Method and apparatus for reconstructing image acquisition for extended field of view

Abstract

A method of reconstructing an extended FOV image of an imaging volume of a gantry of an X-ray imaging system, the method comprising: generating first projected and interpolated fill data of a first image of a central region of the imaging volume based on the first image of an annular region of the imaging volume surrounding the central region; generating a first extended image of the central region based on the first projected and interpolated padding data; generating a second projection of the first image of the annular region and interpolated padding data based on the first image of the central region; generating a first expanded image of the annular region based on the second projected and interpolated padding data; and performing back projection based on the first expanded images of the central region and the annular region to reconstruct the expanded field-of-view image.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 458,532, filed April 11, 2023, and U.S. Provisional Patent Application No. 18 / 608,624, filed March 18, 2024, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to image reconstruction for a region of interest within an imaging system, and more specifically to image reconstruction for an extended field of view (FOV) of a volume within an imaging system. Background Technology

[0004] This section provides background information in connection with this disclosure, which is not necessarily prior art.

[0005] Subjects (such as human patients) may undergo surgical procedures to correct or enhance their anatomy. Enhancement of anatomy may include various procedures such as bone movement or enhancement, insertion of implants (i.e., implantable devices), or other appropriate procedures. Surgeons may perform procedures on subjects based on and / or with the aid of images of the patient acquired by an imaging system. Some example imaging systems are magnetic resonance imaging (MRI) systems, computed tomography (CT) systems, and fluoroscopy systems (e.g., C-Arm). ® Or O-Arm ® Imaging system).

[0006] Patient images can help surgeons plan and execute procedures. For example, by allowing surgeons to view a patient's anatomy during a procedure without removing overlapping tissues (including skin and muscle), images can help surgeons perform procedures using less invasive techniques. Summary of the Invention

[0007] This section provides a general overview of this disclosure and is not a full disclosure of the complete scope or all features of this disclosure.

[0008] A method for reconstructing an extended field-of-view image of the imaging volume of an X-ray imaging system gantry is disclosed. The method includes: performing a first spin of the gantry to capture a first set of images of a central region of the imaging volume; and performing a second spin of the gantry to capture a second set of images of an annular region of the imaging volume surrounding the central region. The method further includes: generating first projection and interpolation padding data of the first image of the central region based on the first image of the annular region, wherein the first set of images includes the first image of the central region, and wherein the second set of images includes the first image of the annular region; generating a first extended image of the central region based on the first projection and interpolation padding data; generating second projection and interpolation padding data of the first image of the annular region based on the first image of the central region; generating a first extended image of the annular region based on the second projection and interpolation padding data; and performing backprojection based on the first extended image of the central region and the first extended image of the annular region to reconstruct the extended field-of-view image of the imaging volume.

[0009] In another aspect of this disclosure, an imaging system is disclosed, comprising a gantry and a processor. The gantry includes an aperture having an imaging volume in which a subject is placed. The gantry includes an X-ray source and a detector array arranged to rotate isocentrically about the gantry. The processor is configured to: first spin the gantry to capture a first set of images of a central region of the imaging volume via the detector array; and second spin the gantry to capture a second set of images of a ring-shaped region of the imaging volume surrounding the central region via the detector array. The processor is further configured to: generate first projection and interpolation padding data of a first image of a central region based on a first image of the annular region, the first set of images including the first image of the central region, and the second set of images including the first image of the annular region; generate a first extended image of the central region based on the first projection and interpolation padding data; generate second projection and interpolation padding data of the first image of the annular region based on the first image of the central region; generate a first extended image of the annular region based on the second projection and interpolation padding data; and perform backprojection based on the first extended image of the central region and the first extended image of the annular region to reconstruct an extended field of view image of the imaging volume.

[0010] Further areas of applicability will become apparent from the description provided herein. The descriptions and specific examples in this overview are intended for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0011] The accompanying drawings described herein are for illustrative purposes only, representing the selected embodiments and not all possible specific implementations, and are not intended to limit the scope of this disclosure.

[0012] Figure 1 This is an environmental view of an operating room that includes an imaging system with a pre-reflection processing module according to this disclosure.

[0013] Figure 2 This illustrates the provisions of this disclosure. Figure 1 A functional block diagram of a part of the imaging system.

[0014] Figure 3 Based on this disclosure Figure 1 A cross-sectional side view of a portion of the imaging system, illustrating the source and detector orientation and positioning for central region scanning and circular scanning.

[0015] Figure 4 Based on this disclosure Figure 1 A cross-sectional view of a portion of the imaging system, illustrating the extended detector imaging plane used to capture images of the central and annular regions.

[0016] Figure 5 It is an image of the central region where the source and detector are in the first orientation and position.

[0017] Figure 6 It is an image of the annular region where the source and detector are in the second orientation and position.

[0018] Figure 7 This is an image illustrating the difference in fill between an expanded central region image and a circular image.

[0019] Figure 8 It is based on the implementation of the reverse reconstruction method Figure 7 The reconstructed image is generated from the extended central region image and the ring image.

[0020] Figure 9A and Figure 9B (Collectively referred to as FIG9) illustrates an extended FOV image reconstruction method according to the present disclosure, including pre-reverse projection processing.

[0021] Figure 10 These are image diagrams illustrating an extended central region image and an extended annular region image, including interpolated fill portions and additional fill portions, according to the present disclosure.

[0022] Figure 11 The method for implementing back projection reconstruction based on this disclosure is... Figure 10 The reconstructed image is generated from the extended central region image and the annular region image.

[0023] In several views of all the accompanying drawings, the corresponding reference numerals indicate the corresponding components. Detailed Implementation

[0024] The example implementation will now be described in more complete form with reference to the accompanying drawings.

[0025] The field of view (FOV) of an internal volume within the imaging system can be imaged. This image may include an image of a subject located within the imaging volume. The subject can be a living subject, such as a human patient. Image data of the central and annular regions of the FOV can be acquired, and these image data can be combined to provide an image of the imaging volume that is larger than the image acquired by a single scan by the imaging system. However, it should be understood that image data of inanimate subjects can also be acquired, including the outer shell, casing, interior of the superstructure, etc. For example, image data of the fuselage can be acquired for various purposes, such as diagnosing problems and / or planning repair work.

[0026] An imaging system configured to orient (or tilt) the X-ray source and detector array and to reposition the detector array relative to the X-ray source can be configured with different imaging geometries. The imaging system can be configured to increase the field of view (FOV) for three-dimensional (3D) cone-beam computed tomography (CBCT) imaging. This FOV can be increased beyond the FOV provided when performing a single 360° scan, which includes a single spin of the gantry comprising a 360° rotation of the X-ray source and detector array around the isocenter of the imaging system.

[0027] To generate an increased field of view (FOV), two scans are performed: a first scan centered isocentric and capturing a central cylindrical (or central) region of the imaging volume; and a second scan not centered isocentric and capturing a ring-shaped region surrounding the central region. The first scan includes: initially rotating the gantry and capturing an image of the central region as the X-ray source and detector array rotate around it. The second scan includes: initially rotating the X-ray source and detector array around the source focus (the point or region generating a high percentage of X-rays), and then rotating the gantry a second time and capturing an image of the ring-shaped region. The stated rotation around the focus includes: tilting the X-ray source and detector array and repositioning the detector array to capture the ring-shaped region. The X-ray source and detector array rotate around the ring-shaped region while capturing an image of it. An example of this process is shown in [link to example]. Figures 3 to 4 Examples are shown below and further described in detail.

[0028] Combining image data collected from a scan of the central region with image data collected from a scan of the annular region using backprojection reconstruction methods can lead to artifacts. Example artifacts are shown in... Figure 8 As shown in the diagram, the reconstruction of the collected data can produce artifacts corresponding to the captured overlapping region (referred to as the "overlapping loop") of the two spins. This is the region captured twice during the two-state spin. Artifacts can occur even after smoothing correction for the dual X-ray sampling of the overlapping region. Other artifacts may occur and are attributed to discrepancies in image data processing, such as the difference between the ramp filter outputs of the image data collected for the two spin geometries (the circular geometry of the central region and the ring geometry of the ring region). Some of these discrepancies are a result of a lack of consistency in the image data during image filling before the ramp filter is applied. Inconsistencies occur particularly between the "corresponding" views of the two spins.

[0029] The view of the two spins is provided when the X-ray source is positioned with respect to both spins relative to the isocenter. For the first spin, the X-ray source can be oriented such that the centerline of the X-ray beam generated by the X-ray source passes through the isocenter of the imaging volume. In another embodiment, the centerline of the X-ray beam does not pass through the isocenter and is offset from it, but the X-ray beam does cover the isocenter (i.e., the isocenter is in the image provided by the X-ray beam).

[0030] For the second spin, the X-ray source is tilted such that the centerline of the X-ray source beam is offset from the isocenter. For the second spin, the X-ray beam may not cover the isocenter. For the first spin, the detector array is in a first position relative to the isocenter and the X-ray source, and for the second spin, the detector array is in a second position relative to the isocenter and the X-ray source. The first and second positions of the detector array refer to different radial distances from the isocenter and to the repositioning of the detector array to receive the X-ray beam from the tilted X-ray source. Examples of these orientations and positions are given in... Figure 4 As shown in the image.

[0031] Examples described herein include a system and method for extended FOV imaging of an imaging volume (e.g., at least a portion of the aperture of a gantry on which the subject to be imaged is located). Extended FOV imaging includes capturing: i) a first set of images of a central region of the imaging volume, the first set of images being isocentered around the imaging volume; and ii) a second set of images of a ring-shaped region of the imaging volume, the second set of images not being isocentered around the isocenter. Projected and interpolated padding data is generated against the first set of images based on the second set of images to provide a first extended image. Padding data refers to data appended to an image to extend the image. Padding data may include, for example, column edge data of the image and / or other padding data disclosed herein, the column edge data being repeating, projected and interpolated data. Projected and interpolated padding data is also generated against the second set of images based on the first set of images to provide a second extended image. The generation of the projected and interpolated padding data includes performing a cone-beam projection transformation onto a padding plane (or extended detector plane) of the corresponding image, as further described below. An extended reconstructed image of the imaging volume is then generated based on the first and second extended images.

[0032] Figure 1 A schematic diagram of operating room 20 is shown. A user 24 (such as a surgeon) can perform procedures on a subject (such as patient 28). The subject can be placed on a support (such as a selected portion of the operating table 32 for the procedure). The operating table 32 does not interfere with image data acquisition using imaging system 36. During procedure execution, user 24 can use imaging system 36 to acquire image data of patient 28, allowing the selected system to generate or create images to aid in the procedure execution. Images generated using image data can be two-dimensional (2D) images, three-dimensional (3D) images, or images of appropriate types, such as models (such as three-dimensional (3D) images), long views, single-projection views, etc., and can be generated using image data and displayed as image 40 on display device 44. Display device 44 can be part of and / or connected to processing system 48, which includes user interface 52, such as a keyboard, mouse, stylus, touchscreen as part of display device 44, or a combination thereof. Processor 56 may include one or more processors, processor modules, and / or microprocessors combined with processing system 48 in conjunction with a selected type of non-transitory and / or transient memory 58. A connection 62 may be provided between processor 56 and display device 44 for data communication to allow driving display device 44 to display or illustrate image 40. Processor 56 may be any suitable type of processor that executes instructions included in a program. Processor 56 may be a dedicated processor, such as an application-specific integrated circuit (ASIC).

[0033] Imaging system 36 may include, but is not limited to, the O-Arm system sold by Medtronic Navigation, Inc. ® Imaging system. Imaging system 36 (including O-Arm) ® An imaging system (or other suitable imaging system) may be used during the selected procedure. O-Arm ® Examples of imaging systems are described in U.S. Patent Application Publications 2012 / 0250822, 2012 / 0099772 and 2010 / 0290690, all of which are incorporated herein by reference.

[0034] When, for example, O-Arm is included ® When used in an imaging system, imaging system 36 may include a mobile cart 60, which includes a controller and / or control system 64. Control system 64 may include a processor and / or processor 68 (similar to processor 56), a user interface 67 (such as a keyboard, mouse, or touchscreen), memory 58 (e.g., non-transitory memory), and a display device 69. Memory system 66 may include various instructions executed by processor 68, which acts as a controller to control imaging system 36, including its various components.

[0035] Processor 56 and / or processor 68 may include and / or perform a pre-reverse projection processing module. An example of a pre-reverse projection processing module is provided in... Figure 2 The corresponding part of the method shown in Figure 9 is configured to perform the pre-reverse projection processing module. The pre-reverse projection processing module can perform, for example... Figure 9B Operations 908, 910, 912, and 914.

[0036] Imaging system 36 may include additional components such as gantry 70, an X-ray source (also referred to as a “source assembly” or simply a “source”) 74, and a detector array (also referred to as a “detector assembly” or simply a “detector”) 78 positioned within the gantry. In various embodiments, detector 78 may be referred to individually and / or together with the source unit as the imaging head of imaging system 36. Gantry 70 is movably connected to trolley 60. Gantry 70 may be O-shaped or annular, wherein gantry 70 is substantially annular and includes walls forming volumes in which source 74 and detector 78 can move. Trolley 60 may also be movable. In various embodiments, gantry 70 and / or trolley 60 may be moved during image data acquisition, including moving both simultaneously. Moreover, imaging system 36 may be moved from one operating room to another (e.g., another room) via trolley 60. Gantry 70 may be movable relative to trolley 60, as further discussed herein. This allows the imaging system 36 to be mobile and movable relative to the subject 28, thus allowing it to be used in multiple locations and with multiple protocols, without requiring capital expenditure or space dedicated to a fixed imaging system.

[0037] Processor 68 may be a dedicated application processor. Memory system 66 may be a non-transitory memory, such as a spin disk or solid-state non-volatile memory. In various embodiments, the memory system may include instructions to be executed by processor 68 to perform functions and determine results, as discussed herein. Memory system 66 may be used to store images from imaging system 36 to allow computations to be performed on those images. Memory system 66 may be used to store intermediate and final computation results, such as data for identifying body structures, the distance the imaging system is to travel, and the target location of imaging system 36.

[0038] In various embodiments, the imaging system 36 may include an imaging system that acquires images and / or image data by emitting X-rays and detecting the X-rays after they interact with and / or are attenuated by the subject 28. X-ray imaging can be one imaging modality. It should be understood that other imaging modalities are also possible, such as other high-energy beams.

[0039] Therefore, in imaging system 36, source 74 can be an X-ray emitter that emits X-rays at and / or through the patient 28 for detection by detector 78. As will be understood by those skilled in the art, the X-rays emitted by source 74 can be emitted in a cone shape along a selected principal vector and detected by detector 78. Source 74 and detector 78 may also be referred to together as a source and detector assembly, particularly where source 74 and detector 78 are substantially diametrically opposed (e.g., separated by 180 degrees (°)) within gantry 70.

[0040] Imaging system 36 can move entirely or partially relative to subject 28. For example, source 74 and detector 78 can move around patient 28, such as through 360° motion, spiral motion, partial circular motion, etc. Movement of the source and detector assemblies within gantry 70 during spin of gantry 70 allows source 74 to remain in a fixed position relative to detector 78. Therefore, detector 78 may be described as moving around subject 28 (e.g., in a circle or spiral), and it should be understood that, unless otherwise disclosed, source 74 remains relative to subject. Source 74 and detector 78 can tilt and move relative to each other, as further described below.

[0041] Furthermore, the platform 70 can move (also referred to as "swinging") approximately equidistantly about axis 102 in the direction of arrow 100 relative to the subject 28, such as by moving the trolley 60, as... Figure 1 As illustrated, the table 70 may also be tilted relative to the longitudinal axis 106 of the patient 28, as illustrated by arrow 110. When tilted, the plane of the table 70 may be tilted or form a non-orthogonal angle with the axis 106 of the subject 28.

[0042] The platform 70 can also move longitudinally relative to the subject 28 and / or the trolley 60 along axis 106 in the direction of arrow 114. Furthermore, the trolley 60 can move to move the platform 70. Additionally, the platform 70 can move generally vertically relative to the trolley 60 and / or the subject 28 in the Y-axis direction of arrow 118, generally transverse to axis 106 and parallel to axis 102. The platform can also be moved in the X-direction in the direction of arrow 116 by moving the wheels 117.

[0043] Movement of the imaging system 36, either wholly or partially, allows for the positioning of the source and detector components relative to the subject 28. The imaging system 36 can be precisely controlled to move the source and detector components relative to the subject 28 to generate accurate image data of the subject 28. The imaging system 36 can be connected to the processor 56 via connection 120, which may include a wired or wireless connection or physical medium transmission from the imaging system 36 to the processor 56. Therefore, image data collected using the imaging system 36 can be transmitted to the processor 56 for navigation, display, reconstruction, etc.

[0044] As discussed herein, source 74 may include one or more X-ray sources for imaging subject 28. In various embodiments, source 74 may include a single source that may be powered by more than one power source to generate and / or emit X-rays with different energy characteristics. Furthermore, more than one X-ray source may be source 74 that can be powered to emit X-rays with different energy characteristics at selected times.

[0045] Imaging system 36 can be used with non-navigation protocols or navigation protocols. In a navigation protocol, a locator and / or digitizer, including any one or both of optical locator 130 and / or electromagnetic locator 138, can be used to generate fields and / or receive and / or transmit signals within a navigation domain relative to subject 28. The navigation space or navigation domain relative to subject 28 can be registered with image 40. As understood in the art, correlation is necessary to allow registration of the navigation space defined within the navigation domain with the image space defined by image 40. Patient tracker or dynamic reference frame (or registration device) 140 can be connected to subject 28 to allow dynamic registration of subject 28 to image 40 and maintenance of the registration.

[0046] The patient tracking device or dynamic registration device 140 and device 144 can then be tracked relative to subject 28 to allow navigation procedures. Device 144 may include tracking devices, such as optical tracking device 148 and / or electromagnetic tracking device 152, to allow tracking of device 144 using either or both of optical locator 130 or electromagnetic locator 138. Navigation / detection interface 158 can communicate with device 144 (e.g., via communication line 156), with electromagnetic locator 138 (e.g., via communication line 162), and / or optical locator 130 (e.g., via communication line 166) (e.g., wired or wireless communication). Navigation / detection interface 158 can also communicate with processor 56 via communication line 168 and can convey information (e.g., signals) about various items connected to navigation / detection interface 158. It should be understood that any communication line can be wired, wireless, physical medium transmission or mobility, or any other suitable communication. However, a suitable communication system can be equipped with a corresponding locator to allow tracking of the device 144 relative to the subject 28, thereby allowing the tracking position of the graphic device 144 relative to the image 40 to execute procedures.

[0047] Device 144 may be a ventricular or vascular stent, a spinal implant, a neural stent or stimulator, an ablation device, etc. Device 144 may be an interventional device, or may include or may include an implantable device. Tracking device 144 allows the use of registration image 40 to view the position (including x, y, z localization and orientation) of device 144 relative to subject 28 without having to directly view device 144 within subject 28.

[0048] Furthermore, the imaging system 36 (such as gantry 70) may include an optical tracking device 174 and / or an electromagnetic tracking device 178 for tracking with corresponding optical locators 130 and / or electromagnetic locators 138. Thus, like the trackable device 144, the imaging system 36 may also be tracked relative to the subject 28 to allow for initial registration, automatic registration, or continuous registration of the subject 28 relative to the image 40. Registration and navigation procedures are discussed in U.S. Patent No. 8,238,631, which is incorporated herein by reference. After registration and tracking device 144, an icon 180 may be displayed relative to the image 40, including overlaying on the image. The image 40 may be a suitable image and may include a 2D image, a 3D image, or any suitable image as discussed herein.

[0049] Source 74 may include a single component, which may include a single X-ray tube. As discussed above, X-rays may be emitted from the X-ray tube generally in a cone shape toward detector 78, and generally in the direction from the X-ray tube. The X-ray beam may be emitted as a cone or other suitable geometry.

[0050] Subject 28 may be positioned within an X-ray cone to allow image data of subject 28 to be acquired based on the emission of X-rays toward detector 78 in a vector direction. An X-ray tube may be used to generate a 2D X-ray projection of subject 28 (including a selected portion of subject 28 or any region, area, or volume of interest) based on X-ray irradiation on or detection on a two-dimensional (2D) or flat panel detector (such as detector 78). The 2D X-ray projection may be reconstructed as discussed herein to produce and / or display a three-dimensional (3D) volumetric model of subject 28, a selected portion of subject 28, or any region, area, or volume of interest. As discussed herein, the 2D X-ray projection may be image data acquired using imaging system 36, while a 3D volumetric model may be generated or modeled from the image data.

[0051] For reconstructing or forming 3D volumetric images, appropriate techniques include filtered backprojection, expectation-maximization (EM), ordered subset EM (OS-EM), simultaneous algebraic reconstruction technique (SART), and total variation minimization (TVM), as generally understood by those skilled in the art. Various reconstruction techniques may also, and alternatively, include machine learning systems and algebraic techniques. Applications performing 3D volumetric reconstruction based on 2D projections allow for efficient and complete volumetric reconstruction. Generally, algebraic techniques may involve an iterative process to perform reconstruction of subject 28 for display as image 40. For example, projections of pure or theoretical image data, such as those based on or generated from atlases or stylized models of "theoretical" patients, may be iteratively modified until the theoretically projected image matches the acquired 2D projected image data of subject 28. The stylized model can then be appropriately modified into a 3D volumetric reconstruction model of the acquired 2D projected image data of the selected subject 28 and can be used for surgical treatments such as navigation, diagnosis, or planning. The theoretical model can be associated with the theoretical image data to construct a theoretical model. In this way, a model or image 40 can be constructed based on image data of the subject 28 acquired using the imaging system 36.

[0052] Source 74 may include various elements or features movable relative to the X-ray tube. In various embodiments, for example, a collimator may be positioned relative to the X-ray tube to help form a cone relative to subject 28. The collimator may include various features, such as movable members that help position one or more filters within the X-ray cone before the X-rays reach subject 28. One or more movement systems may be provided to move all and / or individual portions of the collimator. Furthermore, as further discussed herein, various filters may be used to shape the X-ray beam (e.g., to form a cone) into a selected shape before the X-ray beam reaches subject 28. In various embodiments, as discussed herein, the X-rays may be shaped as a thin fan or plane to reach and pass through subject 28 and be detected by detector 78.

[0053] Figure 2 Examples are shown Figure 1 The imaging system 36 is part 200. Although part 200 includes processor 68, Figure 1 Processor 56 may be configured similarly. Processor 68 may include bench control module 202, source module 204, detector module 206, image capture module 208, pre-backprojection processing module 210, and backprojection module 212. Each of processors 68 and 56 may be implemented as one or more processors. In one embodiment, modules 202, 204, 206, 208, 210, and 212 have corresponding code executed by processor 68 and / or 56.

[0054] The backprojection module 212 may include a ramp filter 220 and a cropping module 222 for performing the ramp filtering and cropping operations disclosed herein. The ramp filter may be implemented as a convolution in the spatial domain or a multiplication in the Fourier domain. The ramp filter is an image filter designed to reduce blur caused by simple backprojection. The ramp filter may include multiple filters, such as Ram-Lak filters, noise suppression filters, and / or sharpening filters. This may include implementations of the Sinc, Cosine, and / or Hamming functions. The ramp filter may be a high-pass filter that disallows low frequencies that cause blurring in the image. The ramp filter may be a compensation filter that eliminates star-shaped artifacts caused by simple backprojection.

[0055] The processor 68 may be connected to and / or control the bench motor 230, a source actuator and motor assembly 231 including one or more source motors 232, and / or a detector actuator and motor assembly 233 including one or more detector motors 234. The bench motor 230 may be configured to rotate the rings of the bench. Figure 1 Source 74 and detector 78 are mounted on the ring. Components 231 and 233 may include actuators, motors, brackets, linkages, pivots, rollers, bearings, etc., for orienting and positioning source 74 and detector 78. One or more source motors 232 may be used to tilt and / or move source 74 relative to the isocenter of the imaging volume, relative to detector 78, and / or relative to another component and / or reference point of imaging system 36. One or more detector motors 234 may be used to tilt and / or move detector 78 relative to the isocenter, relative to source 74, and / or relative to another component and / or reference point of imaging system 36. The stated control may be implemented by modules 202, 204, and 206.

[0056] Image capture module 208 can control: i) using Figure 1 The image is captured by source 74 and detector 78; and the image data is stored. The pre-projection processing module 210 can perform the projection and interpolation operations described herein, such as... Figure 9B Operations 908, 910, 912, and 914. Backprojection module 212 performs backprojection to provide the extended and reconstructed FOV image disclosed herein. Ramp filter 220 performs ramp filtering operations, such as... Figure 9B Operation 918. The cropping module 222 crops the image, as per the description... Figure 9B The operation described in 920.

[0057] The following Figures 3 to 4The illustration illustrates two spins, as described above, for capturing a first set of images of the central region and a second set of images of the annular region, along with the associated geometry for each spin. The first spin is associated with the source 74 and detector 78 being oriented and positioned accordingly to capture the central region (i.e., a circular region centered on the isocenter and located within the imaging volume). The second spin is associated with the source 74 and detector 78 being oriented and positioned accordingly to capture the annular region (i.e., an annular region surrounding the central region centered on the isocenter and located within the imaging volume).

[0058] Figure 3 It shows Figure 1 This is a portion 300 of an imaging system 36. The imaging system 36 includes a gantry 70 having a housing 302 and a ring or rotor, represented as a circumference 304. A source 74 and a detector 78 are mounted on and / or connected to the ring. The source 74 is tiltable relative to the ring, the isocenter 306, and the detector 78. The source 74 has a housing 308. The detector 78 is tiltable relative to the ring, the isocenter 306, and the source 74. The detector 78 is also movable relative to the ring, the isocenter 306, and the source 74. This allows the source 74 and the detector 78 to be oriented and positioned to capture a first set of images of a central region 310 and a second set of images of an annular region 312. The central region 310 is located at the center of an imaging volume 313 of the gantry 70. The imaging volume 313 may correspond to at least a portion of the aperture (or opening) of the gantry 70 and refers to the field of view (FOV) of interest. A cross-section of an example object 314 is shown. Although the cross-section is shown centered on isocenter 306, the subject 314 may not be centered within the imaging volume 313, and therefore the cross-section may not be centered on isocenter 306.

[0059] Source 74 and detector 78 are shown in two arrangements. A first arrangement shows source 74 in a non-tilted state, generating a first X-ray beam 320 having a centerline 322 aligned with and extending through the isocenter 306. A second arrangement shows source 74' and detector 78', with housing 308', in a tilted and offset state, generating a second X-ray beam 324 having a centerline 326 offset from the isocenter 306 and not extending through it. During the first scan, source 74 and detector 78 are maintained relative to each other in the shown orientation and position, and rotate 360° around imaging volume 313. During rotation, source 74 and detector 78 follow circumference 304 while maintaining centerline 322 through isocenter 306. During the second scan, source 74' and detector 78' are maintained relative to each other in the shown orientation and position, and rotate around imaging volume 313 while following circumference 304, while maintaining centerline 326 in an offset state.

[0060] Figure 4 It shows Figure 1 A portion 400 of the imaging system 36 illustrates an extended detector imaging plane for capturing images of the central and annular regions. Figure 4 In the image, the gantry 70 is shown as comprising a ring, represented by a circumference 304, a source 74, and an imaging volume 313. The subject 314 is positioned within the imaging volume 313. A central region 310 and an annular region 312 are shown, centered around an isocenter 306.

[0061] Figure 4 The geometry of the corresponding view is illustrated, in which an X-ray beam 320 is generated to provide an image of the central region 310, and an X-ray beam 324 is generated to provide an image of the annular region 312. For each of the X-ray beams 320, 324, the X-ray source 74 may be in the same or nearly the same radial position relative to the isocenter 306. For the first spin, the X-ray source 74 is not tilted, and the centerline of the X-ray beam 320 is aligned with and extends through the isocenter 306. For the second spin, the X-ray source 74 is tilted such that the centerline of the X-ray beam 324 is offset from the isocenter 306 and does not extend through the isocenter.

[0062] For the first spin of the capture center region 310, detector 78 is represented by a first detector plane (or detector surface) 402. For the second spin of the capture ring region 312, detector 78' is represented by a second detector plane (or detector surface) 404. In interpolation padding operations (such as...) Figure 9B During operations 908 and 912, the first detector plane 402 is extended to provide a first extended portion, as indicated by dashed line 410. The second detector plane 404 is also extended to provide a second extended portion, as indicated by dashed line 412.

[0063] Image data collected in association with the first detector plane 402 is interpolated and projected onto a second extension 412 of the second detector plane 404. This projection is indicated by arrow 414 and may be based on first geometric dimensions, such as: i) the length L1 of at least a portion of the first detector plane 402 measured from the intersection 415 between planes 402, 402; and ii) the angle α between the first detector plane 404 and the second extension 412 of the second detector plane 404. Image data collected in association with the second detector plane 404 is interpolated and projected onto a first extension 410 of the first detector plane 402. This projection is indicated by arrow 416 and may be based on second geometric dimensions, such as: the length L2 of at least a portion of the second detector plane 404 measured from the intersection 415 between planes 402, 404; and the angle α between the second detector plane 404 and the first extension 410 of the first detector plane 402. This provides an extended detector image, as further described below and as... Figure 10 As shown.

[0064] An overlap region 420 is shown, referring to the area where X-ray beams 320 and 324 overlap. The overlap region 420 is defined by X-ray beams 320 and 324 and detector planes 402 and 404. During backprojection, the rays contributing to the overlap region 420 are reweighted to account for redundant ray sampling in this region, such as in… Figure 9B During operation 922. In this implementation, reweighting is performed in a smooth manner, including changing the weights from, for example, 1 for some data to values ​​between 0 and 1. Image data of the portion of X-ray beam 320 that overlaps with X-ray beam 324 and is closest to the centerline of X-ray beam 320 is given the highest weight toward the centerline of X-ray beam 320 (e.g., weighted by a1 (or multiplied by a1)), and the edges of X-ray beam 320 that overlap with X-ray beam 324 are given the lowest weight (e.g., weighted by a0 (or multiplied by a0)). Similarly, image data of the portion of X-ray beam 324 that overlaps with X-ray beam 320 is given the highest weight toward the centerline of X-ray beam 324 (e.g., weighted by a0 (or multiplied by a0)), and the edges of X-ray beam 324 that overlap with X-ray beam 320 are given the lowest weight (e.g., weighted by a0 (or multiplied by a0)). A weighted gradient between 0 and 1 is used for the overlapping portion of each of the X-ray beams 320 and 324. In the embodiment, and for each pixel in the pixels corresponding to the portion of the reconstructed image associated with the overlapping region, the weights of the image data corresponding to X-ray beam 320 and the image data corresponding to X-ray beam 324 are summed to 1.

[0065] exist Figure 4In the diagram, the extended portions 410 and 412 of planes 402 and 404 correspond to the following filled regions, which have data that is inconsistent (or different) from the data associated with planes 402 and 404. The filled data is generated during the projection operation of the interpolation and used during backprojection to minimize and / or eliminate artifacts associated with the differences between i) the filled data of the image of the central region 310 and ii) the image of a portion of the annular region 312. Examples of these differences are shown in... Figure 7 The image is shown in the diagram. The filled area is shown for two views. The first view is associated with the source 74 and detector 78 in a first orientation and corresponding position for capturing the image of the central region 310. The second view is associated with the source 74 and detector 78 in a second orientation and corresponding position for capturing the image of the annular region 312.

[0066] The following description Figures 5 to 8 and Figures 10 to 11 Each graph in the diagram includes a number of shading variations to illustrate the variation in image brightness between the bright and dark parts of the image. Although each graph in these diagrams includes a number of shading variations (or brightness variations), each image can include any number of shading variations between the brightest and darkest parts of the image.

[0067] Now for reference Figure 3 and Figure 5 An example image 500 of the central region 310 is shown, with the source 74 and detector 78 in a first orientation and position. The image includes: a bright central region 502 corresponding to the subject 314 in the central region 310; and a dark upper region 504 and a dark lower region 506 corresponding to the regions in the imaging volume 313 located above and below the subject 314. The regions in the imaging volume 313 located above and below the subject 314 include a portion of the annular region 312. The brightness of the central region 502 varies towards the upper region 504 and lower region 506 of the image 500, as well as the side edges 510, 512. The brightness of the central region 502 decreases towards the upper region 504 and lower region 506, as well as the edges 510, 512. The edges 510, 512 are brighter than the central portion 514 of the central region 502.

[0068] Now for reference Figure 3 and Figure 6 An example image 600 of the annular region 312 is shown, in which the source 74 and detector 78 are in a second orientation and position. The image includes: with... Figure 3The image 500 includes a central region 602 corresponding to the outer portion of the subject 314 in the central region 310; and a dark upper region 604, a dark lower region 606, and a dark outer (or side) region 608 corresponding to the regions in the imaging volume 313 located above, below, and to the side of the subject 314. The regions in the imaging volume 313 located above, below, and to the side of the subject 314 include the corresponding portions of the annular region 312. The brightness of the central region 602 varies toward the side region 608 of the image 500. The brightness of the central region 502 decreases toward regions 604, 606, and 608.

[0069] Figure 7 Image diagrams illustrating the difference between the filling of an extended central region image and a ring-shaped image are shown. One method for reconstructing an extended FOV image involves adding filling to images 500 and 600, applying ramp filtering to the resulting extended image, cropping the filtered extended image, and performing backprojection to provide an extended reconstructed image of imaging volume 313. The generation of filling data for image 500 includes determining vertical pixel side-edge data at the side edges 510 and 512 of image 500 (e.g., the color and brightness of each pixel in the first and last columns of image 500), and repeating this data laterally outward as shown to provide extended filling portions 700 and 702. Pixel data in extended filling portions 700 and 702 are matched with pixel data along the side edges 510 and 512. This is similarly performed for image 600, where the vertical pixel side-edge data of the side edges 710 and 712 of image 600 (e.g., the first and last columns) are repeated laterally outward to provide extended filling portions 720 and 722. The pixel data in the extended padding portions 720 and 722 are matched with the pixel data along the side edges 710 and 712.

[0070] It can perform the following on each pair of images generated for the central region 310 and the annular region 312: Figure 7 The above-described filling process applies to the filled data. Each resulting extended image pair can be filtered and cropped, and the resulting filtered and cropped images can be backprojected to provide the resulting reconstructed image. As an example, a ramp filter can be used to filter the resulting extended image pairs. As an example, the Feldkamp, ​​Davis, and Kress (FDK) filtered backprojection algorithm can be used to perform backprojection. The FDK filtered backprojection algorithm can be used for three-dimensional reconstruction based on cone-beam projections of regions 310, 312, which are measured using circular orbits of an X-ray source and detector array. The FDK algorithm may include filtering and cropping as disclosed herein.

[0071] As in Figure 7As can be seen, there is an inconsistency (or difference) between the filled portion 700 and the image 600. Due to these differences, artifacts are generated during the backprojection process. Examples of these artifacts are shown in... Figure 8 As shown in the diagram. This is because the described padding causes an inconsistency between the edge information in the padding portion 700 and the image 600 before the ramp filter calculation, which leads to ring artifacts in the final reconstructed image, such as... Figure 8 As shown.

[0072] Figure 8 A reconstructed image 800 generated based on an extended central region image is shown, which is at least based on image 500 and Figure 7 The filling part 700 and Figure 7 The annular image 600 is generated. The reconstructed image 800 includes artifacts 802, 804, and 806. Artifact 804 is referred to as the annular artifact and is associated with the differences between pixel data at and near edges 510 and 712.

[0073] exist Figure 8 The diagram illustrates control inserts, some of which are designated 810. Control inserts 810 are used as image phantoms during simulations for image reconstruction testing. Control inserts 810 are simulated as actually being located within their corresponding imaging volumes and are used as a reference to evaluate the quality of the reconstructed image. Image data for control inserts 810 are included in the raw image data of the imaging volume. Control inserts 810 help distinguish different image intensities and visualize differences in control levels. The brightness of example control inserts 810 increases around the center of the imaging volume. As an example, the brightness of control inserts 810 can increase by 5% to 10% from one insert to the next. The more noise there is, the harder it is to see control inserts 810 in the reconstructed image. The worse the control inserts appear, the worse the image quality.

[0074] Figure 9A and Figure 9B (Collectively referred to as FIG9) illustrates an extended FOV image reconstruction method according to the present disclosure, including pre-reverse projection processing. This method can be executed by a processor (e.g., one of the processors mentioned herein) and by an imaging system (e.g., Figure 1 The imaging system 36) is implemented. The operation can be performed iteratively.

[0075] At 900, the processor initializes the imaging system. This may include determining the orientation and position of the X-ray source and detector array, setting the image capture frequency, setting the gantry rotation speed, downloading pre-reverse projection processing instructions and / or other imaging instructions, etc.

[0076] The following operations 901, 902, 904, and 906 are part of the image acquisition process. At 901, the processor orients and positions the X-ray source and detector array for the first spin. At 902, the processor performs a central (first) scan, including performing the first spin of the gantry to capture a first set of images of the central region of the imaging volume. Example images included in the first set of images are shown in... Figure 10 The value in the middle is marked as 1000.

[0077] At 904, the processor tilts the X-ray source and detector array, and adjusts the position of the detector array relative to the X-ray source to capture an image of the annular region surrounding the central region within the extended field of view. At 906, the processor performs an annular scan, including performing a second spin to capture a second set of images of the annular region within the extended field of view. The second set of images is correlated with the first set of images to provide an image pair. Example images included in the second set of images are shown in... Figure 10 The middle part is marked as 1002.

[0078] At 907, the processor selects one of the image pairs (i.e., the first image pair or the next image pair) that includes a corresponding image from the first set of images and a corresponding image from the second set of images.

[0079] At 908, the processor generates first projected and interpolated padding data for the central region image by projecting and interpolating the image data of the annular region onto a first extended detector imaging plane corresponding to the first orientation and position of the detector array used to capture the first set of images. As described above, using the annular region image data, the first projected and interpolated padding data for the central region image is generated by projecting image data on the first detector plane onto image data on the extended portion of the second detector plane. This is... Figure 4 Arrow 416 indicates this. Example first projection and interpolation padding data is shown as... Figure 10 The extended image portion 1004. In the current specific implementation, geometric projection is performed by iterating through each pixel in the filled region of the first scan and defining a ray between that point and the source focal point. Then, ray-plane intersection point calculation is performed between this ray and a plane that defines the position of the detector's receiving surface for the corresponding image view of the second scan. The intensity at the ray-plane intersection point is extracted using an interpolation approach (e.g., nearest neighbor interpolation or bilinear interpolation). The intensity value of the filled pixel in the first scan is then set to the value of this interpolation. At 910, the processor extends the central region image using the first projected and interpolated filled data. Operations 908 and 910 are performed by... Figure 4 Arrow 416 indicates.

[0080] At 912, the processor generates second-projected and interpolated filling data for the annular region image by projecting and interpolating the image data of the central region onto a second extended detector imaging plane corresponding to the second orientation of the detector array used to capture the second set of images. As described above, using the central region image data, the second-projected and interpolated filling data for the annular region image is generated by projecting image data on the second detector plane onto image data on the extended portion of the first detector plane. In the current specific embodiment, geometric projection is performed by iterating through each pixel in the filling region of the second scan and defining a ray between that point and the source focus. Then, a ray-plane intersection calculation is performed between this ray and a plane that defines the position of the receiving surface of the detector for the corresponding image view of the first scan. The intensity at the ray-plane intersection is extracted using an interpolation approach (e.g., nearest neighbor interpolation or bilinear interpolation). The intensity value of the filling pixel in the second scan is then set to the interpolated value. At 914, the processor extends the annular region image with the second-projected and interpolated filling data. An example of second-projected and interpolated filling data is shown as follows. Figure 10 The extended image portion 1006.

[0081] At 916, the processor further fills the extended central region image and the extended annular region image. Edges 1010 and 1012 of the extended central region image, which includes image 1000 and the first projected and interpolated fill data 1004, are repeated outwards from edges 1010 and 1012 to provide extended regions 1014 and 1016. Edges 1018 and 1020 of the extended annular region image, which includes image 1002 and the second projected and interpolated fill data 1006, are repeated outwards from edges 1018 and 1020 to provide extended regions 1020 and 1022.

[0082] At 918, the processor performs ramp filtering on the following: i) the resulting extended center region image, which includes image 1000, first projected and interpolated padding data 1004, and additional padding data 1014, 1016; and ii) image 1002, second projected and interpolated padding data 1006, and additional padding data 1020, 1022. The ramp filter (e.g., ramp filter 220) outputs a filtered extended center region image and a filtered extended annular region image. The ramp filter reduces blur in the reconstructed image.

[0083] At position 920, the processor can crop the filtered extended central region image and the filtered extended annular region image to remove, for example, elements related to... Figure 10 The filtered fill regions are associated with the fill data 1014, 1016, 1020, and 1022. In this implementation, all fill regions are cropped.

[0084] At 922, the processor determines whether to process another pair of center and circular images. If so, operation 908 can be performed; otherwise, operation 924 can be performed.

[0085] At 924, the processor can perform backprojection on the cropped, filtered, extended central region image and the cropped, filtered, extended annular region image to generate a reconstructed image of the FOV. This may include using the FDK backprojection algorithm. Backprojection module 212 can, for example, acquire the image and backproject it across the imaging volume, adding the corresponding pixel value for each pixel along the line back to the source and for each voxel to which the line intersects. Backprojection module 212 additively “paints” the data onto the reconstructed voxels. This is done for each detector position. All pixel data values ​​of the detector for a first spin relative to the source at a first position (where there is an intersection with a voxel) are accumulated back to the source. All pixel data values ​​of the detector for a second spin relative to the source at a second position (where there is an intersection with a voxel) are accumulated back to the source. Each voxel refers to a three-dimensional space within the imaging volume. The imaging volume may include, for example, 512×512×512 voxels, or in other words, 512 voxels along each vertical, horizontal and depth side edge of the imaging volume, wherein the imaging volume has a cubic shape.

[0086] In the implementation, as described above, backprojection includes reweighting the overlapping image data. The FDK algorithm performs this reweighting to account for overlapping dual-ray sampling regions. Examples of overlapping regions are shown in... Figure 4 As shown in the diagram. The method can terminate after operation 924.

[0087] In this implementation, all projected images from both scans are filled, then ramped, cropped to their original size, and then backprojected iteratively, one by one. All projected images are backprojected onto the same volume to form a centralized overall reconstruction (or reconstructed image). Processing one by one (or pair by pair) is an example implementation. This processing can be performed in a manner that fills all images in the same stage, etc. The backprojection process is a linear operation. Therefore, the order in which the projections are received can be changed.

[0088] The methods described above include implementing algorithms to improve the processing of captured image data to provide extended FOV images of better quality with minimal or no artifacts. These algorithms may also improve the contrast variation of the images to enhance image sharpness. The method can be implemented during simulations to test the quality of image reconstruction and / or during actual use to improve image reconstruction. The reconstructed images can then be displayed, analyzed, compared, and / or evaluated as described above to detect and diagnose problems in one or more scanned subjects.

[0089] In the above method, padding data is calculated using image data from the edges of two corresponding images. The central region image has a padding area determined by projection interpolation of its corresponding annular region image. For example... Figure 4 As shown, the filled region of the central image is considered an extension of its current imaging plane, and the corresponding annular image data is projected and interpolated onto the filled region of the central image (under cone-beam projection geometry). This process is then repeated for the annular image. The resulting fill can be... Figure 10 I saw it in the middle.

[0090] Figure 11 This demonstrates a method based on back projection reconstruction. Figure 10 A reconstructed image 1100 is generated from an extended central region image and an extended annular region image. The reconstructed image 1100 includes a bright interior portion 1102 corresponding to the annular region and the central region, and a control insert 1104. The control insert 1104 can be used with… Figure 8 The same as the control insert 810.

[0091] The method described in Figure 9 includes using image information from other projections to fill the current image. The method also includes using a cone-beam projection transformation on the fill (or expansion detector) plane of the corresponding image to determine the fill. By expanding the image FOV as disclosed herein, many workflow challenges in operating rooms where it is difficult to center the patient isocentrically can be addressed.

[0092] Example embodiments are provided to make this disclosure thorough and to fully communicate the scope of this disclosure to those skilled in the art. Numerous specific details, such as examples of particular components, apparatus, and methods, are set forth to provide a thorough understanding of embodiments of this disclosure. It will be apparent to those skilled in the art that specific details are not required, example embodiments may be embodied in many different forms, and should not be construed as limiting the scope of this disclosure. In some example embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

[0093] Instructions can be executed by a processor and may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, data structures, and / or objects. The term "shared processor circuitry" covers a single processor circuitry that executes some or all of the code from multiple modules. The term "group processor circuitry" covers processor circuitry that, in conjunction with additional processor circuitry, executes some or all of the code from one or more modules. References to multiple processor circuitry cover multiple processor circuitry on a discrete die, multiple processor circuitry on a single die, multiple cores of a single processor circuitry, multiple threads of a single processor circuitry, or a combination thereof. The term "shared memory circuitry" covers a single memory circuitry that stores some or all of the code from multiple modules. The term "group memory circuitry" covers memory circuitry that, in conjunction with additional memory, stores some or all of the code from one or more modules.

[0094] The apparatus and methods described in this application may be implemented, in part or in whole, by one or more processors (also referred to as processor modules), which may include a dedicated computer (i.e., created by configuring one or more processors) for performing one or more specific functions embodied in a computer program. The computer program includes processor-executable instructions stored on at least one non-transitory, tangible computer-readable medium. The computer program may also include or depend on stored data. The computer program may include a basic input / output system (BIOS) that interacts with the hardware of the dedicated computer, device drivers that interact with specific devices of the dedicated computer, one or more operating systems, user applications, background services, background applications, etc.

[0095] Computer programs may include: (i) assembly code; (ii) object code generated from source code by a compiler; (iii) source code for execution by an interpreter; (iv) source code for compilation and execution by a just-in-time (JIT) compiler; and (v) descriptive text for parsing, such as HTML (Hypertext Markup Language) or XML (Extensible Markup Language). As an example only, source code may be in C, C++, C#, Objective-C, Haskell, Go, SQL, Lisp, or Java. ® ASP, Perl, Javascript ® HTML5, Ada, Active Server Pages (ASP), Perl, Scala, Erlang, Ruby, Flash ® Visual Basic ® Lua or Python ® To write it.

[0096] Communication may include the wireless communications described in this disclosure, which may be wholly or partially compliant with IEEE Standard 802.11-2012, IEEE Standard 802.16-2009, and / or IEEE Standard 802.20-2008. In various specific implementations, IEEE 802.11-2012 may be supplemented by draft IEEE Standard 802.11ac, draft IEEE Standard 802.11ad, and / or draft IEEE Standard 802.11ah.

[0097] The terms processor, processor module, module, or “controller” are used interchangeably herein (unless otherwise specifically indicated), and each may be replaced by the term “circuit”. Any of these terms may refer to, be part of, or include: application-specific integrated circuit (ASIC); digital, analog, or mixed-signal analog / digital discrete circuit; digital, analog, or mixed-signal analog / digital integrated circuit; combinational logic circuit; field-programmable gate array (FPGA); processor circuitry (shared, dedicated, or grouped) that executes code; memory circuitry (shared, dedicated, or grouped) that stores code executed by the processor circuitry; other suitable hardware components that provide the described functionality; or combinations of some or all of the foregoing, such as in a system-on-a-chip.

[0098] Instructions may be executed by one or more processors or processor modules, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Therefore, the terms "processor" or "processor module" as used herein may refer to any of the foregoing structures or any other physical structure suitable for implementing the described techniques. Furthermore, these techniques may be fully implemented in one or more circuit or logic elements.

[0099] The foregoing description of embodiments has been provided for illustrative and descriptive purposes. The foregoing description is not intended to be exhaustive or limiting of the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable and may also be used in chosen embodiments where applicable, even if not specifically shown or described. The same element or feature may be varied in many ways. Such variations are not considered to depart from the invention, and all such modifications are intended to be included within the scope of the invention.

Claims

1. A method for reconstructing an extended field-of-view image of the imaging volume of an X-ray imaging system gantry, the method comprising: Perform a first spin of the stage to capture a first set of images of the central region of the imaging volume; Perform a second spin on the stage to capture a second set of images of a ring-shaped region around the central region of the imaging volume; Filling data for the first projection and interpolation of the first image of the central region is generated based on the first image of the annular region, wherein the first set of images includes the first image of the central region, and the second set of images includes the first image of the annular region; A first extended image of the central region is generated based on the first projection and interpolated fill data. Based on the first image of the central region, generate second projection and interpolated padding data of the first image of the annular region; A first extended image of the annular region is generated based on the second projection and interpolated fill data. as well as Backprojection is performed based on the first extended image of the central region and the first extended image of the annular region to reconstruct the extended field of view image of the imaging volume.

2. The method according to claim 1, wherein the central region of the imaging volume is centered on the isocenter of the gantry.

3. The method according to claim 1, wherein: The central region of the imaging volume is not centered on the isocenter of the gantry; and The isocenters are included in each of the first set of images.

4. The method according to claim 1, wherein the method further comprises: The X-ray source and detector array are oriented and positioned to capture the first set of images; as well as The X-ray source and the detector array are reoriented and repositioned to capture the second set of images.

5. The method of claim 4, wherein the reorientation and repositioning of the X-ray source and the detector array comprises: The X-ray source is maintained at the same radial distance from the isocenter of the gantry, the X-ray source and the detector array are tilted, and the detector array is repositioned relative to the X-ray source to capture an image of the annular region.

6. The method according to claim 1, wherein the method further comprises: The first extended image in the central region is filled based on the edge pixel data of the first extended image in the central region; as well as The first extended image of the annular region is filled with edge pixel data of the first extended image of the annular region.

7. The method according to claim 6, wherein the method further comprises: After filling, ramp filtering is applied to the first extended image of the central region and the first extended image of the annular region.

8. The method according to claim 7, wherein the method further comprises: After ramp filtering, the first extended image of the central region and the first extended image of the annular region are cropped. The back projection is performed after the cropping of the first extended image in the central region and the first extended image in the annular region.

9. The method according to claim 1, wherein: Generating the second projection and interpolating padding data includes: projecting and interpolating image data on the first detector plane onto an extended portion of the second detector plane, wherein the first detector plane is associated with the detector array of the gantry in a first orientation and position for capturing the first set of images, and the second detector plane is associated with the detector array in a second orientation and position for capturing the second set of images; and Generating the first projection and interpolating the fill data includes: projecting the image data on the second detector plane and interpolating it to an extended portion of the first detector plane.

10. The method according to claim 1, wherein: The padding data for generating and interpolating the second projection includes: a geometric projection onto an extended portion of the first detector plane, the first detector plane corresponding to the detection surface of the detector array of the gantry at a first orientation and a first position; and The filling data for generating and interpolating the first projection includes: a geometric projection onto an extended portion of a second detector plane, the second detector plane corresponding to the detection surface of the detector array at a second orientation and a second position.

11. The method according to claim 1, wherein the method further comprises: i) When the first image of the central region is captured, a first X-ray beam is generated via the X-ray source of the gantry; and ii) When the first image of the annular region is captured, a second X-ray beam is generated via the X-ray source, wherein: The first X-ray beam overlaps with the second X-ray beam; and During backprojection, the image data associated with the overlap of the first and second X-ray beams is reweighted to account for redundant sampling.

12. The method according to claim 1, further comprising: Filling data for a third projection and interpolation of the second image of the central region is generated based on the second image of the annular region, wherein the first set of images includes the second image of the central region, and the second set of images includes the second image of the annular region; A second extended image of the central region is generated based on the third projection and interpolated fill data; The fourth projection and interpolated padding data of the second image of the annular region are generated based on the second image of the central region. A second extended image of the annular region is generated based on the fourth projection and interpolated fill data; as well as Backprojection is performed based on the second extended image of the central region and the second extended image of the annular region to reconstruct an image of the imaging volume.

13. An imaging system, the imaging system comprising: A gantry comprising an aperture having an imaging volume in which a subject is placed, the gantry comprising an X-ray source and a detector array arranged to rotate about an isocenter of the gantry; and At least one processor, said at least one processor being configured to: The stage is first spun to capture a first set of images of the central region of the imaging volume via the detector array; The stage is spun a second time to capture a second set of images of a ring-shaped region around the central region of the imaging volume via the detector array; Filling data for generating a first projection and interpolation of the first image of the central region based on the first image of the annular region, wherein the first set of images includes the first image of the central region, and the second set of images includes the first image of the annular region; A first extended image of the central region is generated based on the first projection and interpolated fill data. Based on the first image of the central region, generate second projection and interpolated padding data of the first image of the annular region; A first extended image of the annular region is generated based on the second projection and interpolated fill data. as well as Backprojection is performed based on the first extended image of the central region and the first extended image of the annular region to reconstruct an extended field-of-view image of the imaging volume.

14. The imaging system of claim 13, wherein the central region of the imaging volume is centered on the isocenter.

15. The imaging system according to claim 13, wherein: The central region of the imaging volume is not centered on the isocenter of the gantry; and The isocenters are included in each of the first set of images.

16. The imaging system of claim 13, wherein the at least one processor is further configured to: Orienting and locating the X-ray source and the detector array to capture the first set of images; and The X-ray source and the detector array are reoriented and repositioned to capture the second set of images.

17. The imaging system of claim 16, wherein the at least one processor is further configured to: maintain the X-ray source at the same radial distance from the isocenter, tilt the X-ray source and the detector array, and reposition the detector array relative to the X-ray source to capture an image of the annular region during reorientation and repositioning of the X-ray source and the detector array.

18. The imaging system of claim 13, wherein the at least one processor is further configured to: The first extended image in the central region is filled with edge pixel data of the first extended image in the central region; and The first extended image of the annular region is filled with edge pixel data of the first extended image of the annular region.

19. The imaging system of claim 18, wherein the at least one processor is further configured to: after filling, perform ramp filtering on the first extended image of the central region and the first extended image of the annular region.

20. The imaging system of claim 19, wherein the at least one processor is further configured to: After ramp filtering, the first extended image of the central region and the first extended image of the annular region are cropped; and The back projection is performed after cropping the first extended image of the central region and the first extended image of the annular region.

21. The imaging system of claim 13, wherein the at least one processor is further configured to: The padding data for generating and interpolating the second projection includes: Image data on a first detector plane is projected and interpolated onto an extended portion of a second detector plane, wherein the first detector plane is associated with the detector array in a first orientation and position for capturing the first set of images, and the second detector plane is associated with the detector array in a second orientation and position for capturing the second set of images. and Generating the first projection and interpolating the fill data includes: projecting the image data on the second detector plane and interpolating it to an extended portion of the first detector plane.

22. The imaging system of claim 13, wherein the at least one processor is further configured to: The padding data for generating and interpolating the second projection includes: The geometric projection onto an extended portion of a first detector plane, the first detector plane corresponding to the detection surface of the detector array at a first orientation and a first position; as well as The filling data for generating and interpolating the first projection includes a geometric projection onto an extended portion of a second detector plane, the second detector plane corresponding to the detection surface of the detector array at a second orientation and a second position.

23. The imaging system according to claim 13, wherein: The X-ray source is configured to generate a first X-ray beam when capturing the first image of the central region, and to generate a second X-ray beam when capturing the first image of the annular region; The first X-ray beam overlaps with the second X-ray beam; and During backprojection, the image data associated with the overlap of the first and second X-ray beams is reweighted to account for redundant sampling.

24. The imaging system of claim 13, wherein the at least one processor is further configured to: Filling data for a third projection and interpolation of the second image of the central region is generated based on the second image of the annular region, wherein the first set of images includes the second image of the central region, and the second set of images includes the second image of the annular region; A second extended image of the central region is generated based on the third projection and interpolated fill data; The fourth projection and interpolated padding data of the second image of the annular region are generated based on the second image of the central region. A second extended image of the annular region is generated based on the fourth projection and interpolated fill data; as well as Backprojection is performed based on the second extended image of the central region and the second extended image of the annular region to reconstruct an image of the imaging volume.

Images