.

[0165] Example 12 is the method of any previous or subsequent Example, wherein generating the scatter-corrected image using the object signal profile and the residual scatter estimate comprises: determining a first object signal profile of the one or more object signal profiles, wherein the first object signal profile represents the object signal responses of a first subset of pixels within a first cross-sectional segment of the shadow pixel region; computing a first scatter estimate based on the first object signal profile; correcting the object signal responses of the first subset of pixels corresponding to the first object signal profile; and generating the scatter-corrected image by modifying the object signal responses of the first subset of pixels based on the first scatter estimate.

[0166] Example 13 is the method of any previous or subsequent Example, wherein generating the residual scatter estimate from the one or more projection signal profiles and the one or more object signal profiles further comprises normalizing the projection signal responses of the subset of pixels based on the one or more projection signal profiles to generate normalized projection responses; computing an amplitude of hyperintense signals by multiplying the normalized projection responses to object signal responses of the subset of pixels; and calculating the residual scatter estimate for the subset of pixels using the amplitude of hyperintense signals.

[0167] Example 14 is the method of any previous or subsequent Example, wherein generating the residual scatter estimate from the one or more projection signal profiles and the one or more object signal profiles further comprises: calculating a primary scatter intensity based on the one or more projection signals and the one or more object signal profiles, wherein the primary scatter intensity represents an estimated residual scatter for a plurality of shaded pixels encompassed in the shadow pixel region; calculating a secondary scatter intensity based on a plurality of unshaded pixels falling outside of the shadow pixel region; and generating the residual scatter estimate based on the primary scatter intensity and the secondary scatter intensity.

[0168] Example 15 is an X-ray detector system comprising: a detector comprising a pixel array configured to receive and convert incident X-ray radiation into electrical signals; and an on-detector scatter measurement (OSM) device positioned physically proximate to the detector, wherein the OSM device comprises: a plurality of attenuating elements composed of a material configured to reduce X-ray fluence by approximately 15% to 50%, wherein the plurality of attenuating elements are: oriented as an array along a longitudinal axis extendingDocket No. 303.0140WObetween a first side of the detector and an opposing second side of the detector irrespective of pixel orientation of the pixel array underlying the plurality of attenuating elements; and positioned at a predefined distance above the pixel array to create a shadow pixel region on a subset of pixels of the pixel array when exposed to an X-ray source.

[0169] Example 16 is the X-ray detector system of any previous or subsequent Example, wherein the X-ray detector system further comprises an anti-scatter grid, wherein the OSM device is positioned between the anti-scatter grid and the detector, or above the antiscatter grid.

[0170] Example 17 is the X-ray detector system of any previous or subsequent Example, wherein: each pixel of the pixel array comprises a characteristic dimension corresponding to width, height, or both of the pixel; each attenuating element of the plurality of attenuating elements comprises a diameter that is equal to or greater than the characteristic dimension of the pixels in the pixel array; and the OSM device is disposed at a predefined distance above a surface of the pixel array such that the shadow pixel region cast on the subset of pixels within the pixel array comprises at least two pixels along an axis orthogonal to the longitudinal axis of a respective attenuating element.

[0171] Example 18 is the X-ray detector system of any previous or subsequent Example, wherein: the detector comprises a detector plane comprising the pixel array; and at least one of a pitch or diameter of the plurality of attenuating elements varies across the detector plane.

[0172] Example 19 is the X-ray detector system of any previous or subsequent Example, wherein the material forming the plurality of attenuating elements is selected from the group consisting of: tungsten; lead bismuth tantalum molybdenum, copper; a polymer; a metal-infused polymer; glass fiber-reinforced material; a ceramic material; or a high-density metal alloy, each selected for its X-ray attenuation properties.

[0173] Example 20 is the X-ray detector system of any previous or subsequent Example, wherein: the detector comprises a plurality of detector layers; and the plurality of attenuating elements of the OSM device are disposed in between one or more detector layers of the plurality of detector layers.

Claims

1. Docket No. 303.0140WOCLAIMSWhat is claimed is:

1. An X-ray imaging system comprising:at least one X-ray source configured to emit X-rays;a detector comprising a pixel array configured to detect X-rays emitted from the at least one X-ray source;an on-detector scatter measurement (OSM) device comprising a plurality of attenuating elements, wherein the OSM device is positioned physically proximate to the detector such to generate a shadow pixel region on a subset of pixels within the pixel array of the detector when the X-rays are emitted from the at least one X-ray source; andan image processor in operable communication with the detector to generate a scatter-corrected image of an object positioned between the at least one X-ray source and the detector, wherein the scatter-corrected image is generated based on the shadow pixel region generated by the OSM device.

2. The X-ray imaging system of claim 1 , wherein to generate the scatter-corrected image based on the shadow pixel region generated by the OSM device, the image processor comprises a scatter correction engine, wherein the scatter correction engine is configured to:generate a residual scatter estimate based on the shadow pixel region; and generate the scatter-corrected image based on the residual scatter estimate.

3. The X-ray imaging system of claim 1, wherein the plurality of attenuating elements of the OSM device comprises a plurality of elongated members disposed at a predefined distance above a surface of the pixel array, wherein:each elongated member is oriented parallel to and spaced equidistantly from adjacent elongated members; andthe plurality of elongated members are arranged in a regular linear array with a fixed pitch and a common angular orientation that is parallel to the surface of the pixel array.Docket No. 303.0140WO4. The X-ray imaging system of claim 1, wherein the plurality of attenuating elements of the OSM device comprises a plurality of spherical members disposed at a predefined distance above a surface of the pixel array, wherein:the plurality of spherical members are spaced equidistantly from adjacent spherical members along two orthogonal axes; andthe plurality of spherical members are arranged in a two-dimensional regular array with a uniform pitch along each of the two orthogonal axes such that the centers of the spherical members define a plane parallel to the surface of the pixel array.

5. The X-ray imaging system of claim 4, wherein:each pixel of the pixel array comprises a characteristic dimension corresponding to width, height, or both of the pixel;each attenuating element of the plurality of attenuating elements comprises a diameter that is equal to or greater than the characteristic dimension of the pixels in the pixel array; and the OSM device is disposed at a predefined distance above a surface of the pixel array such that the shadow pixel region cast on the subset of pixels within the pixel array comprises between three and five pixels along an axis orthogonal to a longitudinal axis of a respective attenuating element.

6. The X-ray imaging system of claim 1, wherein:the detector comprises a plurality of detector layers; andthe plurality of attenuating elements of the OSM device are disposed in between one or more detector layers of the plurality of detector layers.Docket No. 303.0140WO7. A method comprising:generating one or more projection signal profiles corresponding to an on-detector scatter measurement (OSM) device positioned between an X-ray source and a detector comprising a pixel array, wherein each projection signal profile represents a projection signal response of a subset of pixels within the pixel array within a cross-sectional segment of a shadow pixel region cast by the OSM device onto the pixel array when X-rays are emitted from the X-ray source:generating one or more object signal profiles corresponding to an object positioned between the X-ray source and the detector, wherein each object signal profile represents an object signal response of the subset of pixels within the cross-sectional segment;generating a residual scatter estimate from the one or more projection signal profiles and the one or more object signal profiles; andgenerating a scatter-corrected image using the object signal profile and the residual scatter estimate.

8. fhe method of claim 7, wherein generating the one or more projection signal profiles corresponding to the OSM device positioned between the X-ray source and the detector comprises:emitting X-rays from the X-ray source towards the detector to cast a shadow onto the pixel array of the detector;identifying a plurality of shaded pixels that fall within a geometrically occluded region defined by the shadow of the OSM device on the pixel array, wherein the plurality of shaded pixels comprises the shadow pixel region;calculating the projection signal response for each shaded pixel within the plurality of shaded pixels forming the shadow pixel region,selecting a first subset of pixels within a first cross-sectional segment of the shadow pixel region; andaggregating the projection signal responses for the first subset of pixels within the cross-sectional segment to form a first projection signal profile, wherein the one or more projection signal profiles comprise the first projection signal profile.Docket No. 303.0140WO9. The method of claim 7, wherein:the OSM device comprises an array of attenuating elements oriented along a longitudinal axis extending between a first side of the pixel array and an opposing second side of the pixel array; and the method further comprises:identifying a first subset of pixels that are positioned along an axis orthogonal to the longitudinal axis of the array of attenuating elements as within a first cross- sectional segment of the shadow pixel region; andgenerating the one or more projection signal profiles corresponding to the OSM device positioned between the X-ray source and the detector comprises:generating a first projection signal profile representing the projection signal response of the first subset of pixels within the first cross-sectional segment of the shadow pixel region, wherein the one or more projection signal profiles comprise the first projection signal profile.

10. The method of claim 7, wherein generating the residual scatter estimate from the one or more projection signal profiles and the one or more object signal profiles further comprises:generating a normalization map of the pixel array based on the one or more projection signal profiles; andgenerating the residual scatter estimate based on the normalization map.

11. The method of claim 7, wherein: generating the scater-corrected image using the object signal profile and the residual scatter estimate further comprises:subtracting the projection signal responses of a plurality of shaded pixels within the shadow pixel region from the object signal responses of the respective plurality of shaded pixels.Docket No. 303.0140WO12. The method of claim 7, wherein generating the scatter-corrected image using the object signal profile and the residual scatter estimate comprises:determining a first object signal profile of the one or more object signal profiles, wherein the first object signal profile represents the object signal responses of a first subset of pixels within a first cross-sectional segment of the shadow pixel region;computing a first scatter estimate based on the first object signal profile; correcting the object signal responses of the first subset of pixels corresponding to the first object signal profile; andgenerating the scatter-corrected image by modifying the object signal responses of the first subset of pixels based on the first scatter estimate.

13. The method of claim 7, wherein generating the residual scatter estimate from the one or more projection signal profiles and the one or more object signal profiles further comprisesnormalizing the projection signal responses of the subset of pixels based on the one or more projection signal profiles to generate normalized projection responses;computing an amplitude of hyperintense signals by multiplying the normalized projection responses to object signal responses of the subset of pixels; andcalculating the residual scatter estimate for the subset of pixels using the amplitude of hyperintense signals.

14. The method of claim 7, wherein generating the residual scatter estimate from the one or more projection signal profiles and the one or more object signal profiles further comprises:calculating a primary scatter intensity based on the one or more projection signals and the one or more object signal profiles, wherein the primary scatter intensity represents an estimated residual scatter for a plurality of shaded pixels encompassed in the shadow pixel region;calculating a secondary scatter intensity based on a plurality of unshaded pixels falling outside of the shadow pixel region; andgenerating the residual scatter estimate based on the primary scatter intensity and the secondary scatter intensity.Docket No. 303.0140WO15. An X-ray detector system comprising:a detector comprising a pixel array configured to receive and convert incident X-ray radiation into electrical signals; andan on-detector scatter measurement (OSM) device positioned physically proximate to the detector, wherein the OSM device comprises:a plurality of attenuating elements composed of a material configured to reduce X-ray fluence by approximately 15% to 50%, wherein the plurality of attenuating elements are:oriented as an array along a longitudinal axis extending between a first side of the detector and an opposing second side of the detector irrespective of pixel orientation of the pixel array underlying the plurality of attenuating elements; andpositioned at a predefined distance above the pixel array to create a shadow pixel region on a subset of pixels of the pixel array when exposed to an X-ray source.

16. The X-ray detector system of claim 15, wherein the X-ray detector system further comprises an anti-scatter grid, wherein the OSM device is positioned either between:the anti-scatter grid and the detector; orthe anti-scatter grid and the X-ray source.

17. The X-ray detector system of claim 15, wherein:each pixel of the pixel array comprises a characteristic dimension corresponding to width, height, or both of the pixel;each attenuating element of the plurality of attenuating elements comprises a diameter that is equal to or less than the characteristic dimension of the pixels in the pixel array; and the OSM device is disposed at a predefined distance above a surface of the pixel array such that the shadow pixel region cast on the subset of pixels within the pixel array comprises at least two pixels along an axis orthogonal to the longitudinal axis of a respective attenuating element.Docket No. 303.0140WO18. The X-ray detector system of claim 17, wherein:the detector comprises a detector plane comprising the pixel array; andat least one of a pitch or diameter of the plurality of attenuating elements varies across the detector plane.

19. The X-ray detector system of claim 15, wherein the material forming the plurality of attenuating elements is selected from the group consisting of:tungsten;lead;copper;molybdenum;bismuth;tantalum;a polymer;a metal-infused polymer;glass fiber-reinforced material;a ceramic material; ora high-density metal alloy, each selected for its X-ray attenuation properties.

20. The X-ray detector system of claim 15, wherein:the detector comprises a plurality of detector layers; andthe plurality of attenuating elements of the OSM device are disposed in between one or more detector layers of the plurality of detector layers.

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