Automatic positioning of the X-ray tube support relative to the detector

Abstract

The positioning system includes a radio frequency (RF)-based localization system, an optical camera, and a controller. The RF-based localization system includes a first RF device attachable to the X-ray detector and a plurality of second RF devices disposed in a known geometric relationship with respect to the X-ray tube and configured to use RE signals to locate the first RF device to provide first position information of the X-ray detector. The controller is configured to generate, based on the first position information of the X-ray detector, a first control signal usable to control the X-ray tube support system to move the X-ray tube to perform a first alignment of the X-ray tube with respect to the X-ray detector.

Description

[Technical Field]

[0001] The present invention relates generally to medical imaging, and more particularly to a positioning system and method, an X-ray imaging system computer program element, for controlling an X-ray tube support system to align an X-ray tube with an X-ray detector. [Background technology]

[0002] Fully motorized X-ray devices fall into the class of diagnostic X-ray imaging devices. These machines are used to acquire X-ray images of various anatomical structures to aid in arriving at a diagnosis. The system has an X-ray tube support geometry that supports the X-ray tube, allowing it to position itself as needed in the examination room. The X-ray detector quantizes the absorbed X-rays to provide a readable image and can be free or mounted on a detector support geometry. Both the X-ray tube and the detector support (if present) may require mechanisms to ensure proper alignment of the X-ray tube to the X-ray detector. Generally, there are three types of alignment, including the X-ray tube to the X-ray detector in terms of center and position, angular alignment, and the vertical source-to-image distance between them. However, without the detector support geometry, alignment must be performed manually, which can be extremely difficult. Summary of the Invention [Problem to be solved by the invention]

[0003] Thus, for example, in the absence of detector support geometry, it may be necessary to facilitate alignment of the x-ray tube relative to the x-ray detector. [Means for solving the problem]

[0004] The object of the present invention is solved by the subject matter of the independent claims, and further embodiments are incorporated in the dependent claims. It is noted that the below-described aspects of the present invention also apply to a positioning system and method for controlling an X-ray tube support system to align an X-ray tube with an X-ray detector, an X-ray imaging system, and a computer program element.

[0005] According to a first aspect of the present invention, there is provided a positioning system for controlling an X-ray tube support system to align an X-ray tube with an X-ray detector. The positioning system includes a radio frequency (RF)-based positioning system, an optical camera, and a controller. The RF-based positioning system includes a first RF device attachable to the X-ray detector and a plurality of second RF devices disposed in a known geometric relationship with the X-ray tube and configured to use RE signals to locate the first RF device to provide first position information of the X-ray detector. The controller is configured to generate, based on the first position information of the X-ray detector, a first control signal usable to control the X-ray tube support system to move the X-ray tube to perform a first alignment of the X-ray tube with respect to the X-ray detector. After the first alignment, the controller is configured to trigger the optical camera to acquire an image to align the X-ray detector to provide second position information of the X-ray detector, and is configured to generate, based on the second position information of the X-ray detector, a second control signal usable to control the X-ray tube support system to move the X-ray tube to perform a second alignment of the X-ray tube with respect to the X-ray detector.

[0006] The inventors of the present invention have found that existing automatic alignment methods that use optical cameras require a direct view of the landmarks o as a prerequisite. If the optical camera does not have a direct view, alignment may have to be done manually.

[0007] To facilitate the automatic alignment procedure, the positioning systems, methods, medical imaging systems, and computer program elements described herein perform a two-step alignment procedure. The first alignment is to identify the approximate position and / or orientation of the X-ray detector or detector docking station using an RF-based location system, such as a Bluetooth-based location system, an RFID-based location system, or an ultra-wideband (UWB)-based location system. Because the first alignment is based on RF signals, direct view of the X-ray detector and landmarks on the detector docking station are not required.

[0008] The second alignment is to use a camera-based localization system to determine the exact position and / or orientation of the X-ray detector or detector docking station. After the source is approximately aligned with the X-ray detector, in this position the optical camera has a view of landmarks on the detector or detector docking station. From this position, the optical camera can be used to precisely position the X-ray tube relative to the X-ray detector. For example, the optical camera can be used to improve accuracy to a few millimeters using image processing from the field of view image.

[0009] In this way, the automatic alignment procedure can be achieved even if the X-ray tube supporting the X-ray tube support system is located away from the X-ray detector. Therefore, manual movements are no longer required. Furthermore, because the alignment is performed automatically in real time, there is no need to perform adjustments for each geometry in the field. Furthermore, automatic positioning can have a significant impact on workflow, as it eliminates the need to manually move the tube support and align it with the X-ray detector, thereby contributing to a significant portion of the workflow for acquiring X-ray images.

[0010] The positioning system will now be described in detail, particularly with reference to the example shown in FIGS.

[0011] According to an embodiment of the present disclosure, the positioning system further comprises a three-dimensional angle sensor attachable to the X-ray detector for three-dimensional angle measurement.

[0012] In some examples, the three-dimensional angle sensor may be part of the first RF device.

[0013] In some examples, the three-dimensional angle sensor and the first RF device may be two separate devices.

[0014] For example, a gyro sensor may be used for three-dimensional angle measurement.

[0015] According to one embodiment of the present disclosure, the first RF device comprises: an RF device removably attachable to the X-ray detector or to the external handle of the X-ray detector; an RF device that is an integral part of an X-ray detector; or RF device that is an integral part of the outer handle of the X-ray detector It has. In some examples, the first RF device may be powered by an x-ray detector. In some examples, the first RF device may be battery powered.

[0016] This is explained in more detail below, particularly with respect to the embodiment shown in Figures 3A and 3B.

[0017] According to one embodiment of the present disclosure, the plurality of second RF devices are disposed on an X-ray tube support system.

[0018] The positions of the multiple second RF devices may be pre-configured relative to the X-ray tube support system, and only the position of the X-ray tube support system relative to the room layout must be calibrated during installation.

[0019] In some examples, the second RF device may be removably mounted to the x-ray tube support system.

[0020] In some examples, the second RF device may be integrated with the x-ray tube support system.

[0021] In some examples, the second RF device may be powered by the x-ray tube support system.

[0022] In some examples, the second RF device may be battery powered.

[0023] This is explained in more detail below, particularly with reference to the example shown in FIG.

[0024] According to one embodiment of the present invention, at least one of the plurality of second RF devices is configured to interface with the x-ray tube support system via a communications protocol.

[0025] For example, at least one of the plurality of second RF devices may be interfaced with the x-ray tube support system to transmit collected sensor data, for example, to a system controller. This is explained in more detail below, particularly with reference to the example shown in FIG.

[0026] According to one embodiment of the present disclosure, an RF-based location system comprises a plurality of ultra-wideband (UWB) devices.

[0027] The UWB device is used to identify the detector position in three-dimensional space. This can be accomplished by using one UWB transmitter located on the X-ray detector and three or more other UWB receivers located on the X-ray tube support system. In some other examples, one UWB receiver can be located on the X-ray detector and three or more other UWB receivers can be located on the X-ray tube support system.

[0028] Various geometric methods can be used to estimate the position of the X-ray detector, including but not limited to trilateration, triangulation, and multilateration.

[0029] According to one embodiment of the present disclosure, the first RF device comprises a UWB transmitter.

[0030] According to one embodiment of the present disclosure, the plurality of second RF devices comprises at least three UWB receivers.

[0031] According to one embodiment of the present invention, there is provided an X-ray detector, the X-ray detector comprising an RF device for position tracking.

[0032] The RF device may be part of the X-ray detector or may be on the external handle of the X-ray detector. An example of an X-ray detector is shown in Figure 3A. An example of an external handle of an X-ray detector is shown in Figure 3B.

[0033] According to one embodiment of the present disclosure, the RF device is a UWB device.

[0034] According to one embodiment of the present disclosure, the X-ray detector is a portable X-ray detector.

[0035] According to a second aspect of the present invention, there is provided an X-ray imaging system comprising an X-ray tube configured to emit an X-ray beam, and an X-ray tube support system configured to support the X-ray tube, the X-ray imaging system further comprising a positioning system according to the first aspect and any associated example for controlling the X-ray tube support system to align the X-ray tube with an X-ray detector.

[0036] In some examples, the x-ray tube support system may be a ceiling support system.

[0037] In some examples, the x-ray tube support system may be a floor-to-ceiling support system.

[0038] In some examples, the x-ray tube support system may be a mobile digital radiography system.

[0039] This is explained in more detail below, particularly with reference to the examples shown in FIGS. According to a fourth aspect of the present invention, there is provided a method of controlling an x-ray tube support system to align an x-ray tube with an x-ray detector, the method comprising: obtaining first position information of the X-ray detector utilizing a radio frequency based localization system, the radio frequency based localization system comprising a first radio frequency device attachable to the X-ray detector and a plurality of second radio frequency devices disposed in a known geometric relationship to the X-ray tube and configured to localize the first radio frequency device using radio frequency signals; generating, by a controller based on first position information of the X-ray detector, a first control signal usable to control the X-ray tube support system to move the X-ray tube to perform a first alignment of the X-ray tube with respect to the X-ray detector; after the first alignment, triggering, by the controller, the optical camera to acquire an image to locate the X-ray detector to provide second position information of the X-ray detector; generating, by the controller, a second control signal usable to control the X-ray tube support system to move the X-ray tube to perform a second alignment of the X-ray tube relative to the X-ray detector based on second position information of the X-ray detector; A method is provided, comprising:

[0040] This is explained in more detail below, particularly with respect to the example shown in FIG.

[0041] According to a further aspect of the present invention there is provided a computer program product comprising instructions for causing the positioning system of the first aspect and any associated examples to perform the steps of the method of the fourth aspect.

[0042] It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in more detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, the subject matter of the claims at the end of this disclosure is intended to be part of the inventive subject matter disclosed herein.

[0043] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0044] In the drawings, as in the literature, like reference numbers generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. [Brief explanation of the drawings]

[0045] [Figure 1] 1 illustrates an exemplary medical imaging system. [Figure 2] 1 illustrates an exemplary positioning system. [Figure 3A] 1 illustrates an exemplary portable X-ray detector. [Figure 3B] 1 illustrates an exemplary portable X-ray detector handle. [Figure 4] 1 shows the positioning system and its relationship to some components of the x-ray tube support system. [Figure 5] 1 shows a flowchart illustrating a method for controlling an X-ray tube support system to align an X-ray tube with an X-ray detector. DETAILED DESCRIPTION OF THE INVENTION

[0046] While the invention has been illustrated and described in detail in the drawings and the following description, such illustration and description are to be considered exemplary or exemplary and not restrictive, and the invention is not limited to the disclosed embodiments.

[0047] For example, while this application describes the invention in medical imaging applications where images are generated using x-rays, it will be understood that the invention may also be advantageously used in applications where images are acquired using any suitable type of penetrating radiation, or any other particle, wave, or field phenomenon. For example, while this application describes a ceiling-mounted digital x-ray system as an example for implementing the inventive approach, it will be understood that the described positioning system is also applicable to other types of x-ray tube support systems, such as floor-to-ceiling support systems, mobile digital radiography systems, etc.

[0048] 1 shows a schematic diagram of a medical imaging system 100 that may be suitable for implementing the present approach. In the example shown, the medical imaging system 100 is a ceiling-mounted digital X-ray system.

[0049] In the illustrated example, medical imaging system 100 includes an X-ray tube head 110 supported from a ceiling (not shown) by an X-ray tube support system 120, a floor-mounted examination table 130 for supporting a patient (not shown) having a defined docking compartment 132 in which a portable X-ray detector 134 may be placed during imaging, and a vertical stand 140 having a defined docking compartment 142 in which the portable X-ray detector 134 may be placed during imaging. Although not shown, it will be understood that the portable X-ray detector 134 may be used for complimentary examinations, for example, on the patient support surface 136 of the floor-mounted examination table 130. An example of a portable X-ray detector 134 is shown in FIG. 3A.

[0050] The X-ray tube support system 120 supports the X-ray tube head 110 and provides translational movement of the X-ray tube head 110 in the longitudinal direction (X) indicated by arrow A, the lateral direction (Y) indicated by arrow B, and the vertical direction (Z) indicated by arrow C.

[0051] Two spaced-apart, parallel support rails 122A and 122B may extend longitudinally along a ceiling (not shown) and be attached thereto by multiple fasteners (not shown). A bridge 124 is supported by the support rails 122A and 122B, which also allow longitudinal movement of the bridge 124 and all that it supports, as shown by arrow A. The bridge 124 may support a lateral carriage 126, allowing lateral movement of the bridge, as shown by arrow B. The lateral carriage 126 supports the X-ray tube head 110 by means of a telescoping tube assembly 128, which effectively functions as a vertically oriented linear bearing. The telescoping tube assembly 128 may be formed from multiple telescoping tubular structural members having bearings that allow longitudinal slidable movement therebetween. Thus, the lateral carriage 126 and the telescoping tube assembly 128 allow vertical movement of the X-ray tube head 110, as shown by arrow C.

[0052] Movement along directions A and C may be powered by longitudinal drive 152 (shown in FIG. 4) and vertical drive 154 (shown in FIG. G.4), respectively. Longitudinal drive 152 and vertical drive 154 may be controlled by system controller 150, which may be housed within lateral carriage 126. Movement along directions A, B, and C may also be performed manually by an operator.

[0053] In the illustrated example, the x-ray tube head 110 may include an x-ray tube assembly 112, an x-ray collimator 114, a control panel 116, and a control handle 118 for use by an operator in selecting a position for the x-ray tube head 110. Information obtained from the control panel 116 may be communicated to a system controller 150, which generates control signals to the longitudinal and transverse drives to move the x-ray tube head 110 in the desired direction. The x-ray tube head 110 is mounted on a telescoping tube assembly 128 for rotation about a transverse axis 121, as indicated by arrow D, which may be powered by an x-ray tube head rotation drive 156 (shown in FIG. 4).

[0054] Rotation of the x-ray tube head 110 allows the x-ray beam to be directed at various desired angles, such as toward the table 130 or toward the vertical stand 140. The x-ray tube head rotation drive 156 may be controlled by the system controller 150.

[0055] Thus, the x-ray tube support system 110, its associated longitudinal and vertical drives 152 and 154, and the x-ray tube head rotation drive 156 cooperate to enable the system controller 150 to orient the x-ray tube head 110 to any position on a reference plane and point the emitted x-ray beam parallel to the X-Z plane and at any angle along the reference plane. Providing three degrees of freedom for the location of the focal spot and the angular orientation of the emitted x-ray beam under the control of the system controller 150 is believed to be sufficient to perform examinations using a variety of desirable radiographic, fluoroscopic, and tomographic imaging modes. However, those skilled in the art will appreciate that this embodiment can be readily modified to incorporate additional degrees of freedom if additional imaging modes are desired.

[0056] In general, there are three types of alignments required for the tube relative to the detector: center / position, three-axis angle, and source-image distance. Current design solutions achieve angular alignment using gyro sensor feedback from the detector, which is applicable in the case of detectors with free-standing detector supports. Both center / position and distance alignment are only possible with detector support geometry and by adjustments during system installation in the field. In the case of free-standing detectors, the radiographer must perform both of these alignments according to his / her judgment.

[0057] To facilitate an automatic alignment procedure for improving workflow, a positioning system 160 is provided for controlling the X-ray tube support system 120 to align the X-ray tube 112 with the X-ray detector 134. This positioning system allows the automatic alignment procedure to be achieved even when the X-ray tube supported by the X-ray tube support system is positioned away from the X-ray detector. Therefore, manual movements are no longer required. Furthermore, because the alignment is performed automatically in real time, there is no need to perform adjustments for each geometry within the field. Furthermore, automatic positioning can have a significant impact on workflow because it eliminates the need to manually move the tube support and align it with the X-ray detector, thereby contributing to a significant portion of the workflow for acquiring X-ray images.

[0058] 2 illustrates an exemplary positioning system 160. The exemplary positioning system includes an RF-based location system 170, an optical camera 180, and a controller 190.

[0059] The RF-based localization system 170 includes a first RF device 172 that is attachable to an X-ray detector 134. An example of an X-ray detector 134 is shown in FIG. 3A. In some examples, as shown in FIG. 3A, the first RF device 172 may be removably attached to or integrated into the portable X-ray detector 134. In some other examples, as shown in FIG. 3B, the first RF device 172 may be removably attached to or integrated into the external detector handle 135 of the portable X-ray detector.

[0060] The RF-based localization system 170 further includes a plurality of second RF devices positioned in a known geometric relationship relative to the X-ray tube. For example, as shown in FIG. 2 , the plurality of second RF devices may include three RF devices: RF device 174, RF device 176, and RF device 178. In some other examples (not shown), the plurality of second RF devices may include four, five, six, or more RF devices. The plurality of second RF devices, such as RF devices 174, 176, and 178 shown in FIG. 2 , may be removably attached to or integrated into the X-ray tube support system 120. The locations of the three RF devices 172, 174, and 178 are flexible, but generally, for better accuracy in the location of each of the three RF devices 172, 174, and 178, they should be as far away from one another as possible. The positions of these RF devices may be preconfigured relative to the X-ray tube support system 120; during installation, only the position of the X-ray tube support system 120 relative to the room layout must be calibrated. For example, as shown in FIG. 2 , RF device 174 may be removably mounted or integrated onto bridge 124. RF device 176 may be removably mounted or integrated onto support rail 122B. RF device 178 may be removably mounted or integrated onto X-ray tube head 110. During movement of the ceiling suspension, some of RF devices 174, 176, and 178 may be moved from their initial positions, but the changes can be accurately estimated by using internal position sensor feedback in each axis of X-ray tube support system 120. Finally, one of second RF devices 174, 176, and 178 can act as a master, collecting data from the other RF devices to determine the position of first RF device 172 on the X-ray detector. This master RF device can be interfaced to X-ray tube support system 120 with the necessary communication protocol to provide sensor data to controller 190.

[0061] The plurality of second RF devices, such as RF devices 174, 176, and 178, are configured to identify the position of the first RF device 172 using the RE signal to provide first position information of the X-ray detector 112. In some examples, the first RF device 172 on the X-ray detector may be an RF transmitter, and the plurality of second RF devices, such as RF devices 174, 176, and 178 on the X-ray tube support system 120 may be RF receivers. In some other examples, the first RF device 172 on the X-ray detector may be an RF receiver, and the plurality of second RF devices, such as RF devices 174, 176, and 178 on the X-ray tube support system 120 may be RF transmitters.

[0062] Various geometric methods may be used to estimate the position of the first RF device 120. Examples of geometric methods include, but are not limited to, trilateration, triangulation, and multilateration. Trilateration is based on range measurements from the unknown position of the first RF device (e.g., RF device 172) to other anchor points (e.g., RF devices 174, 176, and 178) with known coordinates. Distance (also called range) may be estimated by measuring different RF parameters such as received power or radio signal propagation time, i.e., time of flight. The triangulation method of positioning is similar to trilateration. The unknown position of the first RF device (e.g., RF device 172) is estimated by measuring the angle between the anchor points (e.g., RF devices 174, 176, and 178) and a point with an unknown position (e.g., RF device 172). Multilateration can be used in systems where only distance information can be measured from the unknown location of a first RF device (e.g., RF device 172) to anchor nodes (e.g., RF devices 174, 176, and 178). A node (e.g., RF device 172) at an unknown location measures the time difference between the arrival of signals from the anchor nodes (e.g., RF devices 174, 176, and 178).

[0063] The RF-based location system 160 may be a Bluetooth Low Energy (BLE)-based location system, a Wi-Fi-based location system, an RFID-based location system, a UWB-based location system, or any combination thereof. For example, considering a UWB-based location system, the first RF device 172 as shown in FIG. 2 may be a UWB transmitter, and multiple second RF devices such as RF devices 174, 176, and 178 as shown in FIG. 2 may be UWB receivers. The UWB-based location system can achieve accuracy within a few centimeters using strategically placed RF devices. Because the accuracy is within a few centimeters for a UWB sensor, the detector is within the field of view of the optical camera 120.

[0064] In some examples, the positioning system may include a three-dimensional angle sensor 173 (see FIG. 4) that can be attached to the X-ray detector for three-dimensional angle measurement. In some examples, the three-dimensional angle sensor may be part of the first RF device. In some examples, the three-dimensional angle sensor and the first RF device may be two separate devices. For example, a gyro inertial measurement unit (IMU) sensor integrated with the first RF device 172 may provide the information necessary to achieve angular alignment of the X-ray tube relative to the X-ray detector.

[0065] The optical camera 120 is used, for example, to improve alignment accuracy to within a few millimeters using image processing from the field of view image. The optical camera 120 may be positioned within the collimator 114 or any other suitable location on the X-ray tube head 110 for the view of the X-ray detector or the area containing the X-ray detector (e.g., a table surface). As used herein, the terms "image" or "image data" should be understood broadly in this case and include any data or electromagnetic radiation image that can be acquired or generated by the optical camera 120. While only a single optical camera 120 is shown in FIG. 2 by way of example, it is understood that multiple optical cameras or multiple image sensors may be deployed. Image data is not limited to the visible spectral range and two-dimensional. Examples of images acquired by the optical camera include, but are not limited to, grayscale images, near-infrared (NIR) images, RGB images, multispectral images, and hyperspectral images. The camera's frame rate may range from 0.3 Hz to 48 Hz, but is not limited to this. The optical camera may be pre-configured to recognize the X-ray detector and its center position using a pattern or unique identifier. This optical camera may be integrated into an X-ray tube support system 120 that includes a system controller 150 for performing the image processing steps necessary to adjust and align the X-ray tube with respect to the X-ray detector.

[0066] Controller 190 may comprise various physical and / or logical components for communicating and manipulating information, which may be implemented as hardware components (e.g., computing devices, processors, logic devices), executable computer program instructions (e.g., firmware, software) executed by various hardware components, or any combination thereof, as desired for a given set of design parameters or performance constraints. In some implementations, controller 190 may comprise one or more microprocessors or computer processors executing appropriate software. The software may be downloaded and / or stored in corresponding memory, e.g., volatile memory such as RAM or non-volatile memory such as flash. The software may comprise instructions that configure one or more processors to perform the functions described herein. Note that controller 190 may be implemented with or without a processor, and may also be implemented as a combination of dedicated hardware to perform some functions and processors (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions. For example, controller 190 may be implemented in a device or apparatus in the form of programmable logic, e.g., as a field programmable gate array (FPGA). 2, controller 190 is embodied in system controller 150. In some other examples (not shown), controller 190 may be embodied as or within another device, such as a workstation.

[0067] The controller 190 may execute instructions to perform the methods described herein, which are explained in detail with respect to the examples shown in FIGS.

[0068] 4 schematically illustrates the positioning system 160 and its relationship to some components of the X-ray tube support system. In the illustrated example, a controller 190 can receive inputs from the RF-based localization system 170, the optical camera 180, and the optional 3D angle sensor 173 of the positioning system 160 to facilitate determining the position and / or orientation of the detector relative to the X-ray tube 112, according to the present technique. Additionally, as discussed herein, based on the relative positions of the source and the detector, the controller 190 can control or adjust the alignment of the X-ray tube 112 with respect to the X-ray detector, e.g., the detector 134. For example, movement of the X-ray tube along directions A and C may be driven by the longitudinal drive 152 and the vertical drive 154, respectively. Rotation of the X-ray tube head may be driven by the head rotation drive 156.

[0069] 5 shows a flow chart illustrating a method 200 of controlling an X-ray tube support system to align an X-ray tube with an X-ray detector. Method 200 will be described with reference to the systems shown in FIGS.

[0070] In block 210, the RF-based localization system 160 acquires first location information of the X-ray detector, e.g., the portable X-ray detector 134. The first location information includes approximate location information that may not be sufficiently accurate, e.g., to an accuracy of better than one to two centimeters, depending on the RF localization technology. The RF-based localization system 160 includes a first RF device, e.g., RF device 172 shown in the figure. With reference to FIGS. 3A and 3B, the first RF device 172 can be attached to the X-ray detector 134 or the X-ray detector handle 135. The first RF device 172 can be part of the X-ray detector itself or on the external handle of the X-ray detector. Alternatively, the first RF device 172 can be removably attached to the X-ray detector or the external handle of the X-ray detector. The RF-based localization system 160 further includes multiple second RF devices, such as RF devices 174, 176, and 178 shown in FIG. 2, positioned in a known geometric relationship with respect to the X-ray tube and configured to locate the first RF device using the RE signal.

[0071] In some examples, the first RF device may be an RF transmitter and the second RF device may be an RF receiver. In some examples, the combination of an RF receiver and a transmitter may be the other way around. In other words, the detector should have a transmitter only if the X-ray tube support system has an RF receiver, and if the detector has an RF receiver, the tube support should have an RF transmitter.

[0072] The RF-based location system may be a Bluetooth / BLE, Wi-Fi, RF identification (RFID), UWB-based location system, or any combination thereof. For example, considering a UWB-based location system, the first RF device 172 as shown in FIG. 2 may be a UWB transmitter, and multiple second RF devices such as devices 174, 176, and 178 as shown in FIG. 2 may be UWB receivers. Three UWB receivers 174, 176, and 178 disposed on the X-ray tube support system may receive signals from the UWB transmitter 172 from the X-ray detector, and a time-difference-of-arrival (TDOA) approach may be used to determine the difference in the arrival times of the signals between each receiver 174, 176, and 178 to locate the transmitter position.

[0073] In block 220, based on the first position information of the X-ray detector, the controller 190 generates a first control signal usable to control the X-ray tube support system to move the X-ray tube to perform a first alignment of the X-ray tube with respect to the X-ray detector. For example, movement of the X-ray tube along directions A and C may be driven by the longitudinal drive 152 and the vertical drive 154, respectively. Rotation of the X-ray tube head may be driven by the head rotation drive 156. Because the RF-based localization system can have an accuracy within a few centimeters, the X-ray detector is within the field of view of the optical camera 180 after the first alignment.

[0074] In block 230, after the first alignment, the controller 190 triggers the optical camera 180 to acquire an image for identifying the position of the X-ray detector to provide second position information of the X-ray detector. The second position information includes fine position information, i.e., precise position information. The portable X-ray detector 134 may be used for a free examination or may be inserted into a defined docking compartment of the floor-mounted examination table 130 or the vertical stand 140. In some examples, when the portable X-ray detector 134 is inserted into the defined docking compartment of the floor-mounted examination table 130, the controller 190 may analyze an image of one or more landmarks provided on the patient support surface 136 of the floor-mounted examination table 130 to identify the position of the X-ray detector. In some examples, when the portable X-ray detector 134 is inserted into the defined docking compartment in the vertical stand 140, the controller 134 may analyze a marking or pattern on the surface 146 to identify the position of the X-ray detector. In some examples, when the portable X-ray detector 134 is used for free-standing examination, for example, positioned on the patient support surface 136 of the floor-mounted examination table 130, the controller 190 can analyze the X-ray detector image to identify the location of the X-ray detector. In this way, the accuracy of locating the X-ray detector can be improved to within the millimeter range or sub-millimeter range.

[0075] In block 240, based on the first position information of the X-ray detector, the controller 190 generates a second control signal usable to control the X-ray tube support system to move the X-ray tube to perform a second alignment of the X-ray tube relative to the X-ray detector.

[0076] In another exemplary embodiment of the invention, a computer program or a computer program element is provided, characterized in that it is adapted to execute, on a suitable system, the method steps of the method according to one of the previous embodiments.

[0077] Thus, a computer program element may be stored in a computer unit that may be part of an embodiment of the present invention. This computing unit may be adapted to perform or trigger the execution of the steps of the above-mentioned method. Furthermore, it may be adapted to operate the components of the above-mentioned apparatus. The computing unit may be adapted to operate automatically and / or to execute user commands. The computer program may be loaded into the working memory of a data processor. The data processor may thus be equipped to perform the method of the present invention.

[0078] This exemplary embodiment of the present invention encompasses both computer programs that use the present invention from the beginning and computer programs that, through updates, convert existing programs into programs that use the present invention.

[0079] Furthermore, the computer program element may provide all the steps necessary to fulfill the steps of the exemplary embodiments of the procedures described above.

[0080] According to a further exemplary embodiment of the present invention, a computer readable medium, such as a CD-ROM, is presented, the computer readable medium having stored thereon a computer program element, the computer program element being as described in the previous section.

[0081] The computer program may be stored and / or distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless communication systems.

[0082] However, the computer program may also be presented via a network such as the World Wide Web and downloaded into the working memory of a data processor from such a network. According to a further exemplary embodiment of the invention, a medium for making a computer program element available for downloading is provided, the computer program element being configured to perform a method according to one of the aforementioned embodiments of the invention.

[0083] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. a positioning system for controlling the x-ray tube support system to align the x-ray tube with the x-ray detector, a radio frequency based location system; An optical camera, Controller and and The radio frequency based location system comprises: a first high frequency device attachable to the X-ray detector; a plurality of second radio frequency devices arranged in a known geometric relationship with respect to the x-ray tube and configured to locate the first radio frequency devices using radio frequency signals to provide first position information of the x-ray detector; and configured to generate, based on first position information of the X-ray detector, a first control signal usable to control the X-ray tube support system to move the X-ray tube to perform a first alignment of the X-ray tube with respect to the X-ray detector; After the first alignment, the controller is configured to trigger the optical camera to acquire an image to locate the X-ray detector to provide second position information of the X-ray detector, and is configured to generate, based on the second position information of the X-ray detector, a second control signal usable to control the X-ray tube support system to move the X-ray tube to perform a second alignment of the X-ray tube relative to the X-ray detector. Positioning system.

2. a three-dimensional angle sensor attachable to the X-ray detector for three-dimensional angle measurement; 10. The positioning system of claim 1, comprising:

3. The first high frequency device a radio frequency device removably attachable to the X-ray detector or to an external handle of the X-ray detector; a radio frequency device which is an integral part of the X-ray detector; or a radio frequency device that is an integral part of the outer handle of said X-ray detector; having at least one of 3. The positioning system according to claim 1 or 2.

4. The positioning system according to claim 1 , wherein the plurality of second high frequency devices are arranged on the X-ray tube support system.

5. 5. The positioning system of claim 4, wherein at least one of the plurality of second radio frequency devices is configured to interface with the X-ray tube support system using a communication protocol.

6. The positioning system of claim 1 , wherein the radio frequency based location system comprises a plurality of ultra wideband devices.

7. The location system of claim 6 , wherein the first radio frequency device comprises an ultra-wideband transmitter.

8. The positioning system of claim 7 , wherein the ultra-wideband transmitter comprises the three-dimensional angle sensor.

9. 9. The positioning system according to claim 5, wherein the plurality of second radio frequency devices comprises at least three ultra-wideband receivers.

10. 1. An x-ray imaging system comprising: an x-ray tube configured to emit an x-ray beam; an X-ray tube support system configured to support the X-ray tube; a positioning system according to any one of claims 1 to 9 for controlling the X-ray tube support system to align the X-ray tube with the X-ray detector; An X-ray imaging system comprising:

11. 11. The X-ray imaging system of claim 10, wherein the X-ray detector comprises a radio frequency device for position tracking.

12. 12. The x-ray imaging system of claim 11, wherein the high frequency device is an ultra-wideband device.

13. 13. The X-ray imaging system according to claim 11, wherein the X-ray detector is a portable X-ray detector.

14. 1. A method of controlling an x-ray tube support system to align an x-ray tube with an x-ray detector, the method comprising: obtaining first position information of the X-ray detector utilizing a radio frequency based localization system, the radio frequency based localization system comprising a first radio frequency device attachable to the X-ray detector and a plurality of second radio frequency devices disposed in a known geometric relationship to the X-ray tube and configured to localize the first radio frequency device using radio frequency signals; generating, by a controller based on first position information of the X-ray detector, a first control signal usable to control the X-ray tube support system to move the X-ray tube to perform a first alignment of the X-ray tube with respect to the X-ray detector; after the first alignment, triggering, by the controller, the optical camera to acquire an image to locate the X-ray detector to provide second position information of the X-ray detector; generating, by the controller, a second control signal usable to control the X-ray tube support system to move the X-ray tube to perform a second alignment of the X-ray tube relative to the X-ray detector based on second position information of the X-ray detector; A method comprising:

15. A computer program product comprising instructions to cause a positioning system according to any one of claims 1 to 9 to perform the steps of the method according to claim 14.

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