Automatic positioning of X-ray tube support relative to detector

Abstract

The invention relates to medical imaging. In order to facilitate alignment of an X-ray tube relative to an X-ray detector, a positioning system (160) for controlling an X-ray tube support system to align the X-ray tube with the X-ray detector is provided. The positioning system includes a radio frequency (RF)-based positioning system (170), an optical camera (180), and a controller (190). The RF-based positioning system comprises a first RF device (172) attachable to the X-ray detector and a plurality of second RF devices (174, 176, 178) arranged in a known geometrical relationship with respect to the X-ray tube (112) and configured for positioning the first RF device using RF signals in order to provide first position information of the X-ray detector. The controller is configured to generate a first control signal based on first position information of the X-ray detector, the first control signal being operable to control the X-ray tube support system to move the X-ray tube in order to perform a first alignment of the X-ray tube relative to the X-ray detector. After the first alignment, the controller is configured to trigger the optical camera to acquire an image to position the X-ray detector so as to provide second position information of the X-ray detector, and to generate a second control signal based on the second position information of the X-ray detector, the second control signal being operable to control the X-ray tube support system to move the X-ray tube, so as to perform a second 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 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. Background Art

[0002] All-electric X-ray devices belong to the category of diagnostic X-ray imaging devices. These machines are used to obtain X-ray images of various anatomical structures in order to provide support in the process of obtaining diagnostic results. The system has an X-ray tube support geometry that supports the X-ray tube and enables it to position itself in the examination room as required. The X-ray detector that quantifies the absorbed X-rays to provide a readable image can be free or mounted on the detector support geometry. Both the X-ray tube and the detector support (if present) may have the required mechanisms to ensure the correct alignment of the X-ray tube relative to the X-ray detector. Typically, there are three types of alignment including the X-ray tube relative to the X-ray detector (in terms of center and position, angular alignment, and the vertical distance from the source to the image between the two). However, in the absence of a detector support geometry, alignment may have to be performed manually, which is extremely challenging. Summary of the invention

[0003] Therefore, there is a need to facilitate alignment of an X-ray tube relative to an X-ray detector, for example, for situations where there is no detector support geometry.

[0004] The objects of the invention are solved by the subject-matter of the independent claims, wherein further embodiments are incorporated in the dependent claims. It should be noted that the following described aspects of the invention also apply to a positioning system and method for controlling an X-ray tube support system for aligning 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, a positioning system for controlling an X-ray tube support system to align an X-ray tube with an X-ray detector is provided. 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 that can be attached to the X-ray detector; and a plurality of second RF devices that are arranged in a known geometric relationship relative to the X-ray tube and configured to use an RF signal to position the first RF device so as to provide first position information of the X-ray detector. The controller is configured to generate a first control signal based on the first position information of the X-ray detector, and the first control signal can be used to control the X-ray tube support system to move the X-ray tube so as to perform a first alignment of the X-ray tube relative to the X-ray detector. After the first alignment, the controller is configured to trigger the optical camera to acquire an image to position the X-ray detector so as to provide second position information of the X-ray detector; and generate a second control signal based on the second position information of the X-ray detector, and the second control signal can be used to control the X-ray tube support system to move the X-ray tube so as to perform a second alignment of the X-ray tube relative to the X-ray detector.

[0006] The inventors of the present invention have found that existing automatic alignment methods using optical cameras require a direct view of the landmarks 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 process, the positioning system, method, medical imaging system and computer program element as described herein perform a two-step alignment process. The first alignment is to use an RF-based positioning system (e.g., a Bluetooth-based positioning system, an RFID-based positioning system, and an ultra-wideband (UWB)-based positioning system) to identify the approximate position and / or orientation of the X-ray detector or detector docking station. Since the first alignment is based on RF signals, a direct view of the landmarks on the X-ray detector and the detector docking station is not required.

[0008] The second alignment is to use a camera-based positioning system to identify the exact position and / or orientation of the X-ray detector or detector docking station. After the source is roughly aligned with the X-ray detector, the optical camera will have a view of the landmarks on the detector or detector docking station at this position. From this position, the X-ray tube can be accurately positioned relative to the X-ray detector using the optical camera. For example, using image processing of the field of view image, the accuracy can be improved to a few millimeters using the optical camera.

[0009] In this way, an automatic alignment process can be achieved even if the X-ray tube supported by the X-ray tube support system is arranged far away from the X-ray detector. Therefore, manual movement is no longer necessary. In addition, since the alignment is automatically performed in real time, there is no need to make adjustments on site with respect to each geometry. In addition, automatic positioning can have a significant impact on the workflow, since there is no need to manually move the tube support and align it with the X-ray detector, thus facilitating a large part of the workflow of acquiring X-ray images.

[0010] The positioning system is described in detail below, especially for Figure 2 and Figure 4 The example shown in .

[0011] According to an embodiment of the present disclosure, the positioning system further includes a three-dimensional angle sensor that can be attached to the X-ray detector for three-dimensional angle measurement.

[0012] In some examples, the three-dimensional angle sensor can 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 gyroscope sensor can be used for three-dimensional angle measurement.

[0015] According to an embodiment of the present disclosure, the first RF device includes at least one of the following:

[0016] - an RF device removably attachable to the X-ray detector or to an external handle of the X-ray detector;

[0017] - an RF device as an integrated part of an X-ray detector; or

[0018] - RF device as an integrated part of the external handle of the X-ray detector.

[0019] In some examples, the first RF device may be powered by the X-ray detector.

[0020] In some examples, the first RF device may be powered by a battery.

[0021] This will be described in detail below, especially for Figure 3A and Figure 3B The example shown in .

[0022] According to an embodiment of the present disclosure, a plurality of second RF devices are arranged on the X-ray tube supporting system.

[0023] The positions of the plurality of second RF devices relative to the X-ray tube support system may be preconfigured, and during installation only the position of the X-ray tube support system relative to the room layout must be calibrated.

[0024] In some examples, the second RF device is removably attached to the X-ray tube support system.

[0025] In some examples, the second RF device may be integrated with the X-ray tube support system.

[0026] In some examples, the second RF device may be powered by the X-ray tube support system.

[0027] In some examples, the second RF device may be powered by a battery.

[0028] This will be described in detail below, especially for Figure 2 The example shown in .

[0029] According to an 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 communication protocol.

[0030] For example, at least one of the plurality of second RF devices may be interfaced with the X-ray tube support system to transmit the collected sensor data to, for example, a system controller.

[0031] This will be described in detail below, especially for Figure 2 The example shown in .

[0032] According to an embodiment of the present disclosure, an RF-based positioning system includes a plurality of ultra-wideband (UWB) devices.

[0033] The UWB device is used to locate the detector position in three-dimensional space. This can be achieved by using one UWB transmitter positioned on the X-ray detector and three or more other UWB receivers positioned on the X-ray tube support system. In some other examples, one UWB receiver may be positioned on the X-ray detector and three or more other UWB receivers may be positioned on the X-ray tube support system.

[0034] Various geometric methods may be used to estimate the position of the X-ray detector. Examples of geometric methods may include, but are not limited to, trilateration, triangulation, and multilateration.

[0035] According to an embodiment of the present disclosure, the first RF device includes a UWB transmitter.

[0036] According to an embodiment of the present disclosure, the plurality of second RF devices include at least three UWB receivers.

[0037] According to an embodiment of the present invention, an X-ray detector is provided, wherein the X-ray detector comprises an RF device for position tracking.

[0038] The RF device may be part of the X-ray detector, or located on an external handle of the X-ray detector. Figure 3A An example of an X-ray detector is shown. Figure 3B An example of an external handle of an X-ray detector is shown.

[0039] According to an embodiment of the present disclosure, the RF device is a UWB device.

[0040] According to an embodiment of the present disclosure, the X-ray detector is a portable X-ray detector.

[0041] According to a second aspect of the present disclosure, an X-ray imaging system is provided. The X-ray imaging system includes 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 also includes a positioning system for controlling the X-ray tube support system to align the X-ray tube with the X-ray detector according to the first aspect and any associated examples.

[0042] In some examples, the X-ray tube support system can be a ceiling support system.

[0043] In some examples, the X-ray tube support system may be a floor to ceiling support system.

[0044] In some examples, the X-ray tube support system may be a mobile digital radiography system.

[0045] This will be described in detail below, especially for Figure 2 and Figure 4 The example shown in .

[0046] According to a fourth aspect of the present invention, there is provided a method for controlling an X-ray tube support system to align an X-ray tube with an X-ray detector, the method comprising:

[0047] - obtaining first position information of the X-ray detector using a radio frequency (RF) based positioning system, wherein the RF based positioning system comprises a first RF device attachable to the X-ray detector and a plurality of second RF devices arranged in a known geometric relationship relative to the X-ray tube and configured to use RF signals to position the first RF device;

[0048] - generating a first control signal based on the first position information of the X-ray detector, the first control signal being used to control the X-ray tube support system to move the X-ray tube so as to perform a first alignment of the X-ray tube relative to the X-ray detector;

[0049] - after the first alignment, triggering the optical camera to acquire an image to position the X-ray detector, so as to provide second position information of the X-ray detector; and

[0050] - generating a second control signal which can be used to control the X-ray tube support system to move the X-ray tube in order to perform a second alignment of the X-ray tube relative to the X-ray detector.

[0051] This will be described in detail below, especially for Figure 5 The example shown in .

[0052] According to another 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.

[0053] It should be understood that all combinations of the aforementioned concepts and the additional concepts discussed in more detail below (provided that these concepts are not mutually inconsistent) are contemplated as part of the inventive subject matter disclosed herein. In particular, all combinations of the claimed subject matter appearing at the end of this disclosure are contemplated as part of the inventive subject matter disclosed herein.

[0054] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In the drawings, like reference numerals generally refer to like components throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.

[0056] Figure 1 An exemplary medical imaging system is shown.

[0057] Figure 2 An exemplary positioning system is shown.

[0058] Figure 3A An exemplary portable X-ray detector is shown.

[0059] Figure 3B An exemplary portable X-ray detector handle is shown.

[0060] Figure 4 The positioning system and its relationship to some components of the X-ray tube support system are shown.

[0061] Figure 5 A flow chart describing a method for controlling an X-ray tube support system to align an X-ray tube with an X-ray detector is shown. DETAILED DESCRIPTION

[0062] While the invention has been illustrated and described in detail in the drawings and following description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

[0063] For example, although the present application describes the present invention in the context of medical imaging applications that use X-radiation to produce images, it should be understood that the present invention may also be advantageously used in applications that use any suitable type of penetrating radiation or any other particle, wave or field phenomenon to obtain images. For example, although the present application describes a ceiling mounted digital X-ray system for implementing the present method by way of example, it should be understood that the described positioning system may also be applied to other types of X-ray tube support systems, such as floor to ceiling support systems, mobile digital radiography systems, etc.

[0064] Figure 1 A medical imaging system 100 which may be suitable for implementing the present method is schematically illustrated.In the illustrated example, the medical imaging system 100 is a ceiling mounted digital X-ray system.

[0065] In the illustrated example, the 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 can be positioned during imaging), and a vertical stand 140 (having a defined docking compartment 142 in which the portable X-ray detector 134 can be positioned during imaging). Although not shown, it is understood that the portable X-ray detector 134 can be used for free examination, for example, on a patient support surface 136 of the floor mounted examination table 130. Figure 3A An example of a portable X-ray detector 134 is shown.

[0066] The X-ray tube support system 120 supports the X-ray tube head 110 and provides translation 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.

[0067] Two spaced apart parallel support rails 122A and 122B may extend longitudinally along a ceiling (not shown) and be attached to the ceiling by a plurality of fastening means (not shown). The bridge 124 is supported by the support rails 122A and 122B, which also allows the bridge 124 and all objects supported by it to move longitudinally, as indicated by arrow A. The bridge 124 may support a transverse slide 126 and allow the bridge to move laterally, as indicated by arrow B. The transverse slide 126 supports the X-ray tube head 110 via a telescoping tube assembly 128, which in effect serves as a vertically oriented linear bearing. The telescoping tube assembly 128 may be formed of a plurality of nested tubular structural members having bearings to allow longitudinal slidable movement therebetween. Thus, the transverse slide 126 and the telescoping tube assembly 128 allow the X-ray tube head 110 to move vertically, as indicated by arrow C.

[0068] The movement in directions A and C can be respectively driven by longitudinal actuators 152 (such as Figure 4 The longitudinal drive 152 and the vertical drive 154 can be controlled by a system controller 150, which can be housed in the transverse carriage 126. Movements in directions A, B, and C can also be performed manually by an operator.

[0069] 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 an operator to use in selecting a position of the X-ray tube head 110. Information obtained from the control panel 116 may be transmitted to a system controller 150, which generates control signals to the longitudinal drive and the vertical drive to move the X-ray tube head 110 in a desired direction. The X-ray tube head 110 is mounted on the telescoping tube assembly 128 so as to rotate about the transverse axis 121, as indicated by arrow D. This may be accomplished by an X-ray tube head rotation drive 156 (e.g., Figure 4 shown) to provide power.

[0070] Rotation of the X-ray tube head 110 allows the X-ray beam to be directed at various desired angles, such as toward the examination table 130 or toward the vertical support 140 . The X-ray tube head rotation drive 156 may be controlled by the system controller 150 .

[0071] Thus, the X-ray tube support system 110, its associated longitudinal and vertical drives 152, 154, and the X-ray tube head rotation drive 156 cooperate to allow the system controller 150 to direct the X-ray tube head 110 to any position on a reference plane parallel to the XZ plane and to direct the emitted X-ray beam at any angle along the reference plane. It is believed that providing three degrees of freedom for the position of the focal point and the angular direction of the emitted X-ray beam is sufficient to perform examinations using a variety of desired radiographic, fluoroscopic, and tomographic imaging modes under the control of the system controller 150. However, the skilled artisan will appreciate that this embodiment can be readily modified to include additional degrees of freedom if additional imaging modes are desired.

[0072] Generally speaking, three types of alignment are required of the tube relative to the detector in terms of center / position, three-axis angles, and source-to-image distance. Current design solutions use gyro sensor feedback from the detector to achieve angular alignment, which is applicable to the case of detectors without supports and with detector supports. Only in the case of detector support geometry, center / position and distance alignment can be achieved by adjustments during installation of the system in the field. In the case of free detectors, the radiographer must perform both alignments based on his / her judgment.

[0073] In order to facilitate the automatic alignment process in order to improve the workflow, a positioning system 160 for controlling the X-ray tube support system 120 in order to align the X-ray tube 112 with the X-ray detector 134 is provided. With the positioning system, the automatic alignment process can be achieved even if the X-ray tube supported by the X-ray tube support system is arranged far away from the X-ray detector. Therefore, manual movement is no longer required. In addition, since the alignment is automatically performed in real time, there is no need to adjust it for each geometry on site. In addition, automatic positioning can have a significant impact on the workflow, because there is no need to manually move the tube support and align it with the X-ray detector, thereby facilitating a large part of the workflow for acquiring X-ray images.

[0074] Figure 2 An exemplary positioning system 160 is shown. The exemplary positioning system includes an RF-based positioning system 170, an optical camera 180, and a controller 190.

[0075] The RF based positioning system 170 includes a first RF device 172 attachable to the X-ray detector 134 . Figure 3A An example of an X-ray detector 134 is shown. In some examples, such as Figure 3A As shown, the first RF device 172 may be removably attached to or integrated with the portable X-ray detector 134. In some other examples, such as Figure 3BAs shown, the first RF device 172 may be removably attached to or integrated with the external detector handle 135 of the portable X-ray detector.

[0076] The RF-based positioning system 170 also includes a plurality of second RF devices arranged in a known geometric relationship relative to the X-ray tube. Figure 2 As shown, the plurality of second RF devices may include three RF devices, namely, 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. Figure 2 The RF devices 174, 176, and 178 shown in FIG. 1 may be removably attached to or integrated with the X-ray tube support system 120. The positions of the three RF devices 172, 174, and 178 are flexible, but generally, for better positional accuracy, each of the three RF devices 172, 174, and 178 should be as far away as possible relative to the other. The positions of these RF devices can be pre-configured relative to the X-ray tube support system 120, and during installation, only the position of the X-ray tube support system 120 relative to the room layout needs to be calibrated. For example, if Figure 2 As shown, the RF device 174 may be removably attached to or integrated into the bridge 124. The RF device 176 may be removably attached to or integrated into the support rail 122B. The RF device 178 may be removably attached to or integrated into the X-ray tube head 110. During the movement of the ceiling suspension device, some of the 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 the X-ray tube support system 120. Finally, one of the second RF devices 174, 176, and 178 can act as a master RF device that collects data from the other RF devices in order to determine the position of the first RF device 172 on the X-ray detector. The master RF device can be interfaced with the X-ray tube support system 120 via a desired communication protocol to provide sensor data to the controller 190.

[0077] The plurality of second RF devices (e.g., RF devices 174, 176, and 178) are configured to use RF signals to locate the first RF device 172 so as 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 (e.g., 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 (e.g., RF devices 174, 176, and 178 on the X-ray tube support system 120) may be RF transmitters.

[0078] Various geometric methods may be used to estimate the position of the first RF device 120. Examples of geometric methods may include, but are not limited to, trilateration, triangulation, and multilateration. The trilateration method is based on range measurement, 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. The distance (also referred to as range) can be estimated by measuring different RF parameters (e.g., received power or radio signal propagation time, i.e., flight time). The triangulation method in the positioning method 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 point (e.g., RF device 174, 176, and 178) and the point with unknown position (e.g., RF device 172). Multilateration can be used in a system that can only measure the information of the distance difference between the unknown position of the first RF device (e.g., RF device 172) and the anchor node (e.g., RF device 174, 176, and 178). A node at an unknown location (eg, RF device 172) measures the time difference between arrivals of signals from anchor nodes (eg, RF devices 174, 176, and 178).

[0079] The RF-based positioning system 160 may be a positioning system based on Bluetooth Low Energy (BLE), a positioning system based on Wi-Fi, a positioning system based on RFID, a positioning system based on UWB, or any combination thereof. For example, taking a positioning system based on UWB as an example, Figure 2 The first RF device 172 shown may be a UWB transmitter, while a plurality of second RF devices (eg, Figure 2 The RF devices 174, 176 and 178 shown may be UWB receivers. A UWB-based positioning system may achieve accuracy within a few centimeters using properly positioned RF devices. Since the accuracy is within a few centimeters when using UWB sensors, the detector will be within the field of view of the optical camera 120.

[0080] In some examples, the positioning system may include a three-dimensional angle sensor 173 (see Figure 4 ), which can be attached to the X-ray detector for three-dimensional angle measurement. In some examples, the three-dimensional angle sensor can be part of the first RF device. In some examples, the three-dimensional angle sensor and the first RF device can be two separate devices. For example, a gyroscopic inertial measurement unit (IMU) sensor integrated with the first RF device 172 can provide information needed to achieve angular alignment of the X-ray tube relative to the X-ray detector.

[0081] The optical camera 120 is used to improve the alignment accuracy to a few millimeters, for example, using image processing of the field of view image. The optical camera 120 can be positioned in the collimator 114 or at any other suitable location on the X-ray tube head 110 for a view of the X-ray detector or an area containing the X-ray detector (e.g., the examination table surface). The terms "image" or "image data" as used herein should be broadly understood in this case and include any data or electromagnetic radiation image that can be obtained or generated by the optical camera 120. Although in Figure 2 A single optical camera 120 is shown by way of example only, but it will be appreciated that multiple optical cameras or multiple image sensors may be deployed. The image data is not limited to the visible spectrum range and two-dimensional. Examples of images acquired by the optical camera may include, but are not limited to, grayscale images, near infrared (NIR) images, RGB images, multispectral images, and hyperspectral images. The frame rate of the camera may be in the range of 0.3 Hz to 48 Hz, but is not limited thereto. The optical camera may be pre-configured to identify the X-ray detector and its center position using a pattern or a unique identifier. The optical camera may be integrated into an X-ray tube support system 120, which includes a system controller 150 to perform the required image processing processes to adjust and align the X-ray tube relative to the X-ray detector.

[0082] The controller 190 may include 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) that can be executed by various hardware components, or any combination thereof, as desired for a given set of design parameters or performance constraints. In some implementations, the controller 190 may include one or more microprocessors or computer processors that execute appropriate software. The software may be downloaded and / or stored in a corresponding memory, such as a volatile memory (e.g., RAM) or a non-volatile memory (e.g., flash memory). The software may include instructions to configure one or more processors to perform the functions described herein. It is worth noting that the controller 190 may be implemented with or without a processor, and may also be implemented as a combination of dedicated hardware for performing some functions and a processor (e.g., one or more programmed microprocessors and associated circuits) for performing other functions. For example, the controller 190 may be implemented in a device or apparatus in the form of programmable logic, for example, as a field programmable gate array (FPGA). In Figure 2 In the example of FIG. 1 , the controller 190 is implemented in the system controller 150. In some other examples (not shown), the controller 190 may be implemented as other devices (eg, a workstation) or implemented in other devices.

[0083] The controller 190 can execute instructions to perform the methods described herein, which will be directed to Figure 4 and Figure 5 The examples shown in the table are explained in detail.

[0084] Figure 4 The positioning system 160 and its relationship to some components of the X-ray tube support system are schematically shown. In the illustrated example, according to the present method, the controller 190 can receive input from the RF-based positioning system 170, the optical camera 180, and the optional three-dimensional angle sensor 173 of the positioning system 160 to determine the position and / or orientation of the detector relative to the X-ray tube 112. In addition, as described herein, based on the relative position of the source and the detector, the controller 190 can control or adjust the alignment of the X-ray tube 112 relative to the X-ray detector (e.g., detector 134). For example, movement of the X-ray tube in directions A and C can be driven by the longitudinal drive 152 and the vertical drive 154, respectively. Rotation of the X-ray tube head can be driven by the head rotation drive 156.

[0085] Figure 5 A flow chart describing a method 200 for controlling an X-ray tube support system to align an X-ray tube with an X-ray detector is shown. Figure 2 and Figure 4 The method 200 is described with reference to the illustrated system.

[0086] At block 210, the RF-based positioning system 160 obtains first position information of an X-ray detector (e.g., the portable X-ray detector 134). The first position information includes approximate position information, which may not be accurate enough, for example, its accuracy may exceed 1 to 2 centimeters, depending on the RF positioning technology. The RF-based positioning system 160 includes a first RF device, such as Figure 3A and Figure 3B The first RF device 172 is shown as an RF device that 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 can be located on an 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 positioning system 160 also includes a plurality of second RF devices, such as Figure 2 The RF devices 174, 176 and 178 are shown arranged in a known geometric relationship relative to the X-ray tube and are configured to use the RF signal to position the first RF device.

[0087] 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 an RF transmitter may be vice versa. 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.

[0088] The RF-based positioning system can be a positioning system based on Bluetooth / BLE, Wi-Fi, RF identification (RFID), UWB, or any combination thereof. Taking the UWB-based positioning system as an example, Figure 2 The first RF device 172 shown may be a UWB transmitter, while a plurality of second RF devices (eg, Figure 2 The devices 174, 176 and 178 shown) can be UWB receivers. The three UWB receivers 174, 176 and 178 located on the X-ray tube support system can receive the signal from the UWB transmitter 172 from the X-ray detector, and can use the time difference of arrival (TDOA) method to check the signal arrival time difference between each receiver 174, 176 and 178 to locate the transmitter position.

[0089] At box 220, based on the first position information of the X-ray detector, the controller 190 generates a first control signal, which can be used to control the X-ray tube support system to move the X-ray tube so as to perform a first alignment of the X-ray tube relative to the X-ray detector. For example, the movement of the X-ray tube along directions A and C can be driven by the longitudinal drive 152 and the vertical drive 154, respectively. The rotation of the X-ray tube head can be driven by the head rotation drive 156. Since the RF-based positioning system can have an accuracy within a few centimeters, after the first alignment, the X-ray detector will be located within the field of view of the optical camera 180.

[0090] At box 230, after the first alignment, the controller 190 triggers the optical camera 180 to acquire an image to position the X-ray detector so as to provide second position information of the X-ray detector. The second position information includes fine position information, i.e., accurate position information. The portable X-ray detector 134 can be used for free inspection or inserted into a defined docking compartment in the floor-mounted inspection table 130 or the vertical bracket 140. In some examples, if the portable X-ray detector 134 is inserted into a defined docking compartment in the floor-mounted inspection table 130, the controller 190 may analyze an image of one or more landmarks disposed on the patient support surface 136 of the floor-mounted inspection table 130 to position the X-ray detector. In some examples, if the portable X-ray detector 134 is inserted into a defined docking compartment in the vertical bracket 140, the controller 134 may analyze a mark or pattern on the surface 146 to position the X-ray detector. In some examples, if the portable X-ray detector 134 is used for free examination, for example, positioned on the patient support surface 136 of the floor mounted examination table 130, the controller 190 may analyze the image of the X-ray detector to position the X-ray detector. In this way, the accuracy of positioning the X-ray detector may be improved to the millimeter range or less.

[0091] At box 240, based on the first position information of the X-ray detector, the controller 190 generates a second control signal, which can be used to control the X-ray tube support system to move the X-ray tube so as to perform a second alignment of the X-ray tube relative to the X-ray detector.

[0092] In another exemplary embodiment of the present invention, a computer program or a computer program element is provided, characterized in that it is adapted to execute the method steps of the method according to one of the preceding embodiments on a suitable system.

[0093] Therefore, the computer program element can be stored on a computer unit, which can also be part of an embodiment of the present invention. The computing unit can be adapted to perform or induce the steps of performing the above method. In addition, it can be adapted to operate the components of the above device. The computing unit can be adapted to automatically operate and / or execute the user's commands. The computer program can be loaded into the working memory of a data processor. Therefore, the data processor can be equipped to perform the method of the present invention.

[0094] This exemplary embodiment of the invention covers two computer programs, one computer program which uses the invention right from the start and one computer program which converts an existing program into a program which uses the invention by means of an update.

[0095] Furthermore, the computer program element can provide all necessary steps to complete the procedures of an exemplary embodiment of the method as described above.

[0096] According to another exemplary embodiment of the present invention, a computer readable medium, such as a CD-ROM, is proposed, wherein a computer program element is stored on the computer readable medium, the computer program element being described in the previous section.

[0097] The computer program may be stored and / or distributed on suitable media, such as optical storage media or solid-state media provided 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 telecommunications systems.

[0098] However, the computer program may also be presented over a network such as the World Wide Web and may be downloaded from such a network into a working memory of a data processor. According to another exemplary embodiment of the present invention, a medium for making a computer program element available for downloading is provided, the computer program element being arranged to perform a method according to one of the previously described embodiments of the present invention.

[0099] Other variations to the disclosed embodiments may be understood and implemented by those skilled in the art in practicing the claimed invention, by studying the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may perform the functions of multiple items recited in the claims. The fact that some 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 (160) for controlling an X-ray tube support system to align an X-ray tube with an X-ray detector, the system comprising: - Radio frequency RF based positioning system (170); - Optical camera (180); and - a controller (190); Wherein, the RF-based positioning system includes: - a first RF device (172) attachable to said X-ray detector, and a plurality of second RF devices (174, 176, 178) arranged in a known geometric relationship relative to the X-ray tube (112) and configured to use RF signals to position the first RF device so as to provide first position information of the X-ray detector; wherein the controller is configured to generate a first control signal based on the first position information of the X-ray detector, and the first control signal can be used to control the X-ray tube support system to move the X-ray tube so as to perform a first alignment of the X-ray tube relative to the X-ray detector; and Wherein, after the first alignment, the controller is configured to trigger the optical camera to acquire an image to position the X-ray detector so as to provide second position information of the X-ray detector, and to generate a second control signal based on the second position information of the X-ray detector, and the second control signal can be used to control the X-ray tube support system to move the X-ray tube so as to perform a second alignment of the X-ray tube relative to the X-ray detector.

2. The positioning system according to claim 1, wherein: The positioning system also includes: - A 3D angle sensor attachable to said X-ray detector for 3D angle measurement.

3. The positioning system according to claim 1 or 2, in, The first RF device includes at least one of the following: - an RF device removably attachable to the X-ray detector or to an external handle of the X-ray detector; - an RF device as an integral part of said X-ray detector; or - An RF device as an integrated part of the external handle of the X-ray detector.

4. A positioning system according to any one of the preceding claims, in, The plurality of second RF devices are arranged on the X-ray tube supporting system.

5. The positioning system according to claim 4, in, At least one of the plurality of second RF devices is configured to interface with the X-ray tube support system via a communication protocol.

6. A positioning system according to any one of the preceding claims, in, The RF-based positioning system includes a plurality of ultra-wideband (UWB) devices.

7. The positioning system according to claim 6, in, The first RF device includes a UWB transmitter.

8. The positioning system according to claim 7, in, The UWB transmitter includes the three-dimensional angle sensor.

9. A positioning system according to any one of claims 5 to 8, in, The plurality of second RF devices include at least three UWB receivers.

10. An X-ray imaging system (100), comprising: - an X-ray tube (112) configured to emit an X-ray beam; - an X-ray tube support system (120) configured to support the X-ray tube; - A positioning system (160) 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 (134).

11. The X-ray imaging system according to claim 10, in, The X-ray detector comprises a radio frequency (RF) device (172) for position tracking.

12. The X-ray imaging system according to claim 11, in, The RF device is an ultra-wideband UWB device.

13. The X-ray imaging system according to claim 11 or 12, in, The X-ray detector is a portable X-ray detector.

14. A method (200) for controlling an X-ray tube support system to align an X-ray tube with an X-ray detector, the method comprising: - obtaining (210) first position information of the X-ray detector using a radio frequency (RF) based positioning system, wherein the RF based positioning system comprises a first RF device attachable to the X-ray detector and a plurality of second RF devices, the plurality of second RF devices being arranged in a known geometric relationship relative to the X-ray tube and configured to use RF signals to position the first RF device; - generating (220) a first control signal by a controller based on the first position information of the X-ray detector, the first control signal being capable of being used to control the X-ray tube support system to move the X-ray tube so as to perform a first alignment of the X-ray tube relative to the X-ray detector; - after the first alignment, the controller triggers (230) the optical camera to acquire an image to position the X-ray detector so as to provide second position information of the X-ray detector; and - generating (240) a second control signal by the controller based on the second position information of the X-ray detector, wherein the second control signal can be used to control the X-ray tube support system to move the X-ray tube so as to perform a second alignment of the X-ray tube relative to the X-ray detector.

15. A computer program product comprising instructions for causing 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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