Device for positioning an X-ray imaging system, medical imaging apparatus, and method for performing X-ray imaging of a spinal structure

Abstract

The present invention relates to positioning an X-ray imaging system. In order to provide an improved relative positioning of an X-ray imaging system for spinal intervention, a device (10) for positioning an X-ray imaging system is provided. The device comprises a data storage unit (12), a processing unit (14) and an output unit (16). The data storage unit is configured to store and provide 3D image data (18) of a spinal region of interest of an object, the spinal region of interest comprising a portion of a spinal structure, the spinal structure comprising at least one vertebra. The processing unit is configured to: select at least one vertebra of the spinal structure as a target vertebra; segment at least the target vertebra in the 3D image data; wherein the segmentation comprises identifying at least one anatomical feature of the target vertebra; defining a position of a predetermined reference line based on a spatial arrangement of the at least one anatomical feature; and determining a target viewing direction of the X-ray imaging system based on the reference line. The output unit is configured to provide the target viewing direction for the X-ray imaging system.

Description

Technical Field

[0001] The present invention relates to an apparatus for positioning an X-ray imaging system, a medical imaging device for spinal intervention, and a method for performing X-ray imaging of spinal structures. Background Art

[0002] During minimally invasive procedures, or also during open procedures, X-ray imaging (e.g., fluoroscopic imaging) is used for navigation or for inspection when a navigation system is used. In order to be able to interpret the X-ray images, certain projections are used, which may require a specific orientation of the X-ray imaging system (e.g., a C-arm device) relative to a certain part of the anatomical structure of the object. For example, during spine-related interventions, a true AP (anteroposterior, i.e., from the front to the back of the object) view of the vertebrae can be provided. Another example of a standard view provided is a true side view of the vertebrae or a view providing the so-called Scotty dog ​​landmark of the vertebrae. These viewing directions require precise alignment of the X-ray imaging system with respect to the object. As an example, this can be provided by manual adjustment, and multiple X-ray images will be required, and this adjustment will increase the patient and operator dose before the operator finds the correct position of the C-arm. This position can be different for each vertebral level along the spine, which can also be cumbersome. Summary of the invention

[0003] There would therefore be a need for improved relative positioning of X-ray imaging systems for spinal interventions.

[0004] The objects of the invention are solved by the subject matter of the independent claims; further embodiments are included in the dependent claims. It should be noted that the aspects of the invention described below also apply to an apparatus for positioning an X-ray imaging system, a medical imaging device for spinal interventions and a method for X-ray imaging of spinal structures.

[0005] According to the present invention, a device for positioning an X-ray imaging system is provided. The device includes a data storage unit, a processing unit and an output unit. The data storage unit is configured to store and provide 3D image data of a spinal region of interest of an object, the spinal region of interest including a portion of a spinal structure, the spinal structure including at least one vertebra. The processing unit is configured to select at least one vertebra of the spinal structure as a target vertebra. The processing unit is configured to segment at least the target vertebra in the 3D image data. The segmentation includes identifying at least one anatomical feature of the target vertebra. The processing unit is also configured to define the position of a predetermined reference line based on the spatial arrangement of the at least one anatomical feature. The processing unit is also configured to determine a target viewing direction of the X-ray imaging system based on the reference line. The output unit is configured to provide the target viewing direction for the X-ray imaging system.

[0006] This provides a viewing direction in which the spinal structures, in particular the selected vertebrae, are shown in a desired or required manner, for example in which minimal structural overlap occurs and in which minimal distortion is shown. Thus, the determined target viewing direction may represent an optimal viewing direction. This optimal viewing direction can then be used for the imaging step. By determining the adjusted optimal viewing direction, the user can be supported and the workflow can be facilitated since only minimal input or action from the user is required. In particular, the optimal viewing direction is determined based on existing data and positioning information so that the desired X-ray view can be achieved without trial and error imaging. Thus, a reduction in X-ray dose is achieved for both the subject and the operator. Therefore, the present invention relates to X-ray imaging and how to achieve a good positioning of the imaging system with respect to the optimal viewing direction.

[0007] According to an example, an input unit is also provided. The input unit is configured to provide a spatial relationship between the 3D image data and the X-ray imaging system. In addition, the processing unit is configured to determine a spatial relationship between a current viewing direction of the X-ray imaging system and the target viewing direction. The processing unit is further configured to convert the spatial relationship into a motion vector. The processing unit is further configured to control the movement of the X-ray imaging system and the object relative to each other according to the motion vector.

[0008] According to an example, the processing unit is configured to: identify a surface of an endplate of the at least one vertebra as the at least one anatomical feature, and identify a pair of pedicle portions of the at least one vertebra, and identify a spinous process between the endplates of the at least one vertebra. The processing unit is further configured to define a line extending between the pedicle portions, extending through the spinous process, and also extending parallel to the surface of the endplate as the reference line.

[0009] According to the present invention, a medical imaging device for spinal intervention is also provided. The device includes an imaging system having an X-ray source and an X-ray detector, wherein the X-ray detector is configured to acquire an X-ray image of the anatomical structure of an object. The device also includes a device for positioning the X-ray imaging system according to one of the aforementioned examples. The X-ray source, together with the X-ray detector and the object, are movable relative to each other. The X-ray source, together with the X-ray detector and the object, are movable according to a target viewing direction determined by the device for positioning the X-ray imaging system.

[0010] According to an example, the imaging system is further configured to provide 3D data of an anatomical structure of the object.In addition, the processing unit is configured to calculate the 3D image data based on the 3D data.

[0011] According to an example, to provide a spatial relationship between the 3D image data and the imaging system, at least one current 2D X-ray image is provided by the imaging system and the at least one current 2D X-ray image is registered with the 3D image data. Features are identified in the at least one current 2D X-ray image, and the features of the at least one current 2D X-ray image are registered with matching features in the 3D image data. The determined target viewing direction is adjusted based on the registration of the 3D image data with the at least one current 2D X-ray image. The at least one current 2D X-ray image is registered with the 3D image data on a per vertebral basis.

[0012] According to an example, a plurality of screws are detected as the feature. The processing unit is configured to calculate a 3D reconstruction of the screws based on at least two 2D X-ray images from different directions. The processing unit is further configured to register the reconstructed screws with the 3D image data.

[0013] In an example, the X-ray image (eg, fluoroscopic image) is also used to create a 3D model of the screw.

[0014] According to the present invention, a method for performing X-ray imaging of spinal structures is also provided. The method comprises the following steps:

[0015] a1) providing 3D image data of a spinal region of interest of a subject, the spinal region of interest comprising a portion of a spinal column structure, the spinal column structure comprising at least one vertebra;

[0016] b) selecting at least one vertebra of the spinal column structure as a target vertebra;

[0017] c) segmenting at least the target vertebra in the 3D image data; wherein the segmentation comprises identifying at least one anatomical feature of the target vertebra;

[0018] d) defining a position of a predetermined reference line based on the spatial arrangement of the at least one anatomical feature; and

[0019] e1) determining a target viewing direction of the X-ray imaging system based on the reference line.

[0020] According to the example, the following steps are also provided:

[0021] a2) providing a spatial relationship between the 3D image data and the X-ray imaging system;

[0022] e2) determining a spatial relationship between a current viewing direction of the X-ray imaging system and the target viewing direction, and converting the spatial relationship into a motion vector; and

[0023] f) Moving the X-ray imaging system and the object relative to each other according to the movement vector.

[0024] According to an example, said segmentation in step c) comprises identifying:

[0025] c1) a surface of an endplate of said at least one vertebra; and

[0026] c2) a pair of pedicle portions of the at least one vertebra; and

[0027] c3) spinous processes between said endplates of said at least one vertebra.

[0028] The defining of the reference line in step d) includes defining a line extending between the pedicle portions and through the spinous processes and parallel to the surface of the endplate as the reference line.

[0029] In the example, only two of the above groups c1), c2) and c3) are identified, and the definition of the reference line in step d) comprises defining a line that fulfills at least two of the following criteria as a reference line:

[0030] extending between the pedicle portions, and

[0031] Extends through the spinous processes, and

[0032] Extends parallel to the surface of the endplate.

[0033] According to one aspect, the determination of the target viewing direction is based on the anatomical landmarks defined in the segmentation step. These landmarks provide independently determined reference lines that are then taken to set the target viewing direction based on a general definition or general criteria. Thus, adjustment of the target viewing direction and therefore alignment for a particular object is provided by the segmentation plus the definition of the reference lines.

[0034] In an example, a medical system is provided, the medical system comprising a medical imaging system capable of taking three-dimensional images of anatomical structures and a possibly different medical imaging system capable of taking 2D X-ray fluorescence images from one or more directions. Optionally, the imaging system is tracked or integrated with a navigation system. In addition, a segmentation algorithm capable of segmenting related anatomical structures is provided, and on a per-vertebral basis, a registration method registers 2D X-ray fluorescence images from one or more directions to the 3D anatomical structure. In addition, an algorithm for automatically applying the correct rigid registration by detecting related / active vertebrae is provided by using the selected process (step), the selected planning and / or the position of the surgical instrument (e.g., if a tracking system is used).

[0035] In another example, the system can calculate the optimal C-arm position and / or patient table position based on the segmentation results, the selected procedure (step), the selected plan and / or the position of the device (eg, if a tracking system is used).

[0036] In another example, a robotic system performs accurate surgery by continuously applying re-registration based on repeated X-ray fluoroscopy from one or more directions.

[0037] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Exemplary embodiments of the present invention will be described below with reference to the following drawings:

[0039] Figure 1 An example of an apparatus for positioning an X-ray imaging system is schematically shown.

[0040] Figure 2 An example of a medical imaging apparatus for spinal intervention is shown.

[0041] Figure 3 The basic steps of an example of a method for X-ray imaging of spinal structures are shown.

[0042] Figure 4 Shows Figure 3 An example of a method.

[0043] Figure 5 Shows Figure 3 Another example of the method.

[0044] Figure 6 An example of a segmented spinal column structure as a projection of a 3D dataset is shown.

[0045] Figure 7 An X-ray image with a segmented spine is shown.

[0046] Figure 8 An example of the calculated orientation is shown.

[0047] Fig. 9 Additional workflow steps for the 2D-3D fluorescence registration algorithm are shown.

[0048] Fig.10 The steps of the spine segmentation process are shown.

[0049] Fig.11 Schematically illustrated is a screenshot of the registration user interface after acquisition of a fluorescence image.

[0050] Fig.12 Schematically illustrates a screenshot after acquisition of two fluorescence images. DETAILED DESCRIPTION

[0051] Certain embodiments will now be described in more detail with reference to the accompanying drawings. In the following description, similar drawing reference numerals are used for identical elements even in different drawings. Matters defined in the description (e.g., detailed construction and elements) are provided to assist in a comprehensive understanding of exemplary embodiments. Moreover, since well-known functions or constructions will obscure the embodiments with unnecessary details, well-known functions or constructions will not be described in detail. In addition, expressions such as "at least one of ... " before the list of elements modify the entire list of elements without modifying the individual elements of the list.

[0052] Figure 1An example of an apparatus 10 for positioning an X-ray imaging system is schematically shown. The apparatus 10 includes a data storage unit 12, a processing unit 14, and an output unit 16. The data storage unit 12 is configured to store and provide 3D image data 18 of a spinal region of interest of a subject, the spinal region of interest including a portion of a spinal structure including at least one vertebra. The processing unit 14 is configured to select at least one vertebra of the spinal structure as a target vertebra. The processing unit 14 is also configured to segment at least the target vertebra in the 3D image data. The segmentation includes identifying at least one anatomical feature of the target vertebra. The processing unit 14 is also configured to define a position of a predetermined reference line based on a spatial arrangement of the at least one anatomical feature. The processing unit 14 is also configured to determine a target viewing direction of the X-ray imaging system based on the reference line. The output unit 16 is configured to provide the target viewing direction for the X-ray imaging system.

[0053] In an example, the 3D image data is provided based on rotational angiography.

[0054] In one option, the 3D image data is provided as pre-operative image data.

[0055] In another option, the 3D image data is provided as intraoperative image data.

[0056] like Figure 1 As shown by the dashed line in , as an option, an input unit 20 is provided. The input unit 20 is configured to provide a spatial relationship between the 3D image data and the X-ray imaging system. The processing unit 14 is configured to determine a spatial relationship between a current viewing direction of the X-ray imaging system and a target viewing direction. The processing unit 14 is also configured to convert the spatial relationship into a motion vector. The processing unit 14 is configured to control the movement of the X-ray imaging system and the object relative to each other according to the motion vector.

[0057] Control of the movement of the X-ray imaging system by the processing unit is provided as an option. Such control can also be provided by a separate unit or device, for example an actuation unit or a movement unit of the X-ray imaging system and / or an actuation unit or a movement unit of a movable object support, for example a patient table.

[0058] In an example not shown in further detail, the processing unit 14 is configured to: identify a surface of an endplate of at least one vertebra as at least one anatomical feature, and identify a pair of pedicle portions of at least one vertebra, and identify a spinous process between the endplates of at least one vertebra. The processing unit 14 is further configured to define a line extending between the pedicle portions, extending through the spinous process, and extending parallel to the surface of the endplate as a reference line.

[0059] In an example not shown in further detail, an interface unit is provided, which is configured to receive an input from a user for selecting at least one vertebra of the spinal column structure as a target vertebra.

[0060] The interface unit can be provided by a keyboard, a mouse, a switch button, a touch screen or any other suitable device.

[0061] In a further option, the selection of one or more target vertebrae is provided based on procedure (pathway) planning during an intervention planning procedure using surgical (pre-operative) data.

[0062] In a further option, selection of one or more target vertebrae is provided based on the current position of a device (e.g., a Jamshidi needle, a probe, etc. for insertion into the vertebrae). The position of the device is determined using a tracked device or optical image analysis with deep learning.

[0063] In an example not shown in further detail, the data storage unit 12 is configured to store the determined target viewing direction for the object and use the stored determined target viewing direction for the further object. The processing unit 14 is configured to spatially register the further object to the X-ray system and adjust the determined target viewing direction for the current spatial arrangement of the further object.

[0064] Figure 2 A medical imaging apparatus 100 for spinal intervention is shown. The apparatus includes an imaging system 102 having an X-ray source 104 and an X-ray detector 106, which is configured to acquire an X-ray image of an anatomical structure of an object. In addition, an example of an apparatus 10 for positioning an X-ray imaging system according to one of the aforementioned examples is provided. The X-ray source 104 together with the X-ray detector 106 and the object are movable relative to each other. The X-ray source 104 together with the X-ray detector 106 and the object are movable according to a target viewing direction determined by the apparatus 10 for positioning an X-ray imaging system.

[0065] In an example, the imaging system is an X-ray imaging system.

[0066] In an example, the X-ray imaging system includes a C-arm structure 108 , wherein an X-ray source 102 and an X-ray detector 104 are attached to opposite ends of a C-arm 110 .

[0067] As a further option, a patient table 112 is provided as a subject support. Figure 2 A target 114 is also illustrated in a simplified manner in FIG.

[0068] The apparatus 10 for positioning an X-ray imaging system is shown as a console 120 having a display 122 and interface instruments such as a keyboard 124, a tablet computer 126, a mouse 128 and other input devices (eg, a control panel 130).

[0069] In one option, the imaging system is further configured to provide 3D data of the anatomical structure of the object.The processing unit 14 is configured to calculate 3D image data based on the 3D data.

[0070] In an example, the medical system is configured to automatically position the C-arm. The term "automatically" refers to the process provided by the processing unit 14 to determine and control the steering of the C-arm by the processor to achieve the target viewing direction. Of course, collision control instruments and other safety features can be provided. In one option, the subject support (e.g., the patient table 112) is movable.

[0071] In an example, fluoroscopic imaging is combined with 3D intraoperative imaging and navigation to perform minimally invasive spinal surgery. The 3D intraoperative data of the spine is segmented into a model in which the different parts are labeled, such as each vertebra, lamina, and pedicle.

[0072] Due to the determined target viewing direction, providing positioning of the C-arm based on the reference lines to obtain the required X-ray projection images consumes less time. Because no separate X-ray images are required to align the X-ray imaging system, the dose to the patient and the operator is reduced. The registration of the 3D image data with the patient (on the one hand) and with the X-ray imaging system (on the other hand) further reduces the number of X-ray projection images.

[0073] In one option, the system can store the view currently used in the segmentation and can recalculate the same view for the next object based on the segmentation of the data for that object. In one option, the shutter is arranged to restrict the view to the segmented vertebrae. In another option, the shutter is arranged to allow the view to also cover adjacent vertebrae.

[0074] In one option, determination of a target viewing direction is provided for spinal surgery or other surgical or interventional procedures in which "standardized" projection images are used so that predetermined viewing directions can be defined and provided for selection.

[0075] As an option, to provide a spatial relationship between the 3D image data and the imaging system, at least one current 2D X-ray image is provided by the imaging system and the at least one current 2D X-ray image is registered with the 3D image data. Features are identified in the at least one current 2D X-ray image and the features of the at least one current 2D X-ray image are registered with matching features in the 3D image data. The determined target viewing direction is adjusted based on the registration of the 3D image data with the at least one current 2D X-ray image. The at least one current 2D X-ray image is registered with the 3D image data on a per vertebral basis.

[0076] In an example, the 3D image data comes from a different imaging system or modality. For example, the 3D image data comes from a CT scanner or an MRI scanner.

[0077] In another example, the 3D image data comes from the same imaging system or modality. For example, the 3D image data comes from a C-arm X-ray imaging system that is also used for the fluoroscopic 2D live image (which is also referred to as the current image).

[0078] Registration of at least one current 2D X-ray image with the 3D image data on a per vertebral basis is provided as an option, for example to allow for flexion movements of the spine.

[0079] In an example, the processing unit 14 is configured to determine the position of the shutter or wedge and the detector rotation based on the segmented contour of the vertebra.

[0080] This allows further adjustment of the X-ray dose to the subject.

[0081] In one option, the feature is a plurality of screws. The processing unit 14 is configured to calculate a 3D reconstruction of the screw based on at least two 2D X-ray images from different directions. The processing unit 14 is further configured to register the reconstructed screw with the 3D image data.

[0082] In an example, the 3D reconstruction of the screw is based on the model.In addition or instead of the screw, other landmarks, anatomical structures or artificial landmarks can also be used for the registration of the 2D X-ray image with the 3D image data.

[0083] In another example, a (potentially model-based) 3D reconstruction of the screw is performed based on fluorescence snapshots taken from two or more directions. By fusing the reconstruction of the screw onto previously acquired image data, an extremely low-dose 3D verification scan can be achieved.

[0084] As an example, the previously acquired image data is based on images acquired using a flat panel detector C-arm volume acquisition function that is integrated with a device for providing angiographic images (eg, a C-arm X-ray imaging system).

[0085] As an example, the previously acquired image data is based on images acquired by rotational angiography, a medical imaging technology based on X-ray imaging and enabling the acquisition of 3D volumes similar to CT (e.g., during hybrid surgery or during catheter interventions using a rigid or fixed C-arm). The C-arm rotates around the patient and acquires a series of X-ray images, which are then reconstructed into a 3D image by software algorithms. This technology is also known as flat-panel volume CT or cone-beam CT. As an example, the previously acquired image data is based on images acquired by XperCT provided by Philips.

[0086] Fluorescence registration (eg, fluorescence-XperCT registration) is used to ensure that the overlay is spatially correct in the case of spinal distortions due to procedure-induced or spinal distortions due to differences in spinal curvature from preoperative data.

[0087] In one option, an optical imaging system 132 is provided. The optical imaging system 132 is configured to track the object. The processing unit 14 is configured to use the detected position of the object for a registration step of registering at least one 2D X-ray image with the 3D image data. In an example, the optical imaging system includes a visible light camera. In another example, an infrared camera is provided.

[0088] In the example, the optical imaging system 132 is therefore an optical navigation system for tracking the position of the patient. The estimate of the position is used to initialize the registration algorithm to a) reduce the computation time, b) prevent misregistration to the wrong vertebral level, which may occur in particular if the field of view of the 2D or 3D information is small.

[0089] In another example, the sensors of the X-ray system and the subject support (e.g., a patient table) are used to globally track the position of the patient in the X-ray image. The estimate of the position is used to initialize the registration algorithm to a) reduce computation time, b) prevent misregistration to the wrong vertebral level, which may occur especially if the field of view of the 2D or 3D information is small.

[0090] Figure 3 The basic steps of an example of a method 200 for X-ray imaging of spinal structures are shown. The method 200 includes the following steps:

[0091] In a first step 202 (also referred to as step a1)), 3D image data of a spinal column region of interest of a subject is provided, the spinal column region of interest comprising a portion of a spinal column structure including at least one vertebra.

[0092] In a second step 204 (also referred to as step b)), at least one vertebra of the spinal column structure is selected as a target vertebra.

[0093] In a third step 206 (also referred to as step c)), at least the target vertebra is segmented in the 3D image data. The segmentation comprises identifying at least one anatomical feature of the target vertebra.

[0094] In a fourth step 208 (also referred to as step d)), a position of a predetermined reference line is defined based on the spatial arrangement of at least one anatomical feature.

[0095] In a fifth step 210 (also referred to as step e1)), a target viewing direction of the X-ray imaging system is determined based on the reference line.

[0096] In one option, selection of at least one vertebra is provided manually.

[0097] In another option, the selection of at least one vertebra is automatically provided based on entered object-related data (eg type and location of the planned intervention).

[0098] The target viewing direction can be defined as along the reference line.

[0099] The target viewing direction is predetermined such that an optimal view is achieved. The term "optimal" relates to a view in which the maximum amount of information is visible and provides minimal distortion or occlusion. It should be noted that one or more optimal viewing directions may be defined. As an example, a true AP view is provided as an optimal viewing direction. In a further example, the target viewing direction provides a true lateral view of the vertebra. In a further example, the target viewing direction provides a view giving a so-called Scotty dog ​​landmark of the vertebra, wherein the structure provides an outline that reminds of the outline of Scotty the dog.

[0100] Thus, the method provides a segmentation algorithm capable of segmenting the relevant anatomical structures. An algorithm is also provided for calculating the best possible C-arm position and / or object table position based on at least one of the group of: the segmentation result, the selected procedure (step), the selected plan and the position of the device (e.g. if a tracking system is used).

[0101] The position of the predetermined reference line is spatially determined with respect to the 3D image of the spine.

[0102] Figure 4 Shows Figure 3An example of a method, wherein:

[0103] In a first additional sub-step 212 (also referred to as step a2)), a spatial relationship between the 3D image data and the X-ray imaging system is provided.

[0104] In a second additional sub-step 214 (also referred to as step e2)), a spatial relationship of a current viewing direction of the X-ray imaging system to a target viewing direction is determined and converted into a movement vector.

[0105] In an additional step 216 , the X-ray imaging system and the object are moved relative to each other according to the movement vector.

[0106] In one option, the 3D image data is adjusted for the current position of the object to be imaged based on the target viewing direction.

[0107] In another option, the current position of the object to be imaged is adjusted for the 3D image data based on the target viewing direction.

[0108] In a third option, the current position of the object to be imaged and the 3D image data are adjusted with respect to each other based on the target viewing direction.

[0109] Figure 5 Shows Figure 3 A further example of the method of , wherein the segmentation in step c) comprises a step 218 of identifying:

[0110] c1) a surface of an endplate of at least one vertebra; and

[0111] c2) a pair of pedicle portions of at least one vertebra; and

[0112] c3) The spinous process between the end plates of at least one vertebra.

[0113] The definition of the reference line in step d) includes defining 220 a line extending between pedicle portions, extending through the spinous processes, and extending parallel to the surface of the endplate as the reference line.

[0114] In examples, the spine includes a plurality of vertebrae.

[0115] In the example, for the true AP view, the orientation of the C-arm is based on the normal of the endplate, the two pedicles, and the orientation of the spinous process.

[0116] In an example, a geometric mean is calculated for the segmented features to facilitate geometric calculations of the reference lines.

[0117] In an example, step c) further comprises: determining a plane between the surfaces of the end plates, the plane extending parallel to the surfaces of the end plates; and determining a line on the plane serving as an axis of symmetry for the two pedicles, the line also extending the spinous processes.

[0118] In an example, providing a spatial relationship between the 3D image data and the X-ray imaging system is repeated for at least two vertebrae along the spine.

[0119] In the example, a spatial relationship is provided separately for each vertebra.

[0120] In an example, the determined target viewing direction for the object is stored and the stored determined target viewing direction is used for the further object.The further object is spatially registered to the X-ray system and the determined target viewing direction is adjusted for the spatial arrangement of the further object.

[0121] In an example, for realignment, X-ray images are acquired and these images are also used for visual interpretation.

[0122] The target viewing direction provides the optimal view of the target vertebra.

[0123] In an example, to provide a spatial relationship between the 3D image data and the X-ray imaging system, at least one current 2D X-ray image is provided by the X-ray imaging system, and the at least one current 2D X-ray image is registered with the 3D image data. Features are identified in the at least one current 2D X-ray image, and the features of the at least one current 2D X-ray image are registered with matching features in the 3D image data. A determined target viewing direction is adjusted based on the registration of the 3D image data with the at least one current 2D X-ray image. The at least one current 2D X-ray image is registered with the 3D image data on a per vertebral basis.

[0124] Registration on a per vertebral basis is provided as an option.

[0125] In the example, the feature is a target vertebra.

[0126] In order to provide a spatial relationship between the X-ray systems that will be used for imaging along the target viewing direction, a current 2D X-ray image is used. The spatial position of the X-ray system is known for this current 2D X-ray image. By registering the current 2D X-ray image with the 3D image data, a spatial link from the X-ray imaging system to the 3D space of the 3D image data is given. Thus, even when the object moves, a registration of the current position with respect to the world of the 3D image data can be given.

[0127] In an example, minimally invasive spinal surgery is provided with a mobile X-ray system, wherein preoperative data (e.g., from CT or MRI (e.g., where a virtual CT-like data set is calculated from the MRI images)) is registered to a navigation system using one or more 2D X-ray images (e.g., two X-ray images). The registration process required by the surgical navigation system is provided by registering each vertebra based on the fluoroscopic image.

[0128] Registration on a per vertebral basis is provided as an option.

[0129] In an example, automatic and accurate per-vertebra registration of the spinal anatomy is provided by using fluorescent (fluoroscopic) X-ray images. The registration enables, for example, accurate surgical navigation, and also enables automatic positioning of mobile X-ray systems. The registration is also suitable for automatic and accurate robotic guidance by accurate real-time surgical navigation using constant automatic re-registration. Correct rigid registration can be applied, for example, by calculating a planned path or selecting active vertebrae at the intersection of a tracking instrument and a spinal segmentation result to automatically apply the correct rigid registration.

[0130] Determination of the target viewing direction based on the current 2D X-ray image can be applied to spinal surgeries involving 2D X-ray imaging, typically in conjunction with surgical navigation and / or robotic guidance. It is also applicable to other types of surgeries in which anatomical structures have a known spatial relationship to the spine.

[0131] In an example, the object is tracked by the optical imaging system and the detected position of the object is used for a registration step of registering at least one 2D X-ray image with the 3D image data.

[0132] In an example, the 3D image data is provided as pre-acquisition image data or intra-operative image data.

[0133] In an example, 3D intraoperative data of a spine is provided, which is segmented into a model in which different parts are identified (ie, labeled), such as each vertebra, lamina, and pedicle.

[0134] Figure 6 An example of a segmented spinal column structure 300 is shown as a projection of a 3D data set. A plurality of vertebrae 302 are shown. Additionally, as an example, pedicle screws 304 can be seen.

[0135] exist Figure 74, a fluoroscopic image 400 of a true AP view (anteroposterior, i.e., from the front to the back of the subject) is shown for a certain vertebra. In the example, a true AP view is defined as an X-ray projection image in which the anterior and posterior edges of the vertebral endplates and the spinous processes of the vertebra are seen overlapping on a line between two pedicles. A true AP view is a meaningful view for a surgeon, who uses the true AP view, for example, to check the position of a device (e.g., a K-wire) relative to the vertebra.

[0136] The fluoroscopic image 400 shows a plurality of vertebrae 402, and also shows some interventional tools 404. Two lines 406 indicate the surfaces of the endplates of selected vertebrae of the plurality of vertebrae.

[0137] Figure 8 Another X-ray image 500 with a segmented spine having a plurality of vertebrae is shown. Different interventional tools 504 are shown. In the segmented spine, a vertebra 502' is selected and the segmentation includes identifying at least one anatomical feature of the target vertebra. As an example for an anatomical feature, two surfaces 506 of an endplate of at least one vertebra are identified. Additionally, a pair of pedicle portions 508 of at least one vertebra are identified. Furthermore, a spinous process 510 between the endplates of at least one vertebra is identified.

[0138] Fig. 9 Steps of a further workflow 600 for a 2D-3D Fluoro-XperCT registration algorithm are shown. An X-ray image 602 is provided and forwarded to a machine-based registration 604. As an example, the X-ray image 602 is provided as CWIS (Collection Workflow Integration System) data 606. The X-ray image 602 is also provided to a gradient difference determination 610, for example as pixels 608. Additionally, XperCT volume data 612 is provided, for example as voxels 614 and forwarded to projections 616 of the labeled voxels, which are provided to the gradient difference determination 610, for example as DRR (Digital Reconstructed Radiograph) pixels 618. The gradient difference determination 610 provides a result as a fitness value 620 for an optimizer 622 based on CMAES (Covariance Matrix Adaptive Evolution Strategy). An initial registration 624 is provided and forwarded to a first computation step 626, to which the result from the optimizer 622 is also provided. The result of the first calculation step 626 is provided to a second calculation step 628, for example as an mv (matrix vision) matrix 630. The second calculation step 628 is also provided with the result of the machine-based registration 604, which may be provided as a further mv (matrix vision) matrix 632. The result of the second calculation step 628 is provided to the projection 616, for example as a further mv (matrix vision) matrix 634. The loop arrow 636 indicates that iteration is thereby provided.

[0139] In the example, these steps are applied to X-ray fluoroscopic images and the results are combined in optimizer 622. Voxel labeling is done based on the spine segmentation.

[0140] In an example, the spine segmentation process is provided as a registration process comprising a global registration step and a registration step for each "level" along the spine (ie, each level of vertebrae) to determine distortions of the spine.

[0141] Fig.10 Another workflow 700 for providing spinal segmentation processing is shown. For voxel labeling, in the example, the following is provided as shown. The registration process includes several steps. As a start, volume data 702 is provided. In addition, vertebra segmentation 704 is foreseen. A 2D3D registration 706 is provided, for example, using all segmented vertebrae to provide 2D3D registration 706. For example, all segmented vertebrae are globally registered. Next, a registration 708 of two adjacent vertebrae is provided, and as an option, a 2D3D registration 710 for each vertebra is performed thereafter. This is done to maximize the capture range of the algorithm. The registration performed with each vertebra is then shifted in a shifting step 712, and the shifting step 712 is performed to ensure that the displacement of the vertebrae can occur during the registration process. Except for shifting the registration step with one level, each step of the registration uses the registration result of the previous step. If the registration step fails because not all levels give good results, the registration step is repeated using the best registration results of all levels as a starting point. After the shift, an analysis step 714 checks if the distortion between neighbors is acceptable. The found registrations for all vertebrae are combined. It is analyzed if the found similarity is better than the similarity found with the shift level and if the best found similarity is better than the worst found similarity. After this, a registration is applied 716 to the vertebrae based on the currently selected planning path.

[0142] In the example, the segmentation of the vertebrae has already been completed for the planning work step of the surgical navigation system, so that this result can be reused.

[0143] In the example, the registration step uses two automatic position control (APC) views: a "true AP" view of the currently selected vertebra, and a rotated view (>40 degrees) for the first view. For the registration itself, it is not required to use the "true AP" view, but this view can also be used by the physician for visual inspection. The rotated view is not fully lateral, because in most cases the patient table is lowered.

[0144] In an example, the user interface (UI) instructs the user to press the accept button with instructions until the C-arm stops and then acquires an X-ray image. The acquired X-ray image is shown, and the user is asked to press the accept button again until the C-arm stops and then acquires another X-ray image. After acquiring the X-ray image, the user can start registration.

[0145] Fig.11 A screenshot 800 of a registration user interface is schematically illustrated after acquisition of a fluorescence image 802 .

[0146] Fig.12 A screenshot 900 for a registration user interface after acquisition of a first fluorescent image 902 and a second fluorescent image 904 is schematically illustrated.

[0147] The found registration is applied to the planning data and is selected based on the currently selected planning path. This means that the APC position is also updated. In the example it is provided that the user is able to visually check the result of the registration. It may also be provided that a clear indication is shown to the user if the registration fails or if the registration is not available for the selected planning path.

[0148] The term "subject" may also be referred to as an individual."Subject" may also be referred to as a patient, but it should be noted that this term does not indicate whether any condition or disease actually exists in the subject.

[0149] In a further exemplary embodiment of the present invention, a computer program or a computer program element is provided, characterized in that it is adapted to execute the method steps of the method according to one of the preceding exemplary embodiments on a suitable system.

[0150] Therefore, the computer program element can be stored on a computer unit or can be distributed on more than one computer unit, and the computer program element can also be part of an embodiment of the present invention. The computing unit can be suitable for executing or causing the execution of the steps of the above-mentioned method. In addition, the computing unit can be suitable for operating the parts of the above-mentioned device. The computing unit can be suitable for automatic operation and / or running the user's command. The computer program can be loaded into the working memory of a data processor. Therefore, a data processor can be equipped to perform the method of the present invention.

[0151] Aspects of the present invention can be implemented in a computer program product, which can be a set of computer program instructions stored on a computer-readable storage device, which can be run by a computer. Instructions of the present invention can be any interpretable or executable code mechanism, including but not limited to scripts, interpretable programs, dynamic link libraries (DLLs) or Java classes. The instructions can be provided as complete executable programs, partial executable programs, modifications (e.g., updates) to existing programs or extensions (e.g., plug-ins) to existing programs. In addition, the parts of the processing of the present invention can be distributed on multiple computers or processors.

[0152] As discussed above, a processing unit (e.g., a controller) implements a control method. A controller can be implemented in a variety of ways using software and / or hardware to perform the various functions required. A processor is an example of a controller that employs one or more microprocessors that can be programmed using software (e.g., microcode) to perform the required functions. However, a controller may also be implemented with or without a processor, and may also be implemented as a combination of dedicated hardware for performing some functions and a processor (e.g., one or more programmed microprocessors and associated circuits) for performing other functions.

[0153] Examples of controller components that may be employed in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs).

[0154] This exemplary embodiment of the invention covers both a computer program that right from the beginning uses the invention and a computer program that is converted by means of an update into a program that uses the invention.

[0155] Furthermore, the computer program element may be able to provide all necessary steps to fulfill the procedure of an exemplary embodiment of the method as described above.

[0156] According to another exemplary embodiment of the present invention, a computer readable medium, such as a CD-ROM, is provided, wherein the computer readable medium has a computer program unit stored on the computer readable medium, the computer program unit being described by the previous section. The computer program can be stored and / or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0157] However, the computer program may also be present on a network, such as the World Wide Web, and can be downloaded from such a network into a working memory of a data processor. According to a further exemplary embodiment of the present invention, a medium for making a computer program element available for download is provided, the computer program element being arranged to perform a method according to one of the previously described embodiments of the present invention.

[0158] It must be noted that embodiments of the present invention are described with reference to different subject matters. In particular, some embodiments are described with reference to method claims, while other embodiments are described with reference to apparatus claims. However, unless otherwise stated, a person skilled in the art will infer from the above and following descriptions that, in addition to any combination of features belonging to one type of subject matter, any combination of features relating to different subject matters is also considered to be disclosed in the present application. However, all features can be combined to provide synergistic effects that are more than the simple addition of the features.

[0159] Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description should be considered illustrative or exemplary rather than restrictive. The present invention is not limited to the disclosed embodiments. Those skilled in the art will be able to understand and implement other variations to the disclosed embodiments in practicing the claimed invention by studying the drawings, the disclosure, and the claims.

[0160] In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. Although certain measures are recited in mutually different dependent claims, this does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A device (10) for positioning an X-ray imaging system, the device comprising: Data storage unit (12); Processing unit (14); as well as Output unit (16); wherein the data storage unit is configured to store and provide 3D image data (18) of a spinal region of interest of a subject, the spinal region of interest comprising a portion of a spinal column structure, the spinal column structure comprising at least one vertebra; wherein the processing unit is configured to: select at least one vertebra of the spinal column structure as a target vertebra; segment at least the target vertebra in the 3D image data; wherein the segmentation comprises identifying at least one anatomical feature of the target vertebra; defining a position of a predetermined reference line based on a spatial arrangement of the at least one anatomical feature; and determining a target viewing direction of an X-ray imaging system based on the reference line; and Wherein, the output unit is configured to provide the target viewing direction for the X-ray imaging system.

2. The device according to claim 1, wherein: Also available: Input unit (20); wherein the input unit is configured to provide a spatial relationship between the 3D image data and the X-ray imaging system; and Wherein, the processing unit is configured to: determine the spatial relationship between the current viewing direction of the X-ray imaging system and the target viewing direction; and convert the spatial relationship into a motion vector; and wherein the processing unit is configured to control the movement of the X-ray imaging system and the object relative to each other according to the motion vector.

3. The device according to claim 1 or 2, wherein: The processing unit is configured to: identify a surface of an endplate of the at least one vertebra as the at least one anatomical feature, and identify a pair of pedicle portions of the at least one vertebra, and identify a spinous process between the endplates of the at least one vertebra; and Wherein, the processing unit is further configured to define a line extending between the pedicle portions, extending through the spinous process, and extending parallel to the surface of the endplate as the reference line.

4. The device according to claim 1 or 2, wherein: An interface unit is provided, which is configured to receive a user's input for selecting the at least one vertebra of the spinal column structure as the target vertebra.

5. The device according to claim 1 or 2, wherein: The data storage unit is configured to: store the determined target viewing direction with respect to the object, and use the stored determined target viewing direction for another object; Therein, the processing unit is configured to spatially register the further object to the X-ray imaging system and to adjust the determined target viewing direction for a current spatial arrangement of the further object.

6. A medical imaging device (100) for spinal intervention, the device comprising: An imaging system (102) having an X-ray source (104) and an X-ray detector (106) configured to acquire an X-ray image of an anatomical structure of a subject; as well as Device (10) for positioning an X-ray imaging system according to any one of claims 1 to 5; wherein the X-ray source together with the X-ray detector and the object are movable relative to each other; and Therein, the X-ray source together with the X-ray detector and the object are movable according to a target viewing direction determined by the device for positioning the X-ray imaging system.

7. The medical imaging apparatus according to claim 6, wherein: The imaging system is further configured to provide 3D data of the anatomical structure of the subject; and Wherein, the processing unit is configured to calculate the 3D image data based on the 3D data.

8. The medical imaging apparatus according to claim 6 or 7, wherein: In order to provide a spatial relationship between the 3D image data and the imaging system, at least one current 2D X-ray image is provided by the imaging system and the at least one current 2D X-ray image is registered with the 3D image data; wherein a feature is identified in the at least one current 2D X-ray image, and wherein the feature of the at least one current 2D X-ray image is registered with a matching feature in the 3D image data; wherein the determined target viewing direction is adjusted according to the registration of the 3D image data with the at least one current 2D X-ray image; and Therein, the at least one current 2D X-ray image is registered with the 3D image data on a per vertebral basis.

9. The medical imaging apparatus according to claim 8, wherein: The feature is a plurality of screws; and Wherein, the processing unit is configured to: calculate a 3D reconstruction of the screw based on at least two 2D X-ray images from different directions; and register the reconstructed screw with the 3D image data.

10. The medical imaging apparatus according to claim 6 or 7, wherein: supply: Optical imaging system (108); wherein the optical imaging system is configured to track the object; and The processing unit is configured to use the detected position of the object for a registration step of registering the at least one 2D X-ray image with the 3D image data.

11. A method (200) for performing X-ray imaging of a spinal structure, comprising the following steps: a1) providing (202) 3D image data of a spinal region of interest of a subject, the spinal region of interest comprising a portion of a spinal column structure, the spinal column structure comprising at least one vertebra; b) selecting (204) at least one vertebra of the spinal column structure as a target vertebra; c) segmenting (206) at least the target vertebra in the 3D image data; wherein the segmenting comprises identifying at least one anatomical feature of the target vertebra; d) defining (208) a position of a predetermined reference line based on the spatial arrangement of the at least one anatomical feature; and e1) determining (210) a target viewing direction of an X-ray imaging system based on the reference line.

12. The method according to claim 11, wherein: Also available: a2) providing (212) a spatial relationship between the 3D image data and the X-ray imaging system; e2) determining (214) a spatial relationship between a current viewing direction of the X-ray imaging system and the target viewing direction, and converting the spatial relationship into a motion vector; and f) moving the X-ray imaging system and the object relative to each other according to the movement vector (216).

13. The method according to claim 11 or 12, wherein: The segmentation in step c) comprises identifying (218): c1) a surface of an endplate of said at least one vertebra; and c2) a pair of pedicle portions of the at least one vertebra; and c3) spinous processes between the endplates of the at least one vertebra; And wherein the defining of the reference line in step d) includes defining (220) a line extending between the pedicle portions, extending through the spinous processes, and extending parallel to the surface of the endplate as the reference line.

14. A computer program element for controlling an apparatus according to any of claims 1 to 5 or a medical imaging device according to any of claims 6 to 10, the computer program element being adapted to perform the steps of the method according to any of claims 11 to 13 when run by a processing unit.

15. A computer-readable medium having stored thereon a program element according to claim 14.

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