Position determining method, method for actuating an x-ray device and medical system

Abstract

Rapid and precise recording of a VOI is provided while monitoring a robot-assisted movement of a medical object through a hollow organ of a patient. For actuating an x-ray device that has a recording system, a user input for the recording of a recording region is accepted. A previously recorded three-dimensional volume image of at least part of the body, in particular of the hollow organ is provided. A length of travel covered by the object from measurement data and/or control data of the robotic system is ascertained. The current position of the object is ascertained on the basis of the three-dimensional volume image making use of the ascertained length of travel covered and a starting position of the object. The recording system of the imaging device is moved for isocentering and/or superimposing the recording region about the current position of the object. An image of the recording region is recorded.

Claims

1. A method for determining a current position of an object that has been inserted into a hollow organ of a patient, wherein the object is moved by a drive mechanism of a robotic system, the method comprising: acquiring a previously recorded three-dimensional volume image of at least part of the hollow organ comprising at least a starting position of the object, acquiring path planning data that was created previously based on the previously recorded three-dimensional volume image, ascertaining, in the previously recorded three-dimensional volume image, a length of travel covered by the object from measurement data and/or control data of the robotic system, determining and/or calculating the current position of the object using the ascertained length of travel covered, the path planning data, and the starting position of the object, automatically actuating, by a system control unit of an x-ray device, a recording system of the x-ray device so that the current position of the object is situated at the isocenter of the recording system and/or a recording region of the recording system is superimposed at the current position of the object, and recording a recording region image of the recording region.

2. The method as claimed in claim 1, wherein the robotic system has a drive system which comprises a drive and causes the object to advance, and wherein measurement data and/or control data of the drive system is used to ascertain the length of travel covered by the object.

3. The method as claimed in claim 1, wherein the x-ray device is registered in advance with the at least one previously recorded three-dimensional volume image and/or the path planning data.

4. The method as claimed in claim 1, wherein a user input is accepted which triggers the method.

5. The method as claimed in claim 1, wherein the x-ray system has a patient table and wherein the patient table is also moved to isocenter and/or superimpose the recording region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and further advantageous embodiments as per features in the subclaims are explained in greater detail below with reference to schematically illustrated exemplary embodiments in the drawings, without thereby restricting the invention to these exemplary embodiments.

(2) FIG. 1 shows one embodiment of a sequence of a method for determining a current position of an object that has been inserted into the body of a patient;

(3) FIG. 2 shows one embodiment of a sequence of a method for actuating an x-ray device while monitoring a robot-assisted movement of a medical object through a hollow organ of a patient;

(4) FIG. 3 shows an example view of a current position of an object, calculated on the basis of a volume image;

(5) FIG. 4 shows an example view of a medical system; and

(6) FIG. 5 shows an example view of a VOI volume image recorded by the method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) FIG. 1 shows acts of a method for determining a current position of an object that has been inserted into the body, in particular into a hollow organ (i.e., a vascular system, vascular tree, bronchial system, etc., for example), of a patient, which object can be moved through the hollow organ in a robot-assisted manner by a robotic system. Robotic systems by which (semi)automatic movement of an object, e.g., a catheter, stent and/or guide wire, can be effected in a hollow organ of a patient with the aid of a robot are known in principle, e.g., from EP 3406291 B1. After some time during which the object has been moved, it becomes necessary for e.g., an operator (e.g., a doctor) to check the position or determine the current position.

(8) In a first act 30, a previously recorded three-dimensional volume image (pre-op) of at least part of the body, in particular the hollow organ, is provided. Such volume images are generally prepared to obtain an overview of the entire treatment region and in order to allow, e.g., path planning to be performed for the movement of the object. The previously recorded volume image is or was previously registered with e.g., the coordinate system of the patient. Such a volume image may have been prepared by e.g., a CT, an MR or an angiography x-ray device.

(9) In a second act 31, the length of travel already covered by the object as a result of the robot-assisted advance is ascertained from measurement data and/or control data of the robotic system. For example, the data of a stepping motor that causes the advance can be retrieved and used here. The data can be processed and converted accordingly to obtain the length of travel covered. However, only the distance can generally be ascertained from the length of travel covered, not the exact path or the exact position.

(10) Therefore, in a third act 32, the current position of the object is then ascertained or calculated on the basis of the three-dimensional volume image, making use of the ascertained length of travel covered and the starting position of the object. For the purpose of illustration, FIG. 3 shows the previously created volume image V.sub.pre with the hollow organ H depicted therein. The previously planned path G for the travel of the object O is shown in the previously created volume image V.sub.pre. Starting from the starting position A of the object, the length of travel L covered is then applied to the planned path G and the current position P of the object O is thereby obtained very precisely. This can also be performed without a path plan and on the basis of the previously created volume image V.sub.pre alone. To be able to retrace the course that was actually followed e.g., at branch points of the hollow organ, and for approximate orientation, information from fluoroscopy recordings or data from other navigation systems can also be used here.

(11) FIG. 2 shows a sequence of a method for actuating an x-ray device, which method uses the position determining method according to FIG. 1. For example, a medical system 1 as shown in FIG. 5 is used for this. The medical system 1 has a robotic system and an x-ray device 10. The robotic system is configured for semiautomatic or automatic movement of the medical object O, e.g., an instrument, stent, guide wire or catheter, in a hollow organ of a patient 15. A semiautomatic actuation in this case is understood to mean e.g., an actuation that can be transferred from an operator via an input unit 17 (e.g., joystick, touchpad, rotary switch, etc.) to a robot control unit 8. The robotic system has at least a robot control unit (controller) 8 and a robot-assisted drive system 7. The drive system 7 is configured to move the medical object e.g., in the hollow organ of the patient 15 based on control signals from the robot control unit 8 after it has been introduced at an entry point. The drive system 7 in this case includes at least a drive and a drive mechanism (not shown, e.g., disclosed in EP 3406291 B1), said drive mechanism being separably coupled to the guide wire 5, for example. By the drive mechanism and the drive, the guide wire 5 can be advanced and withdrawn longitudinally and/or additionally moved in a rotary manner. The length of travel of the longitudinal advance can be determined from measurement data or control data of the drive system (e.g., a stepping motor). The robot control unit 8 is connected to an input unit (input device) 17 (e.g., arranged remotely from the patient) which can be operated by an operator, e.g., a cardiologist or radiologist performing the intervention. The control signals are transferred from the input unit 17 (e.g., one or more joysticks, touchpads, control buttons, etc.) to the robot control unit 8, and in this way the movements of the object are semiautomatically actuated. Alternatively, the operator can also carry out path planning for the object or have a path plan created automatically. This is transferred to the robot control unit 8, whereby movement can take place completely automatically. The path plan can also be used as a reference in the case of semiautomatic movement.

(12) To have an overview of the intervention and the movement, the x-ray device 10 is provided. The x-ray device 10 has e.g., a C-arm 13 which supports an x-ray source 12 and an x-ray detector 11 and is connected to a system control unit 16. The C-arm 13 is so arranged as to be movable relative to the patient, and the whole x-ray device can be moved in the case of a mobile x-ray device. Alternatively or additionally, the patient table 19 can also be moved relative to the x-ray device or recording system. The x-ray device 10 makes it possible to create images of a recording region that can be depicted and display said images on a display unit (display screen) 18. The robot control unit 8 and the system control unit (controller) 16 of the imaging device can exchange data bidirectionally and communicate with each other. It is also possible to provide a combined control unit (controller) including the robot control unit 8 and the system control unit 16. The medical system 1 also includes a calculation unit (calculator, controller, or processor) 20, which is configured to ascertain a length of travel covered by the object from measurement data and/or control data of the drive system and to determine and/or calculate the current position of the object on the basis of the previously created volume image making use of the ascertained length of travel covered and the starting position of the object. Registration of the robotic system with the x-ray device can be performed in advance, e.g., using previously created 3D image data.

(13) If an operator requires a precise 3D representation of the object and its environment, e.g., in the vicinity of a vascular branch point, in the form of a VOI recording, the operator performs a user input. The user input is accepted by e.g., the system control unit 16 (fourth act 33) and this acceptance triggers the method; see FIG. 2. In a first act 30, a previously recorded three-dimensional volume image (pre-op) V.sub.pre of at least part of the body, in particular the hollow organ, is then provided. The previously recorded volume image is or was previously registered with e.g., the coordinate system of the x-ray device (or already directly created by this). In a second act 31, the length of travel already covered by the object as a result of the robot-assisted advance is ascertained from measurement data and/or control data of the robotic system. For example, the data of a stepping motor which causes the advance can be retrieved and used here. The data can be processed and converted accordingly to obtain the length of travel covered. However, only the distance can generally be ascertained from the length of travel covered, and not the exact path. Therefore, in a third act 32, the current position of the object is then ascertained or calculated on the basis of the three-dimensional volume image, making use of the ascertained length of travel covered and the starting position of the object. Once the current position of the object has been ascertained, it is forwarded to the system control unit 16 of the x-ray device 1 for the actuation and, in a fifth act 34, the recording system of the x-ray device (and/or the patient table 19) is moved automatically such that isocentering of the current position of the object is achieved. In particular, the object becomes the central point of the recording region. Furthermore, a superimposition (e.g., by a collimator) is also performed, so that only the object and its immediate environment, i.e., the VOI, are superimposed. The precise dimensioning of the VOI can be preset or selected automatically. This may represent e.g., a quarter or less of the volume of a complete image. Finally, in a sixth act 35, a VOI volume image V.sub.VOI of the superimposed recording region is recorded with the object O and its immediate environment; see FIG. 5. By virtue of such a VOI volume image, it is possible more effectively to identify e.g., critical situations during movement of the object (e.g., in the case of vascular branch points or vascular occlusions) and therefore to achieve a better diagnostic opinion and treatment. As a result of automating the method, it is possible to perform an image recording quickly and effortlessly.

(14) The method can be made even more resilient by sensor technology, e.g., a navigation system, for the tip or the central point (in the case of stents) of the object, e.g., EM tracking.

(15) The advantage of the proposed method lies in the automation of the resource-intensive positioning of the recording system (and possibly the patient table). In this way, it is possible to generate a VOI volume image, i.e., a significantly smaller volume image in respect of the x-ray window, of the desired recording region, i.e., the object and its immediate environment. By virtue of the smaller image region, the x-ray dose is significantly reduced and therefore the risk to the patient is minimized in comparison with a full-format 3D recording.

(16) The embodiments can be briefly summarized as follows: for a particularly rapid and precise recording of a VOI while monitoring a robot-assisted movement, performed by a robotic system, of a medical object through a hollow organ of a patient, a method including the following acts is provided for the purpose of actuating an x-ray device that has a recording system: accepting a user input for the recording of a recording region, providing a previously recorded three-dimensional volume image of at least part of the body, in particular of the hollow organ, ascertaining a length of travel covered by the object from measurement data and/or control data of the robotic system, determining and/or calculating the current position of the object on the basis of the three-dimensional volume image making use of the ascertained length of travel covered and the starting position of the object, automatically moving the recording system of the imaging device for the purpose of isocentering and/or superimposing the recording region which includes the current position of the object, recording an image of the recording region, in particular in the form of a VOI volume image.

(17) It is intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.

(18) It is to be understood that the elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims can, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent, and that such new combinations are to be understood as forming a part of the present specification.