DE29623941U1 - Neuronavigation system - Google Patents

Description

Attorney file: 45 442 X

Applicant: BrainLAB Med. Computersysteme GmbH

Neuronavigation system

The invention relates to a reflector referencing system according to claim 1 and a marker system according to claim 11.

Neuronavigation systems establish the connection between the treating surgeon, i.e. the patient's anatomy as he sees it during treatment, and diagnostic data obtained, for example, by a computer tomography scan and visually displayed by a computer unit with an image output.

In order to establish the above-mentioned connection, i.e. to make the current patient anatomy and position as well as the real spatial position of surgical instruments and treatment apparatus visible on the computer screen, devices must be provided which can determine the patient position and thus the exact location of the body parts to be treated as well as the location of the surgical instruments and in particular their tips in an initial position and track them during the operation.

For this purpose, a computer unit is usually provided to which two or more reference cameras are connected. The cameras are then used to determine the spatial position of artificial or natural landmarks attached to patients as well as the spatial position of radiation emitters attached to surgical instruments.

In previous systems, the landmarks attached to the patient are handled as follows:

Before the CT scan is performed, a set of artificial landmarks is attached to the patient in the area to be treated. These landmarks, which can be captured by cameras both during the CT scan and later during the treatment, are completely identical to one another. They are stuck on using plasters, for example.

After the treatment, the data from the computer tomography, i.e. both the position data of the identical artificial landmarks and the position of the treatment target and the surrounding areas, are entered into the computer system, which is arranged on the operating table together with the referencing or recording cameras. This is followed by a time-consuming step in which the surgeon has to point to the individual landmarks on the patient with a pointing device, after which he has to enter into the computer which of the identical landmarks in the operating position corresponds to the one recorded in the computer tomography. To do this, all of the landmarks have to be approached several times, and each time the complex manual assignment to the computer tomography (CT) data has to be carried out. Since the landmarks attached with plasters do not have any characteristic reference points that cannot be missed when approaching them with the tip of an instrument, only a relatively imprecise position determination can take place.

Another disadvantage is that the conventional landmarks are no longer easily visible after being covered with sterile cloths due to their flat design and can therefore no longer be positioned precisely if the patient is already covered. This causes particular difficulties if the patient changes position at a later stage of the operation and the landmarks have to be moved to again with a pointing device for readjustment.

Another disadvantage is that once the known landmarks have been attached to the patient, they can no longer be removed in such a way that they can be replaced by other landmarks with the same exact position.

Conventional radiation systems for surgical instruments and treatment devices are constructed as follows:

Two or more active emitters, which emit infrared rays, for example, are attached to each instrument or treatment device and act as point emitters on a surface. The instrument contains an electronic device that enables the signals to be emitted, with the instrument being connected to the computer unit at its rear end by a cable. The computer unit can use the emitted signals to

Identify the spatial position of the instruments or their tips.

This conventional instrument referencing system, as known from DE 296 OO 990 Ul, for example, also has some disadvantages, which are discussed below. Even the use of active, i.e. self-emitting signal generators has the disadvantage that electronic devices must be provided in the instruments, which makes the manufacture of the instruments more expensive. The cables to the computer unit attached to each instrument are also a hindrance during operations and can be very in the way of treatment given the large number of instruments that often have to be used.

The emitters, which are arranged as points on a surface of the instrument, can only be detected by the camera system within a very limited angular range, i.e. they can easily be covered by the instrument itself or the surgeon's hand.

These instruments can only be sterilized using gas sterilization. Gas sterilization can take up to a day, meaning that if they are used frequently, several sets of instruments must be purchased in order to have sterilized treatment equipment available at all times.

A serious disadvantage of the traditional referencing system is that the surgeon can only use the instruments provided by the manufacturer. However, many surgeons are used to their own set of instruments and would have to adapt when using a different predetermined set of instruments, which can also have a negative impact on the treatment outcome.

The disadvantage is that conventional neuronavigation systems do not provide a simple calibration system with which the angle or distance position of the acquisition or referencing cameras can be recorded or recalibrated at any time without complications. Since these cameras are often subject to changes in position during an operation, for example if one of the treating persons bumps into the camera stand, quick and easy recalibration during the treatment is of great importance.

From US-A 5,389,101 a method and a device for photogrammetric surgical localization are known, as described by the preamble of claim 1. Disadvantageously, the system works with video cameras that capture visible light, so that distinguishing the reference markers reflecting this light from other light reflections in the surgical area is very difficult and requires a high level of computational effort.

A surgical microscope is usually used in neurosurgical treatments. Such microscopes are usually devices mounted on heavy feet and frames, with the actual microscope attached to the end of an articulated arm that allows the microscope to be moved both manually and by motor and can report position data, for example by recording the angle of the arm joints, to a computer unit used in neuronavigation.

The feet or stands of such microscopes must be very heavy and stable so that if the microscope is bumped into, its position could be changed and the entire neuronavigation of the microscope, which has only been calibrated to the initial position, does not collapse. In fact, microscopes cannot usually provide any additional position feedback to the neuronavigation computer other than the position data resulting from the arm position.

Finally, ultrasound diagnostic systems, such as those used for examinations during pregnancy, are often used in neurosurgical treatments. The disadvantage of conventional systems was that the position of the body parts detected could be determined in relation to the ultrasound emitter and receiver, but it was not possible to easily classify this data in a neuronavigation system provided on the operating table.

An ultrasound diagnostic system in which the ultrasound head can be localized by means of the actively emitting LEDs previously described as disadvantageous is known from US-A 5,197,476.

It is the object of the present invention to use a reflector referencing system

or a marker system to make the localization of surgical instruments and treatment equipment as well as the referencing of the patient's anatomy and the treatment activity significantly easier and more precise.

This object is solved by the subject matter of the independent claims. Advantageous embodiments are defined by the subclaims.

The referencing system works with passive reflectors instead of active signal emitters known from the state of the art. It is used for surgical or medical instruments and treatment equipment. For this purpose, a radiation source for infrared radiation, at least two cameras and a computer unit connected to the cameras with a graphic screen output are used. The reflector referencing system has at least two reflectors for this infrared radiation, which are attached to instruments or treatment equipment in an arrangement that is only characteristic for this group of reflectors. The advantage of such a referencing system with passive signal transmitters, i.e. reflectors, is in particular that, due to the characteristic individual arrangement of the reflectors, each surgical instrument reflects a detectable image that is only characteristic for this instrument itself. The computer unit therefore immediately recognizes each individual instrument via the camera detection and can, for example, clearly show its tip position on the screen.

Since passive, i.e. reflective emitters are used, no cable connection to the computer unit and no electronic "inner workings" of the instruments are required. This gives the surgeon greater freedom of movement; obstructions caused by cables are eliminated.

The reflectors, which can be attached to instruments or treatment equipment using adapters, make it possible to carry out autoclave sterilization of the instruments when the reflectors are removed. In contrast to the gas sterilization used in the state of the art, such autoclave sterilizations can be carried out in a much shorter time (about 20 minutes). It is therefore only necessary to provide one or more sets of sterilized reflectors, which are adapted to the

Instruments sterilized by autoclave sterilization can be applied. This means that it is no longer necessary to provide several sets of complete instruments, as was the case with the current state of the art.

The reflectors, which can be removably attached to the surgical instruments using adapters, can be positioned at a certain distance from the attachment surface. This measure results in a much larger angular range in which the reflectors can still be detected by the camera system compared to conventional systems.

According to an advantageous embodiment of the reflector referencing system, the reflectors are spherical and provided with a reflective coating. Such spheres produce a uniform reflection image when viewed from all spatial directions.

Advantageously, two of the reflectors are attached to an instrument, in particular a pointer or a calibration rod, via attached plug connections. Such plug connections allow the reflectors to be attached and removed with precise positioning and easily. The distances between the two reflectors are determined by the positions of the plug connections for each instrument, which enables it to be located and identified by the navigation system in every phase of the operation.

According to a further embodiment of the referencing system, three reflectors are attached to at least one arm end of an adapter designed with three reflector arms and a fastening foot, wherein the fastening foot can be attached to a surgical instrument or a treatment device. The three reflectors attached to the arm ends of the adapter are in turn provided in a characteristic arrangement, i.e. for each adapter, for example, the angle position of the arms and their length are individually unique, which creates a characteristic reflection image for each adapter. The great advantage of this embodiment is that such a group of reflectors with their adapter can be attached to practically any surgical instrument via their fastening foot. This opens up the possibility for a surgeon to continue using his usual instruments, i.e. to integrate them into the neuronavigation system. All that is required here is a short calibration on a reference adapter, which will be described later, in order to

to communicate the position of the tip of the surgical instrument. This adapter system also simplifies the sterilization of the instruments in the manner already discussed. The system provides a sufficient number of adapters with characteristic reflector groups so that all necessary instruments can be used with the neuronavigation system.

The above-mentioned reference adapter also comprises a mounting base which has three reflectors which can be fastened in a particularly characteristic arrangement at the end of three arms, the base being provided at its end with a clamping device which can be flexibly adapted to the respective fastening point.

This reference adapter has two functions in particular. Firstly, it can be attached to a point that is firmly connected to the operating table, for example to the holding device for the part of the body to be treated. This, and the fact that the computer unit assigns its characteristic image only to this reference adapter, ensures that precise positioning of all patient anatomy data and a reflection pattern that is fixed to the patient is still possible even if it becomes necessary to move or tilt the operating table during an operation, or if there are accidental changes in position due to a bump. The reflection of the reference adapter reports the position of the system part that is firmly connected to the patient to the computer unit at all times, so that no inaccuracies or breakdown of navigation can occur due to such shifts.

The clamp on the attachment base of the reference adapter can be designed in different ways. For example, it is designed for attachment to a holding device with a screw clamp, while if it is attached to a bone part, soft and positionally flexible clamp ends are used, which do not damage the bone tissue. The latter option is particularly useful for operations in the spinal area, where the reference adapter is attached to vertebral processes, for example.

According to one embodiment of the reference adapter, it preferably has a conical funnel trough with a centric calibration point at the starting point of the three arms.

This is where the second function of the reference adapter comes into play. As already explained above, the reference adapter in the navigation system is a point that is fixed in position relative to the patient. This property can be exploited by simultaneously assigning a calibration point to the reference adapter, which can be used to determine the tip positions of surgical instruments. As will be explained below, the spatial position of other equipment can also be determined using this calibration point.

Surgical instruments, particularly instruments that the surgeon has been working with for a long time, can be equipped with a three-reflector adapter, as described above, which then produces a reflection image that is characteristic of this instrument. However, the navigation system must be informed where the tip of this instrument is located. The calibration point on the reference adapter is used for this. The surgeon brings the tip of his instrument to the known calibration point. This is made easier by the funnel shape of the conical depression that converges at this point, and the tip is also fixed so that it lies completely still. The surgeon then carries out a few spatial movements with the end of the surgical instrument where the three-reflector adapter is located. During this movement, since the tip of the instrument is stationary, each reflector moves on a path that lies in a spherical surface with the vertical distance of the reflector from the center of the funnel. The computer unit of the navigation system can identify this special movement and "knows" that a tip calibration is currently being carried out with this three-reflector adapter. It calculates the distance of the tip to the respective reflectors and thus the tip position of the surgical instrument and assigns this to the characteristic reflector pattern of the three reflectors attached to the instrument. The instrument is thus calibrated and clearly identified; it can be used throughout the entire operation.

The marker system for referencing and determining the position of body parts to be treated neurosurgically comprises at least three artificial landmark attachments and the same number of fastening devices for attaching the landmarks to the patient. Each individual landmark attachment provides a characteristic signal that is unique to itself both for diagnostic patient data acquisition and for subsequent treatment monitoring.

Image. For treatment monitoring, the landmark attachments are designed as reflectors for the infrared radiation from a radiation source.

Compared to the state of the art, which, as already mentioned, works with identical landmarks, for example those stuck on with plasters, the marker system has the following advantages:

The landmarks can be recorded individually during the computer tomography and automatically recognized by the navigation system after the computer tomography. The individually determined and recorded landmarks are assigned to only one position in the spatial coordinate system. There is no risk of the landmarks being confused when they are recorded by the neuronavigation system via the camera.

This design eliminates the need for the lengthy first referencing step for the landmarks, which was previously considered negative in the state of the art. The surgeon still has to approach at least three landmarks individually. However, the task of manually assigning the position of each landmark is eliminated, as the neuronavigation system recognizes the reflection of the landmark approached and assigns its position only to the landmark recorded in the computer tomography that produces the same characteristic image. This saves all the time required for the landmark assignment. As the spatial arrangement of the landmarks in relation to one another also produces a characteristic image in the neuronavigation system, it is usually sufficient to approach three landmarks with a position pointer, the tip position of which is known to the system, for example via an aforementioned reflector arrangement, in order to carry out sufficiently accurate referencing of the patient's anatomy data. The marker system therefore advantageously allows much faster and more accurate position determination and referencing of body parts to be treated neurosurgically.

The landmark attachments or landmarks described above can consist of metal bodies that can be individually distinguished due to their specific material density, size, shape and arrangement in relation to one another during data acquisition in a computer tomograph and during position detection with infrared cameras. They preferably consist of

Fastening devices made of removable aluminum bodies that have a specific shape or size. Such aluminum bodies are easy to manufacture and are easy to grasp due to their metallic nature. They are also relatively light and therefore do not detach the fastening devices to which they are detachably attached from the patient due to their own weight. The two-part nature of the landmarks also plays a special role. The fastening devices, which are attached to the patient's skin at their lower part with an adhesive, for example, can be designed to be slightly raised, for example as a base. The respective landmark can be attached to this base using a plug connection or another type of quick-release fastener. This basically makes it possible to exchange the landmarks to carry out special adjustment processes. Furthermore, the entire marker with fastening base and attached landmark stands out so much from the patient's anatomy that it can still be easily located even after being covered with sterilizing cloths.

In a particularly preferred embodiment, the marker system is supplemented by comprising an additional set of funnel-shaped landmarks, the center of the funnel corresponding to the center of the landmarks for which they can be exchanged before referencing on the operating table.

Such an addition to the marker system can greatly increase the accuracy of the positioning and referencing of the patient's anatomy. The landmarks used in computed tomography are removed from the attachment devices on the patient after the computed tomography and replaced by landmarks that have a device such as a tapered inner funnel. Using such an inner funnel, the middle or starting point of which is positioned exactly in the center of the landmark, the tip of a surgical instrument can be positioned immovably and precisely during referencing.

For example, if the landmark used in the CT scan was a sphere with a certain diameter, this can be replaced after the CT scan by, for example, a three-quarter sphere with the same diameter, which has a funnel at its upper section that converges exactly at the center of the sphere.

The three-quarter sphere is still identifiable as the same landmark as the full sphere it replaced because of its identical diameter.

During the previously described landmark recognition step, the surgeon can now use a position indicator to move precisely to the center of the landmark due to the funnel shape. This makes it easy to avoid inaccuracies when moving to this point, as can occur with the state-of-the-art system, whose landmarks do not have distinct locations, and the referencing and positioning of the landmark center is carried out with excellent accuracy. In this referencing process, as in the calibration process explained above, the tip of the position indicator can be held in one place using the calibration point of the reference adapter while its end is moved. When referencing the respective landmark, the computer unit is informed that landmark referencing is currently taking place by the tip remaining still while the position indicator is moving.

The "funnel design" is also advantageous when the landmarks need to be re-referenced for some reason during an operation. If the patient has already been covered with sterile cloths and the landmarks are under these cloths, they are still easy to identify due to their raised structure. Due to the funnel shape and because the sterilization cloths are thin, the center of the landmarks can now be positioned very precisely even if the landmarks are already covered with cloths. If the referencing needs to be repeated, the patient does not have to be freed from the cloths and covered again after the referencing, which is never possible in practice.

In a calibration procedure for determining the angle and distance position of referencing cameras, a calibration tool with two reflectors attached at predetermined positions with a known distance is introduced into the recording area of both cameras, the calibration tool is spatially moved in the recording area, several intermediate positions of the calibration tool of the referencing cameras are recorded and individually converted into spatial coordinates by means of a computer unit, and the computer unit calculates and stores the angle and distance positions from the spatial positions of the reflectors.

Distance between the cameras.

The possibility that one of the participants in the operation could bump into the camera stand or the cameras themselves during an operation is not completely unreasonable. However, if the position of the cameras changes during an operation, suddenly changed images can be delivered to the computer system. The previously described method offers an advantageous option for carrying out a recalibration that takes little time, but also for easily carrying out an initial calibration. The computer unit knows the shape of the reflectors and their distance on the calibration tool and can therefore, in a separate camera position calibration step, recognize this calibration tool when it is swiveled in the recording area of the cameras. The information resulting from "snapshots" of several positions of the calibration tool during its movement allows the computer unit to draw conclusions about the camera position based on the known data of the calibration tool. The computer unit can record the camera position after just a short time. This method saves time during the initial setup and, because it is quick to implement and simple, is also ideal for readjustment after a camera position change.

When moving the calibration tool spatially during the camera calibration process, it is advantageous if both reflectors are as far apart as possible at all times, in relation to the projected camera detection plane. Therefore, in an advantageous embodiment of the calibration process, the spatial movement of the calibration tool and thus of the reflectors is continuously displayed on a graphic screen output, for example the screen of the neuronavigation system. The movements can then be carried out in such a way that both reflection points on the screen are always as far apart as possible, which enables faster and more precise calibration.

A pointer equipped with removable reflectors can be used as a calibration tool, which is required for every operation anyway. The data of the reflectors and their distance are then entered into the system as data of the calibration tool.

Alternatively, it is possible to use a separate calibration rod with removable reflectors, which is then used each time as part of the respective system. Advantageously, such a calibration rod can be longer than, for example, a pointer. This also improves the speed and accuracy of the calibration.

The reflector referencing system can also be used to control a surgical microscope. The microscope can comprise a microscope stand with a base and several arms that are connected to one another and can be moved in space by motor and manually, and a microscope holding or control unit.

Initially, it was found to be a disadvantage of state-of-the-art microscopes that they can only report their position back to a computer unit of a neuronavigation system based on the angular position of the support arm parts. They therefore have to be equipped with very heavy stands and feet so that an unintentional movement of the microscope cannot make neuronavigation referenceless and thus end it.

The use of the referencing system for microscope control now offers the possibility of further feedback of the position data of the microscope. Due to the special arrangement of the reflectors, a neuronavigation system can identify this arrangement as a microscope reflector arrangement at any time. The microscope position is thus communicated to the computer via the camera system as an immediate spatial position. Even if the microscope is moved, the data from the arm joint position and that from the reflector position can therefore be compared at any time; neuronavigation remains intact even if the microscope changes position unintentionally.

Advantageously, the spatial position of the microscope is determined during a first calibration by focusing the microscope optics on a point with known spatial coordinates, preferably the calibration point of a reference adapter, wherein the focusing data are transmitted to the computer unit by means of a data transmission device, while the same computer unit determines the spatial position of the microscope by means of the reflectors and the cameras.

This is where the previously mentioned calibration function of a reference adapter, which is also equipped with a three-reflector arrangement, comes into play again. In order to inform the computer unit where the microscope is in a starting position, the focus of the microscope can be focused on the funnel center of a previously described reference adapter. The computer then receives data on the zoom factor and the focusing distance from the microscope via a data transmission device, for example a data line, and thus knows the position of the focusing point because the spatial location of the calibration point is known, as well as the position of the microscope from the reflection points of the reflectors attached to the microscope. From this data, an exact position of the microscope can be determined.

After the first calibration, it is now also possible to carry out the following control sequences by controlling the movement motors of the microscope via the computer unit or by providing feedback of the microscope movements and position data to the computer unit:

a) automatic tracking and focusing of an instrument tip, the position of which is known to the computer unit via reflectors;

b) automatic focusing of a stored or predefined treatment point; and

c) Focusing a treatment point from different spatial and angular positions of the microscope.

This allows the following activities to be carried out: The surgeon points to a spot on the area to be treated with the tip of a position indicator equipped with reflectors and known to the navigation system, whereupon the computer unit identifies the coordinates of this spot and moves the microscope to this spot and sets the focus precisely there. This saves the surgeon time-consuming maneuvering with the microscope control system. The surgeon can also give the system a specific point that he has already focused on to save. This point can then be focused again by the microscope at any time with a simple command. Sometimes, especially when focusing on cavities with only small openings, the imaginary micro-

The scope focus line can be "swivelled" around this opening. With this control it is also possible to store the swivel point of this line and to carry out the previously described illumination.

Furthermore, it is possible to use a referencing system according to the invention for referencing an ultrasound diagnostic system with an ultrasound emitter and receiver and an evaluation unit and a screen output connected to them. This is characterized in that a reflector adapter with at least three reflectors is attached to the ultrasound emitter and receiver, which is integrated in a reflector referencing system described above.

With this kind of training, the data obtained with an ultrasound diagnostic device can now be placed in a neuronavigation system. The ultrasound emitter and receiver also have a group of reflectors with a special arrangement that is identified only for them by the computer. If the data obtained by the ultrasound system is compared with the anatomical data from the computer tomography, this system can also prevent difficulties that arise, for example, when the tissue to be treated "collapses" slightly after the tissue layers above the treatment area have been opened.

The reflector referencing system according to the invention can be used in a neuronavigation system with a marker system according to the invention, whereby the microscope control can also be used. All of these system parts can be used and implemented separately, but can also be used in any combination, whereby the advantages described above over the prior art come into play.

In the following, embodiments of the invention will be explained in more detail with reference to the accompanying figures. They show:

Figure 1 shows a frame in which a computer unit with operating elements is housed, on which a computer monitor stands as a graphic screen output unit and to which a camera holder with two infrared cameras is attached;

Figure 2 shows a neurosurgical pointer with reflectors attached to it;

Figure 3 a pair of surgical forceps, to the rear end of which an adapter with three specially arranged reflectors is attached;

Figure 4 shows a cross-section through a pointer provided with two reflectors;

Figure 5 is a plan view of a reference adapter with three reflectors and a calibration point;

Figure 6 is a reduced view of a calibration rod;

Figure 7 shows a landmark attachment as used in a computed tomography scan;

Figure 8 shows a landmark attachment as used for referencing landmarks on the operating table;

Figure 9 shows a cross-section through a mounting base for the landmark attachments from Figures 7 and 8; and

Figure 10 is a plan view of the mounting base of Figure 9.

In an operating room in which the neuronavigation system is used, there is a frame at one end of an operating table, for example, as indicated in Figure 1 with the reference number 10. A computer unit 11 and various other control units, such as a keyboard (not designated), are housed in this frame. Connected to this computer unit is the screen 12 placed on the frame. This displays sectional planes or images of the patient's anatomy in various views, including a 3D view, and also shows the positions of surgical instruments or reflectors on these instruments and on treatment equipment. In addition, additional information can be output in various fields.

A camera holder 13 is also attached to the upper part of the frame on which the screen 12 stands. This camera holder 13 is adjustable and carries two infrared cameras, designated 14, at the ends of its upper arms.

Of course, the previously described components are connected to each other by data transmission lines. The cameras 14 capture the area of the operating table in which the treatment takes place and can measure three-dimensional spatial coordinates of surgical

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B ·

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Instruments and treatment equipment that are equipped with reflectors that reflect infrared radiation.

For example, the patient's head is fixed to a locking device on the operating table. The coordinates of the patient's anatomy are initially communicated to the computer unit 11 shown in Figure 1 by a marker system described below using computer tomography data, with the current arrangement of the markers during the operation also being referenced on site using the computer unit and the cameras.

For this purpose, for example, a point pointer 20 shown in Figure 2 is used. The point pointer 20 has two reflectors 21 and 22 attached to it by plug connections. The distance and the shape of these reflectors 21 and 22 are known to the computer unit 11; i.e. this point pointer 20 is one that is always assigned to the respective computer system. The position of the tip 23 of the position pointer 20 is also known to the computer unit 20. If this position pointer 20 is brought into the detection field of the cameras 14, it can be recognized immediately by the system, i.e. its tip 23 can be made visible on the screen 12.

Figure 3 now shows a pair of surgical tweezers 30. An adapter 31 is detachably connected to the rear end of these tweezers 30, which has three reflectors 32, 33 and 34 on its arms, which have a characteristic arrangement that is only assigned to this adapter 31 in the navigation system. Such tweezers 30 can be any pair of tweezers to which the adapter 31 can be attached. This can therefore also be a pair of tweezers that a neurosurgeon has been working with for years. In order for the tweezers 30 to be used, the neuronavigation system must first be informed of the position of their tip 35. To do this, as already described previously with regard to the reflector referencing system, the tip 35 of the tweezers is moved to a point in space known in the navigation system, whereupon circular movements are carried out with the end of the tweezers 30. The computer unit 11 detects the special arrangement of the reflectors 32, 33 and 34 via the cameras 14 and can determine the tip position from their movements when the tip 35 of the tweezers 30 is stationary.

The pointer 20 from Figure 2 and the tweezers 30 from Figure 3 are examples of

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are suitable for all instruments used in neurosurgical interventions. The system works wirelessly with a reflector adapter with passive reflectors, as shown in Figure 3. These can also be attached to ultrasound diagnostic devices and neurosurgical microscopes, for example, whereby the calibration of a microscope is then carried out, as described, by focusing on a known calibration point.

Figure 4 shows a sectional view of the point indicator 20 from Figure 2 in a different plane. It is clear here that the reflectors 21 and 22 are attached to the position indicator 20 by plug connections. The reflectors 21, 22 are therefore removable. Since the reflectors 21, 22, which are usually designed with a sensitive reflective coating, are the only parts of the position indicator 20 that are highly sensitive to sterilization, this position indicator 20 with the removable reflectors 21, 22 can be sterilized very easily and quickly. Once the reflectors 21, 22 have been removed, an autoclave sterilization can be carried out, for example, after which a new prepared set of sterilized reflectors 21 and 22 is plugged on. The position indicator 20 can thus be sterilized and reused after a short time.

Figure 5 shows a top view of a reference adapter 50, which has already been described several times before and which is attached to a part that is stationary relative to the patient by means of a clamping device that is hidden under its center in this view. This part can be, for example, the locking device for the head of a patient or a dome process in a vertebral body.

The reference adapter 50 consists of the arms 51, 52 and 53, which have a length and angle that is unique to it. Reflectors 54, 55 and 56 are attached to the end of these arms 51, 52 and 53. This group of reflectors and their characteristic arrangement and/or size enable the neuronavigation system to clearly identify the position of the reference adapter 50 at any time. The position of the reference adapter 50 normally remains the same during an operation. However, if it becomes necessary to reposition the patient, the reference adapter 50, which is fixedly connected to the referenced patient anatomy, can be detected and tracked by the navigation system at any time, even subsequently, so that the overall position of the patient reference system can also be provided to the computer unit at any time.

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11 remains known.

The calibration point 57 plays a special role with regard to the reference adapter 50, which in this example is arranged at the starting point of the three arms 51, 52 and 53. It is located in a depression so that it can be approached with precise positioning by instrument tips (for example the position indicator tip 23, Figure 2 or the tweezers tip 35, Figure 3). After this approach, the instrument then moves, the center of which is the tip, i.e. the depression of the reference adapter 50 in the calibration point 57. The calibration already described in detail can be carried out.

A calibration tool, in this case a calibration rod 60, is shown in Figure 6 on a very reduced scale. This calibration rod 60 should actually have a length of at least about 40 cm. A reflector 61, 62 is arranged at each end of the calibration rod 60 at a predetermined distance known to the computer 11. The characteristic properties of the reflectors 61, 62, which are also designed to be removable here, namely their size and their distance from the calibration rod 60, are known to the computer unit 11 and are only assigned to this rod. This rod 60 can then be used to carry out the calibration process already described for the angular or distance position of the cameras 14.

Figure 7 shows a landmark attachment as used in the CT scanner to capture the patient's anatomy. This attachment is designated 70. It consists of a spherical main body 71, which is, for example, an aluminum sphere. In this aluminum sphere, which can be individually identified by both the CT scanner and the neuronavigation system on the basis of its unique size in the system, a locking projection 72 is attached at the bottom, with which the landmark attachment 70 can be pushed into and locked into a fastening device 90 (Figure 9).

A landmark attachment, by which the landmark attachment 70 from Figure 7 is replaced after the computer tomography, is designated as attachment 80 in Figure 8. The dimensions of the landmark main body 81, i.e. the sphere diameter, correspond to that of the landmark main body 71 from Figure 7. The landmark attachment 80 is modified in that an upper part of the sphere is cut off and a trough-shaped funnel 83 is incorporated into the sphere.

whose tip is located exactly in the center of the ball, as shown in the cutout of Figure 8. The locking projection 82 corresponds exactly to the locking projection 72 (Figure 7).

After patient data has been recorded in the CT scanner, the landmark attachment 70 is replaced by the landmark attachment 80. Because both spheres have the same diameter, the landmark attachment 80 can be identified by the neuronavigation system as the same landmark as that recorded as landmark 70 in the CT scan. The depression with the funnel-shaped converging tip allows the tip of a surgical instrument to be precisely positioned at the center of the sphere during the referencing step for the landmark 80 as part of the calibration of the neuronavigation system. This makes referencing easier and more precise, and it can also be carried out after covering with sterile cloths.

Figure 9 shows a fastening device 90 which is attached to the underside of the device by means of an adhesive, for example to the skin of a patient. The base 92 of this fastening device 90 has an insertion opening 91 into which both the landmark attachment 70 and the landmark attachment 80 from Figures 7 and 8 can be inserted and locked. Figure 10 shows an upper view of the fastening device 90. It can be seen that an additional nose-shaped opening 100 is made in the base 92 through which the locking projections 72, 82 can be inserted. After turning the entire landmark attachments 70 and 80, their lower projections lock into the through hole 91 of the base behind its lower shoulder and remain firmly in place there.

Having explained the most important components of the neuronavigation system so far, the invention will now be explained further and in more detail by presenting a typical treatment procedure:

First, five landmark bases 92 are attached to the skin of a patient whose brain is to be subjected to neurosurgical surgery. To reference the anatomical data during a computer tomography scan, five spherical aluminum landmark attachments 70 are inserted into the bases 92. The locations at which the landmarks are attached are selected in such a way that they can be seen during the procedure.

They should be as close to the area to be treated as possible and as far apart as possible from each other. At least three landmarks must be used, but the use of two additional landmarks can give the system greater accuracy and safety.

Next, a computer tomography scan is performed, in which the areas to be treated and the landmarks are identified and their position is related to one another.

While the patient is being taken to the surgery, the computer tomography data is saved on optical disks and then taken to the computer unit 11, which reads out the data and displays it as images on the screen 12. These images are cross-sectional images in various planes and a 3D image. The surgeon can plan his surgical strategy based on this display. While the patient is being prepared for anesthesia, the position of the cameras 14 on the stand is calibrated. To do this, the surgeon takes a calibration rod 60 with two reflectors 61 and 62 and moves it in the detection zone of the cameras 14. By detecting around ten current positions of the reflectors 61 and 62 on the calibration rod 60 at short intervals, the system can detect and store the camera position.

The patient's head is now made spatially immobile using a locking device on the operating table. The spherical landmark attachments 70 are then replaced by the partially spherical landmark attachments 80 provided with positioning funnels 83.

After sterilization, the patient is covered with a sterile drape, which can also cover the landmarks 80. The draping can be done using conventional cloths or a transparent film.

In the next step, a reference adapter 50 is attached to the fixing device for the patient's head. It is identified by its special reflector arrangement, its position and the position of its calibration point 57 are determined by the neuronavigation system.

The surgeon can now use a pointer that is also identified and known to the system

20 move to the five landmark attachments 80 in such a way that the tip 23 of the point pointer 20 moves exactly into the funnel tip, i.e. the center of the sphere 81. From the known data of the respective landmarks, which can be individually distinguished, the system can identify the respective landmarks within seconds and thus also incorporate the patient anatomy data from the computer tomography into its recording system. The position of the tips of neurosurgical instruments can now be displayed relative to the anatomy data on the screen 12. After calibration at the calibration point 51 of the reference adapter 50, this also applies to any surgical instruments onto which a reflector adapter 31 has been attached.

In order to determine the exact location where an intervention must be performed, the tip of a pointer pointing to the scalp can be virtually extended. The surgeon sees the lesion to be treated virtually using the screen output and can predict the optimal intervention path by also virtually extending his instrument.

After opening the skull at the location thus found, a pair of tweezers 30 with a three-reflector adapter 31 attached to it can be calibrated at the calibration point 57 of the reference adapter 50 as described above, i.e. the exact location of the tweezers tip 35 is determined. The lesion can now be resectioned using these tweezers 30, with the surgeon being able to follow the tip 35 of the tweezers 30 on the screen 12 at all times.

This method allows the lesion to be resected while largely avoiding the destruction of healthy tissue. Furthermore, the operation could be carried out in a very short time. All instruments used could be moved wirelessly due to the use of passive reflectors, which spared the surgeon from any inconvenience during the operation. He could use his own usual instruments by using three-reflector adapters. All of these factors could lead to an overall improvement in the treatment outcome.

Claims (14)

1. Reflector referencing system for surgical or medical instruments ( 20 , 30 ) and treatment apparatus with at least two cameras ( 14 ) and a computer unit ( 11 ) connected to the cameras ( 14 ) with a graphic screen output ( 12 ), characterized by a radiation source for infrared radiation ( 14 ) and a reflector group with at least two reflectors ( 21 , 22 ) for this infrared radiation, wherein the reflectors are attached to the instruments ( 20 , 30 ) or treatment apparatus in an arrangement that is characteristic only for this reflector group. 2. Reflector referencing system according to claim 1, characterized in that the reflectors ( 21 , 22 ) are removably attached via adapters ( 24 , 31 ). 3. Reflector referencing system according to claim 1 or 2, characterized in that the reflectors ( 21 , 22 , 32 , 33 , 34 ) are spherical and have a reflective coating. 4. Reflector referencing system according to one of claims 1 to 3, characterized in that two reflectors ( 21 , 22 ) are attached to an instrument, in particular a pointer ( 20 ) or a calibration rod ( 60 ), via plug connections ( 24 ). 5. Reflector referencing system according to one of claims 1 to 3, characterized in that three reflectors ( 32 , 33 , 34 ) are fastened to at least one arm end of an adapter ( 31 ) designed with reflector arms and a fastening foot, wherein the fastening foot can be fastened to a surgical instrument ( 30 ) or a treatment apparatus. 6. Reflector referencing system according to one of claims 1 to 3, characterized in that at least three reflectors are attached to an adapter for attachment to a surgical microscope. 7. Reflector referencing system according to one of the preceding claims, characterized in that it further comprises a three-armed reference adapter ( 50 ) with a fastening foot, which also has three reflectors ( 54 , 55 , 56 ) attachable in a special characteristic arrangement at each arm end, the foot being provided at its end with a clamp that flexibly adapts to the respective fastening point. 8. Reflector referencing system according to claim 7, characterized in that the reference adapter preferably has a conically converging funnel trough with a central calibration point ( 57 ) for the tips of the surgical instruments ( 20 , 30 ) at the starting point of the three arms ( 51 , 52, 53 ). 9. Reflector referencing system according to one of claims 1 to 8, characterized in that a reflector group is attached to a surgical microscope. 10. Reflector referencing system according to one of claims 1 to 9, characterized in that a reflector group is attached to an ultrasound emitter/receiver of an ultrasound diagnostic system. 11. Marker system for referencing and determining the position of body parts to be treated neurosurgically, with
at least three artificial landmark attachments ( 70 ), and an equal number of fastening devices ( 90 ) for fastening the landmark attachments ( 70 ) to the patient,
characterized in that
the landmark attachments ( 70 ) produce a characteristic image both during diagnostic patient data acquisition and during subsequent treatment monitoring, wherein they are designed as reflectors for the infrared radiation of a radiation source for treatment monitoring. 12. Marker system according to claim 11, characterized in that the landmark attachments ( 70 ) consist of metal bodies which can be individually distinguished due to specific material density, size, shape and arrangement during data acquisition in a computer tomograph. 13. Marker system according to claim 12, characterized in that the landmark attachments ( 70 ) consist of aluminum bodies of a detectably specific shape and/or size which can be removed from the fastening devices ( 90 ). 14. Marker system according to claims 11 to 13, characterized in that it comprises an additional set of funnel-shaped landmark attachments ( 80 ), the funnel center of which corresponds to the center of the landmark attachments ( 70 ), for which they can be exchanged before referencing on the operating table.