Calibration of X-ray devices

Abstract

A generalized calibration routine applicable to any rotation center of the X-ray device is implemented for X-ray imaging. [Solution] The method includes performing calibration and imaging of an X-ray device by calibrating the X-ray device by implementing a generalized calibration routine applicable to any rotation center of the X-ray device, and by measuring calibration parameters of the X-ray device that describe at least the mechanism of the X-ray device. It further includes imaging a patient's volume by projecting an X-ray beam onto a detector through the volume based on a desired scanning trajectory or based on calibration parameters, thereby generating multiple X-ray images. It further includes generating an estimated projection geometry corresponding to the imaging using the calibration parameters and the desired scanning trajectory. It also includes generating a reconstruction of the volume corresponding to the multiple X-ray images using the estimated projection geometry and motion artifact compensation.

Description

Technical Field

[0001] The present disclosure relates to the calibration and imaging of X-ray devices, and more particularly to implementing a generalized calibration routine applicable to any center of rotation of an X-ray device for X-ray imaging.

Background Art

[0002] In X-ray imaging, calibration can be performed to adjust and standardize an X-ray device for taking X-ray images. Calibration can be performed to maintain image quality and ensure that the device operates within the required specifications.

[0003] Calibration can include alignment procedures to properly align the X-ray beam with the detector of the X-ray device and the object being imaged. Additionally, the voltage and current used for exposure may be calibrated to ensure the correct exposure level. In addition, the sensitivity of the detector can be adjusted to ensure a uniform response across the surface of the detector.

Summary of the Invention

Means for Solving the Problems

[0004] According to one embodiment of the present disclosure, a method calibrates an X-ray device by implementing a generalized calibration routine applicable to any center of rotation of the X-ray device, and measures calibration parameters of the X-ray device that describe at least the mechanics of the X-ray device, thereby performing calibration and imaging of the X-ray device. The method further includes imaging a patient's volume by projecting an X-ray beam onto a detector through a volume based on a desired scan trajectory or based on the calibration parameters, and generating a plurality of X-ray images. The method further includes generating an estimated projection geometry corresponding to the imaging using the calibration parameters and the desired scan trajectory. The method also includes generating a reconstruction of the volume corresponding to the plurality of X-ray images using the estimated projection geometry and motion artifact compensation.

[0005] In one embodiment, the calibration parameters include external calibration parameters that describe how the components of the X-ray device move in space, and the calibration parameters further include internal calibration parameters that describe the relative positions of the components of the X-ray device relative to one another.

[0006] According to one embodiment of the present disclosure, the X-ray device includes a processor and a memory that communicates with the processor and has one or more computer program instructions stored in the memory, the computer program instructions, when executed by the processor, cause the X-ray device to perform operations including calibrating the X-ray device by performing a generalized calibration routine applicable to any rotation center of the X-ray device, measuring calibration parameters of the X-ray device that describe at least the mechanism of the X-ray device, imaging a volume by projecting an X-ray beam through the volume onto a detector based on a desired scan trajectory or calibration parameters to generate a plurality of X-ray images, and generating an estimated projection geometry corresponding to the imaging using the calibration parameters and the desired scan trajectory. The X-ray device further generates a reconstruction of the volume corresponding to the plurality of X-ray images using the estimated projection geometry and motion artifact compensation.

[0007] According to one embodiment of the present disclosure, a non-temporary computer-readable storage medium stores computer-readable instructions, which, when executed by the processor of the X-ray device, cause the X-ray device to calibrate the X-ray device by performing a generalized calibration routine applicable to any rotation center of the X-ray device; to measure calibration parameters of the X-ray device that describe at least the mechanism of the X-ray device; to image a volume by projecting an X-ray beam through the volume onto a detector based on a desired scan trajectory or calibration parameters, to generate a plurality of X-ray images; and to generate an estimated projection geometry corresponding to the imaging using the calibration parameters and the desired scan trajectory. The X-ray device is further configured to generate a reconstruction of the volume corresponding to the plurality of X-ray images using the estimated projection geometry and motion artifact compensation.

[0008] To facilitate the identification of any particular element or action description, the most significant digit of the reference number refers to the figure number in which that element is first introduced. [Brief explanation of the drawing]

[0009] [Figure 1] This is a block diagram of the network of a data processing system according to an exemplary embodiment.

[0010] [Figure 2] This is a block diagram of a data processing system according to an exemplary embodiment.

[0011] [Figure 3A] This figure shows a sketch of an X-ray device according to an exemplary embodiment.

[0012] [Figure 3B] This figure shows a sketch of an X-ray device and X-ray beam according to an exemplary embodiment.

[0013] [Figure 4] This figure shows a sketch of an X-ray device illustrating a first volume and a first center of rotation according to an exemplary embodiment.

[0014] [Figure 5] This figure shows a sketch of an X-ray device illustrating a first volume and a first center of rotation according to an exemplary embodiment.

[0015] [Figure 6] This figure shows routine 600 according to an exemplary embodiment. [Modes for carrying out the invention]

[0016] overview The following detailed explanation includes numerous specific details as examples to provide a complete understanding of the relevant teachings. However, it is clear that these teachings may be practiced without such details. In other examples, well-known methods, procedures, and / or components are described at a relatively high level without detail to avoid unnecessarily obscuring aspects of these teachings.

[0017] An exemplary embodiment recognizes that an X-ray device may have a plurality of predefined rotation centers that can be used to capture X-ray images of an object, such as a patient's volume. Each predefined rotation center may correspond to the volume being imaged, and each predefined rotation center may have a corresponding trajectory or path that the detector and X-ray source of the X-ray device can follow to image the volume. Calibration can be performed for each predefined rotation center. Thus, for example, in the case of an X-ray device with 10 predefined rotation centers, 10 corresponding calibration routines can be performed to calibrate the X-ray device.

[0018] Accordingly, the exemplary embodiment discloses a method comprising performing a generalized calibration routine applicable to any rotation center. The generalized calibration routine comprises traversing a trajectory including linear translation and obtaining calibration parameters that describe at least the mechanism of the X-ray device. The exemplary embodiment further discloses imaging a volume, using the calibration parameters to estimate a projection geometry for use with motion artifact compensation, and generating a reconstruction of the imaged volume. Motion artifact compensation compensates for (reduces) errors in estimating the projection geometry so that the generalized calibration routine can be used for all rotation centers to improve the quality of the resulting reconstruction.

[0019] Exemplary embodiments are described in relation to a particular type of machine. Exemplary embodiments are also described, only as examples, in relation to other scenes, subjects, measurements, devices, data processing systems, environments, components, and applications. Any particular form of these and other similar artifacts is not intended to limit this disclosure. Any suitable form of these and other similar artifacts can be selected within the scope of the exemplary embodiments.

[0020] Furthermore, exemplary embodiments may be implemented with respect to any type of data, data source, or access to a data source via a data network. Any type of data storage device can, within the scope of this disclosure, provide data locally in a data processing system or via a data network to one embodiment of this disclosure.

[0021] Exemplary embodiments are described by way of example only, using specific codes, hardware, algorithms, designs, architectures, protocols, layouts, schematics, and tools, and are not limited to the exemplary embodiments. Further, the exemplary embodiments are described in some examples using specific software, tools, and data processing environments only for the purpose of clarifying the description. The exemplary embodiments can be used in conjunction with other equivalent or similarly intended structures, systems, applications, or architectures. For example, other equivalent devices, structures, systems, applications, or their architectures can be used in conjunction with such embodiments of the present disclosure within the scope of the present disclosure. The exemplary embodiments can be implemented in hardware, software, or a combination thereof.

[0022] Examples of the present disclosure are used only for the purpose of clarifying the description and are not limited to the exemplary embodiments. Additional data, operations, actions, tasks, activities, and manipulations can be contemplated from the present disclosure and are intended within the scope of the exemplary embodiments.

[0023] The advantages listed herein are merely examples and are not intended to be limiting to the exemplary embodiments. Additional or different advantages can be realized by specific exemplary embodiments. Further, specific exemplary embodiments may have some, all, or none of the advantages listed above.

[0024] Exemplary Environment Figure 1 shows a block diagram of a data processing system environment in which an exemplary embodiment may be implemented. The data processing environment 100 is a network of engines and computers in which an exemplary embodiment may be implemented. The data processing environment 100 may include a network / communication infrastructure 102. The network / communication infrastructure 102 is a medium used to provide communication links between various devices, databases, and computers connected to each other within the data processing environment 100. The network / communication infrastructure 102 may include connections such as wired connections, wireless communication protocols, or other appropriate data connections.

[0025] The X-ray device 118 can carry out the embodiments described herein. The X-ray device 118 may include a calibration engine 116 which may further include an embedded application for using data from the X-ray device 118 to perform a generalized calibration routine. The embedded application may also run in any data processing system (server 104 or server 106, client 110), such as a client-server application 112 in server 104.

[0026] X-ray radiography can be performed by positioning an X-ray source on one side of the patient (e.g., the patient's dental area) and causing the X-ray source to emit X-rays through a volume toward an X-ray detector located on the other side of the patient. As the X-rays pass from the X-ray source through the patient and the volume, their energy is absorbed to varying degrees depending on the composition of the volume, and the X-rays that reach the X-ray detector form a two-dimensional (2D) X-ray image or projection image (also known as a radiograph) based on the cumulative absorption through the volume.

[0027] Returning to Figure 1, the client or server is merely an illustrative role of a particular data processing system connected to the network / communication infrastructure 102, and is not intended to exclude other configurations or roles for these data processing systems. Servers 104 and 106 are coupled to the network / communication infrastructure 102 along with the storage unit 108. Software applications can run on any computer within the data processing environment 100. Client 110 is also coupled to the network / communication infrastructure 102. A data processing system such as server 104 or server 106, client 110 may contain data and may have software applications or software tools running on it.

[0028] As an example only, and without implying any limitations on such architectures, Figure 1 shows certain components that can be used in an exemplary embodiment of one particular set of features. As another example, one embodiment can be distributed across several data processing systems and data networks as shown, while another embodiment can be implemented on a single data processing system within the scope of the exemplary embodiment.

[0029] The data processing environment 100 may include additional servers, clients, and other devices not shown. Server 104 may include a server application 112 that can be configured to implement one or more of the functions described herein for displaying recovery suggestions according to one or more embodiments.

[0030] In the illustrated example, the data processing environment 100 may be the Internet. The network / communication infrastructure 102 can represent a collection of networks and gateways that communicate with each other using the Transmission Control Protocol / Internet Protocol (TCP / IP) and other protocols. Figure 1 is intended as an example and is not intended as an architectural limitation to different exemplary embodiments.

[0031] In particular, the data processing environment 100 can be used to implement a client-server environment in which exemplary embodiments can be carried out. The client-server environment enables the distribution of software applications and data across a network so that applications function by using interactions between a client data processing system and a server data processing system. The data processing environment 100 can also employ a service-oriented architecture that allows interoperable software components distributed across a network to be packaged together as a coherent business application. The data processing environment 100 can also take the form of a cloud and employ a cloud computing model of service delivery to enable convenient on-demand network access to a shared pool of configurable computing resources (e.g., networks, network bandwidth, servers, processing, memory, storage, applications, virtual machines, and services) that can be rapidly provisioned and released with minimal administrative effort or interaction with service providers.

[0032] Referring to Figure 2, this figure shows a block diagram of a data processing system in which an exemplary embodiment may be implemented. The data processing system 200 is an example of another type of device in which a computer, such as the X-ray device 118, client 110, or server 104 in Figure 1, or computer-enabled program code or instructions that perform the process may be located for the exemplary embodiment.

[0033] The data processing system 200 is described as a computer, but is not limited to that. Embodiments in the form of other devices may modify the data processing system 200, such as by adding a touch interface, and may even exclude certain illustrated components from the data processing system 200, without departing from the general description of the operation and function of the data processing system 200 described herein.

[0034] In the illustrated example, the data processing system 200 employs a hub architecture including a northbridge and memory controller hub (NB / MCH) 202 and a southbridge and input / output (I / O) controller hub (SB / ICH) 204. The processing unit 206, main memory 208, and graphics processor 210 are coupled to the northbridge and memory controller hub (NB / MCH) 202. The processing unit 206 may include one or more processors and may be implemented using one or more heterogeneous processor systems. The processing unit 206 may also be a multicore processor. In certain embodiments, the graphics processor 210 can be coupled to the northbridge and memory controller hub (NB / MCH) 202 through an accelerated graphics port (AGP).

[0035] In the illustrated example, the local area network (LAN) adapter 212 is coupled to the southbridge and input / output (I / O) controller hub (SB / ICH) 204. The audio adapter 216, keyboard and mouse adapter 220, modem 222, read-only memory (ROM) 224, universal serial bus (USB) and other ports 232, and PCI / PCIe devices 234 are coupled to the southbridge and input / output (I / O) controller hub (SB / ICH) 204 via bus 218. The hard disk drive (HDD) or solid state drive (SSD) 226a and CD-ROM 230 are coupled to the southbridge and input / output (I / O) controller hub (SB / ICH) 204 via bus 228. PCI / PCIe devices 234 may include, for example, Ethernet adapters, add-in cards, and PC cards for notebook computers. PCI uses a cardbus controller, while PCIe does not. The read-only memory (ROM) 224 may be, for example, a flash binary input / output system (BIOS). Hard disk drives (HDDs) or solid state drives (SSDs) 226a and CD-ROMs 230 can use, for example, integrated drive electronics (IDE), serial advanced technology attachment (SATA) interfaces, or variations such as external SATA (eSATA) and micro SATA (mSATA). Super I / O (SIO) devices 236 can be coupled to the southbridge and input / output (I / O) controller hub (SB / ICH) 204 via bus 218.

[0036] Memory such as main memory 208, read-only memory (ROM) 224, or flash memory (not shown) are some examples of computer-usable storage devices. Hard disk drives (HDDs) or solid-state drives (SSDs) 226a, CD-ROMs 230, and other similarly usable devices are some examples of computer-usable storage devices, including computer-usable storage media.

[0037] The operating system runs on the processing unit 206. The operating system coordinates and controls the various components within the data processing system 200 shown in Figure 2. The operating system may be a commercially available operating system for any type of computing platform, including, but not limited to, server systems, personal computers, and mobile devices. An object-oriented or other type of programming system works in conjunction with the operating system and can provide calls to the operating system from programs or applications running on the data processing system 200.

[0038] Instructions for an operating system, an object-oriented programming system, and an application or program such as the server application 112 in Figure 1 reside on a storage device, such as in the form of code 226b on a hard disk drive (HDD) or solid-state drive (SSD) 226a, and can be loaded into at least one of one or more memories, such as main memory 208, for execution by the processing unit 206. The processes of the exemplary embodiment may be carried out by the processing unit 206 using computer implementation instructions that may reside, for example, in main memory 208, read-only memory (ROM) 224, or one or more peripheral devices.

[0039] Furthermore, in some cases, code 226b can be downloaded from a remote system 214b via a network 214a (such as a network / communication infrastructure 102), and similar code 214c can be stored in a storage device 214d in other cases, code 226b can be downloaded to the remote system 214b via the network 214a, and the downloaded code 214c is stored in the storage device 214d.

[0040] The communication unit may include one or more devices used to send and receive data, such as a modem or network adapter. The memory may be, for example, main memory 208, or a cache such as the cache found in the northbridge and memory controller hub (NB / MCH) 202. The processing unit may include one or more processors or CPUs.

[0041] When a computer or data processing system is described as a virtual machine, virtual device, or virtual component, the virtual machine, virtual device, or virtual component operates in the manner of the data processing system 200, using virtualized representations of some or all of the components shown in the data processing system 200. For example, in a virtual machine, virtual device, or virtual component, processing unit 206 appears as a virtualized instance of all or some of the hardware processing units 206 available in the host data processing system; main memory 208 appears as a virtualized instance of all or some of the main memory 208 that may be available in the host data processing system; and hard disk drive (HDD) or solid-state drive (SSD) 226a appears as a virtualized instance of all or some of the hard disk drive (HDD) or solid-state drive (SSD) 226a that may be available in the host data processing system. In such cases, the host data processing system is represented by the data processing system 200.

[0042] Figure 3A shows a sketch of the operation of an X-ray device 118 according to an exemplary embodiment. The X-ray device 118 comprises a detector 302 and a light source 306. The X-ray device may have multiple rotation centers 312. A rotation center 312 is a center or reference point within a volume 304 around which the light source 306 and detector 302 move for X-ray acquisition. The light source and detector can move along trajectories (light source trajectory 316 and detector trajectory 314) for each rotation center 312. The rotation centers 312 can be predefined. Conventionally, a rotation center may have corresponding trajectories for the light source and detector that the light source and detector pass through. By calibrating the X-ray device for each rotation center, it becomes possible to obtain information about the actual scanning path that may deviate from the desired scanning path due to tolerances in the behavior of the components of the X-ray device, for example. Therefore, in conventional calibration processes, the more rotation centers that are available, the more time-consuming it becomes. The exemplary embodiment discloses a generalized calibration routine that is applicable to all rotation centers and can be performed once.

[0043] As shown in Figure 3B, the X-ray beam 308 is projected while the device rotates around the patient's head 310, particularly around the volume 304 of the patient's head 310 or the volume 304 of another object. By performing a single generalized calibration routine as described herein, calibration parameters can be obtained for use during reconstruction so that artifacts caused by deviations can be corrected.

[0044] The generalized calibration routine will be further described with reference to Figure 4. Figure 4 shows a volume 304 having a rotation center 312. The rotation center 312 has a trajectory. Other rotation centers and trajectories, such as a rotation center 502 and its corresponding trajectory (not shown) (see Figure 5), may be available for the X-ray device 118. However, instead of using these trajectories, the generalized calibration routine can be performed. When the generalized calibration routine is performed, the trajectory used in the generalized calibration routine may also be generalized by selecting a trajectory that is not based on any particular rotation center 312. For example, the trajectory selected for the generalized calibration routine may be at least partially non-circular. As an example, linear translation can be performed to generate a non-circular segment of the trajectory, as described herein. By generalizing the calibration and the corresponding trajectory, calibration parameters are generated for use in estimating the projection geometry for each scan, and the estimated projection geometry can be used in conjunction with a motion artifact compensation process to reduce artifacts in reconstruction. Artifacts are artifacts that can be caused by errors in the estimation of the projection geometry. By doing so, different centers of rotation can be freely selected for patient scanning, without necessarily depending on a predetermined center of rotation.

[0045] More specifically, exemplary embodiments disclose calibrating an X-ray device 118 by performing a generalized calibration routine for any number of rotation centers 312 of the X-ray device 118, which may or may not be predetermined rotation centers. The generalized calibration routine is performed to measure calibration parameters of the X-ray device 118 for use in subsequent estimation of the projection geometry, which is further utilized for volume reconstruction. The calibration parameters are parameters that describe at least the mechanism of the X-ray device 118 and indicate how the X-ray device 118 moves. The calibration parameters may be calculated for selected positions of the device trajectory during the generalized calibration routine. In general, the calibration routine can be used to determine the projection geometry, by determining the geometric conditions and dependencies between motor / actuator control and the projection geometry. The projection geometry may describe, for example, the position of the light source 306, the position of the detector 302, how the light source 306 and detector 302 rotate and move around the patient, the distance angle between the light source 306 and the detector, the pixel size of the detector, and other projection parameters. During the generalized calibration routine, an X-ray exposure or a series of X-ray exposures can be performed. In the case of an X-ray exposure, the X-ray beam 308 is generated under different conditions of the X-ray device (e.g., different motor conditions, motor positions, motor usage periods, number of motors used simultaneously, light source / detector positions, etc.). At least one X-ray projection of the calibration routine shows a calibrator (not shown) with known geometric properties. Furthermore, at least one of the X-ray exposures includes configuring the motor to produce linear motion instead of rotational motion. This can result in a linear section of the trajectory of the generalized calibration routine. For example, a non-circular segment of the trajectory taken by the detector 302 and light source 306 can be obtained by shifting the rotation center 312 from a first location to a second location during exposure, or by performing translational motion of the detector 302 and light source 306.

[0046] The calibration parameters include external calibration parameters that describe how the components of the X-ray device move in space and / or the mechanical properties of the components of the X-ray device 118. External calibration parameters may include the positions of the detector 302 and the light source 306. External calibration parameters may also include information about how the motors are controlled to produce movement such as linear translation, which helps measure the device-specific mechanical properties.

[0047] Calibration parameters can also include internal calibration parameters that describe the relative positions of components of the X-ray device relative to each other. Examples of internal calibration parameters include u / v shift, u0 / v0 point, distance from the X-ray source to the detector, and detector pixel size. With respect to u / v shift and u0 / v0 point, generally two coordinate systems can be used: a global patient-aligned 3D system with axes x, y, and z where the positive z-axis usually points to the top of the patient, and a second coordinate system for the rotating detector. To avoid naming confusion, the two axes for the rotating detector are called the u-axis and v-axis. The sensor v-axis is usually oriented in approximately the same direction as the patient's z-axis. Detector shift in the imaging plane can be expressed as u / v shift. A special feature point that describes the detector alignment is the u0 / v0 point, which marks the point where the X-ray beam is perpendicular to the detector plane. Furthermore, the interaction of external calibration parameters, internal calibration parameters, and motor control properties results in parameters of known kinematic device models. In some embodiments, the generalized calibration routine includes imaging a calibrator having known geometric properties and measuring internal calibration parameters. This provides six X-ray device components relative to the calibrator and their relative positions. For example, the calibrator may be an X-ray opaque spherical structure that can be used in several planes, at predetermined locations for each plane. In some embodiments, there are at least three planes and at least four calibrators for each plane. Alternatively, a tube having a predetermined shape (e.g., round) and predetermined dimensions (e.g., diameter) can be used. In some embodiments, the generalized calibration routine does not involve movement of the X-ray device, and the internal calibration parameters are used in generating estimated projection geometry. More specifically, if the generalized calibration routine is a single exposure (or series of exposures) without device movement, the internal parameters are those that can be estimated for use.

[0048] In this embodiment, once a generalized calibration routine is completed, the patient's volume can be imaged at any desired rotation center, and the calibration parameters can be used to calculate the projection geometry for reconstructing the imaged patient's volume. More specifically, the volume 304 of the patient's head 310 (or other object) is imaged by projecting an X-ray beam 308 through the volume 304 onto the detector 302, based on a desired scan trajectory or based on the calibration parameters, generating multiple X-ray images. For example, the operator can define a scan area and select the position and size of the volume 304, determining the device trajectory that can traverse to capture the volume. The device trajectory can be selected to optimize scanning of a specific volume 304 selected by the operator, since the volume 304 is not limited to any particular number of predetermined volumes. If necessary, the calculated calibration parameters can be used to control the X-ray device 118 during patient imaging. This allows for slight adjustments to the motor control parameters and optimization of the scan trajectory. The calibration parameters can be applied during the device control / imaging process, the reconstruction process, or both. Other measurement data (such as optical data from a camera indicating the patient's position) can be used to obtain an appropriate device trajectory. In the embodiment, estimates of the projected geometry can be used. Motor control parameters are known for any intended movement of the device. These can be combined with mechanical device configuration parameters without using calibration parameters, or the device configuration parameters can be improved using calibration parameters.

[0049] In this embodiment, after scanning the patient, the calibration parameters and the desired scan trajectory are used to generate an estimated projection geometry corresponding to the patient scan. The calibration parameters help to obtain a more accurate scan trajectory based on the desired scan trajectory, and the more accurate the scan trajectory, the closer it is to the actual scan trajectory. More specifically, the actual scan trajectory of the X-ray device 118 may differ from the desired scan trajectory. Using the calibration parameters helps to obtain an estimate of the actual trajectory for use when reconstructing the patient scan volume 304. More specifically, the theoretical geometry of the X-ray device 118 can be known. The theoretical mechanism of the X-ray device can also be known. Thus, the theoretical movement of the X-ray device 118 can be calculated. However, due to slight thresholds or offsets between different manufactured X-ray devices 118, and some limitations regarding scanning accuracy, performing a generalized calibration routine allows for the generation of calibration parameters that can be used to improve theoretical knowledge about the X-ray device 118 and to obtain more accurate practical knowledge about the X-ray device 118, without being limited to any particular center of rotation. A more accurate, actual piece of knowledge may be the estimated scan trajectory used to obtain the estimated projection geometry, which is then also used for the reconstruction of volume 304.

[0050] In this embodiment, after generating estimated projection geometry for patient scanning, a three-dimensional reconstruction of volume 304 is generated using the estimated projection geometry and motion artifact compensation.

[0051] More specifically, artifacts may be present in the reconstructed volume due to slight inaccuracies or assumptions that may have been made in the estimated projection geometry. Therefore, the reconstruction of the volume may be carried out by utilizing motion artifact compensation and estimated projection geometry. Motion artifact compensation can not only compensate for patient motion but also for errors in assumptions regarding the estimated device trajectory, and thus the estimated projection geometry. This is because motion artifact compensation can compensate for both patient movement and device movement. Since the estimated device trajectory is potentially not 100% accurate, motion artifact compensation can also compensate for it, but this is because the difference is a relative error (a patient moving differently to the device than expected is similar to a device moving differently to the patient than expected, and both manifest as errors in projection geometry). Motion artifact compensation is performed on individual patient scans or recordings (multiple X-ray projection images used for volume reconstruction) and therefore helps to mitigate / reduce the need for multiple calibrations of multiple rotation centers. In embodiments, several classes of motion artifact compensation can be used, including: Firstly, motion artifact compensation algorithms that use X-ray projection data to explicitly estimate patient motion relative to the device. From a mathematical standpoint, this is equivalent when the patient moves or when the device moves differently from the planned trajectory. If estimated patient movement information is used, a new volume reconstruction with reduced artifacts can be performed. Secondly, a motion artifact compensation algorithm can be used that acts as a volume filter but does not explicitly estimate the actual movement between the device and the patient. In the second case, a conversion of the artifact-containing input volume to an artifact-reduced output volume may be performed.

[0052] Figure 6 shows routine 600 for calibrating the X-ray device for patient measurement. Routine 600 may be performed by or in conjunction with the calibration engine 116. In block 602, the calibration engine 116 calibrates the X-ray device 118 by performing a generalized calibration routine applied to any selected rotation center of the X-ray device 118. The generalized calibration routine measures calibration parameters of the X-ray device that describe at least the mechanism of the X-ray device. In block 604, the calibration engine 116 images the volume 304 by projecting the X-ray beam 308 through the volume 304 onto the detector 302 based on a desired scan trajectory or based on the calibration parameters, generating multiple X-ray images. In block 606, the calibration engine 116 uses the calibration parameters and the desired scan trajectory to generate an estimated projection geometry corresponding to the imaging of the volume 304. This causes the estimated projection geometry to approximate the actual projection geometry. In block 608, routine 600 generates a reconstruction of the volume corresponding to multiple X-ray images using estimated projection geometry and motion artifact compensation. Motion artifact compensation corrects for any remaining errors in the estimation of the estimated projection geometry.

[0053] Accordingly, computer implementation methods, systems or apparatuses, and computer program products are provided in exemplary embodiments for the calibration and imaging of X-ray devices and other related features, functions, or operations. Where an embodiment or part thereof is described in relation to a certain type of device, the computer implementation method, system or apparatus, computer program product, or part thereof is adapted or configured for use with a suitable equivalent form of that type of device.

[0054] The present invention may also be a system, method, and / or computer program product in an integration of any possible level of technical detail. The computer program product may include one or more computer-readable storage media having computer-readable program instructions for causing a processor to perform an aspect of the present invention.

[0055] A computer-readable storage medium can be a tangible device capable of holding and storing instructions for use by an instruction execution device. A computer-readable storage medium may, for example, be an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. A non-exhaustive list of more specific examples of computer-readable storage media includes portable computer diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disk read-only memory (CD-ROM), digital multipurpose disks (DVDs), memory sticks, floppy disks, mechanically encoded devices such as punched cards or grooved raised structures on which instructions are recorded, and any suitable combination thereof. Computer-readable storage media, including computer-readable storage devices used herein, should not be construed as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses passing through optical fiber cables), or transient signals themselves, such as electrical signals transmitted through wires.

[0056] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network may include copper transmission cables, optical transmission fibers, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives computer-readable program instructions from the network and transfers the computer-readable program instructions for storage in a computer-readable storage medium within each computing / processing device.

[0057] The computer-readable program instructions for performing the operation of the present invention may be either assembler instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, configuration data for integrated circuits, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk and C++, and procedural programming languages ​​such as the "C" programming language or similar programming languages. The computer-readable program instructions can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or it may be connected to an external computer (for example, via the Internet using an Internet service provider). In some embodiments, for example, an electronic circuit including a programmable logic circuit, a field-programmable gate array (FPGA), or a programmable logic array (PLA) can execute computer-readable program instructions by personalizing the electronic circuit using state information of computer-readable program instructions in order to carry out aspects of the present invention.

[0058] Aspects of the present invention will be described herein with reference to flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present invention. It will be understood that each block in the flowcharts and / or block diagrams, as well as combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer-readable program instructions.

[0059] These computer-readable program instructions may be provided to the processor of a general-purpose computer, a dedicated computer, or other programmable data processing device for manufacturing a machine, and as a result, instructions executed via the processor of the computer or other programmable data processing device create means for performing functions / actions specified in one or more blocks of a flowchart and / or block diagram. These computer-readable program instructions may also be stored in a computer-readable storage medium that can instruct a computer, a programmable data processing device, and / or other device to function in a particular manner, and as a result, a computer-readable storage medium having stored instructions includes a product containing instructions that perform modes of functions / actions specified in one or more blocks of a flowchart and / or block diagram.

[0060] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing device, or other device to perform a series of operational steps on the computer, other programmable data processing device, or other device to generate a computer implementation process, and as a result, the instructions executed on the computer, other programmable device, or other device perform functions / actions specified in one or more blocks of a flowchart and / or block diagram.

[0061] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible embodiments of the systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagram may represent a module, segment, or part of an instruction containing one or more executable instructions for performing a specified logical function. In some alternative embodiments, the functions described in the blocks may be performed in an order different from the order shown in the figures. For example, two blocks shown consecutively may actually be executed substantially simultaneously, or blocks may sometimes be executed in reverse order depending on the functions they relate to. It should also be noted that each block in the block diagram and / or flowchart diagram, as well as any combination of blocks in the block diagram and / or flowchart diagram, may be performed by a dedicated hardware-based system that performs a specified function or action, or by executing a combination of dedicated hardware and computer instructions.

[0062] conclusion Exemplary systems and methods for X-ray calibration and imaging are disclosed herein, but they are not intended to be limiting, as other examples can be obtained by considering the drawings and description herein. For example, any combination of the following examples is possible.

[0063] Example 1: A method comprising: calibrating an X-ray device by performing a generalized calibration routine applicable to any rotation center of the X-ray device; measuring calibration parameters of the X-ray device that describe at least the mechanism of the X-ray device; imaging the volume by projecting an X-ray beam through the volume onto a detector based on a desired scanning trajectory or the calibration parameters, thereby generating a plurality of X-ray images; generating an estimated projection geometry corresponding to the imaging using the calibration parameters and the desired scanning trajectory; and generating a reconstruction of the volume corresponding to the plurality of X-ray images using the estimated projection geometry and motion artifact compensation.

[0064] Example 2: The method according to Example 1, wherein the trajectory of the generalized calibration routine is different from the trajectory of an arbitrary predefined center of rotation.

[0065] Example 3: The method according to Example 1 or any other example, wherein the calibration parameters include external calibration parameters that describe how the components of the X-ray device move in space, and the calibration parameters further include internal calibration parameters that describe the relative positions of the components of the X-ray device relative to one another.

[0066] Example 4: The method according to Example 3 or any of the aforementioned examples, wherein the trajectory of the generalized calibration routine includes a non-circular segment configured to measure the external calibration parameters.

[0067] Example 5: The generalized calibration routine is the method of Example 3 or any of the aforementioned examples, comprising imaging a calibrator having known geometric properties and measuring the internal calibration parameters.

[0068] Example 6: The method according to Example 5 or any of the aforementioned examples, wherein the generalized calibration routine does not involve movement of the X-ray device, and the internal calibration parameters are used when generating the estimated projection geometry.

[0069] Example 7: The method according to Example 1, wherein the reconstruction includes at least one of a CBCT (cone-beam computed tomography) volume, a panoramic X-ray image, and a cephalometric image.

[0070] Example 8: The method according to Example 1 or any other example, wherein the motion artifact compensation corrects artifacts in the reconstruction caused by errors in estimating the estimated projection geometry.

[0071] Example 9: The method of Example 1 or any other example, further comprising using a position encoder or optical barrier to obtain additional positional information regarding the components of the X-ray device, and generating the estimated projection geometry based on the additional positional information.

[0072] Example 10: The method of Example 1 or any other example, wherein the desired scanning trajectory takes into account an image quality consideration to achieve a predetermined image quality.

[0073] Example 11: The method according to any of the above examples, where the image quality study is a speed study or a sensor timing study.

[0074] Example 12: An X-ray device comprising a processor and a memory that communicates with the processor and has one or more computer program instructions stored in the memory, wherein when the computer program instructions are executed by the processor, the memory causes the X-ray device to perform any of the methods described in Examples 1 to 10.

[0075] Example 13: The X-ray device according to Example 12, further comprising a position encoder or optical barrier configured to obtain additional positional information relating to the components of the X-ray device, wherein the computer program instructions, when executed by the processor, cause the X-ray device to perform an operation including generating the estimated projection geometry based on the additional positional information.

[0076] Example 14: A non-temporary computer-readable storage medium that stores computer-readable instructions, which, when executed by the processor of an X-ray device, cause the X-ray device to perform any of the methods described in Examples 1 to 10.

[0077] Example 15: The reconstruction comprises at least one of a CBCT (cone-beam computed tomography) volume, a panoramic X-ray image, and a cephalometric image, in the non-temporary computer-readable storage medium described in Example 14.

Claims

1. Calibrating the X-ray device by performing a generalized calibration routine applicable to any rotation center of the X-ray device, and measuring calibration parameters of the X-ray device that describe at least the mechanism of the X-ray device, The method involves imaging the volume by projecting an X-ray beam onto a detector through the volume based on a desired scanning trajectory or the calibration parameters, thereby generating multiple X-ray images. Using the calibration parameters and the desired scanning trajectory, an estimated projection geometry corresponding to the imaging is generated. Using the estimated projection geometry and motion artifact compensation, a reconstruction of the volume corresponding to the plurality of X-ray images is generated. Methods that include...

2. The method according to claim 1, wherein the trajectory of the generalized calibration routine is different from the trajectory of an arbitrary predefined center of rotation.

3. The calibration parameters include external calibration parameters that describe how the components of the X-ray device move in space. The calibration parameters further include internal calibration parameters that describe the relative positions of the components of the X-ray device relative to each other. The method according to claim 1.

4. The method according to claim 3, wherein the trajectory of the generalized calibration routine includes a non-circular segment configured to measure the external calibration parameter.

5. The method according to claim 3, wherein the generalized calibration routine includes imaging a calibrator having known geometric properties and measuring the internal calibration parameters.

6. The generalized calibration routine does not involve the movement of the X-ray device. The internal calibration parameters are used when generating the estimated projection geometry. The method according to claim 5.

7. The method according to claim 1, wherein the reconstruction comprises at least one of a CBCT (cone-beam computed tomography) volume, a panoramic X-ray image, and a cephalometric image.

8. The method according to claim 1, wherein the motion artifact compensation corrects artifacts in the reconstruction caused by errors in estimating the estimated projection geometry.

9. To obtain additional positional information regarding the components of the X-ray device using a position encoder or optical barrier, To generate the estimated projection geometry based on the additional location information. The method according to claim 1, further comprising:

10. The method according to claim 1, wherein the desired scanning trajectory takes into account considerations for image quality to achieve a predetermined image quality.

11. The method according to claim 10, wherein the examination of image quality is an examination of speed or an examination of sensor timing.

12. X-ray device, Processor and A memory that communicates with the processor and has one or more computer program instructions stored in the memory, and when the computer program instructions are executed by the processor, the X-ray device Calibrating the X-ray device by performing a generalized calibration routine applicable to any rotation center of the X-ray device, and measuring calibration parameters of the X-ray device that describe at least the mechanism of the X-ray device, The method involves imaging the volume by projecting an X-ray beam passing through the volume onto a detector based on a desired scanning trajectory or the calibration parameters, thereby generating multiple X-ray images. Using the calibration parameters and the desired scanning trajectory, an estimated projection geometry corresponding to the imaging is generated. Using the estimated projection geometry and motion artifact compensation, a reconstruction of the volume corresponding to the plurality of X-ray images is generated. Memory that enables the execution of operations including An X-ray device equipped with the following features.

13. The calibration parameters include external calibration parameters that describe how the components of the X-ray device move in space. The calibration parameters further include internal calibration parameters that describe the relative positions of the components of the X-ray device relative to each other. The X-ray device according to claim 12.

14. When the aforementioned computer program instruction is executed by the processor, it is directed to the X-ray device. The trajectory of the generalized calibration routine is configured to include a non-circular segment configured to measure the external calibration parameters. The X-ray device according to claim 13, which enables the device to perform an operation including the operation described above.

15. When the aforementioned computer program instruction is executed by the processor, it is directed to the X-ray device. The generalized calibration routine is configured to image a calibration body having known geometric properties and measure the internal calibration parameters. The X-ray device according to claim 13, which enables the device to perform an operation including the operation described above.

16. When the aforementioned computer program instruction is executed by the processor, it is directed to the X-ray device. The motion artifact compensation corrects artifacts in the reconstruction caused by errors in estimating the estimated projection geometry. The X-ray device according to claim 12, which causes the device to perform an operation including the operation described above.

17. A position encoder or optical barrier configured to obtain additional positional information regarding the components of the X-ray device. Furthermore, When the computer program instruction is executed by the processor, it causes the X-ray device to perform an operation that includes generating the estimated projection geometry based on the additional positional information. The X-ray device according to claim 12.

18. When executed by the processor of the X-ray device, the X-ray device will perform the following: The X-ray device is calibrated by performing a generalized calibration routine applicable to any rotation center of the X-ray device, and calibration parameters of the X-ray device that describe at least the mechanism of the X-ray device are measured. Based on a desired scanning trajectory or the calibration parameters, the volume is imaged by projecting an X-ray beam through the volume onto a detector, thereby generating a plurality of X-ray images. Using the calibration parameters and the desired scanning trajectory, an estimated projection geometry corresponding to the imaging is generated. Using the estimated projection geometry and motion artifact compensation, a reconstruction of the volume corresponding to the multiple X-ray images is generated. A non-temporary computer-readable storage medium that stores computer-readable instructions.

19. The calibration parameters include external calibration parameters that describe how the components of the X-ray device move in space. The calibration parameters further include internal calibration parameters that describe the relative positions of the components of the X-ray device relative to each other. The non-temporary computer-readable storage medium according to claim 18.

20. The reconstruction comprises at least one of a CBCT (cone-beam computed tomography) volume, a panoramic X-ray image, and a cephalometric image, as described in claim 18, for the non-temporary computer-readable storage medium.

Images