CN115414059A - System and method for image reconstruction - Google Patents

Abstract

The present invention relates to systems and methods for image reconstruction. The present invention provides an imaging system comprising an x-ray image reconstruction system combined with an optical imaging system and/or a tracking system. In some embodiments, the imaging system may include an x-ray image reconstruction system and a three-dimensional optical imaging system, the x-ray image reconstruction system configured to generate three-dimensional image data of at least one interior portion of the target object below the surface of the target object, the three-dimensional The optical imaging system is configured to reconstruct an image of a surface of at least a portion of the target object by generating surface three-dimensional image data. The three-dimensional optical imaging system can be registered to the tomosynthesis image reconstruction system such that the three-dimensional image data from the tomosynthesis image reconstruction system and the three-dimensional image data from the three-dimensional optical imaging system can be used as constraints to improve the object of interest The image quality of the image.

Description

Systems and methods for image reconstruction

This application is a divisional application of Chinese patent application 201780029798.4 entitled "System and Method for Image Reconstruction" filed on March 24, 2017.

Related Patent Applications

This patent application is a continuation-in-part of co-pending U.S. Patent Application Serial No. 14/198,390, filed March 5, 2014, and entitled "IMAGING SYSTEMS AND RELATED APPARATUSAND METHODS" Apparatus and methods), pursuant to 35 U.S.C. § 119(e) of the United States Patent Act, this patent application claims the right to the following patent: U.S. Provisional Patent Application Serial No. 61/773,025, filed at March 5, 2013, and titled "IMAGING SYSTEM". Pursuant to Title 35, United States Patents, Section 119e, this patent application also claims the right to the following patent: U.S. Provisional Patent Application No. 62/313,041, filed March 24, 2016, and titled "SYSTEMS AND METHODS FOR IMAGE RECONSTRUCTION" (system and method for image reconstruction). The aforementioned patent applications are hereby incorporated by reference in their entireties.

Statement of Government Support

This invention was made with government support under SBIR Grant No. 1456352 awarded by the National Science Foundation. The government has certain rights in this invention.

Contents of the invention

Surgeons and interventional radiologists use medical imaging to guide them in procedures known as image-guided interventions (IGI). In surgery, IGI is most often performed with a C-arm.

The C-arm is an intraoperative x-ray system that creates real-time 2D projection images. This imaging modality is called fluoroscopy. C-arms are popular because they are economical and their use does not prolong the procedure.

Another alternative option is to use an intraoperative x-ray 3D imager. These 3D imagers include CT scanners, or cone beam CT (CBCT) scanners, or C-arms. These systems provide a 3D representation of the anatomy, which can be extremely valuable for complex anatomy, or where precise 3D localization is important (eg, for oncology and/or spinal surgery). Such 3D images are static, and the system needs to be coupled with a navigation system to simulate real-time imaging. Navigation systems can also be used with preoperative imaging.

However, although these 3D imagers provide superior visibility compared to fluoroscopy, it also has disadvantages. First, it complicates and prolongs the time required for surgery. Additionally, intraoperative scanners surround the patient and make it difficult for the surgeon to access the anatomy being imaged, and the CBCT's C-arm has moving parts that can interfere with the patient, user, and/or bystanders (surgeon as well as staff) ).

Some methods, devices, and systems disclosed herein relate to intraoperative x-ray scanning. In some embodiments, these methods and systems can advantageously provide rapid 3D reconstruction (near real-time), which does not require the use of surgical navigation systems. In some embodiments, the system can have an open geometry, allowing the user to access the anatomy during imaging, which can improve surgical procedures, and/or improve integration with other systems. Alternatively or in addition, some embodiments may be configured to avoid having any exposed moving parts—that is, for example, any exposed parts that move during the imaging process that could cause injury to the patient, user, and/or bystanders .

In some embodiments, a system may include: a) a gantry for moving a plurality of radiation sources through one or more paths; and b) one or more radiation detectors for Can be configured to move relative to the patient and/or pathway, or can be stationary relative to the patient and/or pathway. In some embodiments, one or more of the paths may comprise a continuous path. The one or more paths may include, for example, a path over which the radiation source moves continuously in a single direction. Thus, multiple paths of multiple radiation sources may overlap in whole or in part. In other embodiments, one or more of the paths may be an oscillating path (ie, the radiation source oscillates along one or more paths), and need not overlap any other path in other radiation sources.

In other embodiments, a single mobile radiation source may be provided. For such embodiments, the mobile radiation source may be configured to move within an enclosed source gantry or other such enclosure configured so as to avoid having any exposed moving parts during imaging. It should be understood, however, that one or more features or components of such systems may be configured to move between imaging sessions, for example, to allow for proper positioning of a patient. Such systems should still be considered constructed to avoid having any exposed moving parts during imaging.

In the case of the source gantry, the detection device may be placed on the opposite side/hemisphere of the source gantry relative to the patient. The system may also include: c) a processor for repeatedly sampling the radiation detector as the plurality of radiation sources are moved to generate a plurality of radiation absorption images for each radiation source; and d) a computer and computing A program that applies a reconstruction algorithm to a radiation absorption image to generate a 3-dimensional reconstruction of a region of interest of the subject. The computing program may be configured to update the 3-dimensional reconstruction (or related information/information related thereto). The system may also include: e) a display or interface that provides 3D dataset information (or related information/extracted therefrom) to the user.

A method may be performed to create a three-dimensional and time-varying reconstruction of a region of interest of an object. In some implementations, a method can include acquiring a radiation absorption image of a subject region of interest by passing a plurality of radiation sources through one or more paths. Radiation absorption images may be acquired by one or more radiation detectors. As multiple radiation sources move, one or more radiation detectors may resample to generate multiple radiation absorption images for each radiation source. The system can iteratively obtain the projected geometry, (eg, by using an encoder, and by "look-up" to previously obtained geometric calibration parameters).

Algorithms, such as reconstruction and/or motion estimation and correction algorithms, can be applied to the radiation absorption image, and the associated projected geometry, to generate a three-dimensional reconstruction of the object region of interest. In some implementations, the reconstruction algorithm may include an iterative reconstruction algorithm and/or a motion estimation and correction algorithm. The three-dimensional image may be updated as new radiation absorption images are acquired by one or more radiation detectors and multiple moving radiation sources. The image, at least a portion of the image, and/or data derived from and related to imaging processing/analysis may be displayed to a user. In some implementations, this step can include displaying on a display, such as a monitor, visual information derived from the three-dimensional reconstruction of the object region of interest.

The subject technology is illustrated, for example, in terms of the various aspects described below. Examples of aspects of the subject technology are described in numbered (1, 2, 3, etc.) clauses for convenience. These are provided as examples only, not limitations of the subject technology. It should be noted that any dependent clauses may be combined in any combination and placed into corresponding independent clauses, eg Clause 1 or Clause 5. Other terms may be set forth in a similar manner.

1. An imaging system for providing image reconstruction data of an object, the system comprising:

an array of at least two radiation sources configured to move along a curved path substantially in a plane; and

Detectors that are not in a plane, the array is configured such that the radiation sources emit radiation towards the detectors in a sequence in which each radiation source emits at substantially the same frequency.

2. The system of clause 1, wherein the curved path of the radiation source is closed.

3. The system of clause 2, wherein the curved path of the radiation source is circular or elliptical.

4. The system of clause 1, wherein the radiation source moves along a curved path.

5. The system of clause 4, wherein the radiation source oscillates along a curved path.

6. The system of clause 4, wherein the radiation sources are configured to move in a first direction along a curved path, and return in reverse towards their respective initial positions.

7. The system of clause 5, wherein the curved path of the radiation source comprises an open curved path.

8. The system of clause 7, wherein the radiation source comprises four radiation sources, and each of the four radiation sources moves along an independent open curved path, each path having an arc of approximately 90°.

9. The system of clause 8, wherein the individual open curved paths collectively form a circular shape.

10. The system of clause 8, wherein the individual open curved paths collectively form an elliptical shape.

11. The system of clause 4, further comprising at least one gantry member housing a radiation source, wherein the radiation source moves within the gantry member while the gantry member remains stationary relative to the detector.

12. The system of clause 4, further comprising at least one gantry member housing the radiation source, wherein the gantry member moves relative to the detector while the radiation source remains stationary relative to the gantry member.

13. An imaging system for providing image reconstruction data of a subject, the system comprising at least one radiation source moving along a curved path within a closed gantry and emitting radiation towards at least one detector, The detector is not coplanar with the curved path along which the radiation source emits radiation at at least two regions.

14. The system of clause 13, wherein the radiation source is configured to move from a first position along the curved path to a second position along the curved path, and reverse direction at the second position to return to the first position .

15. The system of clause 14, wherein the radiation source emits radiation along at least two regions along a curved path when moving towards the second position.

16. The system of clause 14, wherein the curved path of the radiation source comprises an open curved path.

17. The system of clause 13, wherein the curved path of the radiation source is closed.

18. The system of clause 17, wherein the curved path of the radiation source is circular or elliptical.

19. An imaging system for providing reconstructed image data of a subject and for allowing access to the subject while imaging, the system comprising:

at least one radiation source configured to move along a path formed by a first curve and a second curve, the first curve lying substantially in the first plane and the second curve lying outside the first plane;

a radiation detector positioned and configured to receive radiation emitted by the radiation source when the object is interposed therebetween; and

A processor configured to receive radiation absorption data from the detector and apply a reconstruction algorithm.

20. The system of clause 19, wherein the processor comprises two or more processors.

21. The system of clause 19, wherein the second curve lies substantially in the second plane.

22. The system of clause 19, further comprising: using the radiation absorption data to generate the 3D x-ray image.

23. The system of clause 22, wherein the 3D x-ray image of the object is generated as the first radiation source moves along the path.

24. The system of clause 22, further comprising a display for providing a visual representation of the 3D x-ray image of the anatomy.

25. The system of clause 19, further comprising a second radiation source configured to move along a path spaced from the first radiation source.

26. The system of clause 24, wherein the first radiation source and the second radiation source are positioned opposite each other along the path and move at the same speed.

27. The system of clause 24, wherein the detectors include a first radiation detector and a second radiation detector configured to move through the second path, the first radiation detector The second path has a third curve substantially on the second plane, and a fourth curve outside the second plane.

28. The system of clause 19, wherein the path is a generally cylindrical sine wave.

29. The system of clause 19, wherein the path is a generally spherical sine wave.

30. The system of clause 19, wherein the detector is stationary.

31. The system of clause 19, wherein the detector is moved along the second path at a position opposite the first radiation source such that radiation emitted by the first radiation source passes through the object towards the detector.

32. The system of clause 19, further comprising an enclosed gantry for supporting the first radiation source.

33. The system of clause 19, wherein the first radiation source is housed in a generally annular structure.

34. The system of clause 19, wherein the first radiation source and the second radiation source are housed in separate structures.

35. The system of clause 19, wherein the first radiation source and the second radiation source are rotatable through a continuously changing angle.

36. The system of clause 19, wherein the detectors comprise separate first and second detectors.

37. The system of clause 19, wherein the processor is configured to repeatedly sample the detector.

38. The system of clause 19, wherein the path is continuous.

39. The system of clause 19, wherein the path is discontinuous and the first radiation source only moves around a portion of the object.

40. A method for generating x-ray image data of a subject, the method comprising:

moving the first radiation source relative to the object along a path having a first curve lying substantially on the first plane and a second curve lying outside the first plane; and

Projected images of the patient are recorded at different recording angles as the first radiation source moves along the path.

41. The method of clause 40, wherein the second curve lies substantially in the second plane.

42. The method of clause 40, wherein the first radiation source moves along a substantially cylindrical sinusoidal path.

43. The method of clause 40, further comprising moving the second radiation source along the path and spaced from the first radiation source.

44. The method of clause 40, wherein recording the projected images comprises recording projected images at the same frequency.

45. The method of clause 44, further comprising setting the first radiation source at a first energy level, and setting the second radiation source at a second energy level.

46. The method of clause 40, further comprising constructing, by the processor, a 3D x-ray image from the projection image, wherein constructing the 3D x-ray image comprises constructing a 3D x-ray image from the subtracted projection image.

47. The method of clause 46, further comprising subtracting projection images taken at different times from substantially the same location.

48. The method of clause 46, further comprising subtracting projection images taken at substantially the same location at different energies.

49. The method of clause 40, further comprising constructing, by the processor, a 3D x-ray image from the projection image.

50. The method of clause 48, further comprising updating the 3D x-ray image when generating the new subtraction projection image.

51. The method of clause 48, wherein constructing a 3D x-ray image comprises applying a multi-resolution technique to provide a first 3D image having a first resolution, and subsequent images having a higher resolution than the first resolution.

52. The method of clause 48, further comprising displaying the 3D x-ray image on a display.

In an example of an imaging system according to some embodiments of the present invention, the system may include: an x-ray tomosynthesis image reconstruction system and a three-dimensional optical imaging system, the x-ray tomosynthesis image reconstruction system configured to generate at least one internal portion of a target object in Three-dimensional image data below the surface of the target object, the three-dimensional optical imaging system configured to reconstruct an image of at least a portion of the surface of the target object by generating surface three-dimensional image data. The optical imaging system can be registered to the tomosynthesis image reconstruction system. The system may also include a processor configured to apply an image reconstruction algorithm to generate a three-dimensional image of the reconstructed target object. The reconstruction algorithm can be configured to use the 3D image data from the tomosynthesis image reconstruction system, and the surface 3D image data from the 3D optical imaging system as constraints, such as density constraints or geometric constraints, to improve the image of the 3D image data quality, and reconstruct the image of the target object.

In some embodiments, the reconstruction algorithm may include iterative reconstruction techniques.

In some embodiments, the 3D optical imaging system can also be configured to reconstruct an image of at least a portion of the surface of the surgical instrument or implant by generating surface 3D image data for at least a portion of the surface of the surgical instrument or implant. Accordingly, the density constraints may include, at least in part, a density distribution derived from the surgical instrument or implant, and the reconstruction algorithm may be configured to apply the density distribution of the surgical instrument or implant as a constraint to improve image quality of the three-dimensional image data.

In some embodiments, the system can be configured to apply the constraint of zero density in surface three-dimensional image data. In some such embodiments, the target object may include a patient, and a constraint of zero density may be applied to an area outside at least a portion of the surface of the target object and outside at least a portion of the surface of the surgical instrument.

In some embodiments, at least a portion of the constraints may be derived from a priori three-dimensional mass attenuation image registered with at least a portion of the surface of the target object by surface registration.

In another example of the imaging system according to other embodiments, the system may include: an x-ray tomosynthesis image reconstruction system and a three-dimensional optical imaging system, the x-ray tomosynthesis image reconstruction system is configured to generate a region of interest in the target object Three-dimensional image data of the subsurface, the three-dimensional optical imaging system configured to generate three-dimensional image data of the surface of at least a portion of the target object. The optical imaging system can be registered to the x-ray tomosynthesis image reconstruction system, and the three-dimensional optical imaging system can also be configured to generate three-dimensional image data of the surface of the tool to be inserted in the region of interest of the target object, and when the tool is relative to the target object surface As it moves, 3D image data of the tool's surface is generated. The system may also include: a processor and a display configured to compile three-dimensional image data of the tool's surface over time and obtain a trajectory of the tool relative to the target object; the display configured to display at least a portion of the region of interest, and a dynamic to accurately display the trajectory of the tool relative to the region of interest.

In some embodiments, tools may include surgical instruments.

In some embodiments, the system can be configured to allow the user to select a preferred trajectory of the surgical instrument relative to the region of interest, and the processor can be configured to dynamically calculate a variance measure between the preferred trajectory and the trajectory.

In some embodiments, the display can be configured to display at least one of a numerical value corresponding to the variance measure and an image showing both the trajectory and the preferred trajectory.

In some embodiments, the system can be configured to allow the user to select a target within the target object's region of interest and dynamically display the distance between the tool and the target.

In some embodiments, the imaging system can be configured to dynamically adjust the region of interest in response to movement of the tool.

In some embodiments, the imaging system can be configured to dynamically define a region of interest so as to encompass a point adjacent to the distal tip of the tool. In some such embodiments, the imaging system can be configured to dynamically modify the display as the region of interest is defined by movement of the distal tip of the tool.

In an example of a four-dimensional imaging system according to some embodiments, the system may include: an x-ray tomosynthesis image reconstruction system and a tracking system, the x-ray tomosynthesis image reconstruction system configured to generate three-dimensional image data of at least a portion of a target object, the The tracking system is configured to track movement of at least a portion of the target object and generate motion data for a motion model based on the movement of at least a portion of the target object. A processor may also be provided that is configured to generate, over time, a reconstructed three-dimensional image comprising four-dimensional image data of at least a portion of the target object. The reconstruction algorithm may be configured to use the three-dimensional image data from the tomosynthesis image reconstruction system and to generate four-dimensional image data using the motion data from the tracking system.

In some embodiments, the motion model may include the use of rigid transformations.

In some embodiments, the tracking system can include a three-dimensional tracking system. In some such embodiments, the tracking system can include a three-dimensional imaging system. The three-dimensional imaging system may be configured to use motion data from the three-dimensional imaging system to generate movement for reconstructing the three-dimensional image.

In some embodiments, the tomosynthesis image reconstruction system can also be configured to generate motion data based on movement of at least a portion of the target object, and the imaging system can be configured to combine the motion data from the tracking system with the tomosynthesis image from the tomosynthesis image The motion data of the reconstruction system is used to generate a reconstructed three-dimensional image of the movement.

In yet another example of an imaging system according to some embodiments, the system may include a three-dimensional tracking system and an x-ray tomosynthesis imaging system, the three-dimensional tracking system being configured to generate a first data layer including a tool or implant The x-ray tomosynthesis imaging system is configured to obtain projection image data of at least a portion of the target object and a tool or implant moving relative to the target object. The 3D tracking system can be registered to the tomosynthesis imaging system. The system may also include a processor configured to generate the second data layer by the three-dimensional tracking system and generate projection image data by the tomosynthesis imaging system. In some embodiments, the processor is configured to use a reconstruction algorithm to separately reconstruct the first data layer and the second data layer, each data layer having different constraints, and the processor is further configured to combine the first data layer with A second data layer to generate a reconstructed three-dimensional image of at least a portion of the target object relative to the tool or implant.

In some embodiments, the 3D tracking system can be configured to use a priori density distribution to identify the tool or implant, and the 3D tracking system can also be configured to use the obtained density distribution based on the tool or implant to improve the first The reconstruction of the second data layer, and thus improve the reconstruction of the three-dimensional image.

In some embodiments, the three-dimensional tracking system may include a three-dimensional optical imaging system configured to generate motion data by tracking movement of the tool or implant.

In some embodiments, at least one of tool or implant shape and color can be used to identify the tool or implant using a priori density distribution and the obtained tool or implant based density distribution to improve the second Reconstruction of data layers and thus improved reconstruction of 3D images.

Additional features and advantages of the subject technology will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the subject technology. The advantages of the subject technology will be realized and attained by the written description and implementation thereof and the structure particularly pointed out in the accompanying drawings.

It is to be understood that both the foregoing general description, and the following detailed description are exemplary and explanatory, and are intended to further explain the subject technology.

Features, structures, steps or characteristics disclosed herein in connection with one embodiment may be combined in any suitable manner with one or more alternative embodiments.

Description of drawings

The written disclosure herein describes non-limiting and non-exhaustive exemplary embodiments. With reference to some such exemplary embodiments shown in the accompanying drawings, in which:

Figure 1 is a perspective view of an embodiment of an imaging system.

Figure 2 shows an alternative embodiment of an imaging system.

Figure 3A is a schematic diagram of an alternative embodiment of an imaging system.

Figure 3B is a schematic diagram of another alternative embodiment of an imaging system.

Figure 4 is a schematic diagram of yet another embodiment of an imaging system.

Figure 5 shows yet another embodiment of an imaging system.

FIG. 5A is a cross-sectional view taken along line 5A-5A in FIG. 5 .

FIG. 5B is a cross-sectional view taken along line 5A-5B in FIG. 5 .

Figure 6A is a schematic diagram of yet another embodiment of an imaging system.

Figure 6B is a schematic diagram of yet another embodiment of an imaging system.

Figure 7 shows another embodiment of an imaging system.

Figure 8 shows yet another embodiment of an imaging system.

Figure 9 shows yet another embodiment of an imaging system.

Figure 10 is a perspective view of an embodiment of an imaging system.

FIG. 11 is a close-up view of the imaging components of the imaging system of FIG. 10 .

Fig. 12 is a flowchart illustrating an implementation of a method for generating reconstructed image data of at least a portion of an object.

Fig. 13 is a flowchart illustrating another implementation of a method for generating reconstructed image data of at least a portion of an object.

Fig. 14 is a flowchart illustrating yet another implementation of a method for generating reconstructed image data of at least a portion of an object.

15 is a perspective view of an imaging system including an x-ray imaging system and an optical imaging system, according to some embodiments.

16 is a perspective view of an imaging system including an x-ray imaging system and a tracking system, according to some embodiments.

Figure 17 shows an imaging system comprising an x-ray imaging system and an optical imaging system, with a graph showing how the inventive principles using the imaging system may allow improved accuracy of the density distribution associated with a patient's region of interest.

18A and 18B show an unconstrained reconstruction and a constrained reconstruction of the spinal anatomy, respectively.

19 is a perspective view of an imaging system including an x-ray imaging system and an optical tracking system for tracking and imaging a surgical tool and a region of interest, according to some embodiments.

20 is a schematic diagram illustrating the operation of an imaging system including a 3D optical system and an x-ray system, according to some embodiments and implementations.

21 is a schematic diagram illustrating the operation of an imaging system including a tracking system and an x-ray system, according to some embodiments and implementations.

22 is a schematic diagram illustrating the operation of an imaging system including a tracking system and an x-ray system, according to other embodiments and implementations.

detailed description

It will be readily understood that the components of the invention as generally described and illustrated in the figures herein may be arranged and designed in many different configurations. Accordingly, the following more detailed description of device embodiments is not intended to limit the scope of the disclosure, but is merely a representative example of possible embodiments of the disclosure. In some instances, well-known structures, materials, or operations are not shown or described in detail.

Disclosed herein are various embodiments and implementations of devices, methods, and systems for providing imaging data. In some embodiments, the system may use multiple radiation sources moving generally along a path or trajectory. Using multiple radiance sources increases the speed at which the system can acquire projections from the full path, which reduces acquisition time and update latency.

Various additional embodiments of devices, methods, and systems are disclosed herein that relate to image reconstruction and/or image reconstruction optimization processes, such as, in some embodiments and implementations, using tracking systems and/or camera pairs for image-guided 3D and/or 4D reconstructions are optimized for processing, some embodiments of which may incorporate one or more elements of an x-ray imaging system, such as the aforementioned multiple moving radiation sources.

The following terms are defined herein as follows:

Imaged Object: An object or collection of objects imaged by an image reconstruction system.

Mass attenuation reconstruction: A method for determining the mass attenuation properties of an imaged object with volume.

Optical reconstruction: A method of determining reflective surfaces of an imaged object.

3D x-ray image reconstruction system: A system that acquires x-ray projection images and performs mass attenuation and/or linear attenuation reconstruction of the object being imaged.

3D optical image reconstruction system: A system that acquires an optical image and performs optical reconstruction of the object being imaged.

Tracking System: A system that provides the position and/or orientation of an object relative to a frame of reference.

In some embodiments, the radiation source can move substantially along one or more paths or trajectories, which can be circular in a common plane. The one or more paths or trajectories may also substantially follow cylindrical sine waves or saddle paths, spherical sine waves, hyperbolic parabolic paths, or other three-dimensional paths or trajectories. Other paths may be vertical or linear along at least a portion of the extent. One or more paths may have multiple peaks and troughs, such as 2 peaks and 2 troughs (e.g., as along a saddle edge), 3 peaks and troughs, 4 peaks and troughs, 5 peaks and troughs Wait. Additionally, some embodiments may be configured such that one or more paths undulate with different amplitudes or peaks and valleys. The one or more paths may traverse or pass through a plane and/or be at least partially within a plane passing through the object to be imaged. One or more paths may be curved in one or more planes. One or more paths may have continuous curves or bends. In some embodiments, one or more paths may be non-continuous paths, such as open curved paths that extend along less than the entire circumference of, or do not completely surround, the target space or object. For example, an open curved path may include a start point that is separated or spaced from its end point, such as a 90 degree arc of a circle or ellipse. One or more paths may define one or more corners, sharp turns, or discontinuities. Multiple independent paths may be used for multiple independent sources and/or detectors, wherein one or more sources and/or detectors move along multiple independent paths.

In some embodiments, one or more paths of one or more radiation sources can be configured to at least substantially match one or more paths of one or more radiation detectors. In some such embodiments, for example, one or more source paths may have the same shape (not necessarily the same size) as the detector paths. In certain preferred embodiments, the radiation sources are configured to move at the same angular velocity relative to the detection sources such that each source is positioned at a position corresponding to the position of the detector at a given moment in time. Thus, for example, in an embodiment where one path is larger than the other, one or more sources and/or detectors on the larger path will move further than one or more sources and/or detectors on the smaller path. Fast (but the same angular or rotational speed).

In other embodiments, one or more detectors may be stationary relative to the patient and/or one or more pathways. The system may comprise two or more paths of at least one radiation source and/or at least one radiation detector.

In some embodiments, the system may include one or more paths above the target space for at least one radiation source and/or at least one radiation detector and one or more paths below the target space for at least one radiation source and/or at least one radiation detector path.

For example, the system may comprise at least one radiation source and/or at least one radiation detector in a path above the target space, wherein at least one radiation source and/or at least one radiation detector is below the target space. In other embodiments, the system may include at least one radiation source and/or at least one radiation detector in two paths below the target space and at least one additional radiation source and/or in two paths above the target space or at least one radiation detector.

In some embodiments, the system can have radiation sources that rotate, allowing the system to operate with a limited/fewer number of sources and still cover the angular density (e.g., the angular density of projections at each angle), which One point is necessary for good image reconstruction quality.

Furthermore, in some embodiments, in order for the user to have access to the patient's anatomy, the system may use a source gantry that is separate from the patient and on the opposite side of the patient from the detection device. For example, the system may provide access to the user through access to the anatomy between the gantry and the detection device, and also provide compatibility with surgical tables. In other examples, the system may provide the user with access to the anatomy above the gantry and/or detection device. In such embodiments, the system may include a track.

Separation in two hemispheres (one for the radiation source and one for the detection device) makes the mathematical problem of solving 3D images (also called image reconstruction) ill-posed. Therefore, during such image reconstruction, computer-intensive iterative algorithms (based on iterative forward and backward projection) can be used that exploit regularization (usually a prior constraint that helps the algorithm converge).

Additionally, in some embodiments with multiple rotating detectors, detectors other than viewing the projected image may be used to observe the backscattered x-rays. Backscattered x-rays can be used to improve the quality of the reconstruction, for example, by dynamically changing the regularization function.

FIG. 1 illustrates an embodiment of an imaging system 100 including a gantry 110 . The gantry 110 includes a circular gantry configured to contain and/or house one or more mobile radiation sources. The term "gantry", as used herein, should be understood to encompass any structural element configured to position various radiation sources and/or detectors within a suitable imaging location. The gantry 110 also includes a closed gantry that is configured to avoid having any exposed moving parts—that is, any exposed parts that move during the imaging procedure, for example, that could pose a risk to the patient, user, and/or or bystanders are injured. Accordingly, each of the radiation sources (not shown) contained within the gantry 110 is configured such that no moving parts that would facilitate such movement are exposed outside the gantry 110 .

Imaging system 100 also includes a detector 120, which may include a flat panel detector. Detector 120 may also comprise a static single digital detector.

The gantry 110 may house one or more radiation sources, such as an x-ray source extending substantially along a path. The path can be any of the various shapes discussed above. FIG. 1 shows one possible configuration in which detector 120 is positioned below the patient and gantry 110 is positioned above patient 50 . The gantry 110 may be configured to rotate on itself, thereby rotating the one or more radiation sources contained therein or thereon. Alternatively, one or more radiation sources may be configured to move independently of the stationary gantry 110 .

As shown in FIG. 1 , gantry 110 may be configured to move one or more radiation sources in a circular or elliptical path over bed 60 on which patient 50 lies. Circular or elliptical paths can be in a single plane if desired. Additionally, one or more detector panels, such as detector panel 120, may be positioned below the one or more sources and patient 50 to detect radiation emanating therefrom. As shown, one or more detectors 120 may be positioned on the bed below the patient. However, in alternative embodiments, one or more detectors may be positioned below the patient on or within a separate housing, or as described below, may be positioned above the patient.

In some embodiments, at least one of a) the gantry and b) the detector assembly can be hollow. The relatively small cross-section of the hollow element allows the user to access the anatomy from the hollow portion of the source and/or detector by placing the hollow portion close to the patient, thereby eliminating or at least reducing the risk of direct exposure of the surgeon to the x-ray beam , provide compatibility with lighting equipment during surgery, and/or otherwise make surgery more convenient and/or less risky.

In embodiments where the detector assembly is hollow, the detector assembly may be formed from a static detector (or an assembled plurality of static detectors), or may include a plurality of rotating detectors corresponding to one or more radiation sources . In some embodiments, one or more detectors may be positioned over multiple radiation sources. Such embodiments can be of great value because they can allow the source of x-rays or other radiation to be located below the patient, and the detector to be located above the patient, thereby reducing scattered-type radiation to the surgeon (scattered radiation tends to be directed towards a source such as watching the surgeon's foot "bounce").

In some embodiments, where the source and detector gantry is close to the patient and the user accesses the anatomy from the central opening of the circular gantry or through another hollow portion of the system, the shape of the source and detector can have a portion along the patient axis. Off-centre to allow easy positioning of the system along the patient's axis during surgery. An example of such a configuration is shown in Figure 5 and will be discussed in more detail in conjunction with this figure.

As mentioned above, the outgoing path or trajectory can be any connected shape: oval or bean-shaped, or a figure-eight. This reduces the possibility of the x-ray source irradiating the surgeon and/or other bystanders who are likely to be standing under the narrowed portion of the figure 8 or bean shape.

FIG. 2 shows an example of another imaging system 200 . Imaging system 200 includes two gantry, namely, gantry 210a and 210b, each gantry including one or more radiation sources configured to move within a path defined by its respective gantry. In some embodiments, both gantry 210a and 210b include multiple moving radiation sources, such as moving x-ray sources. As noted above, in some embodiments, the radiation source may be stationary relative to the gantry, in which case the gantry may be movable. Alternatively, the gantry may be configured to direct one or more radiation sources movable within a path defined by the gantry.

One or both of gantry 210a and 210b may include a radiation source that moves throughout a curved path (in some embodiments, a circle) defined by its respective gantry. Alternatively, one or both of gantry 210a and 210b may be configured such that its corresponding radiation source or sources move within a path only partially defined by its respective gantry.

System 200 also includes a detector 220 comprising a flat panel positioned below table 60 (and below patient 50). As shown in FIG. 2 , door frames 210 a and 210 b may each be tilted inward toward detector panel 220 . In other words, the detector panel 220 may be positioned along an axis at least substantially parallel to the axis of the patient 50, the portal 210a may be angled relative to such axis in a first direction, and the portal 210b may be in a second, opposite direction. Angled relative to such axes. In some embodiments, one or both of the gantry 210a and 210b may include a dimension, such as a diameter in the case of a circular gantry, that is at least substantially equal to the size of the detector 220 .

3A and 3B show schematic diagrams of another embodiment of imaging systems 300A and 300B, respectively, including three moving radiation sources. FIG. 3A shows a system 300A including three moving radiation sources (ie, radiation sources A, B, and C), each moving along a single circular path 305 . Preferably, each of these sources is moving at least substantially at the same speed and in the same direction along path 305 (shown by arrows), so that the distance between each source remains constant.

As also shown in FIG. 3A , each of the various sources (although three are shown in the figure, any number could be used as desired) can emit x-rays or other radiation toward a detector 320, such as a digital flat panel detector or other such detectors. The intersection between a specific radiation source, a portion of the patient's 50 anatomy, and the detector 320 may allow reconstruction of a specific volume 55 of the patient's anatomy. By moving the source around path 305, various projections of the patient's 50 anatomy can be taken from various directions and used to provide a three-dimensional reconstruction of a volume of the anatomy as desired.

In the embodiment shown in FIG. 3A, each of the various sources may be configured to move along the same path 305 (although at any given time, at distinct points along the path 305), as shown in this figure. indicated by the arrow. However, various other implementations are contemplated. For example, as previously described, various other numbers of sources may be used as desired. In fact, while certain embodiments prefer at least two sources, other embodiments may include a single radiation source, as described in more detail below.

Furthermore, in other embodiments, each of the individual radiation sources, or at least a subset of the radiation sources, may occupy an independent path of travel. For example, Figure 3B shows an embodiment similar to Figure 3A, except that three radiation sources (A, B, and C) oscillate along independent paths. More specifically, source A oscillates between opposite ends of curved path 305A, source B oscillates between opposite ends of curved path 305B, and source C oscillates between opposite ends of curved path 305C, as through indicated by the corresponding arrow.

As also shown in FIG. 3B, the combined trajectory of the individual paths 305A, 305B, and 305C at least substantially matches the shape of the single path 305 in the embodiment of FIG. 3A. Likewise, however, various other numbers of oscillation paths may be employed for various other numbers of radiation sources as desired. For example, two radiation sources may be employed, in which case, provided the sources are configured to oscillate, they may oscillate between respective paths defining semicircles which together define circular paths. Of course, in some embodiments the collective paths of the various sources may not technically touch each other for practical reasons. However, a configuration substantially of the form shown in Figure 3B can be considered to include multiple independent source paths, even though there may be small gaps between individual paths, which substantially define a collective circular path .

As will be appreciated by those of ordinary skill, one or more source paths, whether a single path of multiple sources or a collective path defined by multiple paths taken by a single source, may alternatively comprise other shapes and/or dimensions, which Depends on the desired application scenario. Additionally, some embodiments may be configured to allow reconstruction of one or more of the source pathways, eg, to accommodate different patients, and/or anatomy/features to be imaged.

However, certain preferred embodiments include at least a plurality of radiation sources moving along one or more paths. One or more such pathways may be closed in some such embodiments. Having multiple sources can be used to increase the speed, angular coverage, and/or efficiency with which images, such as snap images, can be acquired. This may allow for shorter acquisition times, and/or shorter imaging update latencies.

Furthermore, it should be understood that while certain preferred embodiments include curved radiation source paths, in other embodiments one or more of the source paths may be linear. In some such embodiments, the collective path defined by all radiation source paths may comprise a polygon. In some such implementations, such polygons may approximate curved paths, such as circles.

System 300B, similar to system 300A, also includes a detector 320, which may include a flat panel detector. The intersection between a specific radiation source, a portion of the patient's 50 anatomy, and the detector 320 may allow reconstruction of a specific volume 55 of the patient's anatomy. Furthermore, having a source (which may be disposed in, on, or otherwise coupled to the gantry) that is independent of the patient and on the opposite side of the patient than the detector can be accessed by accessing the gantry. The anatomy between the frame and the detector provides user access to the anatomy and may also provide compatibility with surgical tables, surgical chairs, and the like.

The emission/detection sequence of the various radiation sources and detectors can also be varied as desired. For example, in some embodiments, the sequence may be sequential. In other words, each source may emit radiation, which is then in turn detected by a detector to provide an image. In some such implementations, each source may be detected to have emitted/emitted radiation before another source (such as an adjacent source) emitted radiation.

Alternatively, the sequence may be parallel. In other words, multiple sources may emit radiation simultaneously, or at least substantially simultaneously, and then be read together by the detector.

Figure 4 shows an alternative embodiment of an imaging system 400 comprising a moving radiation source and a moving detector. As shown in this figure, two radiation sources A and B are configured to move in a curved path 405 . Path 405 may define a shape such as a circle or an ellipse. Radiation sources A and B may be positioned in, on, or otherwise coupled to the gantry, as previously described. Such a portal can be positioned on the first side of the patient 50 .

On a second side of patient 50 opposite the first side, detectors 420A and 420B may be positioned to move along similar path 425 . In some embodiments, path 425 may have a similar or the same shape and/or size as path 405 . Detectors 420A and 420B may comprise flat panel detectors. In some such embodiments, detectors 420A and 420B can be tilted or angled inwardly relative to patient 50, which can be used to help increase the reconstruction volume of images of anatomical structures or features.

In some embodiments, detectors 420A and 420B can move in the same direction as sources A and B. Alternatively, detectors 420A and 420B may move along path 425 in a direction opposite to the direction of movement of sources A and B within path 405 .

In some embodiments, detectors 420A and 420B may be positioned in a horizontal direction relative to the plane and/or axis of patient 50 and/or path 405 . In some such embodiments, the detector and source can be synchronized to allow radiation emission directly to the detector. For example, the detector may be positioned such that radiation will reach the detector at a perpendicular angle, or at least a substantially perpendicular angle, to the detector (assuming the detector comprises a panel or is otherwise flat).

Some embodiments may include a source and detector combination configured to move along the same path. For example, system 400 may also include two additional detectors 420C and 420D interleaved with sources A and B configured to move in path 405 . Detectors 420C and 420D may be configured to receive radiation from sources C and D, which may be configured to move along path 425 with detectors 420A and 420B.

As a further option, in some embodiments, one or more detectors may be positioned above the patient/anatomy and the source may be positioned below the patient/anatomy. This may be useful in certain application scenarios, eg to provide less x-ray or other radiation scatter to the upper part of the surgeon or bystanders.

Figure 5 shows an alternative embodiment of an imaging system 500 including multiple moving radiation sources and detectors. System 500 includes a first housing 510 that defines the paths of two moving radiation sources A and B. As shown in FIG. System 500 also includes a second housing 530 for a corresponding number of detectors 520A and 520B. A patient 50 may be positioned between the radiation source and the detector. Although detectors 520A and 520B are shown as being curved and having a curvature that at least substantially matches housing 530, it should be understood that other embodiments are contemplated in which detectors 520A and 520B comprise flat panel detectors.

As shown in FIG. 5, housing 510 may be shaped to define the non-planar paths of radiation sources A and B. As shown in FIG. More specifically, housing 510 may be configured in a "saddle" shape, or otherwise may include a valley or other such offset region to allow the patient to be partially positioned within this region. This may improve access to certain anatomical regions, and/or may improve image quality.

Similarly, as also shown in FIG. 5 , detector housing 530 may include similar shapes oriented in opposite directions to allow one or more sources to be more closely approximated at a particular moment in time to one or more detectors.

In some embodiments, a rail system may be positioned within one or both of housings 510 and 530 for moving sources A, B and/or detectors 520A, 520B. In alternative embodiments, one or both such housings may instead comprise a shape extending along an axis or plane (or at least extending substantially parallel to a plane). In other words, the "trough" cited above can be omitted. In some such embodiments, housing 510 may be part of a turnstile, if desired. In some embodiments, one of the one or more detectors, and the one or more sources may be configured to move, while one may be stationary. For example, in some embodiments, sources A, B can be configured to move within one or more predetermined paths, and one or more stationary detectors can be used to accommodate radiation from such one or more sources.

5A and 5B are partial cross-sectional views of examples of structures of a system 500 that may be used to house, contain, and/or otherwise facilitate the movement of radiation sources and/or radiation detectors. position and/or move. FIG. 5A shows an annular housing 510 . In some embodiments, the annular housing 510 may be part of a gantry configured to position the housing 510 above (or, in other embodiments, below) the patient to facilitate positioning in the central opening ( For example, imaging of one or more anatomical structures within the central opening of housing 510). While in some embodiments, housing 510 may be positioned at least substantially parallel to a plane along its entire length, other embodiments may include valleys or saddle shapes, as shown in FIG. 5 .

5B is a partial cross-sectional view of another structure or assembly 530 for accommodating, containing, and/or otherwise facilitating positioning of one or more radiation detectors and/or or move. As shown in this figure, structure 530 may also include a housing, similar to housing 510 . However, the housing 530 includes a rectangular cross-sectional shape. However, it is contemplated that in other embodiments, housing 530 may comprise other shapes and, if desired, one or more structures associated with one or more radiation sources may be similar or identical in shape and/or size to : One or more structures associated with one or more radiation detectors. For example, in some embodiments, alternatively or in addition to a gantry or assembly for one or more radiation sources, detector assembly 530 may comprise a saddle shape.

As previously mentioned, structure 530 may be configured to accommodate mobile radiation detectors, such as detectors 520A and 520B, if desired. Alternatively, structure 530 may be configured to house one or more stationary detectors.

As also shown in FIG. 5B , in some embodiments, structure 530 may be configured such that one or more detectors housed therein are angled or otherwise coupled to the structure in an orientation to Imaging is further facilitated. For example, in the illustrated embodiment, structure 530 is configured such that detectors 520A and 520B are angled away from each other. This angulation process also directs the detection faces of these detectors towards the housing 510, which allows radiation from the source or sources contained therein to be directed towards the intervening anatomical feature of interest and then towards the detector(s). .

In some embodiments, the first radiation source and the first radiation detector may form a first device pair. A system may have several device pairs. In some embodiments, pairs of devices can be positioned and configured such that the source in the first pair is positioned on the same side of the patient as the detector in the second pair. The source and detector may travel together along the same path, or at least a similar path on the same side of the patient.

Each radiation source may be paired with and positioned opposite a corresponding radiation detector such that each radiation source moves along the path at a corresponding rate. For example, the sources may move at substantially the same rate. However, in other embodiments, the one or more sources may move at different rates relative to the one or more detectors, as described above, one of the one or more sources and the one or more detectors may be stationary. Preferably, however, the one or more sources move at least at the same angular velocity as the one or more detectors.

Figures 6A and 6B schematically illustrate two alternative embodiments of imaging systems configured to provide additional imaging by means of backscatter imaging. System 600A includes two radiation sources A and B, and a single flat panel detector 620A. As shown in FIG. 6A , a portion 55 of the patient's anatomy can be reconstructed by: a transmission image 622A from source A, and a backscatter image 624A also from source A. Backscatter images can be used to improve image reconstruction quality.

In some embodiments, a detector, such as detector 620A, can include an x-ray grid configured to only allow x-rays to be transmitted therethrough at one or more specific angles. This can be used to filter scattered radiation during transmission (and vice versa).

FIG. 6B shows an alternative embodiment of an imaging system 600B configured to provide both transmission imaging and backscatter imaging. However, system 600B differs from system 600A in that it includes two separate detectors: detector 620B and detector 620B'. Detectors 620B and 620B' are angled inwardly of each other so as to face radiation sources A and B to facilitate imaging. In some embodiments, detectors 620B and 620B' may be configured to move with sources A and B, as previously discussed. In other embodiments, detectors 620B and 620B' may be stationary.

At the imaging instant shown in Figure 6B, the backscattered image of region 55 from source A is received by detector 620B' and the transmitted image of region 55 is received by detector 620B. However, it should be understood that at other points during the operation of the system 600B, the detector 620B' may be receiving a transmission image and the detector 620B may be receiving a backscatter image, depending on the various sources and/or detectors during operation. Locate/Move. It should also be understood that any number of radiation sources may be provided as desired. However, for some embodiments involving more than one radiation source, a sequential firing sequence may be required.

FIG. 7 shows another embodiment of an imaging system 700 . Imaging system 700 includes four radiation sources and four detector panels. However, only two radiation sources and two corresponding detector panels are visible in the figure. More specifically, the figures show radiation sources A and B, which may be positioned over a prone patient 50 . Radiation sources A and B may be configured to move in one or more paths over patient 50 (on table 60) to provide an image of a portion 55 of an anatomical region of interest, such as, for example, a portion of the patient's spine . Two other radiation sources (not shown in Figure 7) may similarly be configured to move around the same or different paths to increase imaging speed.

Two detector panels, namely panels 720A and 720B, may also be provided below the patient 50 . In FIG. 7, detector panel 720A is receiving radiation from source A, and detector panel 720B is receiving radiation from source B. In FIG. Panels 720A and 720B are configured to move in one or more paths on one or more tracks 730 . In the illustrated embodiment, a single track is provided. However, other embodiments are contemplated in which multiple tracks may be provided. Likewise, although not shown in Figure 7, two additional detector panels could be provided if desired. As shown in this figure, the individual detector panels are angled inwardly of each other such that they face their respective radiation sources.

FIG. 8 shows yet another embodiment of an imaging system 800 . Imaging system 800 is similar to imaging system 700 except that radiation sources A and B are positioned below prone patient 50 and detector panels 820A and 820B are positioned above patient 50 . Like imaging system 700, imaging system 800 includes one or more rails 830 configured to move individual detector panels in one or more desired paths.

FIG. 9 shows yet another embodiment of an imaging system 900 . Imaging system 900 includes a path in which both a radiation source and a detector move together. For example, in some embodiments, radiation sources and detectors may be coupled together in pairs. For example, a first source A is coupled to a first detector panel 920A, and a second source B is coupled to a second detector panel 920B. A first pair including source A and detector panel 920A can be coupled to a first rail system 930A, and a second pair including source B and detector panel 920B can be coupled to a second rail system 930B. Track 930A may be configured to move source A and detector panel 920A in a path (eg, over patient 50 ), such as a circular or other curved path. Track 930B may similarly be configured to move source B and detector panel 920B in a second path under patient 50 .

FIG. 9 may be representative of two alternative embodiments of an imaging system 900 . In a first such embodiment, as discussed, one or more sources may be directly coupled to one or more detectors in close proximity to each other. In a second such embodiment, one or more sources may be spaced apart from, but in the same path as, one or more detectors (similar to the embodiment shown in Figure 4). Regarding the latter of these two possible embodiments, FIG. 9 may represent two overlapping images taken at two different points in time during an imaging process in which radiation sources A and B, and detector 920A and 920B are moving.

Of course, those of ordinary skill in the art will recognize that various alternatives are possible. For example, a larger number of source/detector pairs can be used. In some embodiments, two such pairs may be provided in a first path, and two such pairs may be provided in a second path separate from the first path. In certain preferred embodiments, the two paths can be positioned such that the patient, or at least a portion of the patient to be imaged, can be positioned between the two paths. In other embodiments, four source/detector pairs may be provided in the first path and four source/detector pairs are provided in the second path. Preferably, each source/detector pair has a corresponding source-detector pair in a different path, which can be said to be "coupled" in some way. For example, one source/detector pair may be positioned to face a second source/detector pair such that radiation from a source in one such pair will normally be detected by a detector in a "coupled" source/detector pair arrive. As such, coupled source/detector pairs may be configured to move at least substantially the same angular velocity, and may move at an angle to maintain a suitable angulation to provide such results.

The gantry and tracking systems disclosed herein may be combined in some embodiments such that radiation sources and/or detectors may be moved in a rotating gantry comprising a track configured to travel in one or more Sources and/or detectors are moved in a plurality of predetermined paths. For example, in some embodiments, a motor-driven chain may be used to move the source and/or detector in one or more predetermined paths, such as a single circular, elliptical, or other curved path.

FIG. 10 shows another embodiment of an imaging system 1000 . Imaging system 1000 includes imaging assembly 1005 including gantry 1010 and detector 1020 . The gantry 1010 includes one or more radiation sources. In some embodiments, the gantry 1010 can be configured to move one or more such radiation sources in one or more predetermined paths. For example, in some embodiments, a track system may be provided, as discussed above. The mast 1010 may also include a generator and/or batteries, if desired. The battery can be embedded inside the gantry housing to shorten the wiring between the stationary and moving parts of the system. In the configuration shown in FIG. 10 , the surgeon and/or robot may operate on and/or operate on the patient from the center of the "halo" or donut hole of the gantry 1010 .

System 1000 also includes positioning arm 1015 coupled to gantry 1010 . Positioning arm 1015 includes a C-shape that may be configured to secure gantry 1010 and/or a detector, such as detector 1020, with the gantry and detector being rigid relative to each other. But other shapes are possible, provided that the C-shape allows for one or more radiation sources and one or more detectors to be rotated together as a single unit, entering the patient's anatomy from different angles, and/or from different angles It may be useful in terms of snapping images. However, other embodiments are contemplated where the gantry and/or radiation source can be positioned/moved (between imaging cycles) independently of the one or more detectors.

In the illustrated embodiment, detector 1020 includes a bend detector. Thus, this detector can also be used as a bed or stationary tray, so that the patient can, for example, lie down or otherwise place the anatomical region of interest on the detector panel. However, in alternative embodiments, one or more radiation detectors may be positioned below such beds/trays/panels.

In some embodiments, detector 1020 may comprise a digital flat panel detector configured to capture and digitize x-ray or other electromagnetic radiation absorption images in conical x-ray projections delivered by one or more radiation sources . One or more detectors and/or detector assemblies may alternatively be flat or "v" shaped, if desired.

System 1000 also includes a pair of structural risers 1045 that may be configured to allow imaging assembly 1005 to be moved up and down to accommodate different table heights, patient sizes, and the like.

Base 1050 may be provided, for example, to include a power source, counterweight, electronics, and the like. A swivel wheel 1052 may also be provided to allow for movement of the imaging assembly 1005 around.

In some embodiments, base 1050 can be configured to fit and be stored within a recess of a corresponding workstation, including, for example, a computer and/or monitor. For example, in the illustrated embodiment, a workstation 1060 is provided that includes a recess 1062 for receiving at least a portion of the base 1050 . Workstation 1060 includes a monitor 1064 and computer 1066, which can be used for visualization and image reconstruction.

FIG. 11 shows imaging assembly 1005 of imaging system 1000 in a rotated configuration. Accordingly, one or more portions of imaging assembly 1005 may be configured to allow rotation to accommodate patient imaging or otherwise facilitate the imaging process. As indicated by arrow 1002, in some embodiments this may be accomplished by inserting a positioning arm 1015 into a corresponding curved housing 1017 in imaging assembly 1005, which may be coupled to gantry 1010 and detect One or both of the devices 1020. Detector 1020 may similarly be configured to move along a track defined by housing 1017 . One or more elements 1045 may be coupled to one or more housings 1017, if desired.

Preferably, the gantry 1010 and detector 1020 are movable together as a unit such that the relative positions of the one or more radiation sources and detectors are maintained. However, alternative embodiments are contemplated in which the gantry 1010 or another structural enclosure that houses or otherwise contains one or more radiation sources may operate independently of the one or more corresponding radiation detectors between imaging sessions. Locate/Move.

In one or more of the above embodiments, the radiation source may be configured to rotate or otherwise move about a center point of a circular or otherwise curved path, and to move along the path. In embodiments configured to oscillate about such a path, each source may be configured to move along the path from an initial or first position, then reverse at a second position to return to the first position. As the source or sources are moved, they may be configured to emit radiation at at least two locations along the path. Additionally, each source can be moved along an independent open curved path if desired. The open curved paths of the sources may collectively form a circle, ellipse, or other shape. A circle, ellipse, or other shape may be a planar shape, or lie partially or completely outside a single plane.

For example, in some embodiments, four radiation sources may be included in the imaging system, and each of the four sources may be configured to move along open curved paths, each having an arc of about 90 degrees, such that The four sources together have 360 degree coverage (whether the collective path is circular, elliptical, or otherwise shaped).

12, 13, and 14 illustrate specific implementations of imaging methods 1200, 1300, and 1400, respectively, that may be performed by one or more of the imaging systems and/or devices discussed herein.

In any of the methods disclosed herein, a "projection" may comprise a series of absorption projection images, each associated with the necessary geometric parameters describing the geometric relationship between the imaging volume and the associated projection.

An example of this methodology is described in the following document: Cone-Beam Reprojection Using Projection-Matrices, published in IEEE TRANSACTIONS ON MEDICALIMAGING, VOL.22, NO.10, OCTOBER 2003 ("IEEE Medical Transactions on Imaging, Vol. 22, No. 10, October 2003). This paper is incorporated herein by reference in its entirety.

In these exemplary methods, the output 3D volume may be a volume representation related to the volume density of the imaged volume. The output 3D volume can be visualized in different user-relevant ways. A typical visualization method is to show a series of slices of the output 3D volume along some axis, for example, to provide coronal, sagittal or axial slices similar to those in computed tomography (CT).

In method 1200, a number of projections 1201 can be obtained from an imaging system (eg, the imaging systems and/or devices discussed herein). In step 1202, a 3D volume 1203 may be reconstructed by projection of the imaging volume. For example, iterative algorithms such as the algebraic reconstruction technique (also known as ART, reference 2) can be used. Examples of such techniques can be found in Algebraic Reconstruction Techniques (ART) for Three-dimensional Electron Microscopy and X-ray Photography, published in: Journal of Theoretical Biology 29(3):471–81 (December 1970) (Theoretical Biology Journal, No. 3: pp. 471-481, December 1970). This paper is also hereby incorporated by reference in its entirety.

The quality and speed of iterative reconstruction depends on the sparse or dense nature of the imaged volume. In method 1200, acquired projections may be characterized by solidity. To obtain a 3D volume with meaningful clinical information, a large number of projections and/or iterative calculations may be required, resulting in increased system latency. The method 1300 shown in FIG. 13 introduces a solution for fast reconstruction (and thus visualization) based on sparse projections. Similar methods exploiting the sparsity of the data, such as accurate image reconstruction from multi-view and limited-angle data from diverging beam ct, have been proposed in the following literature, which is hereby incorporated by reference in its entirety: J X-Ray Sci .Technology, 14:119–139 (2006) (Journal of X-ray Science and Technology, Vol. 14: pp. 119-139, 2006).

In step 1301 of method 1300, a number of reference projections may be obtained.

In step 1302, a number of updated projections may be obtained using an imaging system, eg, one of the imaging systems and/or devices discussed herein.

In step 1303, a sparse projection set may be obtained from the reference projection and the updated projection. This can be achieved using a simple subtraction between the reference projection and the updated projection. Creating sparse projections can be referred to as foreground extraction.

In some implementations, the reference projection may be obtained from (or derived from) the physical systems and/or devices discussed herein, or derived from the reference 3D volume 1305 by, for example, mathematical projection.

Step 1304 may include reconstructing the extracted 3D volume of the foreground, and may operate in a similar manner to step 1202 of method 1200 in some implementations. Due to the sparsity of the extracted foreground projections, the reconstruction algorithm requires a smaller number of projections and/or iterative calculations, thereby shortening the delay.

At step 1306 , the extracted 3D volume of the foreground may be recombined with the reference 3D volume 1305 to generate an updated visualization 3D volume 1307 .

The reference 3D volume in 1305 represents the imaging volume associated with the projection in 1301 . The reference 3D volume may be obtained, for example, using a preoperative CT scan, another prior image, or a reconstruction of an initial higher resolution tomosynthesis reconstruction.

In some implementations, motion estimation and correction can be used to best match the reference 3D volume to the reference projection, and/or ensure sparsity of the foreground extraction. For example, method 1400 may be used to update a reference 3D volume.

Method 1400 may be used to generate an updated 3D volume for visualization, or as a means of providing a better reference 3D volume in method 1300 .

In step 1401 of method 1400, a certain reference 3D volume may be obtained. This reference 3D volume may be obtained, for example, using a preoperative CT scan, another prior image, or a reconstruction of an initial higher resolution tomosynthesis reconstruction.

In step 1402, a number of updated projections may be obtained using an imaging system, eg, any of the imaging systems and/or devices discussed herein.

In step 1403 , the motion may be estimated and corrected using, for example, an iterative gradient descent algorithm, resulting in an updated 3D volume 1404 . Motion correction can be modeled, for example, based on 6 degrees of freedom to describe changes in translation and rotation.

Methods 1200, 1300, and 1400 may rely on obtaining a certain number of projections. As such, system latency in some implementations may depend on the projection acquisition time, and the time to perform the reconstruction method and obtain the 3D volume.

Thus, each of the illustrated methods 1200, 1300, and 1400 can be used in sequence to provide a sequence of 3D volumes, allowing the user to observe changes in the imaged volume.

Each of the illustrated methods 1200, 1300, and 1400 can also be used in parallel computing pipelines to more quickly provide sequences of 3D volumes. Each reconstruction may be based on a certain number of projections (eg, 90), where each re-execution of the method starts after a smaller number of projections (eg, 12, less than 90) are obtained from the system. In this case, instances of the method can be run in parallel with reduced latency.

Each of the illustrated methods 1200, 1300, and 1400 may be implemented around an iterative algorithm (iterative reconstruction algorithm 1202 or 1304, or iterative motion estimation 1403). Therefore, each method can be used continuously by updating the inputs to the iterative algorithm as new inputs become feasible.

In some implementations, one or more of the illustrated methods 1200, 1300, and 1400 can be implemented as a computer program and implemented on a highly parallelized architecture, eg, on a general-purpose graphics processing unit (GPGPU).

A computer program implementing any of the methods 1200, 1300, and 1400 can use optional multi-resolution techniques to quickly update the volume and optimize the image later (start with a smaller number of updated images, lower projected image resolution, smaller number of voxels, then optimize with more images, higher resolution projected images, and larger number of reconstructed voxels).

One or more of the systems disclosed herein may have the unique potential to employ a dual/multi-energy approach, since the radiation sources may be set at different energy levels (kV, or eV). For example, multiple radiation sources may be used that have variable or steady energy levels that are about the same or different from each other.

Some embodiments may also (or alternatively) have the unique potential to employ digital subtraction schemes, since radiation sources can rapidly overlap each other and can subtract from Projection images taken at the same location but at different times. The subtracted projection images may be provided to a 3D algorithm for obtaining a subtracted 3D dataset. Subtracting image projections improves the quality of the reconstruction as the algorithm attempts to reconstruct a sparser volume.

In some embodiments and implementations, subtraction may be for projection images taken at different energy levels (kV or eV).

In some embodiments, improving access for surgeons and interventional personnel may be interchangeable with improving access for robots performing interventional procedures, or simplifying integration with other devices (e.g., integration with radiation therapy systems for targeted tumors) .

As described above, one or more paths of one or more sources and/or one or more detectors may be used for: one or more sources and/or one or more detectors positioned on the subject's first hemisphere. Furthermore, in embodiments where one or more sources and/or one or more detectors in the second hemisphere of the subject move relative to the subject, those sources and/or detectors in the second hemisphere may also move along Any of the paths in question moves. Additionally, the shape of the first path in the first hemisphere may be the same or different from the shape of the second path in the second hemisphere, translated, rotated, mirrored, or mirrored in a similar or dissimilar manner relative to the second path, as desired. Orientation in other ways.

The following additional concepts are disclosed herein, which can be used to perform various implementations of methods, and/or create various embodiments of systems, for embodying and/or implementing one or more of the following concepts of the present invention:

Aided 3D reconstruction: The 3D model of the imaged object obtained from the optical camera (3D optical image reconstruction system) can be used to assist the reconstruction of the imaged object by the 3D x-ray image reconstruction system. For example, when the x-ray imaging system includes an x-ray CT system, a cone-beam CT system, or a tomosynthesis system, such as the systems disclosed in the following patent application: U.S. Patent Application Serial No. 14/198,390, entitled "IMAGING SYSTEMS AND RELATED APPARATUS AND METHODS" (Imaging Systems and Related Apparatus and Methods), which is incorporated herein by reference in its entirety.

Figure 15 shows at 1500 an example of a system for imaging reconstruction using both x-ray tomosynthesis and optical reconstruction. The imaging system 1500 includes an x-ray tomosynthesis image reconstruction system including a gantry 1510 and a detector 1520 . The gantry 1510 includes one or more (preferably a plurality) of x-ray radiation sources (not shown in Figure 15). Gantry 1510 may be configured to move one or more such radiation sources in one or more predetermined paths. For example, in some embodiments, a tracking system may be provided, as previously described.

Also as previously described, imaging system 1500 includes detector 1520 positioned on an opposite side of gantry 1510 such that at least a portion of patient 50 may be positioned between gantry 1510 and detector 1520 . The gantry 1510 is configured to enclose a plurality of x-ray radiation sources within an enclosed portion of the gantry. The gantry 1510 is also configured so as to avoid having any exposed moving parts during an imaging procedure using the imaging system 1500, and is configured to enclose multiple sources of x-ray radiation without completely enclosing the patient 50 or any portion of the patient 50 so that Access to the patient 50 is permitted during the imaging procedure. Of course, in alternative embodiments and implementations, patient 50 may be replaced with another three-dimensional object.

Additionally, unlike embodiments described in connection with previous figures, system 1500 further includes a three-dimensional optical imaging system configured to reconstruct an image of at least a portion of a surface of a target object, such as patient 50, by generating surface three-dimensional image data . The three-dimensional optical imaging system is preferably registered to the tomosynthesis image reconstruction system so that data from both systems can be used to improve image reconstruction. A 3D optical imaging system includes one or more optical cameras configured to generate distance/depth data of a 3D object surface, such as RGB-D camera 1550 . The illustrated embodiment includes four such optical depth detection cameras 1550 , two of which are coupled to detector 1520 and two of which are coupled to gantry 1510 . However, one of ordinary skill in the art will recognize, having the benefit of this disclosure, that alternative types of optical cameras, alternative numbers of optical cameras, and alternative placements of optical cameras may be provided.

The camera 1550 can be configured to reconstruct the contour of the surface of the patient 50, or at least a portion of the surface of the patient 50, and can be used to generate one or more density-constrained profiles to improve the three-dimensional image of the target region of the patient 50 or another three-dimensional object. reconstruction. In a preferred embodiment, the three-dimensional optical imaging system is registered to the tomosynthesis image reconstruction system. For example, contours or patient surfaces may be referenced to the same frame of reference as tomographic reconstruction.

In some embodiments and implementations, multiple independent objects can be imaged using a three-dimensional optical imaging system. Thus, for example, surgical tool 20 and/or implant, or tool/implant combination, can be surface/depth imaged using a three-dimensional optical imaging system. In the example of Figure 15, the camera 1550 is firmly attached to the system 1500 so it can be registered to the x-ray tomosynthesis image reconstruction system through a calibration step. Registration can be described or decomposed as: a translation 3D vector and three rotation directions for each camera. In some embodiments and implementations, multiple cameras may collectively provide a patient profile, tool profile, and/or implant profile, or portions thereof. However, alternative embodiments and implementations are contemplated in which the camera(s) need not be securely attached to components of the system, as explained below.

As also shown in FIG. 15 , system 1500 may also include a monitor or another suitable display 1564 for regenerating reconstructed images in real-time or near real-time in some embodiments and implementations.

One or more such systems, such as system 1500, may perform volume-mass and/or linear attenuation reconstruction. If such a system uses an iterative reconstruction algorithm or an equivalent algorithm, this algorithm may be constrained by a 3D model obtained from one or more optical cameras. Such constraints can be as simple as describing the surface of an object.

Other more complex density constraints can also be used. The outside of the object can be modeled with a low density (usually air), and this volume density constraint can improve the reconstruction, for example, by reducing artifacts otherwise associated with incomplete/less complete reconstruction data. Incomplete data may be limited angle data for reconstruction, or limited views of the reconstructed region of interest. Furthermore, the interior of the object can be modeled as a continuous function that binds the density outside the object to the mass and/or linear attenuation of the solved model (eg, a 3D model in an iterative reconstruction algorithm).

Tracking System I Assisted 4D Reconstruction: Some embodiments of the present invention may allow inducing motion of one or more imaged objects to improve their (their) volumetric quality and/or linear attenuation reconstruction (eg, x-ray based reconstruction). 4D scene reconstruction methods may rely on evolving models that are updated from time to time. Initial rebuilds and post-update rebuilds can be distinguished as typical cases, but in general, this is what can be expected. Positions can change, and any time from the initial reconstruction to the final reconstruction, including any time in between, can be captured by the tracking system. These changes may include patient/table motion, gantry displacement, and/or surgical tools that are the subject of a mass-attenuated reconstruction that are at least partially within the field of view, independently or jointly reconstructed and tracked. In this context, the tracking system may be, for example, an optical tracking system (such as a surgical navigation tracking system), an optical 3D reconstruction system, or an electromagnetic tracking system, among others.

Some systems may implement algorithms that use x-ray imaging to observe motion and advance 4D mass attenuation reconstruction based on such observed motion. Such observations can be further improved when replaced (or combined, see next section) with motion observed by other tracking systems. Accordingly, some embodiments and/or implementations of the invention may involve causing motion that may be captured externally to a quality-attenuated reconstruction system by way of tracking (eg, through a video surveillance scene). The extracted motion parameters can be transferred to a mass decay reconstruction engine.

Accordingly, another example of an imaging system is shown in 1600 in FIG. 16 . System 1600, like system 1500, includes an x-ray tomography system that includes detectors 1620 positioned on opposite sides of gantry 1610 such that at least a portion of patient 50 can be positioned between gantry 1610 and between the detectors 1620 . The gantry 1610 is again configured to enclose multiple sources of x-ray radiation within an enclosed portion of the gantry. The gantry 1610 is also configured so as to avoid having any exposed moving parts during an imaging procedure using the imaging system 1600, and is configured to enclose multiple sources of x-ray radiation without completely enclosing the patient 50 or any portion of the patient 50 so that Access to the patient 50 is permitted during the imaging procedure.

Additionally, system 1600 also includes a three-dimensional motion tracking system 1650 that includes one or more tracking cameras 1655, such as infrared tracking cameras, and one or more markers, such as fiducials. In the illustrated embodiment, the three-dimensional motion tracking system 1650 includes two infrared tracking cameras 1655A and 1655B mounted on a movable stand or assembly. Additionally, three markers are used to track fiducial markers that reflect infrared light, namely, a first marker 1651 positioned on a portion of the x-ray tomography system such as the detector 1620, a second marker 1652 positioned on the surgical tool 20 and a third marker 1653 positioned on a desired portion of the patient 50, such as within the patient's 50 region of interest.

The 3D motion tracking system 1650 is configured to provide motion information, such as absolute motion relative to fixed portions of the tracking cameras 1655A and/or 1655B or associated mounts/assemblies, and/or relative motion between each tracked object. Such motion information can be used to improve the 4D reconstruction, especially if the reconstruction is a model-based reconstruction that includes motion.

In some embodiments, the combined system 1600 can also be configured to provide information to identify what is in the region of interest (and thus the expected radiodensity) and/or where the tool 20 is located (and therefore the specific region of the reconstructed image where the radiodensity is expected) The specific surgical tool 20 at. In some embodiments and implementations, such information can be used to improve the reconstruction by adding this information as a constraint for the iterative reconstruction algorithm. As previously mentioned, the tracker/camera is shown mounted on a movable pole in the embodiment of Fig. 16, and thus is not firmly attached to the x-ray tomography system. Accordingly, registration may be performed between the x-ray tomography system, the three-dimensional motion tracking system 1650 , and the one or more surgical tools 20 . Since the process would be simpler (and constant) if one or more cameras were instead fixed to the x-ray tomography system, alternative embodiments are contemplated where the 3D motion tracking system 1650 may not be able to The ray tomography system moves.

As shown in FIG. 16, system 1600 may also include a monitor or another suitable display 1664 for regenerating reconstructed images in real-time or near real-time in some embodiments and implementations.

Yet another example of an imaging system 1700 is shown in FIG. 17 . As shown in this image, system 1700 again includes an x-ray tomography system including detectors 1720 positioned on the opposite side of gantry 1710 such that at least a portion of patient 50 may be positioned on gantry 1710 and detector 1720. The gantry 1710 is again configured to enclose one or more (preferably, multiple) sources of x-ray radiation within an enclosed portion of the gantry 1710 . The gantry 1710 is also configured so as to avoid having any exposed moving parts during an imaging procedure using the imaging system 1700, and is configured to enclose multiple sources of x-ray radiation without completely enclosing the patient 50 or any portion of the patient 50 so that Access to the patient 50 is permitted during the imaging procedure.

System 1700 also includes a three-dimensional optical imaging system configured to reconstruct an image of at least a portion of a surface of a target object, such as patient 50, by generating surface three-dimensional image data. The three-dimensional optical imaging system is preferably registered to the tomosynthesis image reconstruction system so that data from both systems can be used to improve image reconstruction. A 3D optical imaging system includes one or more optical cameras configured to generate distance/depth data of a 3D object surface, such as RGB-D camera 1750 . The illustrated embodiment includes two such optical cameras 1750 , one coupled to the detector 1720 and the other coupled to the gantry 1710 . In the illustrated embodiment, the camera 1750 is mounted to its corresponding component of the x-ray tomography system using mounting posts 1752 . Likewise, however, alternative types of optical cameras, alternative numbers of optical cameras, and alternative placements of optical cameras may be provided as desired.

The camera 1750 can be configured to reconstruct the contour of the surface of the patient 50, or at least a portion of the surface of the patient 50, and can be used to generate one or more density-constrained profiles to improve the three-dimensional image of the target region of the patient 50 or another three-dimensional object. reconstruction. In a preferred embodiment, the three-dimensional optical imaging system is registered to the tomosynthesis image reconstruction system. For example, contours or patient surfaces may be referenced to the same frame of reference as tomographic reconstruction. This information from both systems can be combined to improve image resolution.

More specifically, as shown by the density distribution in the graph included in FIG. The solution for the actual density of region 55. Thus, by applying a density constraint to the surface of the patient 50 using a three-dimensional optical imaging system, as shown by line DC in FIG. 17, the reconstructed density using this density constraint (shown at line R1) can be improved using the density constraint (shown at line R2), which is closer to the actual density distribution of patient 50 and region of interest 55 (shown at line AD).

Thus, elements with RGB-D camera 1750 or other suitable optical imaging system provide a contour of patient 50 that can be used to constrain the solution of the iterative reconstruction algorithm, which can provide higher resolution. In other words, the density more closely matches the actual density. Figures 18A and 18B show reconstructions of a specific anatomical region of interest, and reconstructions extending beyond the region of interest, respectively, without and with this density-constrained approach. In the case of constrained reconstruction (FIG. 18B), the density outside the patient surface is constrained to be zero in an iterative reconstruction scheme. The quality of the tomofusion reconstruction was improved, and by comparing these images, truncation artifacts were significantly reduced.

FIG. 19 shows yet another example of an imaging system 1900 . The imaging system 1900 likewise includes an x-ray tomosynthesis image reconstruction system including a gantry 1910 and a detector 1920 . As previously described, the gantry 1910 includes one or more (in some embodiments, a plurality) sources of x-ray radiation and can be configured to move one or more such radiation sources in one or more predetermined paths , such as, for example, moving along a circular path adjacent the periphery of the gantry 1910 .

As also previously described, imaging system 1900 also includes a three-dimensional optical imaging system configured to reconstruct an image of at least a portion of a surface of a target object, such as patient 50, by generating surface three-dimensional image data. The three-dimensional optical imaging system is preferably registered to the tomosynthesis image reconstruction system so that data from both systems can be used to improve image reconstruction. The three-dimensional optical imaging system of imaging system 1900 includes one or more optical cameras 1950 , such as RGB-D cameras, configured to generate distance/depth data on the surface of a three-dimensional object, such as region of interest 55 of patient 50 .

The illustrated embodiment includes a single such optical camera 1950 . However, as previously mentioned, other numbers and/or types of cameras may be used. As shown in Figure 19, the camera 1950 can be physically detached from the tomosynthesis image reconstruction system. Thus, for example, camera 1950 may be mounted to a stand, table, or other external component of the system.

Camera 1950 may be used to observe and/or track various objects, such as surgical tool 20 and/or patient 50 . Because the camera 1950 is preferably in registration with the three-dimensional image being reconstructed by the tomosynthesis image reconstruction system, a current trajectory 1966 of the surgical tool 20 can be generated and, in some embodiments and implementations, in the reconstruction region of interest 55 , the trajectory may be regenerated on the display 1964 together with one or more elements/features in the reconstruction region 55 of interest. In some such embodiments and implementations, system 1900 may be configured to generate and/or display trajectory 1966 based on movement outside of patient 50 that tool 20 has tracked prior to entering region of interest 55 . This may be useful for preoperative planning. For example, this feature allows the surgeon/technician to select the desired skin entry point and "navigate" to the target point, allowing the surgeon to make adjustments during tool insertion.

In some such embodiments and implementations, the system 1900 can be configured to generate and/or display other elements to assist the surgeon/technician during surgery. For example, as also shown in FIG. 19 , a user may allow input of a target 1967 and this target may be displayed on a display/monitor 1964 along with the reconstructed image. By comparing the target 1967 with the current trajectory 1966 of the tool 20, the system 1900 can be configured to allow the surgeon/technician or other user to select a preferred trajectory of the surgical instrument relative to the region of interest, and/or dynamically calculate the preferred trajectory A measure of variance from the current trajectory 1966. This may allow, for example, that system 1900 may create and/or display a correction trajectory 1968 relative to target 1967 so that a user may adjust the movement of tool 20 in real-time or near real-time during a surgical procedure.

In some embodiments and implementations, system 1900 can be configured such that display 1934 displays in addition to or as an alternative to the image shown in FIG. 19 of both trajectory 1966 and preferred trajectory 1968. Other information, such as numbers corresponding to variance measures. In some embodiments and implementations, system 1900 can be configured such that a user can select a target, such as target 1967, within an area of interest of a target object, and system 1900 can also display the current distance between tool 20 and target 1967 .

In some embodiments and implementations, the system 1900 can be configured to dynamically adjust the region of interest 55 in response to movement of the tool 20 . For example, in some such embodiments and implementations, the system 1900 can be configured to dynamically define the region of interest 55 so as to encompass points adjacent to the distal tip of the tool 20, such as when the region of interest 55 is defined by the The display 1964 is dynamically modified as the movement of the distal tip is defined.

FIG. 20 shows a schematic diagram of yet another example of an imaging system 2000 . As shown in this figure, a 3D optical system 2050, which may include an infrared tracking system (or in other embodiments, other suitable tracking systems), may be combined with one or more x-ray systems 2020 to provide a 4D reconstruction. In some embodiments and implementations, 4D reconstruction may include model-based reconstruction. In the illustrated embodiment, two x-ray systems 2020A and 2020B are shown, but one of ordinary skill in the art will recognize that the same optical system can be used to perform the steps of systems 2020A and 2020B.

As shown in FIG. 20 , the optical tracking system 2050 can provide a first 3D surface reconstruction when the imaged object is at 2052 at an initial position and orientation (PnO)PnO — 0 , t=t ₀ . The optical tracking system 2050 may then provide a second 3D surface reconstruction when the imaged object is at 2054 at a different position and orientation (PnO)PnO_1 than PnO_0, t=t ₁ .

Motion between PnO_0 and PnO_1 can then be estimated at 2056 . For example, in some embodiments and implementations, the motion of a 3D surface can be assumed to be rigid, or at least substantially rigid, and the motion that minimizes the difference between the two surfaces can be identified (i.e., PNO_1 -0). This can represent a translation and a series of rotations that account for the motion of the 3D surface. However, in embodiments and implementations utilizing a tracking system, it may not be necessary to infer from the surface whether motion has occurred. Instead, the system may provide movement directly by, for example, reflecting fiducial markers, such as markers 1651-1653 in system 1600.

As shown at step 2022, one or more x-ray systems, such as x-ray system 2020A, may also provide imaging of the subject (or at least a portion of it), preferably at or at least substantially at t= _t0 . object) x-ray projection. Preferably, the x-ray system 2020A is used to reconstruct a 3D image of the subject by tomographic reconstruction. In an even more preferred embodiment and implementation, x-ray system 2020A can provide tomosynthesis reconstruction of at least a portion of an imaged subject. The 3D image can represent that the object is at PnO_0 at _t0 .

Then at 2058, a motion calibration may be applied to the reconstruction by both the optical system 2050 and the x-ray system 2020A. For example, in some embodiments and implementations, a 3D to 2D image registration algorithm may be used based on one or more projections of the 3D image by minimizing the difference from the actual measured projections.

The 3D image can be updated using motion estimation PnO_1-0 by applying translation and/or rotation ("actual movement") from the optical system 2050. This image may represent the object at position PnO_1 at t=t ₀ .

X-ray system 2020B (or x-ray system 2020A) may then provide projections of the imaged object (or a portion of the imaged object) at time _t1 or a time at least substantially equal to that time (while the object is at Pn0_1). The projection at, or at least substantially at, t= _t1 , together with the actually moving 3D image, can be used for model-based reconstruction at step 2060 as discussed above to provide at 2070 the object at t=t ₁ and the 3D image at PnO_1.

In some embodiments and implementations, the newly occupied projections can be used to model differences between observed projections and projections of actual moving objects. For example, if a surgical tool was added between _t1 and _t0 , the system 2000 can reconstruct the surgical tool by subtracting the most recently acquired projection using the actual projection from the actual movement model (as described above).

Various embodiments and/or other aspects of implementations in the area of motion compensation may involve combining, or blending (e.g., by averaging or taking other considerations), or using detected motion as a prerequisite for using an optimization engine, The optimization engine tries to observe such motion for later use in 4D quality attenuation reconstruction. In embodiments using a 3D optical reconstruction system, such as system 2000, motion can be estimated based on patient surface displacement.

As previously mentioned, model-based or layer-based 4D reconstruction may utilize a tracking system, such as, in some embodiments, a 3D tracking system. A mass density 4D reconstruction system can model a scene by assuming that the imaged objects are components of the domain, e.g. objects or layers, which can themselves be modeled and/or reconstructed individually, and can then be recombined into a global 4D reconstructed scene . Each domain model or reconstruction can benefit from one or more of the mechanisms described above. One such technical mechanism may be to identify a domain projection matrix by the tracking system when the tracking system is capable of tracking domains individually. For example, an optical tracking system can track multiple surgical tools and patients by having individual optical references, and an optical 3D reconstruction system can track multiple objects by segmentation and modeling based on rigid objects/color and motion.

A more specific example of such a system is shown at 2100 in FIG. 21 . System 2100 may include: one or more x-ray systems, such as a tomosynthesis image reconstruction system; and one or more tracking systems, such as a 3D tracking system. Although two x-ray systems 2120A and 2120B, and two tracking systems 2150A and 2150B are shown in FIG. 21, it should be understood that a single x-ray system and a single tracking system could also be used.

In some embodiments and implementations, the system 2100 can be configured to use the motion estimates of both the one or more x-ray systems 2120A/2120B and the one or more tracking systems 2150A/2150B by combining the motion estimates of the two systems .

The one or more x-ray systems 2120A/2120B may provide projections of the imaged object at t=t ₀ or at least substantially at that time (at PnO — 0 ). The projection can then be used to reconstruct the object by tomography and provide a 3D image of the object (t=t ₀ , PnO — 0 ), as shown at step 2122 .

One or more tracking systems 2150A/2150B may be used to observe the position of the imaged object at t=t0 (at PnO — 0 ).

At substantially t= _t1 , updated x-ray projections of the object from one or more x-ray systems 2120A/2120B can be used to infer the motion of the object between _t0 and _t1 , e.g., by finding The motion of an image is minimized by the difference between the new projection and the actual projection to infer object motion. This first motion estimate is shown in step 2152A.

One or more tracking systems 2150A/2150B may be used to observe the position of the object at _{t =} tl, and infer the motion of the object between _t0 and tl, and provide a second motion estimate at step 2152B.

The first and second motion estimates in steps 2152A and 2152B may then be used in combination to obtain a more accurate third motion estimate at 2152C. In some embodiments and implementations, this can be performed using a weighted average. Alternatively, the second motion estimate can be used as a seed for the first motion estimate, which can speed up the first motion estimate.

The projection at t= _t1 , together with the initial 3D image and motion estimation, can be used to provide a 3D reconstruction 2160 of the object at PnO_1 at t= _t1 . For example, the initial 3D image can actually first be shifted according to the estimated motion, and together with the newly acquired projections can be used for model-based reconstruction, as previously described. This image is more accurate than the initial reconstruction 2122 because the newly acquired projections can be used to model the differences between the observed projections and those of the actual moving object. For example, if a surgical tool is added between _t1 and _t0 , the system can be configured to reconstruct the surgical tool by subtracting the most recently acquired projection using the actual projection from the actual movement model (as described above).

As previously mentioned, in some embodiments and implementations, the trajectory of surgical tools, implants, and/or other movable objects relative to the region of interest is visualized in the mass density reconstruction. For example, the mass density 3D reconstruction can be registered with the 3D optical image reconstruction system to allow intra-operative planning to be performed while the instrument/implant is still outside the x-ray reconstruction volume (eg patient body).

In its simplest form, this can be achieved by visualizing the extended trajectory of the instrument/implant while still outside the body, entering the body, and/or within the body and causing its trajectory and/or point of entry. This can allow for reduced x-ray doses involved because instead of viewing the instrument with a lens, it is visualized through an optical system.

As another example of the possible use of this technique, in some embodiments and implementations, the primary axis of the tool/implant can be extrapolated to x-ray volume and defined relative to the anatomical organ, and previously embedded (if if any) target orientation of the surgical hardware. As another example, if a target point has been selected (e.g., target 1967 from system 1900), the practitioner/user may be provided with an estimate of the distance between the actual location of the tip and the planned location of the tip along the The tool axis is measured.

In some embodiments and implementations, one or more images acquired from a tracking system (such as a 3D optical image reconstruction system) can be used in an intelligent user interface to differentiate the actual tool/implant of interest from the available any other instruments/objects in the image. For example, by identifying the tool/implant in the surgeon's hand, the mass-attenuated volumetric reconstruction can be more accurately re-sliced based on the analysis of the mass-attenuated reconstruction. For example, single value decomposition can be used to identify the longer tool axis or other suitable axis of the movable object relative to the region of interest.

Information about the instrument/tool/implant position and its extended trajectory from the tracking system can also be used to define a local region of interest for the mass attenuation reconstruction system. This may allow the system to reconstruct a volume centered around the instrument, and thus potentially smaller, with higher resolution, and/or exclude foreign objects. This reduces reconstruction time and improves reconstruction resolution. Another benefit of some implementations of this method is that it can make the reconstruction more robust by excluding other objects. This is especially true when reconstructing certain data layers, such as instrument or implant layers in reconstruction algorithms. The local regions of interest may also have different sizes. For example, 2D slices can be obtained linked to the instrument/tool/implant geometry, which can further speed up the reconstruction since 2D reconstruction is orders of magnitude faster than 3D reconstruction.

As another example of improved instrument/tool reconstruction, data from a tracking system can be used to constrain the reconstruction of a 3D x-ray imaging system by providing additional information about the reconstructed object, such as geometric information (diameter, length, etc.), Material composition (eg correlating color and reflectivity or opacity to eg different device/implant densities), and/or other information. Such information can be used for instrument/implant reconstruction constrained x-ray systems. In fact, preliminary data generated by applicants shows that density constraints can greatly improve reconstructions. Automatic visual recognition of instruments/implants can be accomplished by ascertaining certain attributes (e.g., color and/or size of a given surgical kit from a given manufacturer) into a finite space of possibilities, such as the Possible values within a specific surgical kit. Where such information is geometric information, this may add additional dimensional information regarding the correct width, length or other parameters of the instrument/implant. Alternatively or additionally, this may allow reconstruction to use specific density reconstruction constraints for instrument/implant reconstruction layers, thereby improving image quality. These constraints can be statistical or hard constraints.

In another example of a combined 3D x-ray image reconstruction system and a 3D optical image reconstruction system, the combined system may allow both the 3D tracking system and the mass-attenuated 3D reconstruction system to reconstruct with a common frame (or reducible to a common frame) , this general framework can be based on known priors of the joint calibration step. This general framework can be used to implement all of the above steps (e.g., aid reconstruction, account for motion, and/or guide surgery, etc.) in real-time (this may e.g. affect surgical workflow in surgical cases). In some implementations, the joint calibration step can be most accurately accomplished by using a common x-ray geometric calibration fixture (e.g., a helical x-ray calibration phantom, or the "cone" calibration phantom used by some tomosynthesis systems ), where the same markings can be seen on both the x-ray system and the optical system (eg, bbs on a plexiglass structure). Alternatively, the clips may have independent markings at their fixed and known relative positions.

Yet another more specific example of a combined x-ray imaging and tracking system is shown at 2200 in FIG. 22 . System 2200 includes: x-ray system 2220, which may include an x-ray tomosynthesis image reconstruction system, and a tracking system 2250, which may include a 3D tracking system. As previously described, the combined x-ray and tracking system 2200 can be used to combine the data of the systems 2220 and 2250 to more accurately perform a 3D reconstruction of at least a portion of the subject. For example, in some embodiments and implementations, system 2200 may use tracking system 2250 to generate density constraints based on the tracked specific tool or implant, and/or tool/implant position, as shown at 2252 , the density constraint is registered to image space.

In some embodiments and implementations, constraints may be applied as modifications to intermediate solutions in an iterative reconstruction algorithm scheme. For example, envisaged tool densities may be biased towards a priori known tool densities, or as another example, if no tools are used, densities may be forced towards smaller densities (in the range of human tissue versus in the range of stainless steel (e.g., If the tool is stainless steel)).

In some embodiments and implementations, the tracking system 2250 can provide tool/implant identification (and thus a priori condition for tool/implant density), and the tool/implant PnO can be registered to the x-ray imaging system 2220. Tool/implant identification and PnO can then be used to construct density constraints at 2252 (e.g., a transfer function that forces density closer to tools in regions where tools are located, and/or forces density in regions where there are no tools) lower density). The x-ray system 2220 may also provide projections of at least two imaged objects (eg, surgical tools and a portion of the patient's anatomy).

Iterative reconstruction can be performed at 2260 to generate a 3D image. In some embodiments and implementations, algorithms utilizing identified constraints and/or projections with constraints, such as iterative reconstruction algorithms with regularization, penalties, or other constraints, may be used to provide an image of the combined object.

Those skilled in the art will appreciate that modifications may be made to the details of the above-described embodiments without departing from the basic principles presented herein. For example, any suitable combination of the various embodiments and features thereof is contemplated.

In any method disclosed herein that includes one or more steps or actions for performing the method, the method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and/or use of specific steps and/or actions may be modified.

Throughout this specification, any reference to "one embodiment", "anembodiment" or "the embodiment" means that at least one embodiment includes the specific features, structures, or properties described. Thus, as set forth throughout this specification, not all recited phrases, or variations thereof, are referring to the same embodiment.

Similarly, it should be appreciated that in the foregoing description of embodiments, in order to simplify the present disclosure, various features have sometimes been grouped together in a single embodiment, drawing, or description thereof. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim require more features than those expressly recited in that claim. Rather, inventive aspects relate to combinations of less than all features of any single foregoing disclosed embodiment.

Those skilled in the art will recognize that many modifications may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. Accordingly, the scope of the invention should be determined only by the following claims.

Claims (9)

1. A four-dimensional imaging system comprising:

an x-ray tomosynthesis image reconstruction system configured to generate three-dimensional image data of at least a portion of a target object;

a tracking system configured to track movement of at least a portion of the target object and generate motion data for a motion model based on the movement of the at least a portion of the target object; and

a processor configured to generate a reconstructed three-dimensional image of the at least a portion of the target object over time including four-dimensional image data, wherein the reconstruction algorithm is configured to use the three-dimensional image data from the tomosynthesis image reconstruction system and to use motion data from the tracking system to generate the four-dimensional image data.

2. The four-dimensional imaging system of claim 1, wherein the motion model includes the use of rigid transformations.

3. The four-dimensional imaging system of claim 1, wherein the tracking system comprises a three-dimensional tracking system.

4. The four-dimensional imaging system of claim 1, wherein the tracking system comprises a three-dimensional imaging system, and wherein the three-dimensional imaging system is configured to use the motion data from the three-dimensional imaging system to generate movement of the reconstructed three-dimensional image.

5. The four-dimensional imaging system of claim 1, wherein the x-ray tomosynthesis image reconstruction system is further configured to generate motion data based on movement of the at least a portion of the target object, and wherein the imaging system is configured to combine the motion data from the tracking system with the motion data from the x-ray tomosynthesis image reconstruction system to generate movement of the reconstructed three-dimensional image.

6. An imaging system, comprising:

a three-dimensional tracking system configured to generate a first data layer comprising motion data of a tool or implant motion relative to a target object;

an x-ray tomosynthesis imaging system configured to obtain projection image data of at least a portion of the target object and the tool or implant motion relative to the target object, wherein the three-dimensional tracking system is registered to the x-ray tomosynthesis imaging system; and

a processor configured to generate a second data layer by the three-dimensional tracking system and by the projection image data from the x-ray tomosynthesis imaging system, wherein the processor is configured to use a reconstruction algorithm to reconstruct the first data layer and the second data layer, respectively, wherein the first data layer and the second data layer have different constraints, and wherein the processor is configured to combine the first data layer and the second data layer to generate a reconstructed three-dimensional image of at least a portion of the target object and the tool or implant.

7. The imaging system of claim 6, wherein the three-dimensional tracking system is configured to identify the tool or implant using an a priori density distribution, and wherein the three-dimensional tracking system is further configured to use an obtained density distribution based on the tool or implant to improve the reconstruction of the second data layer and thereby improve the reconstruction of the three-dimensional image.

8. The imaging system of claim 6, wherein the three-dimensional tracking system comprises a three-dimensional optical imaging system configured to generate the motion data by tracking movement of the tool or implant.

9. The imaging system of claim 6, wherein at least one of a shape and a color of the tool or implant is used to identify the tool or implant using an a priori density distribution and an obtained density distribution based on the tool or implant to improve the reconstruction of the second data layer and thereby the reconstruction of the three-dimensional image.

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