X-ray ripple marker for X-ray calibration

Abstract

Various embodiments of the present disclosure include a C-arm registration system that employs a controller (70) for registering a C-arm (60) to an X-ray ripple marker (20), the X-ray ripple marker including a ripple pattern (50) that extends radially from a fixed point (40) of the X-ray ripple marker (20). In operation, the controller (70) identifies the ripple pattern (50) within an X-ray image that is generated from an X-ray projection of the C-arm (60) and depicts some or all of the ripple pattern (50), and the identification of the ripple pattern (50) within the X-ray image is characterized by the pose of the C-arm (60) relative to the X-ray projection of the X-ray ripple marker (20). The controller (70) also: analyzes the ripple pattern (50) within the X-ray image to derive one or more transformation parameters that define the pose of the C-arm (60) relative to the X-ray projection of the X-ray ripple marker (20); and registers the C-arm (60) to the X-ray ripple marker (20) based on the (one or more) transformation parameters.

Description

Technical Field

[0001] The present disclosure generally relates to X-ray calibration. The present disclosure specifically relates to imaging of X-ray ripple markers for X-ray calibration. Background Art

[0002] X-ray C-arm systems are often used in minimally invasive surgeries (e.g., orthopedic surgeries, vascular interventions, etc.) to enable a surgeon to view inside a patient's body by taking X-ray images from any direction. More specifically, a mobile C-arm typically has wheels to provide mobility in a room, and once positioned, the mobile C-arm allows a user to adjust the position of the C-arm in five (5) directions. Although this provides flexibility for performing minimally invasive surgeries, the exact position and angle of the X-ray projection are unknown. This prevents a user from using advanced tools, including performing true three-dimensional ("3D") measurements, large field-of-view imaging, dynamic overlay of preoperative or intraoperative information, and target localization for image-guided interventions. Therefore, after positioning the mobile C-arm relative to the patient's body, it is necessary to calculate the pose of the X-ray projection relative to a fixed coordinate system, which is commonly referred to as C-arm registration. Specifically, the position of the mobile C-arm is calculated relative to a fixed coordinate system and is described by a homogeneous transformation consisting of a translation vector (t ∈ R 3 ) and a rotation matrix (R ∈ SO(3)). Thus, the task is to calculate the pair (t, R) that accurately describes the position of the mobile C-arm relative to the fixed coordinate system.

[0003] One historical method for solving C-arm registration required the installation of hardware (e.g., optical tracking markers, inertial markers, etc.) on the C-arm. This method requires adding multiple components to the room and generally has a negative impact on the workflow of the procedure.

[0004] The current practice for C-arm registration is to provide markers with fixed positions in the operating space (e.g., markers attached to a robot or an operating table) and generate X-ray images of the features of the markers to perform C-arm registration (e.g., steel balls or features of known geometry). For such markers, there are cost-benefit trade-offs regarding the required registration accuracy, the number of opaque features on the markers, the size of the markers, the impact on the workflow, and the impact on the X-ray images. Summary of the Invention

[0005] While known C-arm registration methods have proven beneficial, there is still a need for improved techniques to provide accurate and reliable C-arm registration, especially for mobile C-arms. The present disclosure teaches an X-ray ripple marker that creates one or more waves imaged by X-rays, which have characteristics that are a function of the X-ray projection pose of the C-arm relative to the X-ray ripple marker. In some embodiments, the X-ray ripple marker incorporates additional features (e.g., copper balls or steel balls) that enhance the robustness of the registration algorithm.

[0006] One embodiment of the present disclosure is a C-arm registration system employing a C-arm registration controller for registering a C-arm to an X-ray ripple marker, including a ripple pattern radially extending from a fixed point of the X-ray ripple marker. The C-arm registration controller is configured to: identify the ripple pattern within the X-ray image to analyze the ripple pattern in the X-ray image to derive one or more transformation parameters, the X-ray image being generated from an X-ray projection of the C-arm and depicting part or all of the marker; and register the C-arm to the X-ray ripple marker based on the (one or more) transformation parameters.

[0007] The identification of the ripple pattern within the X-ray image is characterized by the pose of the X-ray projection of the C-arm relative to the X-ray ripple marker, and the (one or more) transformation parameters are, by definition, the determined pose of the X-ray projection of the C-arm relative to the X-ray ripple marker.

[0008] The pose of the X-ray projection of the C-arm relative to the X-ray ripple marker includes the position and / or orientation of the X-ray projection of the C-arm within a coordinate system associated with the X-ray ripple marker (e.g., a coordinate system with the fixed point of the X-ray ripple marker as the origin or the coordinate system of an interventional device, such as an interventional robotic system having an X-ray ripple marker attached thereto).

[0009] In one embodiment of the C-arm registration system, the C-arm registration controller employs a non-transitory machine-readable storage medium encoded with instructions for being run by one or more processors to identify the ripple pattern within the X-ray image to analyze the ripple pattern in the X-ray image to derive the (one or more) transformation parameters, the X-ray image being generated from an X-ray projection of the C-arm and depicting part or all of the X-ray ripple marker, and to register the C-arm to the X-ray ripple marker based on the (one or more) transformation parameters.

[0010] Another embodiment of the present disclosure is an image intensifier registration method performed by an image intensifier registration controller. In operation, the image intensifier registration controller: identifies a moiré pattern within an X-ray image that is generated from an X-ray projection of the image intensifier and depicts some or all of the markers, analyzes the moiré pattern in the X-ray image to derive one or more transformation parameters, and registers the image intensifier to the X-ray moiré markers based on the one or more transformation parameters.

[0011] For various embodiments of the present disclosure, the moiré pattern includes a plurality of concentric circular moirés, a first series of concentric arc moirés, and / or a second series of concentric arc moirés that differ from the first series of concentric arc moirés in frequency, phase, and / or amplitude.

[0012] For various embodiments of the present disclosure, the X-ray moiré markers further include a chirp pattern and / or a landmark pattern axially aligned with the moiré pattern.

[0013] For the purposes of the description and claims of the present disclosure:

[0014] (1) Terms in the art, including but not limited to "marker", "X-ray", "image intensifier", "registration", "calibration", "robot", and "transformation parameter", shall be construed as known in the art of the present disclosure and exemplary as described in the present disclosure;

[0015] (2) The term "X-ray moiré markers" broadly encompasses markers incorporating a moiré pattern according to aspects of the present disclosure as described herein by way of example, which extend radially from a fixed point of the marker for creating one or more X-ray imaging waves having characteristics that are a function of the position of the image intensifier relative to the X-ray projection of the X-ray moiré markers;

[0016] (3) The term "wave" broadly encompasses any type of frequency signal, including but not limited to, a fixed frequency signal and a swept frequency signal (e.g., chirp).

[0017] (4) The term "moiré pattern" broadly encompasses an arrangement of one or more circular moirés and / or one or more arc moirés extending radially from a fixed point of the X-ray moiré markers according to aspects of the present disclosure as described herein by way of example, wherein the frequency, phase, and / or amplitude of the one or more circular / arc moirés are used to create one or more X-ray imaging waves;

[0018] (5) The term "chirp pattern" broadly encompasses an arrangement of one or more chirp signals for generating a chirp signal that represents an additional dimension of the degrees of freedom of transformation of the X-ray projection of the image intensifier relative to the X-ray moiré markers;

[0019] (6) The term "landmark pattern" broadly encompasses the arrangement of one or more landmarks disposed on an X-ray ripple marker to locate one or more points (e.g., the center point of the X-ray) on the X-ray ripple marker.

[0020] (7) The term "controller" broadly encompasses all structural configurations of a main circuit board or integrated circuit used to control aspects of the present disclosure as exemplarily described in the present disclosure, as understood in the art of the present disclosure and as described in the examples of the present disclosure. The structural configuration of the controller may include, but is not limited to, (one or more) processors, (one or more) computer-usable / computer-readable storage media, an operating system, (one or more) application modules, (one or more) peripheral device controllers, (one or more) slots, and (one or more) ports. The controller may be housed within a workstation or linked to a workstation. Examples of "workstations" include, but are not limited to, components of one or more computing devices, a display / monitor, and one or more input devices (e.g., keyboard, joystick, and mouse) in the form of a stand-alone computing system, a client computer of a server system, a desktop computer, or a tablet computer;

[0021] (8) The term "application module" broadly encompasses application programs incorporated in or accessible by a controller including electronic circuits (e.g., electronic components and / or hardware) and / or executable programs (e.g., stored in (one or more) non-transitory computer-readable media and / or firmware) for performing a specific program; and

[0022] (9) The terms "data" and "signal" broadly encompass all forms of detectable physical quantities or pulses (e.g., voltage, current, or magnetic field strength) of information and / or instructions for supporting applications as described in the art of the present disclosure and as described in the present disclosure for transmitting aspects of the present disclosure as subsequently described. Data / signal communication of the various components of the present disclosure may involve any communication method known in the art of the present disclosure, including but not limited to data / signal transmission / reception via any type of wired or wireless data link / signal link and reading of data / signal uploaded to a computer-usable / computer-readable storage media.

[0023] When read in conjunction with the accompanying drawings, the foregoing and other embodiments of the invention of the present disclosure and various structures and advantages of the invention of the present disclosure will become more apparent from the detailed description of various embodiments of the invention of the present disclosure. The detailed description and the drawings are merely illustrative of the invention of the present disclosure and not limiting, and the scope of the invention of the present disclosure is defined by the appended claims and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1Illustrates an exemplary embodiment of an X-ray ripple marker in accordance with aspects of the present disclosure.

[0025] Figures 2A - 2D Illustrates an exemplary embodiment of a radial ripple in accordance with aspects of the present disclosure.

[0026] Figure 3A And 3B Illustrates an exemplary embodiment of a platform in accordance with aspects of the present disclosure.

[0027] Figures 4A - 4G Illustrates in accordance with aspects of the present disclosure Figure 1 of an exemplary embodiment of an X-ray ripple marker.

[0028] Figure 5A And Figure 5B Illustrates an exemplary embodiment of C-arm registration in accordance with aspects of the present disclosure.

[0029] Figure 6 Illustrates a first exemplary embodiment of an X-ray projection of a C-arm in accordance with aspects of the present disclosure.

[0030] Figure 7 Illustrates in accordance with aspects of the present disclosure a Figure 6 flowchart of a first exemplary embodiment of C-arm registration.

[0031] Figure 8A And 8B Illustrates an exemplary sine signal transformation in accordance with aspects of the present disclosure.

[0032] Figure 9 Illustrates a flowchart of a first exemplary embodiment of a method for generating transformation parameters in accordance with aspects of the present disclosure.

[0033] Figures 10A - 10E Illustrates in accordance with aspects of the present disclosure Figure 9 of an exemplary generation of transformation parameters.

[0034] Figure 11A And 11B Illustrates in accordance with aspects of the present disclosure Figure 9 of an exemplary marker position approximation / refinement.

[0035] Figures 12A - 12F Illustrates in accordance with aspects of the present disclosure Figure 9 of an exemplary X-ray ripple marker image subtraction.

[0036] Figure 13 Illustrates in accordance with aspects of the present disclosure Figure 6 of an exemplary X-ray projection of a C-arm.

[0037] Figure 14 Illustrates a representation in accordance with aspects of the present disclosure Figure 6 flowchart of a second exemplary embodiment of C-arm registration.

[0038] Figure 15A and 15B Illustrates an exemplary C-arm registration in accordance with aspects of the present disclosure.

[0039] Figure 16A and 16B Illustrates in accordance with aspects of the present disclosure Figure 15A exemplary transformation parameter generation of an X-ray corrugated marker in a first position.

[0040] Figure 17A and 17B Illustrates in accordance with aspects of the present disclosure Figure 15A exemplary transformation parameter generation of an X-ray corrugated marker in a second position.

[0041] Figure 18A and 18B Illustrates in accordance with aspects of the present disclosure Figure 15A exemplary C-arm registration of an X-ray corrugated marker in a third position.

[0042] Figure 19 Illustrates an exemplary embodiment of a C-arm registration controller in accordance with aspects of the present disclosure. Detailed Description

[0043] To facilitate understanding of aspects of the present disclosure, the following description teaches embodiments of an X-ray corrugated marker of the present disclosure. From this description, one of ordinary skill in the art will understand how to apply aspects of the present disclosure to additional embodiments of manufacturing and using an X-ray corrugated marker of the present disclosure. Figures 1 - 4C

[0044] Figure 1 Referring , an X-ray corrugated marker 20 of the present disclosure employs one or more radial corrugations 30 integrated within a platform 40 and radially extending from a fixed point 41 (e.g., the center point of the platform 40) of the platform 40.

[0045] In practice, the platform 40 can have any size and shape that facilitates X-ray imaging of the radial corrugations 30 that extend radially from the fixed point(s) 41 of the platform 40. For example, the platform 40 can have a disc shape or a cuboid shape, where the radial corrugation(s) 30 are integrated onto the same side surface of the disc or cuboid and extend radially from any fixed point (e.g., the center of the disc or cuboid) on that side surface of the disc or cuboid. The dimensions of the disc and cuboid are not limited by the X-ray imaging space of one or a particular type of X-ray imaging system or are common to all X-ray imaging systems.

[0046] Also in practice, the radial corrugations 30 can have any shape and size that partially or fully surround the fixed point. For example, Figure 2A the radial corrugation 30a is shown as a circle that fully surrounds the fixed point 41 of the platform 40, Figure 2B the radial corrugation 30b is shown as a 270° arc that partially surrounds the fixed point 41 of the platform 40, Figure 2C the radial corrugation 30c is shown as a 180° arc that partially surrounds the fixed point 41 of the platform 40, and Figure 2D the radial corrugation 30d is shown as a 90° arc that partially surrounds the fixed point 41 of the platform 40.

[0047] Further in practice, the radial corrugations 30 can be integrated into the platform 40 in any way that facilitates X-ray imaging of the X-ray corrugation markers 20 to distinguish the radial corrugations 30 from the platform 40 within the X-ray image. For example, Figure 3A a cross-section of the platform 40a is shown, which has a plurality of radial corrugations 30 as protrusions 31 that extend upward from the top surface of the platform 40a relative to the fixed point 41a, Figure 3B a cross-section of the platform 40b is shown, which has a plurality of radial corrugations as grooves 32 that extend downward relative to the fixed point 41b to the top surface of the platform 40b. Also by way of example, the X-ray corrugation markers 20 can employ one or more radial corrugations 30 as protrusions and one or more additional radial corrugations 30 as grooves.

[0048] Returning to Figure 1 , for C-arm registration purposes, the radial corrugation(s) 30 are integrated onto the platform 40 to form a corrugation pattern that creates a wave(s) that is X-ray imaged and has characteristics that are a function of the X-ray projection position of the C-arm relative to the X-ray corrugation markers 20, as will be further described in the C-arm registration description using FIGS. 5 - 18 of the present disclosure.

[0049] For example, Figure 4AIllustrated is a radial pattern 50 of (one or more) radial corrugations 30 that can be integrated into the surface of disk 40C or platform 40b for creating (one or more) waves imaged by X-rays, as schematically shown by waves 21a and 21b.

[0050] In practice, the frequency, phase, and / or amplitude of the X-ray imaging waves can be (one or more) characteristics that are a function of the position of the X-ray projection of the C-arm relative to the X-ray corrugation marker 20.

[0051] In addition, in practice, the relative frequency, relative phase, and / or relative amplitude of two or more X-ray imaging waves can be characteristics that are a function of the X-ray projection position of the C-arm relative to the X-ray corrugation marker 20.

[0052] In one embodiment of the corrugation pattern 50 as shown in Figure 4B a corrugation pattern 50a of twenty (20) concentric circular radial corrugations integrated on disk 40c or cuboid 40d provides a five (5)-degree-of-freedom transformation of the X-ray projection of the C-arm to a coordinate system associated with the marker using a single X-ray image.

[0053] In a second embodiment of the corrugation pattern 50 as shown in Figure 4C the corrugation pattern 50b includes a series 51a of nine (9) concentric 90° arc radial corrugations, a series 51b of seventeen (17) concentric 90° arc radial corrugations, a series 51c of nine (9) concentric 90° arc radial corrugations, and a series 51d of seventeen (17) concentric 90° arc radial corrugations. The corrugation pattern 50b also provides a five (5)-degree-of-freedom transformation of the X-ray projection of the C-arm to a coordinate system associated with the marker using a single X-ray image.

[0054] Still referring to Figure 4C , in the practice of the corrugation pattern 50 having multiple arc series, an arc series can be the same as one or more other arc series in terms of frequency, phase, and amplitude, or the arc series can be different from one or more other arc series in terms of frequency, phase, and / or amplitude.

[0055] Arc series 51a and arc series 51c are the same as each other in terms of frequency, phase, and amplitude. Arc series 51a and arc series 51c are the same in phase as arc series 51b and 51d, but are different from arc series 51b and arc series 51d in terms of frequency and amplitude.

[0056] For the corrugation pattern 50 (e.g., Figure 4A the corrugation pattern 50a of Figure 4BFor any embodiment of the corrugated pattern 50b), the chirp pattern of the chirp (e.g., protrusions and / or grooves) can be axially aligned with the corrugated pattern 50 to provide a sixth degree of freedom transformation of the X-ray projection of the C-arm using a single X-ray image into the coordinate system associated with the marker. For example, Figure 4D A circular chirp pattern 52 showing forty (40) chirps surrounding the perimeter of the corrugated pattern 50 is shown.

[0057] In practice, the chirps can be provided on the same side surface of the platform as the corrugated pattern 50, and / or the chirps can be provided on the side surface of the platform opposite to the corrugated pattern 50.

[0058] For any embodiment of the corrugated pattern 50 (e.g., Figure 4A the corrugated pattern 50a of Figure 4B and the corrugated pattern 50b of Figure 4D A fiducial pattern (e.g., a copper ball pattern) can be axially aligned with the corrugated pattern 50 to facilitate the discovery of platform fixed points and / or C-arm registration calculations, including but not limited to final optimization and registration error estimation. For example,

[0059] A fiducial pattern showing a series of sixteen (16) copper balls 53 surrounding the edge of the corrugated pattern 50 is shown.

[0060] One of ordinary skill in the art will understand the broad scope of the embodiments of the X-ray corrugated markers of the present disclosure based on Figures 4A - 4C the description of

[0061] For example, Figure 4E An exemplary X-ray corrugated marker 20a is shown, which uses a protrusion embodiment 31 of the corrugated pattern 50a integrated on the disk 40c ( Figure 4B ), a circular chirp pattern 52 ( Figure 4D ) with a protrusion embodiment 52a of the circular chirp pattern 52 provided on the same side surface or the opposite side surface of the disk 40c as the corrugated pattern 50a, and Figure 4D a fiducial pattern of copper balls 53 surrounding the edge of the corrugated pattern 50 of

[0062] By way of additional example, Figure 4F An exemplary X-ray corrugated marker 20b is shown, which incorporates a protrusion embodiment 31 of the corrugated pattern 50a integrated on the disk 40c ( Figure 4B ) and a progressively spaced protrusion embodiment 52b of the circular chirp pattern 52 provided on the same side surface or the opposite side surface of the disk 40c as the corrugated pattern 50a ( Figure 4D ).

[0063] In another example, Figure 4G an exemplary X-ray ripple marker 20c is shown incorporating a protrusion embodiment 50d of a ripple pattern 50b integrated on a rectangular parallelepiped 40d( Figure 4C ).

[0064] To further facilitate understanding of aspects of the present disclosure, the following description of FIGS. 5-18B teaches embodiments of C-arm registration of the present disclosure. From this description, one of ordinary skill in the art will understand how to apply aspects of the present disclosure to make and use additional embodiments of the C-arm registration of the present disclosure.

[0065] Although Figure 4D the X-ray ripple marker 20a of Figure 4E and the X-ray ripple marker 20b of

[0066] are used for the purpose of describing embodiments of the C-arm registration of the present disclosure, one of ordinary skill in the art will understand how to apply aspects of the present disclosure to perform C-arm registration of the present disclosure using any embodiment of the X-ray ripple marker of the present disclosure.

[0067] Typically in the patient-free mode, the X-ray ripple marker 20 (e.g., the X-ray ripple marker 20a of Figure 4E or the X-ray ripple marker 20b of Figure 4F ) has a fixed position within the intervention space (e.g., attached to the operating table, rail, surgical drape, or intervention robot). The X-ray source 61 and X-ray detector 62 of the C-arm 60 are translated and / or rotated to a position to generate an X-ray image 63 of the ripple pattern 50 of the X-ray ripple marker 20. The C-arm registration controller 70 acquires the X-ray image 63 and performs the C-arm to marker registration 71 of the present disclosure, which depicts the position of the C-arm 60 relative to the X-ray projection of the X-ray ripple marker. Subsequently, the X-ray ripple marker 20 is removed from the imaging space of the C-arm 60 so that a patient can be positioned within the imaging space of the C-arm 60, and an intervention can be performed based on the generated C-arm registration including (one or more) X-ray images 64.

[0068] Typically in the patient mode, the X-ray ripple marker 20 (e.g., Figure 4E the X-ray ripple marker 20a of Figure 4FThe X-ray ripple marker 20b (as shown) is positioned above and adjacent to the X-ray ripple marker 20 in the intervention space (e.g., attachment to the operating table or intervention robot) and the patient's body part of interest (the body part is not shown for clarity of the marker). The X-ray source 61 and X-ray detector 62 of the C-arm 60 are translated and / or rotated to a position to generate an X-ray image 63 of the ripple pattern 50 of the X-ray ripple marker 20. The C-arm registration controller 70 acquires the X-ray image 65a and performs the C-arm to marker registration 71 of the present disclosure, which depicts the position of the C-arm 60 relative to the X-ray projection of the X-ray ripple marker 20, as will be further described in the present disclosure. The C-arm registration controller 70 can additionally perform the ripple marker removal 72 of the present disclosure to remove the X-ray ripple marker 20 (or at least the ripple pattern 50) from the X-ray image 65a to present the X-ray image 65b for display during the intervention based on the C-arm registration of the present disclosure.

[0069] More specifically, for both the patient-free mode and the patient mode, as Figure 6 shown, the C-arm to marker registration 71 involves registering the position of the X-ray projection of the present disclosure relative to the X-ray ripple marker 20 in the 3D coordinate system 21 or 3D coordinate system 22 (only the Y-axis and X-axis are shown, the Z-axis is not shown).

[0070] In practice, the X-ray projection can originate from any point of the X-ray source 61, for example, like Figure 6 the focal spot 65 shown in

[0071] In practice, the X-ray ripple marker 20 can establish a coordinate system 21 with the fixed point of the X-ray ripple marker 20 as the origin of the coordinate system 21, or alternatively, the X-ray ripple marker 20 can be calibrated using the coordinate system 22 of the intervention device (e.g., an intervention robot system with the X-ray ripple marker 20 attached thereto).

[0072] Referring to Figure 7 , stage S82 of the flowchart 80 includes the controller 70 identifying the features of the X-ray ripple marker 20 and the ripple pattern 50 in the X-ray image 63 in the Figure 5A patient-free mode or in the X-ray image 65a in the Figure 5B patient mode. The identification of the ripple pattern 50 in the X-ray image is characterized by the position of the X-ray projection of the C-arm 60 (e.g., the focal spot 65) relative to the X-ray ripple marker 20, meaning that the position and / or orientation of the X-ray projection within the coordinate system 21 or coordinate system 22 is characterized by the ripple pattern 50 as shown in the X-ray image.

[0073] In practice, when the entire X-ray ripple marker 20 is depicted within the X-ray image, knowledge of the geometry of the X-ray ripple marker 20 can be used as a basis for identifying the X-ray marker 20 within the X-ray image, or when a portion of the X-ray ripple marker 20 is shown in the X-ray image, landmark patterns (e.g., the landmark pattern 53 of the copper ball) can be used as a basis for identifying the X-ray marker in the X-ray image.

[0074] For example, in the patient-free mode, the X-ray ripple marker 20 can be aligned between the focal spot 65 and the X-ray detector 62 such that the entire X-ray ripple marker 20 can be depicted within the X-ray image 63 ( Figure 5A ).

[0075] As another example, in the patient mode, the landmark pattern 53 of the copper ball ( Figure 4D ) can be used to find the fixed point (e.g., the center point) of the X-ray ripple marker 20, especially when a portion of the X-ray ripple marker 20 is depicted within the X-ray image 65a ( Figure 5B ).

[0076] Stage S84 of the flowchart 80 involves deriving one or more transformation parameters from the ripple pattern 50 identified in stage S82, such that during stage S86 of the flowchart 80, the X-ray ripple marker 20 and the X-ray C-arm 60 are registered.

[0077] In practice, stage S84 involves generating one or more transformation signals based on one or more frequencies, one or more phases, and / or one or more amplitudes of the radial ripples of the ripple pattern 50 identified in stage 82. The transformation signals can be analyzed during stage S84 to derive one or more transformation parameters that define the position of the X-ray projection of the C-arm 60 (e.g., the focal spot 65) relative to the X-ray ripple marker 20, meaning that now during stage S86, the position and / or orientation of the X-ray projection within the coordinate system 21 or the coordinate system 22 can be determined based on the one or more transformation parameters.

[0078] In one embodiment of stages 84 and 86, particularly for an embodiment of the ripple pattern 50 with a radial ripple arrangement having the same frequency, phase, and amplitude, the pose of the X-ray ripple marker 20 in the C-arm space is described by a rigid body transformation including rotation R and translation t. According to the following common equation [1], the rotation is parameterized using ZXZ Euler angles:

[0079] R(θ z1 , θ x , θ z2 ) = R z (θ z1 )Rx (θ x )R z (θ z2 ) [1]

[0080] wherein, R z (θ) rotates about the z-axis by the angle θ.

[0081] The translation vector t consists of basic displacements along the axes, as shown in the following formula [2]:

[0082]

[0083] Any marker p in the marker space 21 or 22 of p marker ∈ R3 can be transformed into the C-arm space (e.g., with the focal spot 65 as the origin) according to the following formula [3]:

[0084] p C型臂 = R(θ z1 , θ x , θ z2 )p 标记物 + t(tx, ty, tz) [3]

[0085] Similarly, the position of any point in the C-arm space - pC-arm - can be translated into the marker space 21 or 22 according to the following formula [4]:

[0086] p 标记物 = R(θ z1 , θ x , θ z2 ) T p C型臂 - R(θ z1 , θ x , θ z2 ) T t(t x , t y , t z ) [4]

[0087] In the second embodiment of stages 84 and 86, particularly for an embodiment of the ripple pattern 50 having a first series of radial ripples and a second series of radial ripples with a different frequency, phase, and / or amplitude from the first series, the distance from the focal spot 65 to the fixed point of the X-ray ripple marker 20 can be determined according to different frequencies, different phases, and / or different amplitudes, as will be described exemplarily in the present disclosure with the description of 13 - 18B.

[0088] Still referring to Figure 7 , only for the patient mode, stage S88 of the flowchart 80 involves removing the ripple marker 20 from the X-ray image 65a ( Figure 5B) to present an X-ray image 65b ( Figure 5B ). In practice, any technique may be used to remove the X-ray corrugation marker 20 in a manner that minimizes, if not prevents, the introduction of artifacts and / or affects the depiction of the patient's body portion in the same spatial frequency range as the X-ray corrugation marker 20.

[0089] In one embodiment, frequency-based filtering techniques may be utilized during stage S88.

[0090] In a second embodiment, an image subtraction technique may be used, including transforming a model of the X-ray corrugated marker 20 to the actual position and orientation of the X-ray corrugated marker in the X-ray image 65a, thereby subtracting the corrugated marker in the X-ray image 65a with minimal impact on image quality, as will be described in the present disclosure using the Figures 12A - 12F The description is described by way of example.

[0091] The following is a C-arm image of an X-ray marker 20a held by an arm 23 (eg, a robot extension or a C-arm extension) in the context of an X-ray image 63a. Controller 70( Figure 5B ) of a patient model, such as Figure 8A In practice, when the corrugated pattern 50 of the X-ray corrugated marker 20a undergoes perspective transformation, the pattern 50 will become a chirp signal, so the following formula [5] will become the following formula [6], whereby the wave projection parameters c1 and c2 are functions of the perspective transformation parameters:

[0092] s(r)=Aexp(2πjf m r)[5]

[0093]

[0094] Where s(r) is the model sinusoidal mode, A is the amplitude, and f m is the frequency, and s p (s) is the projected geometric transformation pattern of s(r).

[0095] Figure 8BShows the transformation of the sine signal of the X-ray ripple marker 20 through perspective projection. If the marker 20 is parallel to the X-ray detector 62 and at the midpoint of the X-ray projection 120a as shown, the original sine signal 121 of the marker 20 is stretched into a sine signal 122a, where c1 = 0.5 and c2 = 0.0. If the marker 20 is tilted with respect to the X-ray detector 62 and at the midpoint of the X-ray projection 120b as shown, c2 > 0, resulting in a chirp signal 122b (e.g., c1 = 1.0 and c2 = 0.002). Thus, the signal along each diagonal of the marker is transformed into the wave projection parameters c1 and c2 through perspective transformation.

[0096] Figure 9 Illustrates a flow chart 90, which represents Figure 8A The transformation generation method of the X-ray ripple marker 20a shown.

[0097] Refer to Figure 9 , in stage S92 of flow chart 90, the controller 70 processes the acquired X-ray image 63a and the stored marker geometry 110 to calculate the (x bb i (k), y bb i (k)) coordinates 111 of each ball bearing landmark of the X-ray ripple marker 20a, so as to find the (x c i , y c i ) coordinates 112 of the center point of the X-ray ripple marker 20a during stage S94 of flow chart 90.

[0098] In stage S96 of flow chart 90, the controller 70 processes the acquired X-ray image 63a and the calculated center point (x c i , y c i ) coordinates 112 to calculate the wave projection parameters c1 and c2.

[0099] In stage S98 of flow chart 90, the controller 70 processes the acquired X-ray image 63a, the wave projection parameters c1 and c2, and the stored marker geometry 110 and C-arm geometry to obtain an initial approximation of the transformation parameters (t x 0 , t y 0 , t z 0 , θ x 0 , θ y 0 , θz 0 ) 115.

[0100] Stage S100 of the flow chart 90 includes the controller 70 processing transformation parameters (t x 0 , t y 0 , t z 0 , θ x 0 , θ y 0 , θ z 0 ) 115, for each ball carrier landmark (x bb i (k), y bb i (k)) coordinates 111 and the stored marker geometry 110 and the C-arm geometry to obtain transformation parameters (t x , t y , t z , θ x , θ y , θ z ) 116, carrier projection 117 and error / rms 118.

[0101] More specifically, in one embodiment of stages S92 and S94, the marker geometry 110 is such that the connection of the two (2) closest ball carriers defines a line that will intersect at the marker center, as Figure 10A shown. Thus, by splitting BB in the image 63a and grouping them to define rays, the projection of the center of the X-ray ripple marker 20a is identified, as Figure 10A shown. The intersection of these rays defines the center of the X-ray ripple marker 20a in the image space.

[0102] The center of the ball carrier is calculated using a simple threshold or a more advanced algorithm, such as an adaptive threshold or an Otsu threshold. Ball carrier pairs are formed by simple clustering because the radial neighbors of interest are closer than the lateral neighbors. After segmentation, bubbles that are too small or too large are filtered out. Then, the intersection of the rays is calculated using linear least squares.

[0103] In one embodiment of stage S96, for two marker positions of the X-ray ripple marker 20a that are parallel to the X-ray detector 62 and located at the midpoint of the X-ray projection 120a as Figure 8B shown, Figure 10B a graph 123a of the wave projection parameter c1 is illustrated, and Figure 10C a graph 123b of the wave projection parameter c2 is illustrated. For asFigure 8B The two marker positions of the X-ray ripple marker 20a shown in , where the X-ray detector is tilted and located at the midpoint of the X-ray projection 120a, Figure 10D The graph 123c of the wave projection parameter c1 is illustrated, and Figure 10E The graph 123d of the wave projection parameter c2 is illustrated. The calculation of the wave projection parameters c1 and c2 for the diagonal is performed by maximizing the convolution of the image signal along the diagonal with a chirp signal windowed by a Gaussian function.

[0104] In one embodiment of stage S98, c1, c2, and a range of γ values are then used to calculate the position of the X-ray ripple marker 20a down to the twist about the axis of the marker 20a. The initial approximation of the marker position in the image space includes five (5) degrees of freedom calculated from the wave projection parameters c1 and c2 and one (1) degree of freedom for the twist about the z-axis. Angle θ z2 for the twist. Angle θ z2 is the angle that maximizes the normalized cross-correlation between the image signal retrieved at the coordinates corresponding to the edge chirp projection using the 5DOF initial position approximation and the γ twist angle and the model chirp pulse pattern according to the following formula [7]:

[0105]

[0106] Figure 11A Shows the registration verification after the initial approximation, where, due to the error in the twist, the calculated position 124a of the marker 20a is very close to the true position 125b of the marker 20a.

[0107] In one embodiment of stage S100, the least squares method is used to optimize the calculated position. For each ball carrier bi identified in the image; i = 1...n, the model of the corresponding position bmi; i = 1...n is calculated, and then the virtual projection is calculated according to the following formulas [8] and [9] using the approximation parameters tx, ty, tz, θz1, θx, θz2, and the C-arm geometry 115:

[0108]

[0109] where, (xs,ys,zs) T is the position of the source 61 relative to the detector 62 coordinate system, and psz x and psz y are the pixel sizes in the x and y directions. It is assumed that the detector coordinate system coincides with the image coordinate system, only the pixel sizes are different.

[0110] The cost function can then be expressed according to the following formula

[10] :

[0111]

[0112] Minimize the cost function using the "Nelder-Mead" algorithm.

[0113] Figure 11B Registration verification after final optimization is shown, where the calculated position 124c of the marker 20a corresponds to the true position 125b of the marker 20a.

[0114] Reference Figure 7 , for the X-ripple marker 20a in the patient image 65a as shown in Figure 12A The subtraction example of the patient image 65a of the X-ripple marker 20a uses the pre-acquired image 126a of the X-ray image marker 20a in the field of view as shown in Figure 12B . This will be referred to as the marker model. Then additional intervention images with different orientations containing all or part of the marker can be acquired. Match the marker model 20a (e.g., in OpenCV: cv2.findHomography((Pt smodel),(Pt simage)) with the intervention image (such as the intervention image 65a) using a point-to-point homography transformation based on the ball bearing carrier position. In this case, the ball bearing carrier is used for the point-to-point transformation because the ball bearing carrier is a clear reference point in each image, but any other point on the marker can be used to replace the ball bearing carrier. To match the correctly corresponding ball bearing carrier pairs in the marker model 126a with the ball bearing carrier pairs in the intervention image 65a, the ball bearing carriers are detected in a radial order starting from the x-axis of the marker model 126b, as shown in Figure 12C .

[0115] Once the point-to-point homography transformation has been applied to the marker model 126b to provide a rough registration 65c of the intervention marker into the image space, an enhanced correlation coefficient (ECC) optimization routine (e.g., iOpenCV: cv2.findTransformECC()) is used. Once the best alignment between the marker model 126b and the image is achieved, the aligned marker model 126c as shown in Figure 12D is subtracted from the image to present the image 65d of Figure 12E , where the gray level of the subtracted model is optimized based on minimizing the power of the main frequency of the marker in the image. A uniform offset representing the average gray level of the subtracted marker is added back to the image in the marker region. Figure 12F

[0116] Table 1 outlines the subtraction technique

[0117]

[0118]

[0119] Figure 14 illustrates flowchart 140, which represents Figure 15A a method for generating a transformation of the X-ray ripple marker 20b shown.

[0120] More specifically, for both the patient-free mode and the patient mode, as Figure 13 shown, the C-arm to marker registration 71 involves projecting one period according to the following formula [11a] by projecting the perspective transformation of the distance 132 from the X-ray source 130 to the X-ray detector 134 onto the distance 131 from the X-ray source 130 to the X-ray ripple marker 133:

[0121]

[0122] where SM is the distance 132 from the X-ray source 130 to the X-ray ripple marker 133, SD is the distance from the X-ray source 130 to the X-ray detector 134 (which is known from calibration or DICOM data), T M is the time period of the ripple pattern and T I is the image period (calculated from the image). Converting formula [11A] to frequency gives the following formula [11b]:

[0123]

[0124] f M is the frequency of the known ripple pattern, f I is the image frequency (calculated from the image).

[0125] Formula [11b] is used to view the image in one direction. The following formula [11c] is for two directions applicable to the X-ripple marker 20b ( Figure 15A ):

[0126]

[0127] where, is the highest frequency of the known ripple pattern,

[0128] is the highest frequency of the known ripple pattern, is the highest image frequency (calculated from the image) and is the lowest image frequency (calculated from the image).

[0129] In practice, more than two directions can be used. Also in practice, the simplest method is to use the fast Fourier transform (FFT) along the line passing through Figure 15A the center of the X-ray ripple marker 20b in.

[0130] Reference Figure 14 In stage S142 of flowchart 140, controller 70 plots the intensity in each direction through the corrugation pattern of X-ray corrugation marker 20b, and in stage S144 of flowchart 140, controller 70 derives one or more transformation parameters from the FFT analysis of the intensity plot(s).

[0131] For example, Figure 16A illustrates a scenario where the corrugation pattern of X-ray corrugation marker 20b is parallel to the X-ray detector at the first parallel position 151, where line 152L passes through low-frequency radial corrugation series 51a and low-frequency radial corrugation series 51c, and line 152H passes through high-frequency radial corrugation series 51b and high-frequency radial corrugation series 51d.

[0132] For another example, Figure 17A illustrates a scenario where the corrugation pattern of X-ray corrugation marker 20b is parallel to the X-ray detector at the second parallel position 153, where line 154L passes through low-frequency radial corrugation series 51a and low-frequency radial corrugation series 51c, and line 154H passes through high-frequency radial corrugation series 51b and high-frequency radial corrugation series 51d.

[0133] For the first parallel position 151 during stage S142 ( Figure 16A ), Figure 16B shows intensity curves 155L for low-frequency radial corrugation series 51a and low-frequency radial corrugation series 51c at the first position 151, and intensity curves 155H for high-frequency radial corrugation series 51b and high-frequency radial corrugation series 51d.

[0134] For the second parallel position 152 during stage S142 ( Figure 17A ), Figure 17B shows intensity curves 156L for low-frequency radial corrugation series 51a and low-frequency radial corrugation series 51c at the first position 151, and intensity curves 156H for high-frequency radial corrugation series 51b and high-frequency radial corrugation series 51d.

[0135] Figure 15B Shows the FFT analysis 157a of intensity map 155L, the FFT analysis 157b of intensity map 155H, the FFT analysis 157c of intensity map 156L, and the FFT analysis 157c of intensity map 156H.

[0136] For Figure 16A the first position 151, the peak 157a of the FFT analysis is the lowest image frequency of formula [11c] and the peak 157b of the FFT analysis is the highest image frequency of formula [11c]

[0137] For Figure 17A the second position 153, the peak 157c of the FFT analysis is the lowest image frequency of Equation [11c] and the peak 157d of the FFT analysis is the highest image frequency of Equation [11c]

[0138] Return reference Figure 14 , stage S140 of flow chart S146 includes the controller 70 registering the X-ray ripple marker 20b and the X-ray C-arm.

[0139] In one embodiment of stage S140, xcd and ycd represent the center of the X-ray ripple marker 20b in the detector coordinate system, wherein the translation of the X-ray ripple marker is calculated according to the following equations [12a]-[12c]:

[0140] tz = SD – SM

[12]

[0141] tx = xcd * SD / SM

[12]

[0143] ty = ycd * SD / SM

[12]

[0144] The following scenario is illustrated by additional examples: wherein the ripple pattern of the X-ray ripple marker 20b is inclined relative to the X-ray detector at position 158, wherein line 158L passes through the low-frequency radial ripple series 51a and the low-frequency radial ripple series 51c, and line 158H passes through the high-frequency radial ripple series 51b and the high-frequency radial ripple series 51d.

[0145] Figure 18B The FFT analysis 159a of the intensity map of line 158L and the FFT analysis 159b of the intensity map of line 158H are shown. The axis of rotation of the FFT analysis 159a is sharp because the rotation of the ripple pattern caused by the inclination does not change the frequencies of the low-frequency radial ripple series 51a and the low-frequency radial ripple series 51c, while the axis of rotation of the FFT analysis 159b is spread out because the rotation of the ripple pattern caused by the inclination will change the frequencies of the high-frequency radial ripple series 51b and the high-frequency radial ripple series 51d.

[0146] To facilitate further understanding of the various inventions of the present disclosure, the following description of Figure 19 will teach exemplary embodiments of the C-arm registration controller of the present disclosure. From this description, those of ordinary skill in the art will understand how to apply aspects of the present disclosure to make and use additional embodiments of the C-arm registration controller of the present disclosure.

[0147] ReferenceFigure 19 , the C-arm registration controller 170 includes one or more processors 171, a memory 172, a user interface 173, a network interface 174, and a storage device 175 interconnected via one or more system buses 176.

[0148] Each processor 171 can be any hardware device capable of executing instructions stored in the memory 172 or the storage device or otherwise processing data, as known in the technical field of the present disclosure or contemplated hereinafter. In a non-limiting example, the (one or more) processors 171 can include a microprocessor, a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or other similar devices.

[0149] The memory 172 can include various memories as known in the field of the present disclosure or contemplated hereinafter, including but not limited to L1, L2, or L3 caches or system memory. In a non-limiting example, the memory 172 can include static random access memory (SRAM), dynamic RAM (DRAM), flash memory, read-only memory (ROM), or other similar memory devices.

[0150] The user interface 173 can include one or more devices, as known in the field of the present disclosure or contemplated hereinafter, for enabling communication with a user such as an administrator. In a non-limiting example, the user interface can include a command-line interface or a graphical user interface, which can be presented to a remote terminal via the network interface 174.

[0151] The network interface 174 can include one or more devices, as known in the technical field of the present disclosure or contemplated hereinafter, for enabling communication with other hardware devices. In a non-limiting example, the network interface 174 can include a network interface card (NIC) configured to communicate according to the Ethernet protocol. Additionally, the network interface 174 can implement a TCP / IP stack for communication according to the TCP / IP protocol. Various alternative or additional hardware or configurations for the network interface 174 will be apparent.

[0152] As conceived in the technical field of the present disclosure or hereinafter, the memory 175 may include one or more machine-readable storage media, including but not limited to read-only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, or similar storage media. In a non-limiting example, the storage device 175 may store instructions for execution by the (one or more) processors 171 or data that the (one or more) processors 1620 may operate on. For example, the memory 175 may store a basic operating system for controlling various basic operations of the hardware. The memory 175 also stores application modules in the form of executable software / firmware for implementing various functions of the controller 170a as previously described in the present disclosure, including but not limited to, the C-arm to marker registration module 178 and the corrugated marker removal module 179 as previously described in the present disclosure.

[0153] In practice, the controller 170 may be installed within the X-ray imaging system 160, the intervention system 161 (such as an intervention robotic system), or an independent workstation 162 (such as a client workstation or a mobile device such as a tablet) that communicates with the X-ray imaging system 160 and / or the intervention system 161. Alternatively, the components of the controller 170 may be distributed among the X-ray imaging system 160, the intervention system 161, and / or the independent workstation 162.

[0154] Referring Figures 1 - 19 , those of ordinary skill in the art of the present disclosure will appreciate many benefits of the invention of the present disclosure, including but not limited to X-ray corrugated markers that facilitate accurate and reliable C-arm registration, particularly for mobile C-arms.

[0155] Additionally,

[0156] In addition, in view of the teachings provided herein, those of ordinary skill in the art will understand that the structures, elements, components, etc. described in this disclosure / specification and / or depicted in the figures can be implemented in various combinations of hardware and software, and provide functions that can be combined in a single element or multiple elements. For example, the functions of the various structures, elements, components, etc. shown / depicted in the figures can be provided by using dedicated hardware and hardware capable of executing software associated with appropriate software for the additional functions. When provided by a processor, the functions can be provided by a single dedicated processor, by a single shared processor, or by multiple individual processors, some of which can be shared and / or multiplexed. In addition, the explicit use of the terms "processor" or "controller" should not be construed as exclusively referring to hardware capable of running software, but can implicitly and without limitation include digital signal processor ("DSP") hardware, memory (such as read-only memory ("ROM") for storing software, random access memory "RAM"), non-volatile storage devices, etc., and any virtual device and / or machine capable of (and / or configurable to) execute and / or control processes (including hardware, software, firmware, circuits, combinations thereof, etc.).

[0157] In addition, all statements of principles, aspects, and embodiments of the present invention mentioned herein, as well as their specific examples, are intended to cover their structural and functional equivalents. Additionally, it is intended that such equivalent elements include both currently known equivalent elements and equivalent elements developed in the future (e.g., elements developed that can perform the same or substantially similar functions, regardless of their structure). Thus, for example, those of ordinary skill in the art will recognize, in view of the teachings provided herein, that any block diagram presented herein can represent a conceptual diagram of illustrative system components and / or circuits implementing the principles of the present invention. Similarly, those of ordinary skill in the art should recognize, in view of the teachings provided herein, that any process diagram, flowchart, etc. can represent various processes that can be substantially represented in a computer-readable storage medium and run by a computer, processor, or other device with processing capabilities, whether or not such a computer or processor is explicitly shown.

[0158] Having described the preferred and exemplary embodiments of the various and numerous inventions of this disclosure, which are intended to be exemplary and not restrictive, it should be noted that those skilled in the art can make modifications and variations in accordance with the teachings provided herein (including the drawings). Therefore, it should be understood that changes can be made to the preferred and exemplary embodiments of this disclosure within the scope of the embodiments of this disclosure.

[0159] In addition, it is expected that the corresponding and / or related systems for implementing the device / system, etc. can also be used / implemented in and / or with the devices according to the present disclosure and are also expected and considered to be within the scope of the present disclosure. In addition, the corresponding and / or related methods for manufacturing and / or using the devices and / or systems according to the present disclosure are also expected and considered to be within the scope of the present disclosure.

Claims

1. A C-arm registration system, comprising: An X-ray ripple marker (20), which includes a ripple pattern (50) radially extending from a fixed point (40) of the X-ray ripple marker (20); And A C-arm registration controller (70), which is configured to: Identify the ripple pattern (50) within an X-ray image, the X-ray image being generated from an X-ray projection of a C-arm (60) and depicting at least a portion of the ripple pattern (50), Wherein the identification of the ripple pattern (50) within the X-ray image is characterized by the attitude of the C-arm (60) relative to the X-ray projection of the X-ray ripple marker (20); Analyze the ripple pattern (50) within the X-ray image to derive at least one transformation parameter, the at least one transformation parameter defining the attitude of the C-arm (60) relative to the X-ray projection of the X-ray ripple marker (20); and Register the C-arm (60) to the X-ray ripple marker (20) based on the at least one transformation parameter.

2. The C-arm registration system according to claim 1, wherein, The ripple pattern (50) includes: A plurality of concentric ripples.

3. The C-arm registration system according to claim 1, wherein, The ripple pattern (50) includes: A first series of concentric arc ripples.

4. The C-arm registration system according to claim 3, wherein, The ripple pattern (50) further includes: A second series of concentric arc ripples that differ from the first series of concentric arc ripples in at least one of frequency, phase, and amplitude.

5. The C-arm registration system according to claim 1, wherein, The X-ray ripple marker (20) further includes: A chirp pattern axially aligned with the ripple pattern (50).

6. The C-arm registration system according to claim 1, wherein The X-ray ripple marker (20) further includes: A landmark pattern axially aligned with the ripple pattern (50).

7. The C-arm registration system according to claim 1, wherein, The C-arm registration controller (70) being configured to analyze the ripple pattern (50) within the X-ray image includes that the C-arm registration controller (70) is further configured to: Calculate at least one wave projection parameter according to the identification of the ripple pattern (50) within the X-ray image; and Derive the at least one transformation parameter from the at least one wave projection parameter calculated according to the identification of the ripple pattern (50) within the X-ray image.

8. The C-arm registration system according to claim 7, wherein, The C-arm registration controller (70) being configured to analyze the ripple pattern (50) within the X-ray image further includes that the C-arm registration controller (70) is further configured to: Apply the least squares method to the at least one transformation parameter derived from the at least one wave projection parameter calculated according to the identification of the ripple pattern (50) within the X-ray image.

9. The C-arm registration system according to claim 1, wherein, The C-arm registration controller (70) being configured to analyze the ripple pattern (50) within the X-ray image includes that the C-arm registration controller (70) is further configured to: Apply a fast Fourier transform to the intensity profile along a line passing through the X-ray ripple marker to derive a frequency; and Derive the at least one transformation parameter from the frequency derived according to the identification of the ripple pattern (50) within the X-ray image.

10. The C-arm registration system according to claim 1, wherein, The C-arm registration controller (70) is also configured to remove the ripple pattern (50) from the X-ray image.

11. A C-arm registration controller (70), comprising: A non-transitory machine-readable storage medium encoded with instructions for being run by at least one processor to register a C-arm (60) to an X-ray ripple marker (20), the X-ray ripple marker including a ripple pattern (50) radially extending from a fixed point (40) of the X-ray ripple marker (20), the non-transitory machine-readable storage medium including instructions for performing the following operations: Identifying the ripple pattern (50) within the X-ray image, the X-ray image being generated from an X-ray projection of the C-arm (60) and illustrating at least a portion of the ripple pattern (50); wherein the identification of the ripple pattern (50) within the X-ray image is characterized by an attitude of the X-ray projection of the C-arm (60) relative to the X-ray ripple marker (20); Analyzing the ripple pattern (50) within the X-ray image to derive at least one transformation parameter, the at least one transformation parameter defining an attitude of the X-ray projection of the C-arm (60) relative to the X-ray ripple marker (20); and Registering the C-arm (60) to the X-ray ripple marker (20) based on the at least one transformation parameter.

12. The C-arm registration controller (70) according to claim 11, wherein, The instructions for analyzing the ripple pattern (50) within the X-ray image include instructions for performing the following operations: Calculating at least one wave projection parameter according to the identification of the ripple pattern (50) within the X-ray image; and Deriving the at least one transformation parameter from the at least one wave projection parameter calculated according to the identification of the ripple pattern (50) within the X-ray image.

13. The C-arm registration controller (70) according to claim 12, wherein, The instructions for analyzing the ripple pattern (50) within the X-ray image further include instructions for performing the following operations: Applying the least squares method to the at least one transformation parameter derived from the at least one wave projection parameter calculated according to the identification of the ripple pattern (50) within the X-ray image.

14. The C-arm registration controller (70) according to claim 11, wherein, The instructions for analyzing the ripple pattern (50) within the X-ray image include instructions for performing the following operations: Applying a fast Fourier transform to an intensity profile along a line passing through the X-ray ripple marker to derive a frequency; and Deriving the at least one transformation parameter from the frequency derived according to the identification of the ripple pattern (50) within the X-ray image.

15. The C-arm registration controller (70) according to claim 11, wherein, The non-transitory machine-readable storage medium further includes instructions for performing the following operations: Removing the ripple pattern (50) from the X-ray image.

16. A C-arm registration method, capable of being run by a C-arm registration controller (70) for registering a C-arm (60) to an X-ray ripple marker (20), the X-ray ripple marker including a ripple pattern (50) radially extending from a fixed point (40) of the X-ray ripple marker (20), the C-arm registration method including: The corrugated pattern (50) within the X-ray image is identified via the C-arm registration controller (70), the X-ray image being generated from an X-ray projection of the C-arm (60) and depicting at least a portion of the corrugated pattern (50). Wherein, the identification of the corrugated pattern (50) within the X-ray image is characterized by the attitude of the C-arm (60) relative to the X-ray projection of the X-ray corrugated marker (20). The corrugated pattern (50) within the X-ray image is analyzed via the C-arm registration controller (70) to derive at least one transformation parameter, the at least one transformation parameter defining the attitude of the C-arm (60) relative to the X-ray projection of the X-ray corrugated marker (20); and The C-arm (60) is registered to the X-ray corrugated marker (20) via the C-arm registration controller (70) based on the at least one transformation parameter.

17. The C-arm registration method according to claim 16, wherein, Analyzing the corrugated pattern (50) within the X-ray image via the C-arm registration controller (70) includes:[[]] Calculating, via the C-arm registration controller (70), at least one wave projection parameter based on the identification of the corrugated pattern (50) within the X-ray image; and Deriving the at least one transformation parameter from the at least one wave projection parameter calculated based on the identification of the corrugated pattern (50) within the X-ray image.

18. The C-arm registration method according to claim 17, wherein analyzing the corrugated pattern (50) within the X-ray image via the C-arm registration controller (70) further includes:[[]] Applying, via the C-arm registration controller (70), the least squares method to the at least one transformation parameter derived from the at least one wave projection parameter calculated based on the identification of the corrugated pattern (50) within the X-ray image.

19. The C-arm registration method according to claim 16, wherein, Analyzing the corrugated pattern (50) within the X-ray image via the C-arm registration controller (70) includes:[[]] Applying, via the C-arm registration controller (70), a fast Fourier transform to the intensity profile along a line passing through the X-ray corrugated marker to derive a frequency; and Deriving the at least one transformation parameter from the frequency derived based on the identification of the corrugated pattern (50) within the X-ray image via the C-arm registration controller (70).

20. The C-arm registration method according to claim 16, further including:[[]] Removing the corrugated pattern (50) from the X-ray image via the C-arm registration controller (70).

Images