System and method for reducing artifacts in images

Abstract

Selected artifacts, which may be based on distortion or selected attenuation characteristics, can be reduced or removed from the reconstructed image. Various artifacts may appear due to the presence of metallic objects in the field of view. Such metallic objects can be identified and removed from the data used to generate the reconstruction.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Patent Application No. 16 / 375,292, filed April 4, 2019, and also claims the benefit of U.S. Provisional Application No. 62 / 654,038, filed April 6, 2018. The entire disclosures of the above applications are incorporated herein by reference.

[0003] Government licensing rights

[0004] This invention was made with government support under Grant R01-EB-017226 from the National Institutes of Health. The government has certain rights in this invention. Technical Field

[0005] The present disclosure relates to displaying images, and in particular to the correction or reduction of artifacts or distortions. Background Art

[0006] This section provides background information related to the present disclosure which is not necessarily prior art.

[0007] When acquiring image data or images of a selected object, such as a human patient, various artifacts or distortions may occur. For example, when acquiring an X-ray-based image of a subject, certain materials may interfere with the X-rays in a disproportionate or different manner than other materials, such as the subject's tissue. For example, metal or polymer objects may attenuate and / or scatter X-rays in a manner different from the subject's surrounding tissue. These effects of non-tissue materials may cause distortions or artifacts in images generated using the acquired image data. The distortions may be magnified or easily viewed after a reconstruction, such as a three-dimensional reconstruction, based on two-dimensional projections of the subject. Therefore, one may choose to correct for the distortions in an attempt to generate an image for viewing with minimal or no distortion. Summary of the Invention

[0008] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0009] The subject can be imaged using the selected imaging system. In various embodiments, an X-ray imaging system can be used to acquire image data of the subject. The X-ray image data can be acquired according to various techniques, such as using an X-ray system that creates or acquires one or more two-dimensional projections. The two-dimensional projections can be used to generate a three-dimensional reconstruction. Thus, one or more two-dimensional projections can be acquired, for example, in a sequence to generate a three-dimensional reconstruction.

[0010] When acquiring image data of a subject, X-rays are attenuated by the material through which the X-rays pass as they pass from the X-ray source to the detector. The X-rays emitted from the source can be within a spectrum around an average value or within selected boundaries. Thus, an X-ray source that emits X-rays at a selected energy, such as 120 kiloelectronvolts (keV), may actually emit X-rays within a range or spectrum around this value. Thus, the attenuation may be different for each X-ray energy within a particular X-ray energy.

[0011] Furthermore, similar materials, such as soft or hard tissue of a subject, can attenuate X-rays in a similar manner. Various non-tissue materials, such as metal objects (e.g., implants, instruments, etc.), can attenuate X-rays in substantially different ways. For example, non-tissue materials can attenuate and / or reflect or scatter X-rays away from objects in the field of view (FOV) of an X-ray source or detector. It should be understood that non-tissue materials can include objects or materials other than metals, such as polymers, composite materials, etc.

[0012] Images, such as 2D projections, can contain various effects (e.g., distortion) due to various non-tissue objects within the FOV. Distortion can generate artifacts that accumulate or amplify when a reconstruction is generated based on multiple projections. Therefore, the culled portions later used for reconstruction can be repaired by removing distortion and including projections and known effects of selected components or objects in the field of view. The reconstruction can incorporate information based on known facts about components within the X-ray system to reduce or eliminate distortion and artifacts along with the reconstruction.

[0013] Further areas of applicability will become apparent from the description provided herein.The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0015] Figure 1 is an environmental view of an operating room including an optional imaging system and a navigation system;

[0016] Figure 2 is a schematic diagram of an instrument used to insert an implant into a patient;

[0017] Figure 3 is a schematic diagram of the implant in the subject;

[0018] Figure 4 is a flow chart of a process for reducing artifacts or distortion in an image;

[0019] Figure 5is a diagram of the projection without and with restoration; and

[0020] Figure 6 is an illustration of the reconstruction without and with restoration.

[0021] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0022] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0023] refer to Figure 1 and Figure 2 , a diagram showing a surgical area is shown. The surgical area may include a surgical suite. A navigation system 10, which may be used for a variety of surgeries, is placed in the surgical suite for use. The navigation system 10 may be used to track the position of items such as implants or instruments (as discussed herein) relative to a subject such as a patient 14. It should be further noted that the navigation system 10 may be used to navigate any type of instrument, implant, or delivery system, including: guidewires, arthroscopic systems, orthopedic implants, spinal implants, deep brain stimulation (DBS) leads, cardiac pacing leads, ablation instruments, and the like. In addition, instruments may be used to navigate or map any area of ​​the body. The navigation system 10 and the various tracked items may be used in any appropriate surgery, such as typically minimally invasive surgery or open surgery.

[0024] The operating room can further include an imaging system 12. In various embodiments, the imaging system 12 can be interfaced with the navigation system 10. The imaging system 12 can be used to acquire preoperative, intraoperative, postoperative, or real-time image data of the patient 14. In various embodiments, the imaging system 12 can be used to acquire images at selected times to confirm and / or determine the progress of a selected portion of the operation. It will be understood by those skilled in the art that any appropriate subject can be imaged and any appropriate surgery can be performed with respect to the subject. The subject 14 can be a human patient, and the surgery can be a surgical procedure, such as the implantation of a device (e.g., screws, wires, etc.).

[0025] exist Figure 1 The imaging system 12 exemplarily shown in FIG. 1 comprises a system sold by Medtronic Navigation, Inc. having a place of business in Louisville, Colorado, USA. Imaging device. The imaging device 12 can have a generally annular gantry housing 20 that encloses an image capture portion 22. The image capture portion 22 can include an x-ray source or emitting portion 26 and an x-ray receiving or image receiving portion 28 (also referred to as a detector, which is used to detect x-rays passing through the subject 14) positioned approximately or practically 180 degrees from each other within the gantry housing 20. The x-ray emitting portion 26 can emit or generate a cone beam 26x of x-rays. The x-rays in the cone beam 26x will generally encompass a field of view that can include at least a portion of the subject 14, such as a vertebra 124. The detector 28 can detect x-rays that have passed through the subject 14. However, the x-rays may be attenuated and / or scattered by the subject or object in the cone beam 26x. Further, the detector can detect and / or generate two-dimensional (2D) image data or projections.

[0026] In various embodiments, the x-ray source or emitting portion 26 and the x-ray receiving or image receiving portion 28 can be mounted on a rotor (not shown) relative to a track (not shown) within the generally annular gantry housing 20. The image capture portion 22 can be operable to rotate 360 ​​degrees during image acquisition. The image capture portion 22 can rotate about a center point or axis, thereby allowing image data of the patient 14 to be acquired from multiple directions or in multiple planes. The imaging system 12 can include an imaging system disclosed in the following: U.S. Patent Nos. 7,188,998; 7,108,421; 7,106,825; 7,001,045; and 6,940,941, all of which are incorporated herein by reference. However, the imaging system 12 can also include or be replaced by other imaging systems that can also generate three-dimensional views of the patient 14, including C-arm fluoroscopic imaging systems, computed tomography (CT) imaging systems, and the like.

[0027] The position of the image capturing portion 22 may be precisely known relative to any other portion of the imaging device 12. Additionally, as discussed herein, precise knowledge of the position of the image capturing portion 22 may be used in conjunction with the tracking system 29 to determine the position of the image capturing portion 22 and image data relative to a tracked subject, such as the patient 14. For example, the patient tracking device 48 may be placed on the patient 14 to track the patient 14.

[0028] The tracking system 29 can include multiple components associated with or included with the navigation system 10. The tracking system 29 can also include multiple types of tracking systems, including optical tracking systems including an optical locator 40 and / or electromagnetic (EM) tracking systems. The optical locator 40 can "see" or optically track a trackable portion (tracking device) using a camera. The EM locator 42 can generate a field, and the trackable portion (e.g., EM tracking device) can sense the field to determine its position relative to another tracking device in the field. Various tracking devices, including those discussed further herein, can be tracked using the tracking system 29, and the information can be used by the navigation system 10 to display the location of an item. In short, tracking devices such as the patient tracking device 48, the imaging device tracking device 50, and the instrument tracking device 52 allow selected portions of the operating room to be tracked relative to each other using the appropriate tracking system 29 (including the optical locator 40 and / or the EM locator 42).

[0029] It will be appreciated that any of the tracking devices 48, 50, 52 may be an optical tracking device or an EM tracking device, or both, depending on the tracking locator used to track the corresponding tracking device. It will be further appreciated that any suitable tracking system may be used with the navigation system 10. Alternative tracking systems may include radar tracking systems, acoustic tracking systems, ultrasonic tracking systems, and the like.

[0030] An exemplary EM tracking system may include the EM tracking system sold by Medtronic Navigation, Inc. having a place of business in Louisville, Colorado. AXIEM TMNavigation System. Exemplary tracking systems are also disclosed in U.S. Patent No. 8,644,907, entitled “Method and Apparatus For Surgical Navigation,” issued on February 4, 2012; U.S. Patent No. 7,751,865, entitled “Method and Apparatus For Surgical Navigation,” issued on July 6, 2010; U.S. Patent No. 5,913,820, entitled “Position Location System,” issued on June 22, 1999; and U.S. Patent No. 5,592,939, entitled “Method and System for Navigating a Catheter Probe,” issued on January 14, 1997, all of which are incorporated herein by reference.

[0031] Further, for EM tracking systems, it may be necessary to provide shielding or distortion compensation systems to shield or compensate for distortion in the EM field generated by the EM localizer 42. Exemplary shielding systems include those disclosed in U.S. Patent No. 7,797,032, entitled “Method and system for navigating a catheter probe in the presence of field-influencing objects,” issued on September 14, 2010, and U.S. Patent No. 6,747,539, entitled “Patient-shielding and coil system,” issued on June 8, 2004, all of which are incorporated herein by reference. The distortion compensation system may include the distortion compensation system disclosed in U.S. Patent No. 6,636,757, entitled "Method and apparatus for electromagnetic navigation of a surgical probe near a metal object," issued on October 21, 2003, which is incorporated herein by reference.

[0032] With the EM tracking system, the EM localizer 42 and various tracking devices can communicate through the EM controller 44. The EM controller can include various amplifiers, filters, electrical isolation, and other systems. The EM controller 44 can also control the coils of the localizer 42 to transmit or receive EM fields for tracking. However, instead of directly coupling to the EM controller 44, a wireless communication channel (such as that disclosed in U.S. Patent No. 6,474,341, issued on November 5, 2002, entitled "Surgical Communication Power System," which is incorporated herein by reference) can be used.

[0033] It will be understood that the tracking system may also be or include any suitable tracking system, including a tracking system having an optical locator (similar to optical locator 40) sold by Medtronic Navigation, Inc., having a place of business in Louisville, Colorado. and / or S7 TM Navigation system. The optical tracking system may also include the optical tracking systems disclosed in U.S. Patent No. 8,010,177, entitled “Intraoperative Image Registration,” dated August 30, 2011; and U.S. Patent No. 6,235,038, entitled “System For Translation Of Electromagnetic And Optical Localization Systems,” issued May 22, 2001, all of which are incorporated herein by reference. Further alternative tracking systems are disclosed in U.S. Patent No. 5,983,126, entitled “Catheter Location System and Method,” issued November 9, 1999, to Wittkampf et al., which is hereby incorporated by reference. Other tracking systems include acoustic, radiation, radar, and other tracking or navigation systems.

[0034] The imaging system 12 may include a support housing or cart 56. The imaging system 12 may further include a separate image processing unit 58 that may be housed in the cart 56. The navigation system 10 may include a navigation processing unit 60 that may be in communication with or include a navigation memory 62. The navigation memory 62 may include any suitable non-transitory memory, including random access memory, a magnetic media drive, etc. Further, the navigation memory 62 may be integrated with the navigation processing unit 60 or remote from the navigation processing unit 60. The navigation processing unit 60 may receive information (including image data) from the imaging system 12 and tracking information from the tracking system 29 (including the corresponding tracking devices 48-52 and the localizers 40-42). The image data may be displayed as an image 64 on a display device 66 of a workstation or other computer system 68.

[0035] The workstation 68 may include a suitable input device, such as a keyboard 70. It will be appreciated that other suitable input devices may be included, such as a mouse, foot pedal, etc. Furthermore, various processing units, as discussed above, may be incorporated into the workstation or computer system 68. Thus, the user 54 may use various inputs to include commands to the system. Furthermore, a navigation memory 62 or other suitable and / or similar memory may be used to transfer or recall information, such as image data and / or instructions for execution by a selected processing unit. Various processing units, computers, and / or workstations may include internal or local memory and processing units. A processing unit may include a central processing unit, such as a general-purpose computer that executes instructions to perform tasks on a chip. A processing unit may also be a specific circuit, such as an application-specific integrated circuit (ASIC). Thus, a processing unit may be a device that receives information and executes stored or received instructions based on that information. Furthermore, the memory may include transient and non-transient memory systems, such as random access memory, volatile or non-volatile memory, etc.

[0036] The image processing unit 58 can process the image data from the imaging system 12 and can transmit the image data to the navigation processing unit 60 before or after selected processing. However, it will be further understood that the imaging system 12 need not perform any image processing and can transmit the image data directly to the navigation processing unit 60. Thus, the navigation system 10 can include or operate with a single or multiple processing centers or units, which can access a single or multiple memory systems based on the system design. In addition, the processed image data as discussed herein can be displayed on the display device 66 or any suitable display device. Thus, the displayed image need not be displayed with the navigation system 10.

[0037] The patient 14 can be secured to a support 72, such as an operating table, but need not be secured to the table top 72. The table top 72 can include a plurality of straps 74. The straps 74 can be secured around the patient 14 to secure the patient 14 relative to the table top 72. Various devices can be used to position the patient 14 in a static position on the operating table 72. Examples of such patient positioning devices are described in commonly assigned U.S. patent application Ser. No. 10 / 405,068, filed on April 1, 2003, entitled "An Integrated Electromagnetic Navigation And Patient Positioning Device," published as U.S. Patent Application Publication No. 2004 / 0199072, which is hereby incorporated by reference. Other known devices can include fixture.

[0038] In addition, the position (including three-dimensional position and orientation) of the patient 14 relative to the imaging system 12 can be determined by the navigation system 10 having the patient tracking device 48 and the imaging system tracking device 50. As discussed herein, the position (including three-dimensional position and orientation) relative to the patient 14 can be determined at least in part using images acquired from the patient 14. Therefore, the position (including three-dimensional position and orientation) of the patient 14 relative to the imaging system 12 can be determined. The imaging system 12 can know its position and be repositioned to the same position within about 10 microns. This allows for substantially precise placement of the imaging system 12 and precise determination of the position of the imaging device 12. Precise positioning of the imaging portion 22 is further described in the following: U.S. Patent Nos. 7,188,998; 7,108,421; 7,106,825; 7,001,045; and 6,940,941, all of which are incorporated herein by reference. Generally, it can be selected to determine the position of the image data relative to the patient 14. For example, the position (including orientation) of the image data relative to the patient can be used to determine the position of a portion of the patient 14.

[0039] The subject or patient space and image space can be registered by identifying matching points or fiducials in the patient space and related points or equivalent points in the image space. Imaging device 12, such as an imaging device, can be used to generate image data at a precise and known location. This can allow the image data to be automatically or "inherently registered" with patient 14 at the time the image data was acquired. Essentially, due to the accurate positioning of imaging system 12 relative to patient 14, the position of patient 14 relative to imaging system 12 is precisely known. This allows points in the image data to be known relative to points on patient 14 due to the precisely known location of imaging system 12.

[0040] Alternatively, manual or automatic registration can occur by matching fiducials in the image data with fiducials on the patient 14. Image space to patient space registration allows for the generation of a transformation mapping between patient space and image space. According to various embodiments, registration can occur by determining substantially equivalent points in image space and patient space. Equivalent points can include anatomical fiducials or implanted fiducials. Exemplary registration techniques are disclosed in U.S. Patent Application No. 9,737,235, published on August 22, 2017, which is incorporated herein by reference.

[0041] In various embodiments, the navigation system 10 can be used to assist in performing the surgery. However, it should be understood that the navigation system 10 is not required. In various embodiments, the surgery can be performed without the navigation system. However, the surgery can also be performed alone or in combination with the navigation system 10, and the imaging system 12 can be used to perform the selected surgery. The selected surgery can use image data generated or acquired using the imaging system 12. Further, the imaging system 12 can be used to acquire image data at different times related to the surgery (such as during the surgery). As discussed herein, image data of the patient 14 can be acquired after the selected portion of the surgery for various purposes, including confirmation of the portion of the surgery.

[0042] Continue to refer Figure 1, the imaging system 12 can acquire image data, such as a projection of the subject 14. The projection can include a 2D projection that can be displayed as a 2D image. The imaging system 12 can also be used to generate or reconstruct a three-dimensional (3D) image of the patient 14. The patient 14 can be placed relative to the imaging system 12 to allow the imaging system 12 to obtain image data of the patient 14. In order to generate 3D image data, image data can be acquired from multiple perspectives or positions relative to the patient 14. The positions can be positions around the patient 14, such as positions separated by a certain angle by the movement of the detector 28 relative to the subject 14. Each position can be defined or referred to as an angle or theta (θ) position relative to the patient 14. The 3D image or image data of the patient 14 can be used alone or in combination with other information to help perform surgery on the patient 14 or an appropriate subject. However, it will be understood that any appropriate imaging system (including magnetic resonance imaging, computed tomography, fluoroscopy, etc.) can be used to acquire image data (including 3D image data) of the patient 14.

[0043] As discussed above, the imaging system 12 may comprise any suitable imaging system, such as the VISION Imaging System sold by Medtronic Navigation. Imaging system. The imaging system can acquire an image of subject 14 by acquiring image data of subject 14, which may include two-dimensional projections. The projections are acquired by emitting X-rays from source 26 and detecting them at detector 28. The projections can be displayed as two-dimensional images on display device 66 and / or reconstructed into three-dimensional images, such as image 64, for display on display device 66. If various items are positioned within the imaging system's field of view (e.g., within X-ray cone 26x emitted by X-ray source 26) and detected at detector 28, the image (e.g., reconstructed image 64) may contain artifacts or distortion. This distortion refers not only to spatial distortion in the reconstructed image, but also to distortion of the signal recorded by the detector—for example, multi-energy effects associated with energy-dependent detector response (beam hardening) and "null" data or electronic noise contributions (photon starvation). When imaging subject 14, distortion may be generated when various non-tissue elements or materials (e.g., pedicle screws 120, which may be driven or moved by an instrument, such as surgical motor 126) are within X-ray cone 26x. For example, according to various embodiments, a pedicle screw 120 may be implanted in a vertebra 124 of a patient 14. It should be understood that the discussion herein of single or multiple vertebrae is merely exemplary, and that the procedure may generally be performed on any selected number of suitable vertebrae. As is generally understood in the art, during a surgical procedure, the pedicle screw 120 may be positioned in the vertebra 124. Then, after the pedicle screw 120 is placed in the subject 14, but before completing the procedure, such as placement of a connecting rod, or other selected portions of the procedure, an image may be acquired using the imaging system 12. Imaging the subject 14 with the pedicle screw 120 in place may result in distortion in the image projection, which may cause further distortion and / or artifacts in the image reconstruction 64 displayed on the display device 66. Therefore, according to various embodiments, a process may be implemented, such as by instructions executed by the navigation processing unit 60 and / or the imaging processing unit 58, or other suitable processor, to assist in removing and / or processing artifacts to display an undistorted image.

[0044] The process of removing or processing distortion in the image can begin by interpreting or determining that the artifact or distortion in the projection is caused by a selected item (such as an object including an implant or instrument). The selected item can then be replaced in the projection before reconstruction, where the replacement can be performed according to a variety of repair methods. The process can be developed as an algorithm and instructions based thereon, which are stored in a memory such as navigation memory 62 or other suitable memory and executed by one or more processors or processing units (including the processors or processing units discussed above). The reconstruction with the correction or artifact reduction can then be displayed as an image 64 on a display device 66.

[0045] As discussed above, images may be generated and viewed on the display device 66. The acquired images are acquired at selected times using the imaging system 12, which may include Imaging system. For example, images can be acquired during a selected procedure, such as an operative procedure on subject 14. In various embodiments, the operative procedure can include positioning an implant in patient 14. The implant can include a pedicle screw 120 or more than one pedicle screw 120 positioned in one or more vertebrae 124. Figure 3 As illustratively shown, the first and second pedicle screws 120a and 120b are schematically shown as being positioned in the vertebra 124 relative to a midline 140. The midline 140 can be displayed on the display device 66 relative to an image such as the image 64, or can be an example of a midline extending from the posterior to the anterior of the patient 14. After the pedicle screws 120 are positioned in the patient 14 (such as in the vertebra 124), the imaging system 12 can be used to acquire image data of the patient 14 (including the vertebra 124 having the pedicle screws 120a and 120b positioned therein). Figure 3 As shown, the pedicle screw 120 may be positioned in the vertebra 124 in any suitable manner, such as by the user 54 using a drilling motor or tool 126 .

[0046] Acquiring image data of the subject 14 after positioning the pedicle screws 120 within the patient's body may be performed for any appropriate purpose, such as confirming that the pedicle screws 120 are positioned in a selected or predetermined position. During image data acquisition, particularly after placement of the pedicle screws 120 a, 120 b, distortions or artifacts in the images 64 may hinder or slow down confirmation of the correct or accurate position of the pedicle screws 120 in the vertebra 124. Therefore, as discussed further herein, selected processes may be used to reduce and / or correct distortions or errors in the acquired image data before generating the images 64, which may include reconstructions, such as three-dimensional reconstructions, based on one or more projections of the subject 14 acquired using the imaging system 12.

[0047] Go to Reference Figure 4, process or flowchart 200 illustrates an efficient process for removing or processing artifacts in a projection and subsequent reconstruction (e.g., image 64) of a subject 14 for viewing by a user 54. Process 200 allows for efficient (including low computational time and / or required resources) generation of an image 64 for viewing by the user 54 that is free of artifacts and / or shows clear or high-contrast edges of a selected object. In various embodiments, the selected object may include a pedicle screw 120 positioned within a vertebra 124. In various embodiments, process 200 can be used to reduce the computational time for generating a reconstruction having a repaired object as discussed herein to less than approximately three minutes, including less than approximately two minutes. Removal of artifacts can allow for more accurate and clear imaging and / or differentiation between selected objects, such as the pedicle screw 120, and surrounding areas, such as the vertebra 124. It will be understood that the positioning of the pedicle screw 120 within the vertebra 124 is exemplary, and that contrast and / or distortion may occur between any dissimilar materials. Therefore, unless expressly noted otherwise, the discussion herein of the pedicle screw 120 with respect to the vertebra 124 is illustrative.

[0048] Furthermore, it should be understood that the pedicle screw 120 can be formed from one or more selected materials (e.g., a metal or metal alloy) that affect the X-rays when generating the X-ray image data in a manner that causes distortion or artifacts relative to the X-rays used to generate the image data of the vertebra 124. Thus, when generating the image 64 for display on the display device 66, the process 200 can be used to remove or process artifacts in the image data. It should be further understood that the pedicle screw 120 or other selected article can be formed from or include a variety of materials.

[0049] Continue to refer Figure 4 , process 200 is understood to be an image analysis and / or reconstruction process 200 that can be performed alone and / or as part of a selected procedure (e.g., a surgical procedure that includes positioning a pedicle screw 120 in a vertebra 124). Thus, process 200 can also be an algorithm, or include an algorithmic portion, that can be executed by a selected processor or processor system (e.g., imaging processing unit 58 discussed above). However, it should be understood that any suitable processing system can be used to perform process 200 to generate images for display on display device 66.

[0050] Process 200 can be incorporated into other procedures, such as surgical procedures that include placement of selected items, such as pedicle screws 120. Thus, the selected procedure can include starting the procedure in block 204, followed by preparing the subject for surgery in block 206. Preparing the subject for surgery in block 206 can include pre-planning or selecting a position for the pedicle screws 120 or other suitable implant within the subject 14. Such pre-planning or pre-planning can include acquiring pre-operative imaging data of the subject 14 and planning the position of the pedicle screws 120 within the vertebra 124. Further, preparing the subject can include: moving the subject 14 to an operating room on the support 72; making an incision in the subject 14; positioning instruments relative to the subject 14; or other appropriate surgical steps.

[0051] After preparing the subject for surgery in block 206, placement of the selected article within the subject in block 208 may be performed. As discussed above, exemplary embodiments may include positioning a pedicle screw 120 in a vertebra 124, such as Figure 2 The pedicle screw 120 may be any suitable pedicle screw, such as the CD pedicle screw sold by Medtronic, Inc. having a place of business in Minnesota, USA. or Spinal or pedicle screws.

[0052] Additional references Figure 5 , the pedicle screw 120 can include selected portions, such as a first handle portion 120' positioned within a vertebra and / or a second portion 120". such as a head or a universal joint head that is movable relative to the handle. However, it should be understood that the pedicle screw 120 can be any suitable type of pedicle screw positioned within a patient's body. It should be further understood that the selected item positioned in box 208 need not be a pedicle screw, but can be any suitable type of item positioned relative to the subject 14 or any other suitable portion. Typically, the selected item, such as the pedicle screw 120, is formed of a different material (e.g., metal) than the portion in which the selected item is placed, such as the vertebra 124 (e.g., bone tissue).

[0053] After positioning the selected item in block 208, process 200 may be used to help generate a selected or appropriate reconstruction for viewing by user 54. Process 200 may include or begin with acquiring a projection including the selected item in block 220. The acquisition of the projection in block 220 may include acquiring a two-dimensional projection of subject 14. The acquisition may be a real-time image data acquisition, a recall of image data, or a combination of both. Figure 5The projections obtained may include the projections shown in parts (a), (b), and (c). The projections may include the vertebra 124 and the pedicle screw 120.

[0054] like Figure 5 As shown, a pedicle screw 120 is schematically or exemplarily illustrated. The pedicle screw 120 can include various features, such as a stem 120', a head 120", and other portions. The stem 120' can include threads or other features to allow for fastening or connection to a vertebra 124. The head 120" can include additional features, such as a U-shape, and can be movable relative to the stem 120'. The head 120" can then be secured to the stem 120' in a selected manner, such as with a set screw or nut. It should be understood that the stem 120' and the head 120" can be formed of the same material or different materials, such as two different metal alloys or a metal and a polymer.

[0055] However, the pedicle screw 120 can be positioned in the vertebra 124, and images of the vertebra 124 and the screw 120 positioned therein can be acquired. Figure 5 As shown in part (b), one or more of the pedicle screws 120 can be positioned within the patient's body, such as within a vertebra 124. Figure 5 As shown, an image of vertebra 124p is shown, and an image of pedicle screw 120p is shown. The projections may include two-dimensional projections generated by imaging system 12 in the field of view. However, it should be understood that a plurality of projections of subject 14 may be generated in the field of view including vertebra 124 and pedicle screw 120, for example, including approximately 360 projections. However, any appropriately selected number of projections may be acquired and included in process 200. For example, the projections in (b) are represented as theta (θ) = 180 degrees (°) and may therefore be projections acquired at 180° from the origin or starting point.

[0056] As discussed further in this article, Figure 5The projections shown may include multiple projections acquired in any suitable manner. For example, as discussed above, process 200 may be performed using image processing unit 58. Thus, imaging system 12 may generate or collect image data including the projections, and the image data may be immediately processed using imaging processing unit 58. Alternatively or additionally, image data may be acquired using imaging system 12 and then forwarded or transmitted to a selected processing unit or processor. For example, the image data may be transmitted using a coupling such as a wired or wireless protocol, which is stored in a selected storage medium (e.g., a CD-ROM, volatile or non-volatile memory, etc.). Thus, those skilled in the art will appreciate that acquiring the projections in block 220 may include: operating imaging system 12 to acquire image data; receiving image data from a selected memory; or transmitting image data from a selected memory or source to a sourcing unit.

[0057] Regardless of the particular method of acquiring the projections in block 220 that can be further processed, as discussed herein, each of the projections from block 220 may be distorted in the sense that the signal levels recorded by detector 28 are inaccurate. The distortion results in artifacts in the 3D image reconstructed from those projections, such as smearing or shadowing due to the material of the pedicle screw 120 in the field of view that contains the x-ray cone 26x. Figure 5 Part (c) shows a close-up or detail view of the area of ​​interest (AOI) or field of interest.

[0058] The acquisition of the projection in box 220 can comprise a first input to process 200. Additional inputs can comprise known component parameters or known components (KC) in box 226. The known component parameters can be predetermined parameters of a selected item, such as a pedicle screw 120. In various embodiments, for example, the KC can comprise a pedicle screw 120 having a stem 120' and a head 120". The known component parameters can further comprise the type of material of the selected portion of the pedicle screw 120, such as 120' formed of a stainless steel alloy and the head 120". However, it should be understood that the pedicle screw (such as the stem 120') can be formed of other materials, such as titanium or a titanium alloy, a polymer, etc. However, the known parameters in box 226 can comprise characteristics of a selected item, such as a pedicle screw 120.

[0059] The known parameters in box 226 may also include selected dimensions, such as length, width, height, etc. The known parameters in box 226 may further include the number of components or parts of the pedicle screw 120 and the relative geometries of the various components or parts of the pedicle screw. For example, the known parameters in box 226 may include the fixed geometry of the pedicle screw 120 and / or the various possible geometries of the pedicle screw 120. Figure 5 As shown, the pedicle screw 120 includes a stem 120' and a head 120" that are movable relative to each other. Therefore, the known parameters in box 226 may include the range of motion and / or degrees of freedom of motion (eg, possible geometries) of the stem 120' relative to the head 120".

[0060] The known parameters in box 226 may further include known interactions of X-rays with respect to the selected article comprising the pedicle screw 120. The known parameters in box 226 may further include known interactions of X-rays with the stainless steel forming the shaft 120' and the stainless steel forming the head 120". The known parameters in box 226 may further include known interactions of X-rays with titanium or a titanium alloy, a polymer, or other material that may form the pedicle screw 120. The known interactions of the KC may include the amount of attenuation, scattering, absorption, or other selected parameters of the X-rays relative to the material of the pedicle screw 120. The known component parameters may be determined through testing prior to process 200 and saved for further access. Further, the KC may relate to a specific article, such as a pedicle screw 120, that is entered or used to select a specific KC (including a single KC) in box 226.

[0061] Known component parameters, also referred to as parameters of a component or object (e.g., pedicle screw 120), can be defined in various ways (including precise values, as discussed above) and / or defined or determined during a selected procedure. The precise values ​​or parameters can be based on the specifications of the object (e.g., predetermined and / or known technical specifications of the object). The specifications of the object can include features, such as those identified above, including length, diameter, interaction with a multi-energy x-ray beam, or other features. These values ​​can be precise or nearly precise, such as knowing the precise width or range of length, diameter, etc., such as within a selected tolerance. However, in various embodiments, the parameters can also be determined or defined during a selected procedure. As discussed herein, the object can be identified or registered in the projection based on the selected procedure further discussed herein. During the registration process, the object can be parametrically defined and / or determined on the acquired projection. By defining the parameters during the registration process, the parameters (including length, diameter, etc.) can be determined during the selected procedure. These may be based on analysis of the images, or may need to be based on projections of selected known or assumed interactions with the x-ray beam or other features. Thus, the parameters may be predetermined as discussed above and as indicated herein and / or determined during the registration process by analyzing image data acquired in the projections.

[0062] Thus, in various embodiments, the known component parameters in box 226 may be a representation of a selected item, such as a lookup table, comprising the pedicle screw 120. Further, the known parameters in box 226 may comprise a selected specific model, such as a computer-aided design (CAD) model of the pedicle screw 120, including its known materials and its known interactions with X-rays. In various embodiments, the pedicle screw 120 is a CD The pedicle screw may be implanted, and the known component parameters in block 226 may include a CAD model of a specific pedicle screw (including a specific model number and / or its geometry and dimensions) or a deformable spline model (such as a spline model of a cylindrical wire, needle, or rod), as well as known materials, known interactions of materials, etc. The known parameters in block 226 may then be accessed (e.g., recalled by the processing unit 58 ) for use in further portions of process 200 .

[0063] Continue to refer Figure 4Once the projections are acquired in block 220 and the known parameters are acquired or accessed in block 226, registration, also referred to as known component (KC) registration, may occur in sub-block or sub-process 240. The KC registration in block 240 may include various steps or processes, including forward projection in block 250. As discussed further herein, the forward projection in block 250 may then be compared to the projection in block 260. Based on the comparison in block 260, a similarity metric (GC) may be determined in block 270. The comparison in block 260 may then be optimized in block 280 to obtain the similarity metric in block 270. Specifically, the optimizer block 280 may generate a transformation that is again applied to the forward projection in block 250 to determine the similarity metric in block 270 based on the comparison in block 260. Thus, the KC registration in block 240 is an iterative process until the optimizer in block 280 determines an optimized transformation.

[0064] An optimized transformation may be converged, where the difference between the forward projection in block 250 and the projection in block 260 is small or with the selected similarity metric in block 270. The transformation is determined to have converged or optimized to an optimized transformation in the selected transformation of the similarity metric. and can be used in a reconstruction process 290. The reconstruction process 290 is understood to be a sub-process of the artifact or noise reduction process 200. The reconstruction process 290 will be discussed further herein and, briefly, typically combines the acquired projections from block 220 with the optimized or converged transform from block 280.

[0065] Returning to the KC registration process 240, the KC registration process 240 includes registering the known component from box 226 with a selected number of projections (including less than or all of the acquired projections from box 220), which can be used for subsequent reconstruction in the reconstruction subprocess 290. Specifically, the KC registration attempts to determine the portion of the acquired projections from box 220 that matches the known component in box 226. For example, one or more pixels in one or more of the projections are generated by a selected item (e.g., a pedicle screw 120) located within the subject in box 208 and should therefore match the forward projection of the known component from box 226. For example, as discussed above, the pedicle screw 120 can have precise parameters that define the known component parameters in box 226. Therefore, the known parameters represented by k can be input. The digital radiograph reconstruction or digitally reconstructed radiograph (DRR) forms the forward projection in box 250 and can be defined by Equation 1 (Eq. 1):

[0066]

[0067] In Eq.1, the forward projection is the projection of the known component. Specifically, Eq. 1 contains the DRR formed by the input known parameters κ from block 226, which may include a mesh model of the selected item, along a ray incident on the transformed KCK. Therefore, the forward projection A digitally reconstructed radiograph (also referred to herein as a mask) based on the known component parameters κ from block 226 can be compared to the acquired projections (also referred to herein as p). One or more selected transformation models (T) can be employed, such as a rigid homogeneous transformation or a deformable b-spline function. Typically, only one transformation model can be selected in any particular application, but a variety of suitable models or transformations (T) can be selected. Further, the selected parameters k can be included in the optimization process, for example, to model the unknown diameter of a tool having a cylindrical profile.

[0068] The forward projection as defined in block 250 may be compared in block 260 with the acquired projection p from block 220. The comparison in block 260 may allow for the output of a similarity metric, which in various embodiments is defined as gradient correlation (GC). While GC is a suitable similarity metric according to equation 2 (Eq. 2), it should be understood that other similarity metrics may also be used. However, with respect to GC, Eq. 2 includes:

[0069]

[0070] And Eq. 3:

[0071]

[0072] GC is usually forward projected in block 250 and the projections acquired in block 220 (also known as high contrast regions or edges). According to Eq. 2 and Eq. 3, GC is defined as the sum of the normalized cross correlations (NCCs) of the orthogonal image gradients. For example, NCC defines the sum of the image p and Correlation of the normalized intensities of the image gradients a and b, respectively. Thus, as shown in Eq. 2, GC is the sum of the gradients between the forward projection from block 250 and the acquired projection from block 220.

[0073] The optimizer in block 280 is then used to determine whether a convergent transformation has been found or achieved. Specifically, convergence is defined by Equation 4:

[0074]

[0075] The equation can be iteratively solved between the forward projection in block 250 and the acquired projection from block 220. Eq. 4 is used to determine the maximum similarity between the forward projection in block 250 and the acquired projection in block 220. The iteration is performed by determining GC in block 270 based on the comparison in block 260 and then transforming the forward projection from the optimizer in block 280 into a different forward projection in block 250. Thus, for example, when the average change in T is less than about 0.01 millimeters (mm) to about 0.2 mm (inclusive) and about 0.01 degrees to about 0.2 degrees (inclusive), the optimizer block can determine whether the similarity metric in block 270 is the same or has been optimized and / or is within a selected change threshold. The threshold may also or alternatively include or when the change in the similarity metric GC approaches the machine precision used to represent floating point numbers (such as the image processing unit 58).

[0076] If the optimizer in block 280 determines that the threshold has not been reached, then a no path 282 may be followed to the forward projection block 250. The forward projection may then be modified (e.g., determined at a different angle relative to the known components in block 226) to form a new forward projection for comparison with the acquired projection from block 220. If the optimizer block 280 determines that convergence has been achieved (e.g., the difference from the current GC is within a threshold relative to the previous GC), then the converged or optimized transformation It can be output via path 284.

[0077] Suitable optimization techniques, such as those performed by processing unit 58 or other suitable processing units, can be used in optimizer block 280. In various embodiments, a covariance matrix adaptation evolution strategy can be used to achieve optimization. The selected strategy can include a random derivative-free optimization method. However, it should be understood that other suitable optimization methods or techniques can be used in optimizer block 280.

[0078] Once the optimized transformation is outputted by the path 284, the optimized transformation This can be used to modify the projections acquired in block 220. The projections acquired in block 220 can be modified according to any suitable process, including processes discussed further herein. In various embodiments, a repair performed in a selected manner can be performed in a modification block 310, discussed further herein. The repair can include commonly known digital repairs, such as interpolation-based repair of the acquired projections. During interpolation-based repair, pixels or voxels identified as being part of a component or object (e.g., pedicle screw 120) can be replaced with pixels or voxels of a selected type or manner. For example, the pixels identified based on the above-described process 200 can be replaced with a selected model or graphical representation of the object (e.g., pedicle screw 120). Additionally or alternatively, the identified pixels or voxels can be replaced with a selected color or feature that has been identified as an object in the acquired projections. In addition to direct repair from the selected model, interpolation can also be determined or identified, or pixels at the edge or between identified object pixels or voxels or unidentified pixels or voxels can be replaced. Additionally, a selected amount of noise (eg, an optional random noise component) may be added to the inpainted voxels or pixels to selectively characterize the representation of the object in the projection.

[0079] In addition to direct and / or interpolation-based inpainting, various other processes can be used to assist or preform inpainting. For example, a machine learning process or system can be used to perform inpainting on the projection. For example, the pixels or voxels identified in process 200 can be inpainted based on prior training of a machine learning system. For example, a neural network (e.g., a deep learning system) can be used to determine the pixels or voxels to inpaint based on training of previously determined object projections and identification of objects on the projections and inpainting therein. Thus, in various embodiments, inpainting can replace voxels or pixels in the projection according to an appropriate system such as an interpolation or machine learning based system.

[0080] The modification of the projection in box 310 can also include determining or estimating pixel values, such as using a selected modeling of an imaging system such as an x-ray beam to measure or calculate pixel or voxel values. As discussed above, the x-ray beam can include x-rays emitted by the emitter 26. The x-rays in the emitted beam can be polyenergetic, such as comprising a spectrum. Therefore, the emitted x-rays may not only have a single frequency or power. The polyenergetic x-ray beam can interact with the material in a known manner based on the polyenergetic nature of the x-ray beam. As discussed above, the interaction can be understood based on the known components of the various x-ray components (defined by the x-ray spectrum) with the object in the projection. Therefore, the determined pixel values ​​based on the known polyenergetic model of the x-ray beam can be used to generate pixel or voxel values ​​in the projection, and therefore can be used to replace the determined pixels in the projection.

[0081] As discussed above, the projection can be modified in various ways and with appropriate processes. The discussion of repair herein is merely exemplary and is not intended to limit the scope of the subject disclosure of the appended claims. Thus, modification can include repairing the projection acquired in block 220 at the modification (e.g., repair) block 310. The repair block 310 is the first process or step of the reconstruction process 290. The reconstruction process 290 can also be referred to as a metal artifact reduction or removal (MAR) process. Thus, MAR reconstruction can be used to reduce or remove artifacts caused by selected items such as pedicle screws 120. By reducing metal artifacts or other selected artifacts in the repair block 310, the artifacts are removed for subsequent reconstruction. The reconstruction can include or be based on a backprojection reconstruction including filtered backprojection (FBP). In various embodiments, the backprojection can be a three-dimensional (3D) projection in block 320. Reconstruction occurs in block 330, which can form a reconstruction of the image 64 for viewing on the display device 66.

[0082] Continue to refer Figure 4 and Figure 5 , the restoration template 310 uses the optimized transformation to restore the acquired projection from the block 220. As shown in the process 200, the projection (p) is restored using the optimized transformation or the converged transformation is input to the repair block 310. In the repair block 310, the surrounding pixels of the projection (p) can be used to interpolate the area identified by the forward projection of KC. Alternatively, the optimized transformation from the optimizer block 280 can be used to The forward projection is placed at the registration position The DRR that takes into account the various effects of x-ray and metal interactions is mapped into the acquired projection (block 220). In other words, based on the known material interactions with the x-rays contained in the forward projection, the selected multi-energy signal model, which is informed by the KC model of component shape and material content, can be used to map into the acquired projection (block 220) at the registered location. Therefore, in the repair block 310, the pixels in the acquired projection (block 220) that match or have the largest similarity measure with the forward projection from block 250 are replaced with the forward projection from block 250.

[0083] As mentioned above, reference Figure 5 , the projection from box 220 or one of the projections contains the vertebra 124p and the imaged screw 120p. Once the transformation is optimized in box 280, it can be replaced or repaired with the forward projection from box 250 Figure 5 The forward projection of the screw 120p is optimized or best matched in part (b). Figure 5As shown in part (e), the repaired screw 120ip (shown schematically by dashed lines in part (f)) can be repaired or used to replace the screw 120p in the projection and replace the screw in the image (including vertebra 124p). As discussed above, the acquired projections in box 220 can include one or more projections from the projections acquired from subject 14. In various embodiments, the number of projections can include three projections, six projections, all projections, or any appropriate number. In various embodiments, the acquired projections in box 220 can include six projections that are offset or shifted from each other by 30 degrees (or any appropriate selected angle theta (θ)) around subject 14. The similarity metric in box 270 and the optimized transformation in box 280 can be applied to only a portion or a selected number of the projections of subject 14. However, it should be understood that the use of the known component parameters in block 226 can minimize or allow for a fast and efficient registration based on the forward projection in block 250 that similarly or most closely matches the actual projection in block 220 due to the known component parameters in block 226. Likewise, the KC parameters can include size, shape, material, and interaction with x-rays. However, the restoration in block 310 can replace the identified screw 120p with the restored forward projection that has been registered thereto, as discussed above. The projection can then become the restored projection such that the projection in block 310 Figure 5 The restored projection in portion (e) includes the restored selected portion or item.

[0084] The restoration in block 310 may also include various optimization or robustness features. For example, the forward projection from block 250 (which may also be referred to as a mask) may be expanded or extended relative to the precise known component parameters from block 226, which are relative to the projection from block 220. In various embodiments, when the restoration is performed on the projection in block 310, the forward projection mask from block 250 may have or be expanded by one or more pixels. The expansion may help overcome errors such as manufacturing variations, geometric calibration of the imaging system, floating precision errors, or other possible errors. As described above, the selected amount of expansion or extension of the mask helps ensure proper positioning or resolve errors. As discussed herein, it may be that the final reconstruction of image 64 will include the dimensions of the KC parameters from block 220 to demonstrate the extent or final position of the pedicle screw 120 in the vertebra 124 for placement (implantation).

[0085] Further, the optimized transformation from block 280 identifies selected items in the projection to be inpainted in block 310. The inpainting process or method may be selected from any suitable method. For example, the inpainting may include linear interpolation of the selected projection. In various embodiments, the linear interpolation is achieved by generating a Delaunay triangulation (e.g., the Quickhull algorithm disclosed in Barber, CB, Dobkin, DP, and Huhdanpaa, HT, "The Quickhull algorithm for convex hulls," ACM Trans. on Mathematical Software, 22(4):469-483, 1996) on the convex hull of the region masked by the identified transformation from block 280 (e.g., using DRR of the forward projection (block 260)), and then performing barycentric interpolation on each resulting triangle. The restoration process (including, in various embodiments, at least one of interpolation-based or model-based using a KC model) is then repeated for all projections (eg, all projections acquired in block 220 ) and measurements in each of the projections input in block 220 .

[0086] Once the modification in block 310 is complete (e.g., including the restoration in the projections from block 220), a reconstruction can be performed using the modified projections in block 320. As discussed herein, the reconstruction can be any suitable reconstruction. The reconstruction can be used for various purposes as discussed herein.

[0087] In various embodiments, the reconstruction in block 320 may include three-dimensional filtered back projection (3D FBP). In an exemplary embodiment, the 3D FBP may include a Feldkamp-Davis-Kress algorithm reconstruction method generally known in the art. However, it should be understood that other suitable reconstruction (e.g., alternative back projection) methods may be used.

[0088] In addition to and / or in place of filtered back projection, iterative reconstruction can also be performed. The iterative reconstruction can include a model-based iterative reconstruction (MBIR) algorithm. The iterative reconstruction can include iteratively changing the parameters of the model to achieve or minimize the difference between the model and the modified projection from block 310. For example, a model of an object such as a pedicle screw 120 can be identified, and the projection through the model can be iteratively changed to match the modified projection from block 310. When a match is achieved, the model can be used to help reconstruct the model projection.

[0089] Based on the back-projection from block 320, the reconstruction process 290 may output a reconstructed image in block 330. The reconstructed image may be a reconstructed visual display. The visual display may be displayed as an image for viewing, such as by the display device 66.

[0090] The reconstruction output in block 330 may be referred to as a KC-MAR reconstruction and / or a visual display (e.g., a KC-MAR reconstruction visual display). The output, including the visual display, may include or be represented as an image 64 for display on a display device 66 for viewing by a user 54. The reconstruction may include a three-dimensional reconstruction and / or the back projection may be presented as an image for viewing by the user. Figure 6 In row A, the back projection of the uncorrected acquired projection in box 220 is shown. In row B, the reconstruction using process 200 including KC registration 240 and reconstruction process 290 is shown. Figure 6 As clearly shown in FIG, row B with the registered known components repaired reduces metal artifacts or selected distortions. Distortion reduction allows viewing or reconstructing a visual display that includes sharper or higher contrast edges with reduced or minimized smearing and other artifacts in the reconstruction.

[0091] like Figure 6 , row B, the reconstructed visual display may also include selected information based on the known component from box 226. As discussed above, the repair in box 310 may be repaired using a mask from the forward projection in box 250. The forward projection in box 250 includes the known component parameters from box 226. Thus, the repair may include various geometric configurations, such as size, shape, and configuration, and the forward projected mask from box 250 may also include differentiation of materials due to different attenuation due to different materials of the known component. For example, as discussed above, the head 120" of the pedicle screw 120 may be a different material or formed from a different material than the stem 120'. Thus, Figure 6 , the reconstruction in row B can differentiate between reconstructed portions of different materials, such as due to grayscale. Thus, in various embodiments, the reconstructed projection of the head 120″r can have a different or altered grayscale or visual effect than the stem 120′r. This is at least partially due to the fact that the forward projection from block 250 is based on known component parameters. The KC parameters in block 226 can be an exhaustive list of known components, such as the pedicle screw 120.

[0092] Since the known component parameters may include size and geometry, and also material, each effect may be known and applicable to forming the forward projection and the restoration of block 310. Moreover, as discussed above, the known components and their effects on the x-ray projections may be predetermined and known and may be saved and recalled for the forward projection in block 250 and the restoration in block 310. Thus, the back-projection reconstruction in block 320 and the reconstructed visual display or output in block 330, respectively, may also be based on the known component parameters from block 226.

[0093] The reconstructed visual display or the visual display in box 330 can be generated in a variety of formats and / or selected by the user from one or more options. The visual display can include a direct reconstruction of the modified projection from box 310. For example, the reconstruction from box 320 can be displayed for viewing by user 54. As discussed above, the reconstruction can include incorporating the modified projection directly into the reconstructed projection. The multiple projections or the selected multiple projections can be used to generate a three-dimensional (3D) model or visual display for viewing by user 54. Thus, the visual display in box 330 can be a direct visual display or a visual display of the direct reconstruction from box 320.

[0094] In various embodiments, the visual display may also and / or alternatively include pictures or image elements (e.g., voxels or pixels) that coincide with the registered object in the modified projection from block 310. For example, as discussed above, once the object is registered, the projection may have coincident or registered pixels or voxels because the object is replaced with selected other pixels or voxels. For example, the registered voxels in the visual display in block 330 may be replaced with a selected color, gradient, or type of pixel or voxel. Accordingly, since pixels or voxels associated with the registered object may be replaced, an additional or alternative visual display may not be required or generated.

[0095] As a further alternative and / or additional visual display, selected slices or 2D portions can be displayed relative to selected features or parameters of the object. For example, once an object has been identified or registered in a projection (e.g., a pedicle screw 120), slices containing and / or coinciding with the object can be oriented or re-oriented and displayed in a selected manner, such as along the long axis of the object. For example, Figure 6 As shown, the illustration or visual display for display can be oriented so that the long axis 102L of the screw 120 is used to orient the visual display. Thus, the long axis 102L can be used to orient the image vertically, and if multiple slices or 2D images are displayed, all of them can be displayed substantially parallel.

[0096] As a further alternative and / or in addition, a graphical representation can be superimposed or overlaid on a selected image. For example, as discussed above, the object can include a pedicle screw 120. Further, the object can be determined and / or identified based on known components of a model that can include the object. Thus, a selected portion or version of the object (such as its representation or appearance) can be displayed relative to the image. For example, in various embodiments, the graphical representation can be overlaid or superimposed on the image at the registered location of the object.

[0097] Thus, the visual display in frame 330 can comprise any suitable visual display. The visual display can be based on the registered or known position of an object, such as a pedicle screw 120, in the acquired projections. The visual display, such as image 64, can then be displayed on display device 66 for viewing by user 54 for various purposes. Thus, in various embodiments, small artifacts can be reduced in visual display frame 330 so that user 54 can view visual display 64 on display device 66 with significantly reduced and / or eliminated distortion or artifacts in the image, such as those caused by metal or other components.

[0098] In view of the above, the final reconstruction and / or reconstructed visual display in block 330, which can be displayed as image 64 on display device 66, can have significantly reduced or eliminated artifacts due to the altered attenuation or distorted attenuation of X-rays from imaging system 12 used to image subject 14. In addition, known component parameters 226 can help enhance registration in block 280, such as by efficiently and more clearly defining the components used to form the forward projection in 250, making the registration faster. Moreover, the known component parameters from block 226 can further help reduce artifacts and distortions due to the predetermined and known effects of the components used for repair in block 310. Thus, based on process 200, which can be performed by a processing system such as image processing unit 58 discussed above, the final reconstructed image in block 330 is efficiently and quickly generated.

[0099] Example embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those skilled in the art. Many specific details, such as examples of specific components, devices, and methods, are set forth to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that the example embodiments may be embodied in many different forms, and that neither should be construed as limiting the scope of the present disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0100] The foregoing description of the embodiments has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable where applicable and can be used in selected embodiments, even if not specifically shown or described. The same can also be varied in many ways. Such variations are not to be considered as departing from the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.

[0101] In one or more examples, the described techniques can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions can be stored as one or more instructions or codes on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media can include non-transitory computer-readable media, which corresponds to tangible media, such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).

[0102] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Thus, the term "processor," as used herein, may refer to any of the foregoing structures or any other physical structure suitable for implementing the described techniques. Furthermore, the techniques may be fully implemented in one or more circuits or logic elements.

Claims

1. A method for reducing artifacts caused by objects in an image, the method comprising: Access the parameters of the object; creating at least one forward projection of the object based on the accessed parameters; registering the object in the forward projection with at least one acquired projection having the object therein, wherein the at least one forward projection of the object and the at least one acquired projection having the object therein comprise two-dimensional projections; modifying the at least one acquired projection into a representation of the registered object; as well as A reconstruction is generated based on the modified at least one acquired projection. 2 . The method of claim 1 , wherein modifying the at least one acquired projection comprises repairing the representation of the object in the at least one acquired projection.

3. The method according to claim 1, further comprising: Get multiple projections; modifying at least a first sub-plurality of the acquired plurality of projections into the representation of the registered object; Wherein generating the reconstruction comprises generating the reconstruction based on all acquired projections of at least the first sub-plurality of acquired projections of the acquired plurality of projections. 4 . The method of claim 3 , wherein generating the reconstruction based on at least all of the acquired projections in the modified first sub-plurality of the acquired plurality of projections comprises generating a three-dimensional image.

5. The method according to claim 4, further comprising: The reconstructed visual display is generated for display on a display device.

6. The method of claim 5, wherein generating the visual display comprises at least one of: generating a direct reconstruction of modified projection values ​​of the modified first sub-plurality of acquired projections; replacing voxels or pixels coinciding with the registered object in the modified first sub-plurality of acquired projections; orienting the visual display so that the 2D slice coincides with at least one feature of the object; superimposing a graphical representation of the object on a display of at least one of the acquired plurality of projections; or Its combination.

7. The method of claim 4, wherein the generated reconstruction is based on at least one of: filtered backprojection, a model-based iterative reconstruction process, or a combination thereof.

8. The method according to claim 1, further comprising: Determining the parameters of the object comprises at least one of: geometry, number of parts, size, material, interaction of X-rays with the material, degrees of freedom of movement of the object, or a combination thereof.

9. The method of claim 8, wherein creating the at least one forward projection of the object based on the accessed parameters comprises creating a digitally reconstructed radiograph of the object.

10. The method of claim 8, wherein the determined parameters comprise at least one of: precise values ​​based on specifications of the object, parameters defined parametrically of the object, or a combination thereof.

11. The method according to claim 10, wherein parameters of the parametric definition of the object are determined during registration of the object in the forward projection with at least one acquired projection having the object therein.

12. The method of claim 1, further comprising: At least one projection of a subject and the object is acquired, wherein the object is located within the subject.

13. The method of claim 1 , wherein modifying the acquired projection according to the representation comprises at least one of: Performing interpolation-based restoration on the acquired projection; Machine learning-based remediation using prior training; or Multi-energy modeling of the x-rays in the x-ray beam is used to determine estimated pixel or voxel values.

14. The method of claim 1, further comprising: A visual display is generated based on the generated reconstruction, wherein artifacts in the generated visual display caused by the object in the at least one acquired projection are reduced based on the modified at least one acquired projection.

15. A system for reducing artifacts caused by objects in an image, the system comprising: A processor system configured to execute instructions for: Access the parameters of the object; creating at least one forward projection of the object based on the accessed parameters; registering the object in the forward projection with at least one acquired projection having the object therein, wherein the at least one forward projection of the object and the at least one acquired projection having the object therein comprise two-dimensional projections; modifying the at least one acquired projection into a representation of the registered object; as well as generating a reconstruction based on the modified at least one acquired projection; as well as A display device is provided for displaying a visual display based on the generated reconstruction.

16. The system of claim 15, wherein the processor system is further configured to: Access multiple projections; and modifying at least a first sub-plurality of the acquired plurality of projections into the representation of the registered object; Wherein generating the reconstruction comprises generating the reconstruction based on all acquired projections of at least the first sub-plurality of acquired projections of the acquired plurality of projections.

17. The system of claim 16, wherein generating the reconstruction based on at least all of the acquired projections in the modified first sub-plurality of the acquired plurality of projections comprises generating a three-dimensional image.

18. The system of claim 17, wherein the processor system is further configured to: Generating the visual display for display on the display device, the generating comprising at least one of the following: generating a direct reconstruction of modified projection values ​​of the modified first sub-plurality of acquired projections; replacing voxels coinciding with the registered object in the modified first sub-plurality of acquired projections; or orienting the visual display so that the 2D slice coincides with at least one feature of the object; superimposing a graphical representation of the object on a display of at least one of the acquired plurality of projections; or Its combination.

19. The system of claim 15, wherein the processor system is further configured to: Determining the parameters of the object includes all of the following: geometry, dimensions, material and interaction of X-rays with the material of the object.

20. The system of claim 15, further comprising: said object located within the subject; and Wherein the at least one projection is a projection of the subject and the object.

21. A method for reducing artifacts caused by objects in an image, the method comprising: Operate the processor system to: Access the parameters of the object; creating at least one forward projection of the object based on the accessed parameters; registering the object in the forward projection with at least one acquired projection having the object therein, wherein the at least one forward projection of the object and the at least one acquired projection having the object therein comprise two-dimensional projections; modifying the at least one acquired projection into a representation of the registered object; as well as generating a reconstruction based on the modified at least one acquired projection; Show a visual display of the generated reconstruction.

22. The method of claim 21, further comprising operating the processor system to generate the visual display.

23. The method of claim 21, further comprising operating the processor system to access the acquired at least one projection of a subject and the object, wherein the object is located within the subject.

24. The method of claim 23, further comprising operating the processor system to: accessing a plurality of projections of the subject and the object; modifying each of the plurality of projections accessed; and Wherein generating the reconstruction is based on the modified at least one acquired projection and the modified each projection of the accessed plurality of projections.

25. The method of claim 21, further comprising: The parameters of the object are determined including geometry, size, material, and interaction of X-rays with the material of the object.

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