DE102014223386A1 - Robot registration in imaging modalities - Google Patents

Abstract

The invention relates to a method for registering robot systems (12) on imaging systems (1), in particular computer tomography systems. The invention also relates to a suitable imaging system, a robotic system and suitable markers (17). The invention enables registration for robotic systems which is simple and fast and does not require additional systems such as cameras or laser systems.

Description

The invention relates to a method for registering robot systems on imaging systems, in particular computed tomography systems. The invention also relates to a suitable imaging system, a robotic system and suitable markers.

Since computed tomography can be used to produce high-resolution and reliable images of even the smallest details of the human body, computed tomography is often used in conjunction with interventions or operations. Mainly pre-or post-interventional organs, bones, blood vessels or tumors are made visible to allow a particularly good preparation or follow-up of such procedures. In addition, however, computed tomography is also increasingly being used during interventional procedures to render instruments, stents, or catheters three-dimensionally visible and traceable in the body of a patient at high resolution.

The use of a multilayer CT in medical interventions is known. From the document DE 10 2005 034 683 A1 discloses a method for generating computed tomography images during an intervention.

When using CT scanners during medical interventions or surgical procedures, however, there is often the problem that a CT gantry with a recording system requires a lot of space and is inflexible in its positionability, making the procedure difficult for the physician performing the intervention Access to the patient is possible.

Computer Assisted Surgery (CAS) represents a surgical concept and a set of methods that use computer technology to plan surgery, conduct or perform surgical procedures. This includes performing surgical procedures using robotic systems.

In CAS, the actual procedure is defined as surgical navigation. This consists of the interplay of the actions of the surgeon and the surgical robot, which was programmed during preoperative planning to perform certain actions. The control of the robot can be divided into three types: directly supervised, tele-surgical and shared-controlled. In a supervisory system, the operation is performed only by the robot performing preprogrammed movements. In telesurgery, also known as remote-controlled surgery, the surgeon programs the robotic arms directly during the procedure rather than allowing the robotic arms to operate according to a predetermined program. In shared control, the surgeon performs the procedure using the robot by directing it via a stationary hand control. For most robots, the working mode for each individual action can be selected depending on the surgical complexity and the particularities of the case.

The pamphlets EP 2 561 821 A1 . US 2006/0149147 A1 and US 2009/0088773 A1 present different robot systems for the CAS in cooperation with computed tomography devices and / or C-arm systems. Various gripping and auxiliary tools are presented, such as tweezer-like, very precise grippers or probes for taking tissue samples from tumor tissue.

Especially in microsurgical procedures in which the surgeon does not control the robot himself, it is very important that the control system accurately knows the position of the robot. The position of the arms of the robot is usually known via sensors in the robot arms themselves. But it is also important, the orientation of the robot with respect to the imaging system.

Usually, the coordination of the robot takes place with respect to the imaging system via a camera or laser system, wherein the points of interest are marked with a special marker and tracked by means of the camera system. The individual markers can then be related via the camera system. The disadvantage here is that a separate system (camera / laser) is needed and you also have to work with multiple reference systems (camera, robot, patient recording).

The object of the invention is therefore to propose a registration for robot systems, which is simple and fast and does not require additional systems.

This object is achieved by the method according to claim 1, by the imaging system according to claim 7, by the robot system according to claim 11 and a marker according to claim 14.

The solution according to the invention will be described below with reference to the claimed apparatuses as well as to the claimed method. Features, advantages, or alternative embodiments mentioned herein are also applied to the others as well Transfer items and vice versa. In other words, the subject claims directed, for example, to a system may also be developed with the features described or claimed in connection with a method. The corresponding functional features of the method are formed by corresponding physical modules.

The method according to the invention is suitable for registration of robot systems on imaging systems, in particular computer tomography systems. In this case, the invention is suitable for any robot, provided that a position determination of the tool center point (TCP) can be clearly determined on the basis of the axis positions and also the position of the robot foot in space is to be determined unambiguously. This will be the case with most robotic systems as they are permanently installed. Mobile robotic systems are usually stationarily positioned, at least for the time they perform work. only the arms or joint elements of the robot move, the base remains in one place.

The imaging system includes, among other things, an imaging device and a patient receptacle. The image capture device may be, for example, the gantry of a computed tomography device. The patient admission is designed to record an examination object, generally a patient, during an intervention in the context of computer-assisted surgery and to position it along the system axis. When recorded by a computed tomography device, a radiation source and a radiation detector cooperating with the radiation source rotate about the system axis. The radiation source emits radiation in such a way that this radiation is basically detectable for the radiation detector. The radiation is weakened by the respective examination object, in particular by absorption and reflection of the radiation. The data recorded by the detector is assembled into an absorption image and displayed on a terminal.

The imaging system can be assigned a coordinate system which is essentially defined by the orientation of the image recording device in space. It lends itself to an axis along the system axis to arrange and two more coordinate axes each perpendicular to and to each other.

To ensure a precise action of the robot, the system must know where in the room the robot is positioned. The position of the arms and thus the orientation of the robot with respect to its own coordinate system, which has the stationary foot of the robot as a base, is thus known.

The position of the tip of the robot, which may include a gripping, cutting or other tool, is thus defined by a so-called POSE. The POSE is a value that describes a point with orientation in space. This value consists of six entries. The first three describe the coordinates in space (x, y, z), entries four to six describe the orientation in space. With the latter, there are various ways to describe this. An example would be the application of Euler angles in a specific convention.

The problem now is to relate the POSE and the coordinate system of the imaging system. According to the invention, this is done by using the image acquisition device of the imaging system to define the position of the robot system in space with respect to the coordinate system of the image acquisition device.

For this purpose, the imaging system must be able to detect the robot or at least a part thereof and thus detect the position of the robot within the captured image. Then, the position of the robot can be basically coordinated with that with the coordinate system of the image pickup device.

In general, however, the tip of the robot can not be easily detected by the image pickup device. Consequently, the robot should influence the recording as little as possible in order not to have to accept any loss of image quality.

Therefore, a particularly preferred embodiment of the inventive method provides that at least one marker is used for the definition of the position of the robot system in the coordinate system of the imaging system, which can be detected by the image recording device.

It is particularly advantageous if a marker is used which clearly reproduces the position in space. With such a marker, it is possible to determine the position of the robot with only a single shot by means of the image pickup device.

Otherwise, you can make with any marker at least at three different positions recordings using the image pickup device. In this way, then the position of the robot in the coordinate system of the image pickup device can be uniquely determined.

The registration, as performed by a robot, can also be performed with multiple robots. If a plurality of robots are already sufficiently registered with each other beforehand, registration of a robot with the coordinate system of the image pickup device is sufficient to completely define the system as a whole. By designing different markers, a unique determination of a robot can be realized. In a recording, two or more markers can be distinguished from each other and simultaneous registration is possible.

The invention also includes an imaging system, in particular a computed tomography system, which usually comprises at least one robot system in CAS methods. Typically, the imaging system includes an image capture device and a patient acquisition, wherein the imaging system defines a coordinate system through its orientation in space. The at least one robot system should, at least during operation operation, be fixedly positioned at one end on a patient positioned on the patient seat.

According to the invention, a marker is attached to the non-stationary end of the at least one robot. It is unavoidable that the marker is detectable by the image recording device, and that the imaging system is designed such that the position of the robot with respect to the coordinate system of the imaging system is definable by the inclusion of the marker by the image sensing device.

This is of course particularly the case when the marker (s) clearly represent their position in space, so that the position of the or each robot relative to the coordinate system of the imaging system can be defined by a single exposure by the image capture device.

With the imaging system according to the invention, it is also possible to operate a plurality of robots, wherein each robot ideally should have its own markers distinguishable by the image recording device, so that the position of each robot relative to the coordinate system of the imaging system can be defined by the recording of the respective marker by the image recording device is.

The imaging system according to the invention is particularly suitable for microsurgical, minimally invasive interventions.

The invention also includes a robotic system suitable for carrying out the method described above and for use with an imaging system as described above. One end of the robot, i. the foot or attachment should ideally be fixed in position on a patient positioned on the patient's seat, at least during an action. According to the invention, a marker is attached to the non-stationary end of the robot, the marker is detectable by the image recording device. As a result, the position of the robot with respect to the coordinate system of the imaging system can be clearly defined by the recording of the marker by the image recording device of the imaging system.

Particularly preferred is an embodiment of the robot system according to the invention, which has a marker that clearly reflects its position in space, so that the position of the robot with respect to the coordinate system of the imaging system is definable by a single shot by the image sensing device.

The robotic system according to the invention is particularly advantageous for microsurgical, minimally invasive interventions.

The minimum requirement for the marker is three points that can be easily recognized by the recorder. It would be preferable to have an arrangement which ensures that by these points two vectors are spanned, which are mutually orthogonal. One point is at the intersection of both vectors. In addition, the dots should be as small as possible to avoid inaccuracies, but at the same time so large that they can be reliably detected by the image capture device. Distant points increase accuracy.

The three points must be clearly distinguishable in the recorded image from the rest of the structure, in particular the tissue of the patient. This can be achieved by the correct choice of shape or material. Materials that have comparatively little contrast to the rest of the structure, such as plastic or carbon fiber, use shapes that are easy to recognize in the image and thus easy to identify. These can be, for example, triangles or squares, in particular with balls in the corners. These structures are so special that they are easy to find and can not belong to other structures, especially the patient. If possible, the material should not create artifacts in the imaging, otherwise the accuracy suffers. Plastic, carbon fiber or polyester are particularly preferable here. But even small metallic objects, for example, small balls of ball bearings can be used, provided that the metallic objects are small enough. Markers should be preferred from a material, on the one hand not is so dense that all X-rays are absorbed, but on the other hand, it is not almost permeable to X-rays. Otherwise, the marker in the X-ray image can not be recognized exactly.

If the movement of the image recording device and the robot is relatively and precisely measurable to each other, then a simple registration is sufficient. Thus, a registration before each recording is not required. Only undefined movements (e.g., reassembly of the robot or the like) necessitate re-registration.

Show it:

1 a schematic representation of an embodiment of an imaging system according to the invention;

2 a schematic representation of the coordinate systems before registration;

3 a schematic representation of the coordinate systems after registration;

4 a schematic representation of two embodiments of inventive marker.

1 shows an inventive imaging system, in the embodiment shown here, a computed tomography system 1 , In the examples shown here, a patient P lies on a patient couch when taking measurement data 8th , The patient bed 8th is adapted to the patient P during a tomographic recording along a system axis 9 to proceed. When recording the measurement data, a radiation source rotates 2 and one with the radiation source 2 cooperating radiation detector 5 around the system axis 9 , The radiation source 2 emits radiation of the way that this radiation for the radiation detector 5 is basically detectable. The radiation is weakened by the respective examination object, in particular by absorption and reflection of the radiation.

At the in 1 In the exemplary embodiment shown with a computer tomograph, the X-ray detector is a detector with a plurality of rows and columns. The X-ray detectors can each be designed both as a scintillation counter and as directly converting X-ray detectors. Furthermore, they can be designed as counting X-ray detectors which are designed to detect and count individual photons. Furthermore, the computer tomograph has the in 1 shown example of two pairs of interacting radiation sources 2 . 4 in the form of x-ray tubes and radiation detectors 5 . 4 in the form of x-ray detectors. As a result, the computer tomograph shown here is particularly suitable for multiple energy recordings, in which the two x-ray tubes each emit x-radiation with a different energy spectrum. In further, not shown embodiments, the computed tomography of a computed tomography system according to the invention 1 only via one X-ray tube as a radiation source and one X-ray detector as a radiation detector. In a computed tomography scanner, x-ray tube and x-ray detector are in the gantry 6 integrated. The gantry 6 The computed tomography device may be designed such that it is at least one axis perpendicular to the system axis 9 is tiltable. The orientation of the gantry in space defines the coordinate system CT-KOS of the image capture device 6 ,

In addition, the computer tomography system shown here has 1 also via a contrast agent injector 11 for the injection of contrast agent into the blood circulation of the patient P. This allows the measurement data to be recorded by means of a contrast agent such that, for example, the vessels of the patient P can be displayed with an increased contrast. Furthermore, a computed tomography system according to the invention comprises a computer 10 which is also referred to as a workstation. The computer shown here 10 is designed to control the individual units of the computed tomography system such as for controlling the patient bed 8th , the contrast agent injector 11 and the X-ray tube and the X-ray detector. The computer 10 is connected to an output unit and an input unit. The output unit is, for example, one (or more) LCD, plasma or OLED screen (s). The output on the output unit includes, for example, a graphical user interface or the output of image data. The input unit is designed to input data such as patient data as well as to input and select parameters for the individual units of the computed tomography system. The input unit is, for example, a keyboard, a mouse, a so-called touchscreen or even a microphone for voice input.

Next belongs to the computed tomography system according to the invention, a robot system 12 , The robot system is with one foot 13 fixed or fixed either on the ground, on a wall or on the ceiling. The individual arm elements 14 of the robot system 12 are through joints 15 connected.

At the robot system according to the invention 12 is a marker 17 arranged. The position of the robot in space with respect to the coordinate system CT-KOS of the gantry 6 must define the Image pickup device (gantry) 6 through his own recordings the marker 17 identify. The marker 17 can be different. The interaction of markers 17 and captured image gives the exact location of the robot system 12 in space in relation to the coordinate system CT-KOS of the gantry 6 , The interaction of markers 17 and intake can be different. It always requires a clearly recognizable position of the robot from the recordings 12 in the room. This can be achieved, for example, as follows:
• a marker 17 (Dot) is recorded several times but at least three times at different positions in one or more images.
• One marker 17 is so pronounced that it clearly reproduces the situation in the room with a picture

The individual elements 14 of the robot 12 (Multi-body system) know their position to each other. The kinematic chain is the robot 12 is thus known throughout. This also applies to the position of the marker 17 on the robot 12 to.

The position of the tool 16 on the robot system 12 can be described by a so-called POSE. The POSE is a value that describes a point with orientation in space. This value consists of six entries. The first three describe the coordinates in space (x, y, z), entries four to six describe the orientation in space. With the latter, there are various ways to describe this. An example would be the application of Euler angles in a specific convention.

Now eg a picture of the 3D marker 17 made or multiple images of a point marker 17 in different positions, is the orientation of the robot 12 to the image coordinate system CT-KOS known. Once the reference of the image coordinate system CT-KOS to the robot coordinate system ROB-KOS is created, the robot can 12 every point in the shots of the gantry 6 drive.

In 2 schematically shows the situation before the registration of the robot system. The basic coordinate system CT-KOS is processed by the image pickup device 6 and defines its orientation in space.

The robot coordinate system ROB-KOS is initially arbitrarily oriented in space. Only the base is by the stationary foot 13 of the robot system 12 established. Because the robot elements 14 transmitting their position in space is also the position of the top of the robot system 12 known. This can be described by a so-called POSE. First, the coordinate systems ROB-KOS or POSE and CT-KOS are still independent of each other.

In 3 schematically the situation after the registration of the robot system is shown. The coordinate system POSE the top of the robot system 12 and the coordinate system CT-KOS of the imaging system 6 are coordinated. Thus, the reference of the image coordinate system CT-KOS to the robot coordinate system ROB-KOS is created, so that the robot 12 every point in the shots of the image capture device 6 can drive. In 4 are schematically two examples of possible embodiments of a marker according to the invention 17 shown.

The minimum requirement for the marker 17 are three points that can be easily recognized by the recorder 18 , To prefer would be an arrangement which ensures that by these same points 18 two vectors are spanned, which are orthogonal to each other. It should be the one point 18 lie on the intersection of both vectors. The points 18 In addition, they should be as small as possible to avoid inaccuracies, but at the same time so large that they can be reliably detected by the image pickup device. Distant points 18 increase the accuracy.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005034683 A1 [0003]
• EP 2561821 A1 [0007]
• US 2006/0149147 A1 [0007]
• US 2009/0088773 A1 [0007]

Claims (16)

Method for registering robot systems ( 12 ) on imaging systems ( 1 ), in particular computed tomography systems, wherein the imaging system ( 1 ) an image capture device ( 6 ) and a patient admission ( 8th ), wherein the imaging system ( 1 ) is assigned a coordinate system (CT-KOS), which essentially by the orientation of the image pickup device ( 6 ) is defined in space, and wherein the robot system ( 12 ) at least during an action on one of the patient admissions ( 8th ) positioned patients (P) at one end ( 13 ) is stationary, characterized in that the image pickup device ( 6 ) of the imaging system ( 1 ) is used to determine the position of the robot system ( 12 ) in the space relative to the coordinate system (CT-KOS) of the imaging system ( 1 ) define. Method according to claim 1, characterized in that for the definition of the position of the robot system ( 12 ) in the coordinate system (CT-KOS) of the imaging system ( 1 ) at least one marker ( 17 ) used by the image pickup device ( 6 ) can be detected. Method according to claim 2, characterized in that a marker ( 17 ) is used, which clearly reflects the situation in space Method according to claim 2 or 3, characterized in that a marker ( 17 ) at least at three different positions in the images of the image recording device ( 6 ) is recorded. Method according to claim 3, characterized in that with the marker ( 17 ) only one recording by means of the image recording device ( 6 ) is carried out. Method according to one of the preceding claims, characterized in that the method comprises a plurality of robot systems ( 12 ) can be registered. Imaging system ( 1 ), in particular computer tomography system, comprising at least one robot system ( 12 ), whereby the imaging system ( 1 ) an image capture device ( 6 ) and a patient admission ( 8th ), wherein the imaging system ( 1 ) defined by its orientation in space a coordinate system (CT-KOS), and wherein the at least one robot system ( 12 ) at least during an action on one of the patient admissions ( 8th ) positioned patients (P) at one end ( 13 ) is stationary, characterized in that at the non-stationary end ( 16 ) of the at least one robot system ( 12 ) a marker ( 17 ) is attached, that the marker ( 17 ) through the image capture device ( 6 ) is detectable, and the imaging system ( 1 ) is formed such that by receiving the marker ( 17 ) through the image capture device ( 6 ) the position of the robot system ( 12 ) with respect to the coordinate system (CT-KOS) of the imaging system ( 1 ) is definable. Imaging system according to claim 7, characterized in that the imaging system ( 1 ) several robot systems ( 12 ), each robot system ( 12 ) own, through the image capture device ( 6 ) distinguishable markers ( 17 ) and wherein in each case the position of each robot system ( 12 ) with respect to the coordinate system (CT-KOS) of the imaging system ( 1 ) by the inclusion of the respective marker ( 17 ) through the image capture device ( 6 ) is definable. Imaging system according to one of claims 7 or 8, characterized in that the marker (s) ( 17 ) clearly represent their position in space, so that the position of the or each robot system ( 12 ) with respect to the coordinate system (CT-KOS) of the imaging system ( 1 ) by a single shot through the image capture device ( 6 ) is definable. Imaging system according to one of claims 7 to 9, characterized in that the imaging system ( 1 ) is designed such that microsurgical, minimally invasive interventions are executable. Robot system ( 12 ) for an imaging system ( 1 ), in particular computed tomography system, according to one of claims 7 to 10, wherein one end ( 13 ) of the robot system ( 12 ) at least during an action on one of the patient admissions ( 8th Positioned patient (P) is stationarily positioned, dadu rch characterized in that at the non-fixed end ( 16 ) of the robot system ( 12 ) a marker ( 17 ) is attached, that the marker ( 17 ) through the image capture device ( 6 ) is detectable, and that by the inclusion of the marker ( 17 ) through the image capture device ( 6 ) of the imaging system ( 1 ) the position of the robot system ( 12 ) regarding the Coordinate system (CT-KOS) of the imaging system ( 1 ) is definable. Robot system according to claim 11, characterized in that the marker ( 17 ) clearly reflects its position in space, so that the position of the robot system ( 12 ) with respect to the coordinate system (CT-KOS) of the imaging system ( 1 ) by a single shot through the image capture device ( 6 ) is definable. The robot system according to claim 11 or 12, characterized in that the robot system ( 12 ) is designed such that microsurgical, minimally invasive interventions are executable. Markers ( 17 ) for use with a method according to one of claims 1 to 6, an imaging system according to one of claims 7 to 10 or a robot system according to one of claims 11 to 13, characterized in that the marker ( 17 ) during a recording with the image recording device ( 6 ) of the imaging system ( 1 ) is detectable, and that the marker ( 17 ) three through the image capture device ( 6 ) well detectable points ( 18 ) having. Marker according to claim 14, characterized in that by the image acquisition device ( 6 ) well detectable points ( 18 ) Two vectors are spanned, which are orthogonal to each other. Marker according to claim 14 or 15, characterized in that the marker ( 17 ) is made of a material which, when being picked up by the image recording device ( 6 ) causes no image artifacts in the recording, and that the signal of the marker ( 17 ) in the recording differs from the expected signal of the patient (P).

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