Method and system for dynamic annotation of medical images

Abstract

This invention provides various methods and systems for medical imaging systems. In one embodiment, a method for a projection imaging system includes acquiring a first image of a region of interest (ROI) at a first location using the projection imaging system, determining a three-dimensional (3D) position of an annotation on the first image via a geometric transformation of a plane, acquiring a second image of the ROI at a second location using the projection imaging system, determining the position of the annotation on the second image based on the 3D position of the annotation at the first location and the geometry of the second location, and displaying the annotation on the second image in response to satisfying an accuracy check.

Description

Technical Field

[0001] The embodiments of the subject matter disclosed herein relate to medical imaging, and more specifically to X-ray fluorescence imaging. Background Technology

[0002] Non-invasive imaging techniques allow for the acquisition of images of the internal structure or features of a patient or object without the need for invasive procedures. Specifically, such non-invasive imaging techniques rely on various physical principles (such as differential transmission of X-rays through a target volume or reflection of sound waves) to acquire data and construct images or otherwise represent the observed internal features of a patient or object.

[0003] For example, in fluoroscopy and other X-ray-based imaging techniques such as computed tomography (CT), X-ray radiation is directed at the subject, typically a patient in a medical diagnostic application, packaging or luggage in a safety screening application, or a manufactured part in an industrial quality control or inspection application. A portion of the radiation strikes a detector, where image data is collected and used in the image generation process. In images generated by such systems, it is possible to identify and examine internal structures and organs within a patient's body, objects within packaging or containers, or defects (e.g., cracks) within manufactured parts.

[0004] In certain situations, such as in fluoroscopic examinations used to support interventional or navigation procedures, X-rays can be acquired at high frame rates over extended periods to provide real-time image data that can be used to guide or navigate tools within the patient's body. For example, cone-beam computed tomography (CBCT) can be used for interventional X-ray guide pin procedures, preoperative three-dimensional (3D) imaging, and / or intraoperative 3D imaging. In some procedures, contrast agent injection can be used to visualize the vascular system. Summary of the Invention

[0005] On one hand, a method for a projection imaging system includes acquiring a first image of a region of interest (ROI) at a first location using the projection imaging system; determining a three-dimensional (3D) position of an annotation on the first image via a geometric transformation of a plane; acquiring a second image of the ROI at a second location using the projection imaging system; determining the position of the annotation on the second image based on the 3D position of the annotation at the first location and the geometry of the second location; and displaying the annotation on the second image in response to satisfying an accuracy check. In this way, anatomical features of interest can be dynamically and accurately tracked between images with different views.

[0006] It should be understood that the above brief description is provided to introduce selected concepts further described in the detailed embodiments in a simplified form. This is not intended to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed embodiments. Furthermore, the claimed subject matter is not limited to embodiments that address any shortcomings mentioned above or in any part of this disclosure. Attached Figure Description

[0007] The invention will be better understood by referring to the following description of non-limiting embodiments, in which:

[0008] Figure 1 A drawing view of an imaging system according to one embodiment is shown;

[0009] Figure 2 This is a flowchart illustrating a method for dynamic annotation during interventional imaging procedures according to one implementation scheme;

[0010] Figure 3 A schematic diagram showing the geometrically determined three-dimensional location of annotation points according to one embodiment is shown; and

[0011] Figure 4 An example of dynamically tracking annotation points from multiple perspectives is shown according to one implementation scheme. Detailed Implementation

[0012] Now, we will use examples to refer to... Figures 1 to 4 To describe the implementation scheme of this disclosure, Figures 1 to 4 This relates to various implementation schemes for displaying annotations on medical images. During interventional imaging procedures, such as surgical procedures monitored / assisted by fluoroscopic imaging, continuous real-time X-ray images of the patient can be displayed, allowing clinicians to monitor the movement of anatomical features. The imaging chain may include an X-ray tube and an X-ray detector coupled to a C-arm. In the interventional imaging procedure, the imaging chain is positioned around the patient at different angles selected by the clinician, such as by rotating the C-arm, while acquiring X-ray images. The patient may be supported by a table with a position that can also be changed during the procedure, for example by translating the table relative to the C-arm. The acquired X-ray images are two-dimensional (2D) conical projections. These different variations in the imaging chain allow the operator to view anatomical structures at different angles and magnifications. Anatomical features of interest may be visible in one or more of these different images. As the orientation of the X-ray imaging chain and / or the positioning of the table change, the position of the anatomical features of interest in the images also changes.

[0013] In some examples, clinicians label or annotate anatomical structures in images to make it easier to view or locate the feature later. As used herein, the term "annotation" can refer to a precise location defined by one (or more) points in an image, a linear (e.g., line) segment with a precise location within the image, and / or a set of consecutive line segments with a precise location within the image. As an example, this set of line segments may form a shape drawn by the clinician. Furthermore, lengths can be associated with line segments by summing the lengths of each individual line segment. Each annotation may or may not contain associated text (e.g., a label). For example, annotations can be useful when contrast agent injections are performed to view the vascular system. For instance, a vessel injected with contrast agent may be visible in an X-ray image shortly after injection, but may no longer be visible in the X-ray image once the contrast agent has been washed away. As an illustrative example, a clinician can annotate and label a left coronary artery as "left coronary artery" by drawing a shape or line on it, which becomes visible in the image after contrast agent injection. However, because the imaging chain orientation and / or the stage position change throughout the imaging procedure, the location of the anatomical features of interest is no longer aligned with the location of the static annotation.

[0014] Therefore, according to the implementation scheme, a virtual three-dimensional (3D) space can be used to define the location of the annotation in 3D space rather than on the annotated image. The virtual 3D space utilizes knowledge of the position and orientation of different components of the X-ray imaging chain and the stage during annotation. The defined location corresponds to the actual 3D location of the anatomical structure of interest. Then, when additional images are acquired, the 2D location of the annotation on the image is updated as the position and orientation of the imaging chain and stage change. Furthermore, since determining the 3D location from 2D conic projection can produce potential discrepancies, the accuracy of the annotation's display on subsequent images is controlled.

[0015] In this way, anatomical features of interest can be dynamically and accurately tracked across images acquired from multiple different perspectives. This allows clinicians to more quickly and accurately locate annotated (e.g., labeled) features during and after the imaging procedure. As another example, clinicians can spend less time and effort mentally trying to locate the anatomical features of interest throughout the imaging procedure. Furthermore, because the virtual 3D space uses geometric transformations instead of rendering complex 3D models, the amount of computational power required to dynamically update annotations during the imaging procedure is reduced.

[0016] exist Figure 1 The image shows a projection imaging system that can be used to acquire medical images of a region of interest. Figure 2A flowchart of an example method is shown, which can be used to geometrically determine the location of annotations in a virtual 3D space that does not use a fully rendered 3D model of the region of interest. Furthermore, using... Figure 2 This method allows annotations to be projected onto subsequently acquired images, such as images with different perspectives. Figure 3 This schematically demonstrates how the location of annotations in 3D space is determined. Furthermore, in Figure 4 The image shows an exemplary sequence of images demonstrating how annotations can be updated from different perspectives.

[0017] Now turn to the attached diagram. Figure 1 An exemplary embodiment of an imaging system 10 for acquiring and processing image data is schematically illustrated. In the illustrated embodiment, the imaging system 10 is a digital X-ray imaging system designed to both acquire raw image data and process the image data for display. The imaging system 10 can be a fixed or mobile X-ray system. Figure 1 In the embodiments shown, imaging system 10 is depicted as a C-arm fluorescein fluoroscopic imaging system, but it will be understood that other forms of imaging and / or navigation systems may be used within the scope of this disclosure. For example, it will be understood that the techniques of this invention may also be useful when applied to images acquired using other imaging modalities, such as standard, non-fluorescein fluoroscopic X-ray imaging, tomography, etc. The inventive discussion of the fluorescein fluoroscopic imaging modality provides only as an example of a suitable imaging modality. For example, imaging system 10 may be any projection imaging system that acquires a two-dimensional projection of a three-dimensional object.

[0018] Imaging system 10 can acquire X-ray attenuation data from various angles around a patient and is suitable for tomographic reconstruction. Imaging system 10 includes an X-ray source 56 fixed to a C-arm 14. Exemplarily, X-ray source 56 may be an X-ray tube, a distributed X-ray source (such as a solid-state or thermionic X-ray source), or any other X-ray radiation source suitable for acquiring medical or other images. X-ray source 56 may also be referred to as a radiation source. For example, X-ray source 56 may include an X-ray generator and an X-ray tube. X-ray source 56 emits X-ray radiation 16 from focal point 12 in the direction of subject (or object) 18. For example, subject 18 may be a patient. In the depicted embodiment, X-ray radiation 16 is emitted in a cone shape (e.g., a cone beam). The X-ray cone beam passes through the imaging volume of subject 18. An incident portion of X-ray radiation 16 (also referred to as incident X-ray) 20 passes through or surrounds subject 18 and collides (or impacts) with X-ray detector 34, which includes detector array 22. X-ray detector 34 is a digital X-ray detector and may be portable or permanently mounted to imaging system 10. X-ray detector 34 may also be referred to as a radiation detector. In some embodiments, detector array 22 converts incident X-ray photons into detected lower-energy photons. Electrical signals are generated in response to the detected photons, and these signals are processed to reconstruct an image of features within the body of subject 18. X-ray source 56 and X-ray detector 34 together comprise an X-ray imaging chain.

[0019] As an example, detector array 22 may include one or more complementary metal-oxide-semiconductor (CMOS) optical imager panels, each CMOS optical imager panel individually defining an array of detector elements (e.g., pixels). Each detector element generates an electrical signal representing the intensity of the X-ray beam incident at the location of the detector element when the beam illuminates detector array 22. This signal may be digitized and transmitted to a monitor / display device for display.

[0020] Exemplarily, the X-ray source 56 and the X-ray detector 34 are controlled by a system controller 24, which simultaneously provides power and control signals for the operation of the imaging system 10. The system controller 24 may control the X-ray source 56 via an X-ray controller 26, which may be a component of the system controller 24. In such embodiments, the X-ray controller 26 may be configured to provide power and timing signals to the X-ray source 56.

[0021] Exemplarily, the X-ray detector 34 is further connected to a system controller 24. The system controller 24 controls the acquisition of signals generated in the X-ray detector 34 (e.g., acquired by the detector array 22). In an exemplary embodiment, the system controller 24 uses a data acquisition system (DAS) 28 to acquire the signals generated by the detector array 22. The DAS 28 receives data collected by the readout electronics of the X-ray detector 34. The DAS 28 may receive sampled analog signals from the X-ray detector 34 and convert the data into digital signals for subsequent processing by the processor 30, which is discussed in further detail herein. Alternatively, in other embodiments, the digital-to-analog conversion may be performed by a circuitry disposed on the X-ray detector 34 itself. The system controller 24 may also perform various signal processing and filtering functions with respect to the acquired image signals, such as, but not limited to, initial adjustments for dynamic range and digital image data interleaving.

[0022] Furthermore, the X-ray detector 34 includes or communicates with a control circuitry system in or with a system controller 24, which commands the acquisition of signals generated in the detector array 22. The X-ray detector 34 can communicate with the system controller 24 via any suitable wireless communication or via cable or other mechanical connection. Alternatively, operating commands can be implemented within the X-ray detector 34 itself.

[0023] System controller 24 is further operatively connected to C-arm 14 and to stage 32 configured to support subject 18. Motor controller 36 of system controller 24 provides instructions and commands to the mechanical components of C-arm 14 and stage 32 to perform their linear and / or rotational movements. The linear and / or rotational movements of C-arm 14 enable X-ray source 56 and X-ray detector 34 to rotate one or more revolutions around subject 18, such as rotating primarily in the XY plane or at an angle relative to the subject. The distance between X-ray detector 34 and X-ray source 56 can also be adjusted. Furthermore, stage 32 supporting subject 18 can be longitudinally moved relative to the movement of C-arm 14 and / or the planned movement of C-arm 14 to position the patient within the imaging field of view of imaging system 10. Therefore, movement of the patient and / or components of the imaging system for adjusting the imaging field of view may include movement of one or both of C-arm 14 and stage 32.

[0024] Generally, system controller 24 commands the operation of imaging system 10 (such as via X-ray source 56, X-ray detector 34, and the aforementioned positioning system) to execute the examination protocol and process the acquired data. For example, via the aforementioned system and controller, system controller 24 can rotate the gantry supporting X-ray source 56 and X-ray detector 34 around the region of interest or target T, so that X-ray attenuation data can be obtained at various views relative to target T. For example, the central axis 52 of X-ray radiation 16 can be focused on target T. In this example, system controller 24 may also include signal processing circuitry, associated memory circuitry for storing computer-executable programs and routines (such as routines for executing the image processing techniques described herein), configuration parameters, image data, and so on.

[0025] In the depicted embodiment, image signals acquired and processed by system controller 24 are provided to processor 30 for image reconstruction. Processor 30 may be one or more conventional microprocessors. Data collected by DAS 28 may be transferred directly to processor 30 or transferred after being stored in memory 38. Any type of memory suitable for storing data may be utilized by imaging system 10. For example, memory 38 may include one or more optical, magnetic, and / or solid-state memory storage structures. Furthermore, memory 38 may be located at the acquisition system site and / or may include a remote storage device for storing data, processing parameters, and / or routines for image reconstruction, as described below. For example, processor 30 may be operatively coupled to memory 38. An example of image reconstruction may include cone-beam computed tomography (CBCT), in which images acquired at multiple angles around subject 18 are projected relative to each other to form voxels representing a 3D image region. Other forms of image reconstruction may be used, including but not limited to processing image data from detector signals to produce clinically useful images.

[0026] The processor 30 can be configured to receive commands and scan parameters from an operator via an operator workstation 40, which is typically equipped with a keyboard, touchscreen, and / or other input devices. The operator can control the imaging system 10 via the operator workstation 40. Therefore, the operator can use the operator workstation 40 to view the reconstructed images and / or otherwise operate the imaging system 10. For example, a display 42 coupled to the operator workstation 40 can be used to view the reconstructed images and control the imaging process. Additionally, the images can also be printed by a printer 44, which can be coupled to the operator workstation 40.

[0027] Furthermore, the processor 30 and operator workstation 40 can be coupled to other output devices, which may include standard or dedicated computer monitors and associated processing circuitry. One or more operator workstations 40 can be further linked within the system for outputting system parameters, requesting checks, viewing images, etc. Generally, the monitors, printers, workstations, and similar devices provided within the system may be local to the data acquisition components, or may be located remotely, such as elsewhere within the institution or hospital, or in entirely different locations, linked to the image acquisition system via one or more configurable networks (such as the Internet, VPN, etc.).

[0028] It should also be noted that the operator workstation 40 can also be coupled to a Picture Archiving and Communication System (PACS) 46. The PACS 46 can then be coupled to a remote client 48, a Radiology Information System (RIS), a Hospital Information System (HIS), or an internal or external network, allowing other people in different locations to access the raw or processed image data.

[0029] While the foregoing discussion has described various exemplary components of the imaging system 10, these various components may be provided within a common platform or in an interconnected platform. For example, the processor 30, memory 38, and operator workstation 40 may be provided collectively as a general-purpose or special-purpose computer or workstation configured to operate according to various aspects of this disclosure. In such embodiments, the general-purpose or special-purpose computer may be provided as a separate component relative to the data acquisition components of the imaging system 10, or it may be provided in a common platform having such a component. Similarly, the system controller 24 may be provided as part of such a computer or workstation, or as part of a separate system dedicated to image acquisition.

[0030] like Figure 1As shown, the imaging system 10 may also include a variety of alternative embodiments generally configured to meet the specific needs of certain applications. For example, the imaging system 10 may be a fixed system, a mobile system, or a mobile C-arm system, wherein the X-ray detector 34 is either permanently mounted inside one end of the C-arm 14 or removable from the system. Furthermore, the imaging system 10 may be a table and / or wall-mounted system in a fixed X-ray room, wherein the X-ray detector 34 is either permanently mounted to the system or portable. Alternatively, the imaging system 10 may be a mobile X-ray system with a portable X-ray detector. Such a portable X-ray detector may be further configured to have a detachable tether or cable for connecting the detector readout electronics to the scanner's data acquisition system. When not in use, the portable X-ray detector can be detached from the scanning station for storage or transfer. In implementation, the imaging system 10 may be any suitable X-ray-based imaging system, including but not limited to conventional X-ray radiography systems, CT imaging systems, tomographic X-ray radiography systems, C-arm systems, fluoroscopy systems, mammography systems, dual-energy or multi-energy systems, navigation or interventional imaging systems, etc. Furthermore, while an example of a flat panel detector has been described above, a digital detector system that includes an image intensifier and a camera can be used to convert the incident X-rays 20 into a video signal.

[0031] As used herein, the phrase "reconstructed image" is not intended to exclude embodiments of the invention in which data representing an image is generated rather than a visual image. Therefore, as used herein, the term "image" broadly refers to both a visual image and the data representing a visual image. However, many embodiments generate (or are configured to generate) at least one visual image.

[0032] As will be described in more detail below, subject 18 can be imaged using an X-ray imaging chain that includes an X-ray source 56 and an X-ray detector 34. Although not explicitly shown, it is understood that the X-ray imaging chain may also include various lenses (e.g., collimating lenses and / or focusing lenses) and apertures. The X-ray imaging chain is positioned around subject 18 at different angles selected by the operator (e.g., a clinician). Subject 18 lies on a worktable 32, and the position of the worktable 32 may also change throughout the imaging process. The acquired X-ray images are 2D conic projections, and changes in the position of the imaging chain and worktable 32 allow the operator to view the anatomy of subject 18 at different angles and magnifications. For example, the workflow of the imaging procedure may include acquiring several image sequences that can be used to diagnose subject 18 and, if necessary, intervene in subject 18. Anatomical sites of interest can be viewed in these different images. However, as the orientation of the X-ray imaging chain and / or the positioning of the worktable 32 changes, the location of the anatomical sites of interest in the acquired images also changes.

[0033] In some examples, the operator or assistant marks anatomical structures to make them easier to retrieve later. This can be useful, for example, when contrast agents are injected. The injected vessels can then be easily seen in the image. Once the contrast agent is washed away, the location is lost unless it has been marked. However, as mentioned above, the location of the marked anatomical structures can change on the image due to changes in viewing angle.

[0034] in this way, Figure 2 Provided for use such as Figure 1 The example method 200 shown illustrates the dynamic annotation of images acquired during an interventional imaging procedure using an imaging system 10. Method 200 will discuss... Figure 1 The systems and components shown are described herein, but it will be understood that the method can be implemented with other systems and components without departing from the scope of this disclosure. In particular, method 200 will be described in relation to X-ray imaging (e.g., fluorescence microscopy imaging). Method 200 may be implemented as a non-transitory memory of a computing device (such as… Figure 1 Executable instructions in memory 38).

[0035] In method 202, method 200 includes adjusting the imaging chain to a first position to image a region of interest (ROI). For example, the ROI may be an anatomical structure of interest, such as an anatomical region (e.g., the neck), or a feature, such as the subject to be imaged (e.g., the subject of the subject). Figure 1 The subject 18's vascular system (e.g., arteries and / or veins), bones, organs, etc. The first position may include relative to a worktable supporting the subject (e.g., Figure 1The angle (e.g., angular position) of the stage 32). In some examples, the operator of the imaging system can select the ROI and the first position, and can adjust the imaging chain accordingly (e.g., via...). Figure 1 The motor controller 36) is used to center the ROI in the imaging chain at the X-ray source and the X-ray detector of the imaging chain (e.g., Figure 1 Between the X-ray source 56 and the X-ray detector 34. Furthermore, in some examples, the position of the stage can be adjusted (e.g., translated) relative to the imaging chain. In at least some examples, the first position can be a first position relative to time (e.g., an initial position). Therefore, the first position can define the angular and translational position of the imaging chain relative to the stage.

[0036] It is understandable that, in addition to selecting ROI, operators can, for example, do so via operator workstations (e.g., Figure 1 The operator workstation 40) inputs or selects examination information. Examination information may include the examination type and / or examination protocol. For example, the examination type or protocol may specify the anatomical structure being imaged, specify the series of views to be acquired and the corresponding positions of the imaging chain and / or worktable for acquiring these views, and indicate whether a contrast agent was used and its type. For example, a contrast agent may be administered to the subject to aid in the visualization of the anatomical structure of interest. As an example, a contrast agent may be injected to visualize the vascular system.

[0037] As yet another example, the information to be checked may include X-ray tube voltage, current, and pulse width settings for the X-ray source, and frame rate and magnification settings for acquiring images at the X-ray detector. The detector can then generate a synchronization signal when a balance condition is reached and send this signal back to the system controller. The X-ray source can wait for the synchronization signal from the detector and begin generating X-rays at the synchronization signal once X-ray exposure is enabled. The workstation / image processing unit can stop its current activity, initialize the acquisition and image processing modules, and wait for incoming frames. Furthermore, in some examples, the X-ray tube filament can be preheated during the exposure preparation phase (e.g., by applying a certain amount of voltage to the filament before X-ray exposure) to reduce the amount of time it takes for the X-ray tube to reach the current setting. For example, the filament can be heated to a predetermined temperature based on the current setting so that the current setting is reached quickly once exposure begins.

[0038] In 204, method 200 includes activating the X-ray source and acquiring a first image of the ROI. For example, an X-ray exposure may be initiated in response to a command from an operator to form an imaging sequence, and the X-ray tube may be operated at voltage and current settings. This causes X-rays to be generated and sent to the subject, passing through and around the subject, and then striking a detector, thereby acquiring the first image. In some examples, the first image may be the first image of the imaging sequence with respect to time. The first image may be acquired relatively quickly (e.g., 10 milliseconds) after the exposure command is issued. In some examples, the filament of the X-ray tube may be maintained at a high temperature (e.g., relative to room temperature) as described above, which may allow a predefined current to be reached rapidly.

[0039] In 206, method 200 includes displaying a first image. For example, the first image may be output substantially in real time (e.g., when the first image is acquired and there is no intentional delay) to a display operatively coupled to an imaging system (e.g., Figure 1 (Display 42). In addition, the first image can be stored in memory.

[0040] At 208, method 200 includes receiving annotations on the displayed first image. For example, the first image may be displayed within an imaging application or interface that includes annotation tools. The annotation tools enable an operator (or assistant) to interact with the displayed image, such as by drawing one or more lines, points, arrows, boxes, etc., on the displayed image to annotate anatomical features or regions of interest, which will be referred to herein as annotation features. Annotations can be colored, edited, or deleted. In some examples, the operator may also incorporate rulers as annotations or as part of annotations.

[0041] It is understood that in some examples, the operator may not annotate the first image acquired relative to time in the imaging sequence. For example, more than one image may be acquired at the first position, or the imaging chain position may be adjusted before the operator finds a view showing the features to be annotated. Therefore, it is understood that the term "first image" as used herein refers to the first image relative to the time of receiving annotation, and the term "first position" refers to the position of the imaging chain when the first annotated image is acquired. For example, at least a portion of method 200 (e.g., from 202 to 206) may be repeated until annotation is received. Thus, this disclosure is not intended to be limited to receiving annotation of the first image acquired relative to time in the imaging sequence. Furthermore, the first annotated image may also be referred to as a reference image.

[0042] In yet another example, annotation can be performed automatically without operator input (or with reduced operator input). For example, image analysis algorithms can be used to identify anatomical features, such as vascular systems visualized using contrast agent injection. Image analysis algorithms may include, for example, computer vision and / or segmentation algorithms. Furthermore, in at least some examples, the operator can adjust the automatically determined annotations or otherwise interact with them.

[0043] In 210, method 200 includes determining the three-dimensional (3D) location of the annotation based on the geometry of the imaging chain at a first location. For example, the processor can determine the location of the annotation in virtual 3D space by determining the intersection between a line L and a plane P. The line L can be defined as a line between the annotation defined at a location on the X-ray source and the X-ray detector. The plane P can be defined using one of a variety of different strategies. For example, the plane P can be a plane parallel to and spaced apart from the stage by a distance chosen by the operator at the start of the imaging procedure or as part of a pre-programmed examination protocol (e.g., as selected in 202). As another example, the plane P can be parallel to the detector and spaced apart from the detector at a predetermined distance when the annotation is placed (this distance can be the same as or different from the distances described above). Thus, the plane P can be parallel to and spaced apart from a reference object (e.g., the stage or the X-ray detector) at a predetermined distance and exist between the X-ray source and the X-ray detector. Furthermore, the plane P intersects with the subject. The choice between these methods or any other similar methods may depend on the type of clinical procedure being performed. The 3D location of the annotation can also be stored in memory. An example showing line L and plane P will be shown below relative to... Figure 3 Describe it.

[0044] Two virtual points can also be determined. As detailed below, virtual points can be used during accuracy checks to control whether annotations appear on subsequent images. To determine virtual points, the processor can define two additional planes, P1 and P2, parallel to plane P. Planes P1 and P2 can be located on each side of plane P, respectively, and can serve as boundaries for the true 3D anatomical locations of the annotation features. Plane P1 can be spaced apart from plane P in a first direction, and plane P2 can be spaced apart from plane P in a second direction opposite to the first direction. For example, plane P1 can be positioned closer to the X-ray source than plane P, and plane P2 can be positioned closer to the detector than plane P. In some examples, the positions of planes P1 and P2 can be selected based on the subject's thickness, such that both planes P1 and P2 intersect the subject. A first virtual point V1 can be determined at the intersection between L and P1, and a second virtual point V2 can be determined at the intersection between L and P2.

[0045] Furthermore, when a ruler is included in the annotation, the processor can directly derive the magnification. This allows the processor to determine the length of the annotation (e.g., when the annotation is a line) at an anatomical level, assuming the anatomical feature of interest lies in a plane. For example, a ruler comprises a linear segment having a length initially drawn in the 2D image plane of the first image. This length can be determined by calculating the Euclidean distance separating the first end and the second end of the linear segment in plane P. As another example, the length can be determined by multiplying the length of the segment drawn in the first image by a scaling factor associated with the midpoint of the segment, which is determined by the three-dimensional position of that midpoint.

[0046] At 212, method 200 includes adjusting the imaging chain to a subsequent position for imaging the ROI. For example, the subsequent position may be the next position relative to time. That is, the subsequent position occurs later in time (e.g., after the first position). For example, the subsequent position may be a second position that occurs after the first position. The motor controller may adjust the imaging chain to the subsequent position in response to a command received from the operator or according to a selected imaging scheme. The subsequent second position may have a different imaging change angle relative to the stage supporting the subject than the initial first position. Additionally or alternatively, the subsequent position may have a different stage translation compared to the first position. As yet another example, additionally or alternatively, the subsequent position may have a different magnification than the first position. Thus, the second position can provide a different view of the ROI than the first position. Furthermore, the X-ray tube voltage, current, and pulse width settings may be the same as or different from the settings used in the first position.

[0047] At 214, method 200 includes activating an X-ray source and acquiring a subsequent image of the ROI. For example, an X-ray exposure may be initiated in response to a command from an operator, as described above at 204. The X-rays generated in response to the exposure initiation may be sent to the subject, pass through and around the subject, and then strike a detector to acquire a subsequent image. For example, the subsequent image may be a second image acquired relative to a first image. Thus, the second image is a "follow-up" image in the imaging sequence after the first image.

[0048] In step 216, method 200 includes determining the position of the annotation on a subsequent image and the distance between virtual points based on the determined 3D position and the imaging chain geometry in subsequent positions. For example, the processor may project the annotation, defined in 3D space, onto an imaging plane of a subsequent (e.g., second) image, which may be referred to as plane IP. For example, the processor may geometrically determine the position of the annotation knowing the rotational changes of the imaging chain angles, the translational changes of the stage, and / or the magnification changes between the first and second positions, as well as the changes in the 3D position of the annotation via geometric transformations. These configuration elements of the imaging chain (e.g., rotational changes of angles, translational changes of the stage, and / or changes in magnification) are combined in a projection matrix that summarizes the relationship between the 3D space and the image plane of the subsequent plane.

[0049] In 218, method 200 includes determining whether the distance between virtual points satisfies an accuracy check. Based on the geometry of the imaging chain in subsequent positions (e.g., the rotational position of the imaging chain, the position of the stage, and / or the magnification used in subsequent positions combined in the projection matrix), the positions of two virtual points in the current imaging plane IP are determined as standard projections. As an example, the accuracy check is satisfied when the distance between the two virtual points is less than a threshold distance. The threshold distance refers to a non-zero distance stored in memory. As a non-limiting example, the threshold distance can be in the range of 5 mm to 10 mm. Furthermore, the operator can adjust the threshold distance to strengthen or relax the accuracy check. For example, the operator can adjust the threshold distance to be greater than 10 mm when it is useful for a more general approximation of the annotation position on subsequent images.

[0050] If the distance between virtual points satisfies an accuracy check (e.g., the distance is less than a threshold distance), method 200 proceeds to 220 and includes displaying a subsequent image with annotations at a determined location. That is, the processor places the annotations at determined (2D) locations on the displayed image such that the display position of the annotations on the 2D image varies according to changes in the imaging chain geometry to accurately reflect the 3D position of the annotations. In other words, the 3D position of the annotations remains constant, while the position of the annotations on the image changes due to variations in the imaging chain between the first and subsequent positions. An example imaging sequence showing annotations displayed on subsequent images with updated positions is provided. Figure 4 It is shown in the figure and will be described below.

[0051] If the distance between virtual points does not meet the accuracy check (e.g., the distance is greater than or equal to a threshold distance), method 200 proceeds to 222 and includes displaying a subsequent image without annotations. The 3D location of the annotations remains known, but the 2D location of the annotations is not shown on the subsequent image due to inaccurate positioning. For example, displaying annotations at inaccurate locations may confuse the operator or provide other distracting or unhelpful information. Furthermore, the subsequent image can be stored in memory regardless of whether the annotations are displayed overlaid on it.

[0052] In section 224, method 200 includes determining whether acquisition is complete. For example, acquisition is complete when all specified views of the current inspection scheme have been obtained. As another example, the operator can indicate that acquisition is complete via input.

[0053] If the acquisition is not completed, method 200 returns to 212 and includes adjusting the imaging chain to a subsequent (e.g., next) position to image the ROI. As an example, the subsequent position could be a third position that occurs temporally later than the second position. In this way, the image sequence and the annotation position of the current image are continued to be acquired. As an illustrative example, an artery may be visible in the first image due to the use of contrast agent. Therefore, the operator can annotate the artery in the first image. However, the contrast agent will be washed away over time and will no longer be visible in some or all of the subsequently acquired images. Because the annotation position is dynamically updated, the operator can track the position of the artery in subsequent acquired images even after the contrast agent has been washed away.

[0054] If acquisition is complete, method 200 proceeds to 226 and includes deactivating the X-ray source. For example, deactivating the X-ray source may include stopping power supply to the X-ray generator or placing the X-ray source in a low-power "standby" mode, where the X-ray source does not actively generate X-rays until the imaging system is shut down. Furthermore, in some examples, the X-ray detector may not be powered or may be placed in a "standby" mode, where power consumption is reduced and the X-ray detector does not actively generate electrical signals until the imaging system is powered off. Method 200 then ends. For example, the X-ray source may not be activated until the operator selects a new imaging scheme or provides another input to begin a new imaging sequence.

[0055] In this way, annotations received on one medical image acquired via an imaging chain can be displayed on subsequently acquired medical images, their positions dynamically updated as the geometry of the imaging chain changes. As a result, the operator can focus on the examination being performed, rather than trying to mentally link images together to follow anatomical features of interest.

[0056] refer to Figure 3, relative to which it may be included in the imaging system (e.g., Figure 1 The imaging chain in the imaging system 10) illustrates a schematic example of geometrically determining the 3D location of the annotation site of interest. The imaging chain includes an X-ray focus 312 that emits X-ray radiation 316 toward a patient 318 located on a stage 332. The incident portion 320 of the X-ray radiation 316 impacts a detector array 322. Figure 3 An imaging chain is shown at the first position 300 and the second position 301.

[0057] An annotation is received on the acquired first image while the imaging chain is at the first position 300. The annotation is placed at position 303 on the detector array 322. Position 303 is defined by a known coordinate system relative to the detector array 322 and corresponds to the annotation position on the first image. For example, the annotation position on the first image can be mapped to the position of the corresponding portion of the acquired image on the detector array 322. The processor (e.g., Figure 1 The processor 30) defines the plane 302 (e.g., regarding Figure 2 The method describes a plane P, which is parallel to the detector array 322 at a defined distance d1 from the detector array 322. The processor also defines a line 304 extending between the X-ray focus 312 and the position 303 (e.g., regarding...). Figure 2 The method describes the line L). The received annotation can then be associated with a 3D point 310, which is located at the intersection of plane 302 and line 304 that connects X-ray focus 312 with position 303. Note that in other examples, plane 302 is instead defined as plane 350, which is parallel to the stage 332 at a distance d2 above the stage 332.

[0058] The first parallel plane 306 and the second parallel plane 308 are relative to plane 302 (e.g., about). Figure 2 The planes described are P1 and P2. A first parallel plane 306 and a second parallel plane 308 are parallel to and spaced apart from plane 302, respectively. The first parallel plane 306 is closer to the X-ray focus 312 than plane 302, and the second parallel plane 308 is closer to the detector array 322 (and further away from the X-ray focus 312) than plane 302. A first virtual point 314 is defined at the intersection of line 304 and the first parallel plane 306, and a second virtual point 324 is defined at the intersection of line 304 and the second parallel plane 308. The 3D point 310, the first virtual point 314, and the second virtual point 324, associated with the annotation, are all defined within virtual 3D locations without using precise 3D modeling or rendering, reducing the computational resources used to determine the 3D location of the points. Furthermore, the locations are stored in memory.

[0059] The imaging chain is adjusted to the second position 301 to obtain the second image. Thus, the positions of the X-ray focus 312 and the detector array 322 are different relative to the patient 318 and the worktable 332. The positions of the X-ray focus 312 and the detector array 322 have changed relative to the 3D point 310, the first virtual point 314, and the second virtual point 324 associated with the annotation. However, the 3D points 310, 314, and 324 remain unchanged relative to the worktable 332 and the patient 318. Because the virtual 3D positions of the 3D points 310, 314, and 324 are known and the geometry of the imaging chain in the second position 301 is known, the positions of the 3D points 310, 314, and 324 are projected onto the detector array 322, whose position defines the image plane. This image plane is a 2D plane. Through projection, the position of the 3D point 310 associated with the annotation is updated to position 305 on the detector array 322. Thus, based on the known coordinate system of detector array 322, the position of the annotation on the second image is updated by mapping position 305 to the second image. Furthermore, in response to satisfying an accuracy check, the annotation is displayed on the second image; this accuracy check evaluates the distance between position 307 of the first virtual point 314 projected onto the image plane (e.g., the plane of the detector) and position 309 of the second virtual point 324 projected onto the image plane.

[0060] Now go to Figure 4 An example sequence 400 of X-ray images of a phantom including dynamically updated annotations is shown. Sequence 400 includes a first image 402 obtained at a first imaging chain location. The first image 402 serves as a reference image and receives an initial annotation 412. The initial annotation 412 is located at the beginning of a structure that schematically represents an artery in the phantom that has been injected with contrast agent. While this structure does not lose contrast agent over time in the phantom, it is understandable that if instead, imaging were performed on a human subject, the contrast agent would be washed away over time, and the artery would no longer appear dark in the X-ray image.

[0061] Sequence 400 includes a second image 404 obtained at a second imaging chain position different from the first position. The second position includes a 28 mm translation of the phantom relative to the first position of the first image 402, such as by moving the stage supporting the phantom relative to the imaging chain. The processor (e.g., Figure 1 The processor 30) such as according to Figure 2 The method and using Figure 3The geometric analysis, schematically illustrated, determines the location of the updated annotation. Once the updated location is determined, the annotation is displayed as a first updated annotation 414 on the second image 404 (e.g., in response to satisfying an accuracy check). The initial annotation 412 is shown by a dashed line with a thinner linewidth to allow comparison of the positions of the initial annotation 412 and the first updated annotation 414, although it is understood that only the first updated annotation 414 may be displayed on the second image 404. The first updated annotation 414 overlaps with the initial annotation 412, demonstrating good agreement between the calculated location and the exact location of the annotation received on the first image 402.

[0062] A third image 406 is obtained when the imaging chain is in a third imaging chain position that is different from each of the first and second positions. The third imaging chain position is not translated relative to the first imaging chain position used when acquiring the first image 402, but rotated by 5 degrees. The processor again determines the updated position of the annotation, which is displayed as a second updated annotation 416 compared to the initial annotation 412.

[0063] When the imaging chain is at the fourth imaging chain position, a fourth image 408 of imaging sequence 400 is obtained, the fourth imaging chain position being rotated 10 degrees relative to the first imaging chain position. The processor determines the updated position of the annotation on the fourth image 408 based on the 10-degree rotation and displays the annotation as a third updated annotation 418, the position of which is close to the initial annotation 412.

[0064] When the imaging chain is at the fifth imaging chain position, a fifth image 410 of imaging sequence 400 is obtained, the fifth imaging chain position being rotated 15 degrees relative to the first imaging chain position. The processor determines the updated position of the annotation on the fifth image 410 based on the 15-degree rotation and displays the annotation as the fourth updated annotation 420. Because the rotation of the imaging chain is the largest in sequence 400 in the fifth image 410, the accuracy of placement is reduced. For example, the fourth updated annotation 420 is farther from the initial annotation 412 in the fifth image 410 than the third updated annotation 418 is farther from the initial annotation 412 in the fourth image 408. If the processor determines the position of the fourth updated annotation 420 too inaccurately, such as by using the distance between virtual points defined during the initial annotation, the fourth updated annotation 420 will not be displayed on the fifth image 410.

[0065] In this way, images acquired during interventional procedures can be dynamically and accurately annotated to track anatomical structures across views. Dynamic annotation helps users accurately relocate previously identified objects of interest, rather than attempting to mentally track them across views. As a result, the mental burden on users is reduced, allowing them to focus on patient care. Furthermore, because dynamically updated annotations enable accurate tracking of anatomical structures across views, the locations of anatomical structures that may be invisible in some views (e.g., due to contrast agent rinsing) may be known. Additionally, because the method described in this paper does not construct complex 3D models, computational resources are reduced and the speed of dynamic tracking is improved.

[0066] Determining the three-dimensional location of annotations received on two-dimensional medical images during imaging procedures has the following technical advantages: annotations can be repositioned on medical images obtained in subsequent imaging procedures with reduced computational complexity.

[0067] This disclosure provides support for a method for a projection imaging system, the method comprising acquiring a first image of a region of interest (ROI) at a first location using the projection imaging system; determining a three-dimensional (3D) position of an annotation on the first image via a geometric transformation of a plane; acquiring a second image of the ROI at a second location using the projection imaging system; determining a position of the annotation on the second image based on the 3D position of the annotation at the first location and the geometry of the second location; and displaying the annotation on the second image in response to satisfying an accuracy check. In a first embodiment of the method, the projection imaging system includes an X-ray source and an X-ray detector, and wherein determining the 3D position of the annotation on the first image via a geometric transformation of a plane comprises: defining a first plane parallel to and spaced apart from a reference object by a predetermined distance, the first plane being located between the X-ray source and the X-ray detector; defining a line extending between the X-ray source and the position of the annotation on the X-ray detector at the first location; and setting the 3D position of the annotation at the intersection of the first plane and the line. In a second embodiment of the method, optionally including the first embodiment, the reference object is a stage supporting an imaged subject. In a third embodiment of the method, optionally including one or both of the first and second embodiments, the reference object is an X-ray detector. In a fourth embodiment of the method, optionally including one or more of the first to third embodiments, the position of the annotation on the X-ray detector at the first location is determined by mapping the first image onto the coordinate system of the X-ray detector. In a fifth embodiment of the method, optionally including one or more of the first to fourth embodiments, determining the position of the annotation on the second image based on the 3D position of the annotation at the first location and the geometry of the second location includes projecting the 3D position of the annotation onto an image plane parallel to the X-ray detector at the second location. In a sixth embodiment of the method, optionally including one or more of the first to fifth embodiments, the method further includes: defining a second plane parallel to the first plane and closer to the X-ray detector than the first plane; defining a third plane parallel to the first plane and closer to the X-ray source than the first plane; setting a first virtual point where the line intersects the second plane; and setting a second virtual point where the line intersects the third plane. In a seventh embodiment of the method, optionally including one or more of the first to sixth embodiments, the accuracy check includes: projecting the first virtual point and the second virtual point into an image plane parallel to the X-ray detector at the second position; and determining the distance between the projected first virtual point and the projected second virtual point in the image plane at the second position.In an eighth embodiment of the method, which optionally includes one or more of the first to seventh embodiments or each of them, the accuracy check is satisfied in response to the distance being less than a threshold distance, and the accuracy check is not satisfied in response to the distance being not less than the threshold distance, and the method further includes displaying the second image without the annotation in response to the accuracy check not being satisfied.

[0068] This disclosure also provides support for a method for an X-ray imaging system, the method comprising: acquiring a series of images of a region of interest (ROI) of a subject using the X-ray imaging system, adjusting the imaging chain of the X-ray imaging system relative to a stage supporting the subject while acquiring the series; and updating annotations on the position of each image in the series of images based on the geometry of the imaging chain and the stage, while acquiring a given image in the series of images relative to a reference image in the series of images. In a first embodiment of the method, the imaging chain includes an X-ray source and an X-ray detector, and wherein the position of an annotation based on the geometry of the imaging chain and the stage is updated on each of the series of images, while acquiring a given image in the series of images relative to a reference image, includes: receiving the annotation on the reference image while displaying the reference image via a display; defining a first plane located in the space between the X-ray source and the X-ray detector, and a line extending between the positions on the X-ray source and the X-ray detector corresponding to the two-dimensional (2D) position of the annotation on the reference image; determining a three-dimensional (3D) position of the annotation at the intersection of the first plane and the line; and determining the updated position of the annotation on the given image in the series of images by projecting the 3D position of the annotation onto the 2D image plane of the given image. In a second embodiment of the method, optionally including the first embodiment, the 2D image plane of the given image is defined by the angular and translational position of the imaging chain relative to the stage when the given image is acquired. In a third embodiment of the method, optionally including one or both of the first and second embodiments, the first plane is parallel to the X-ray detector when the reference image is acquired and spaced at a predetermined distance from the X-ray source. In a fourth embodiment of the method, optionally including one or both of the first to third embodiments, the first plane is parallel to the stage and spaced at a predetermined distance from the stage. In a fifth embodiment of the method, optionally including one or both of the first to fourth embodiments, the method further includes: displaying the annotation at the updated position on the given image in the series of images via the display in response to the distance between the projections of the virtual points being less than a threshold distance on the given image; and not displaying the annotation at the updated position on the given image in the series of images via the display in response to the distance between the projections of the virtual points not being less than the threshold distance on the given image.In a sixth embodiment of the method, which optionally includes one or more or each of the first to fifth embodiments, the first virtual point of the virtual point is located at a first intersection of the line and the second plane, the second plane being parallel to the first plane and closer to the X-ray source than the first plane, and the second virtual point of the virtual point is located at a second intersection of the line and the third plane, the third plane being parallel to the first plane and closer to the X-ray detector than the first plane.

[0069] This disclosure also provides support for an imaging system comprising: a radiation source configured to project a radiation beam toward a subject located on a worktable; a radiation detector configured to receive the radiation beam projected by the radiation source and impacted by the subject; and a processor operatively coupled to a memory storing instructions that, when executed, cause the processor to: acquire a first image of a region of interest (ROI) of the subject via the radiation detector when the radiation source and the radiation detector are in a first position relative to the worktable; receive an annotation on the first image; determine a three-dimensional (3D) position of the annotation in the subject via a geometric transformation using parallel planes; acquire a second image of the ROI via the radiation detector when the radiation source and the radiation detector are in a second position relative to the worktable; and determine a two-dimensional (2D) position of the annotation on the second image by projecting the determined 3D position of the annotation onto an image plane of the second image. In a first embodiment of the system, in order to determine the 3D position of the annotation in the subject via the geometric transformation using the parallel plane, the memory includes additional instructions that, when executed by the processor, cause the processor to: define a first plane intersecting the subject and parallel to one of the radiation detector and the stage; define a line extending between the radiation source and the position of the received annotation on the radiation detector in the first position; and set the 3D position of the annotation at the intersection of the first plane and the line. In a second embodiment of the system, optionally including the first embodiment, the memory includes additional instructions that, when executed by the processor, cause the processor to: define a second plane parallel to the first plane and spaced apart from the first plane in a first direction; define a third plane parallel to the first plane and spaced apart from the first plane in a second direction opposite to the first direction; define a first virtual point where the second plane and the line intersect; and define a second virtual point where the third plane and the line intersect. In a third embodiment of the system, which optionally includes one or both of the first and second embodiments, the system further includes a display, and wherein the memory includes additional instructions that, when executed by the processor, cause the processor to: project the first virtual point and the second virtual point onto the image plane of the second image; determine the distance between the projected first virtual point and the projected second virtual point on the second image; display the annotation on the second image via the display at the determined 2D location in response to the distance being less than a threshold distance; and display the second image without the annotation via the display in response to the distance being greater than or equal to the threshold distance.

[0070] As used herein, elements or steps listed in the singular and beginning with the word "a" or "an" should be understood to not exclude a plurality of said elements or steps unless such exclusion is explicitly stated. Furthermore, references to "one embodiment" of the invention are not intended to be construed as excluding the existence of additional embodiments that also include the referenced features. Moreover, unless explicitly stated to the contrary, embodiments that "comprise," "include," or "have" elements or multiple elements having a particular characteristic may include additional such elements that do not have that characteristic. The terms "comprise" and "in..." are used as concise linguistic equivalents to the corresponding terms "comprising" and "wherein". Furthermore, the terms "first," "second," and "third," etc., are used merely as notations and are not intended to impose numerical requirements or a particular order of position on their objects.

[0071] This written description uses examples to disclose the invention, including the best mode, and also enables those skilled in the art to practice the invention, including making and using any device or system and performing any included methods. The scope of patentability of the invention is defined by the claims and may include other examples that would occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims if they have structural elements that are not indistinguishable from the literal language of the claims, or if they include equivalent structural elements that have minor differences from the literal language of the claims.

Claims

1. A method for a projection imaging system, the method comprising: The projection imaging system is used to acquire a first image of the region of interest at a first position. The three-dimensional position of the annotation on the first image is determined by using geometric transformations of the plane; The projection imaging system is used to acquire a second image of the region of interest at a second location. The position of the annotation on the second image is determined based on the three-dimensional position of the annotation in the first position and the geometry of the second position; as well as The annotation is displayed on the second image in response to meeting an accuracy check, wherein the projection imaging system includes an X-ray source and an X-ray detector, and wherein determining the three-dimensional position of the annotation on the first image via the geometric transformation using the plane includes: A first plane is defined, which is parallel to and spaced apart from the reference object by a predetermined distance, and the first plane is located between the X-ray source and the X-ray detector; A line extending between the X-ray source and the position of the annotation on the X-ray detector in the first position; and The three-dimensional position of the annotation is set at the intersection of the first plane and the line.

2. The method according to claim 1, wherein the reference object is a stage that supports the subject being imaged.

3. The method of claim 1, wherein the reference object is the X-ray detector.

4. The method of claim 1, wherein the position of the annotation on the X-ray detector in the first position is determined by mapping the first image onto the coordinate system of the X-ray detector.

5. The method of claim 1, wherein determining the position of the annotation on the second image based on the three-dimensional position of the annotation in the first position and the geometry of the second position comprises projecting the three-dimensional position of the annotation onto an image plane parallel to the X-ray detector in the second position.

6. The method according to claim 1, further comprising: A second plane is defined, which is parallel to the first plane and closer to the X-ray detector than the first plane; A third plane is defined, which is parallel to the first plane and closer to the X-ray source than the first plane; Set a first virtual point where the line intersects with the second plane; as well as Set a second virtual point where the line intersects the third plane.

7. The method of claim 6, wherein the accuracy check comprises: The first virtual point and the second virtual point are projected onto an image plane, the image plane being parallel to the X-ray detector at the second position; as well as Determine the distance between a first virtual point and a second virtual point of the projection in the image plane at the second position.

8. The method of claim 7, wherein the accuracy check is satisfied in response to the distance being less than a threshold distance, and the accuracy check is not satisfied in response to the distance being not less than the threshold distance, and the method further comprises displaying the second image without the annotation in response to the failure to satisfy the accuracy check.

9. A method for an X-ray imaging system, the method comprising: The X-ray imaging system is used to acquire a series of images of the region of interest of the subject, and the imaging chain of the X-ray imaging system is adjusted relative to the worktable supporting the subject during the acquisition of the series of images; as well as Based on the geometry of the imaging chain and the platform update annotations on the position of each image in the series of images, a given image in the series of images is obtained relative to a reference image in the series of images. The imaging chain includes an X-ray source and an X-ray detector, and the updating of the annotation position on each of the series of images based on the geometry of the imaging chain and the stage, while acquiring a given image in the series of images relative to a reference image, includes: The annotations on the reference image are received while the reference image is being displayed on the screen; A first plane is defined in the space between the X-ray source and the X-ray detector, and a line extends between the positions on the X-ray source and the X-ray detector that correspond to the two-dimensional 2D positions of the annotation on the reference image; Determine the three-dimensional position of the annotation at the intersection between the first plane and the line; and The updated position of the annotation on the given image in the series of images is determined by projecting the three-dimensional position of the annotation onto the 2D image plane of the given image.

10. The method of claim 9, wherein the 2D image plane of the given image is defined by the angular and translational position of the imaging chain relative to the stage when the given image is acquired.

11. The method of claim 9, wherein when the reference image is acquired and spaced a predetermined distance from the X-ray source, the first plane is parallel to the X-ray detector.

12. The method of claim 9, wherein the first plane is parallel to the worktable and spaced apart from the worktable by a predetermined distance.

13. The method according to claim 9, further comprising: In response to a distance between the projections of virtual points being less than a threshold distance on the given image, the annotation is displayed via the display at the updated position on the given image in the series of images; as well as In response to the distance between the projections of the virtual points being not less than the threshold distance on the given image, the annotation is not displayed at the updated position on the given image in the series of images via the display.

14. The method of claim 13, wherein the first virtual point of the virtual points is located at a first intersection of the line and the second plane, the second plane being parallel to the first plane and closer to the X-ray source than the first plane, and the second virtual point of the virtual points is located at a second intersection of the line and the third plane, the third plane being parallel to the first plane and closer to the X-ray detector than the first plane.

15. An imaging system, the imaging system comprising: A radiation source configured to project a radiation beam toward a subject located on a worktable; A radiation detector configured to receive the radiation beam projected by the radiation source and struck by the subject; and A processor, operatively coupled to a memory storing instructions, which, when executed, cause the processor to: When the radiation source and the radiation detector are in a first position relative to the worktable, a first image of the region of interest of the subject is acquired via the radiation detector; Receive annotations from the first image; The three-dimensional position of the annotation in the subject was determined by using geometric transformations of parallel planes; When the radiation source and the radiation detector are in a second position relative to the worktable, a second image of the region of interest is acquired via the radiation detector; as well as The two-dimensional (2D) position of the annotation on the second image is determined by projecting the determined three-dimensional position of the annotation onto the image plane of the second image. In order to determine the three-dimensional position of the annotation in the subject via the geometric transformation using the parallel plane, the memory includes additional instructions that, when executed by the processor, cause the processor to: A first plane is defined, which intersects the subject and is parallel to one of the radiation detector and the worktable; A line extending between the radiation source and the position of the received annotation on the radiation detector in the first position; as well as The three-dimensional position of the annotation is set at the intersection of the first plane and the line.

16. The imaging system of claim 15, wherein the memory includes additional instructions that, when executed by the processor, cause the processor to: A second plane is defined, which is parallel to the first plane and spaced apart from the first plane in a first direction; A third plane is defined, which is parallel to the first plane and spaced apart from the first plane in a second direction, the second direction being opposite to the first direction; Define the first virtual point where the second plane and the line intersect; as well as Define a second virtual point where the third plane and the line intersect.

17. The imaging system of claim 16, further comprising a display, and wherein the memory includes additional instructions that, when executed by the processor, cause the processor to: Project the first virtual point and the second virtual point onto the image plane of the second image; Determine the distance between the first virtual point projected on the second image and the second virtual point projected on the second image; In response to the distance being less than a threshold distance, the annotation is displayed on the second image via the display at the determined 2D location; as well as In response to the distance being greater than or equal to the threshold distance, the second image without the annotation is displayed via the display.

Images