System and procedure for locating and identifying medical targets

Abstract

Medical system (10) for localizing and identifying multiple medical target objects (12, 14), the system (10) comprising the multiple medical target objects (12, 14) and a measuring device (16) for localizing and identifying the multiple medical target objects (12, 14), wherein - the multiple medical targets (12, 14) have a first medical target (12) and a second medical target (14), - the first medical target object (12) is designed to generate a first magnetic field (20) with a first time course (22), - the second medical target object (14) is designed to generate a second magnetic field (24) with a second time course (26) that is different from the first time course (22), and - the measuring device (16) is designed to detect magnetic field lines (30, 32) of the first magnetic field (20) and the second magnetic field (24) with regard to their direction, strength and temporal progression by means of a magnetic field sensor (28), and to determine a position and orientation of the respective target object (12; 14) from the detected direction and strength by means of a processing device (34), to assign the determined position and orientation to one of the target objects (12; 14) from the temporal occurrence and to output the position and orientation for the assigned medical target object (12; 14).

Description

[0001] The present invention relates to a system for locating and identifying medical targets and a method for locating and identifying medical targets.

[0002] In medical technology, endoscopes are commonly used to visualize internal structures. This allows for diagnoses and surgical procedures. This is primarily based on the fact that the situation is assessed optically, i.e., within the visible field, and actions are selected and performed based on this assessment.

[0003] These optical assessments relate to the superficial situation. These must be evaluated in relation to the patient; therefore, spatial reference and directional detection are important. While the actual application takes place within the patient's body, operation, particularly positioning, is performed externally. The signals must therefore overcome the body barrier, i.e., be transmitted from the inside out. Transmission methods that can penetrate skin or bone, thus eliminating the need for a separate port, are preferred.

[0004] To spatially determine the direction and position of a target object, a suitable signal generator is required, which is connected to the target object or part of the target object in a spatially defined manner, particularly in a fixed arrangement. If the target object is located inside the body, the signal is detected by the signal generator outside the body and processed accordingly, for example, for location determination or navigation.

[0005] Approaches to overcoming the body barrier have already been demonstrated. For example, US 2014 / 0051985 A1 discloses a target-finding system that identifies a surgical target, such as a kidney stone, by placing a transmitter, such as a magnetic source, behind or beside the surgical target and using a circuit to identify an axis to the transmitter, thus defining an axis or path to the surgical target. An array of sensors arranged in an equidistant, coplanar configuration each detects a signal indicating the distance to the emitter. A magnetic resistance sensor, which generates a variable resistance, responds to the distance to a magnetic coil that emits a magnetic field. An identical signal from each of the coplanar sensors indicates the position along an axis passing through a point at the center of the sensors and perpendicular to the plane.

[0006] WO 2010 / 085 877 A1 discloses a method and a device for determining the distance of signal transmission devices. According to WO 2010 / 085 877 A1, the distance determination can be carried out with a single pulse transmitter, operating with a minimum of a single signal transmitter and a single digital receiver and processing circuit. In general, a plurality of pulse transmitter devices can be aligned and positioned virtually simultaneously in three dimensions (XYZ coordinates) using a configuration of multiple digital receivers arranged in any fixed three-dimensional configuration.

[0007] DE 10 2012 223 417 A1 discloses a method in which a defined electromagnetic field is generated by a transmitter of a medical instrument. The generated electromagnetic fields are simultaneously measured by several receivers positioned at the patient table and in the navigation room. The measurement results from the receivers are transmitted to a processing unit. Based on the measurement results processed by the processing unit, the assumption about the position and / or orientation of the medical instrument is verified.

[0008] It is an object of the present invention to demonstrate an improved system and an improved method for the localization and identification of medical target objects, According to a first aspect, the task is solved by a medical system for locating and identifying multiple medical target objects, the system comprising the multiple medical target objects and a measuring device for locating and identifying the multiple target objects, wherein - the multiple medical targets include a first medical target and a second medical target, - the first medical target is designed to generate a first magnetic field with a first temporal profile, - the second medical target is designed to generate a second magnetic field with a second time course that differs from the first time course, and - the measuring device is designed to detect magnetic field lines of the first magnetic field and the second magnetic field with regard to their direction, strength and temporal progression by means of a magnetic field sensor, and to determine a position and orientation of the respective target object from the detected direction and strength by means of a processing device, to assign the determined position and orientation to one of the medical target objects from the temporal occurrence and to output the position and orientation for the assigned medical target object.

[0009] One advantage of this solution is that more than one communication channel can be established. Specifically, information such as position and orientation can be captured from multiple medical targets and uniquely assigned to each target. This allows for the tracking and monitoring of work with multiple targets.

[0010] The aforementioned temporal occurrence is detected via the progression of one of the magnetic fields. It is preferred that multiple changes are detected by the magnetic field sensor, allowing conclusions to be drawn from the detected changes as to which of the target objects is causing them. For this purpose, each target object has, in particular, its own signature, clocking, frequency, intervals, clock sequence, or amplitude variance. A person skilled in the art knows, with knowledge of the expected shape of the useful signal, how many samples are required to distinguish one useful signal from another, so this aspect will not be discussed further here.

[0011] The proposed solution offers further advantages. Firstly, it boasts a good signal-to-noise ratio. While the general operating conditions are such that the expected potential interference signal is higher than the desired signal, the proposed solution enables good detection of the desired signal despite these unfavorable conditions. Furthermore, the desired signal can be isolated from other ambient signals, thus minimizing these superimposed influences. Additionally, magnetic signals pass through physical barriers such as skin and bone without loss of information and are therefore not affected or only negligibly disrupted.

[0012] Furthermore, the detection process is stateless and atomic. This means that no knowledge or consideration of a previous history of position and / or orientation is required. This distinguishes the proposed solution from other methods that determine position by summing the movement paths of the target object. In those methods, displacements are continuously detected and processed using accelerometers. Here, knowledge of the complete sequence of movement paths is necessary.

[0013] The spatial orientation of the magnetic field of the respective target object is known. Knowing this orientation, the measured direction and strength allow us to deduce the location of the magnetic field sensor within the magnetic field. From this, we can then determine the location of the target object, and in particular, a defined reference point of the target object.

[0014] In some embodiments, the magnetic field of the respective target object can be switched on and off; in other preferred embodiments, it is generated by a magnetic coil and can be controlled by controlling the current flow through the magnetic coil. In such an embodiment, the magnetic coil can be controlled by electrical impulses.

[0015] The useful signal is a magnetic signal; more precisely, the field lines, and in particular the field line envelope of the magnetic field, constitute the useful signal. This useful signal thus has an elliptical shape, meaning it is a spatial signal defined by its strength, direction, and position. The magnetic field sensor uses the magnetic component to detect the magnetic spatial signal (X, Y, Z). This spatial signal can be visualized as a three-dimensional object representing this elliptical shape, i.e., the shape of the signal. Furthermore, one can imagine this elliptical shape as being composed of many small segments, each of which can be described as a vector. By identifying these vectors, or direction vectors, the position and orientation of the respective target object can be determined.

[0016] This completes the task.

[0017] In a preferred embodiment, the magnetic fields are generated by a pulse-like control.

[0018] The magnetic field sensor reacts to all magnetic influences, such as the Earth's magnetic field, running motors, steel beams, etc. However, these are static or at least defined dynamic signal forms (50 Hz or higher). The control by pulses, especially the control of a magnetic coil, can be used in such a way that these ambient signals can be separated from the useful signal by means of an evaluation filter. Specifically... Furthermore, this pulse controllability, i.e., in particular the switching on and off, can also be designed in such a way that the resulting useful signals can be overloaded. In this case, a source identifier is present in the control pulse. This source identifier is an imprinted meta-information. This achieves the desired duality of, on the one hand, spatial signal information for direction and position, and on the other hand, meta-signal information for channel or source identification, in addition to the temporal profile. It is therefore a digital information transmission from the source, i.e., the target object, to the receiver, i.e., the measuring device. The control pulse can also be varied in its frequency and / or amplitude over time, so that a specific source can be identified alternatively or additionally based on a change in the magnetic field with respect to frequency and / or amplitude over time.

[0019] In a preferred embodiment, the magnetic fields are generated by a wave-like control, in particular by a sinusoidal control.

[0020] One possibility here is to identify a source based on its waveform, e.g., sine wave, square wave, triangle wave, sawtooth wave, etc. For this, the temporal evolution of the spatial signal is measured at a specific point in space, allowing the source to be deduced from the measured time course. Alternatively or additionally, the frequency and / or amplitude of the waveform can be selected and subsequently determined from the temporal evolution of the spatial signal to identify the source. Alternatively or additionally, the frequency and / or amplitude of the waveform can also be varied over time. In this case, the change in frequency and / or amplitude is determined from the temporal evolution of the spatial signal to identify the source.In this way, different signal sources can be differentiated in many different ways, whereby the characteristics shape, frequency, amplitude, shape change, frequency change and amplitude change can be used in any combination or on their own to identify a source.

[0021] In a further preferred embodiment, the first target object periodically generates the first magnetic field with a first frequency, the second target object periodically generates the second magnetic field with a second frequency, and the measuring device has a variable bandpass filter whose center frequency can be selectively set to the first frequency and the second frequency.

[0022] In principle, separating the timing of when the first and second target objects generate their respective magnetic fields ensures that the magnetic fields can be clearly distinguished. With this design, it is even possible to differentiate the magnetic fields when they overlap in time. The bandpass filter ensures that only one signal of the desired magnetic field is captured at a time.

[0023] In a further preferred embodiment, each magnetic field is generated with a respective current, which is a square wave signal, a sawtooth signal, a triangle signal, or, most preferably, a sine wave signal.

[0024] This design allows for good separation between the magnetic fields.

[0025] In a further preferred embodiment, the magnetic field sensor is designed as a component of a tablet, in particular as part of a gyroscope sensor of the tablet.

[0026] In this way, a cost-effective solution can be achieved that also integrates seamlessly into the existing use of a tablet, e.g. for viewing and entering data.

[0027] In another preferred embodiment, the first target object is arranged at a fixed location in space, in particular on an operating table.

[0028] This allows the target object to be spatially referenced to the work environment. For this purpose, the target object can be located outside the body, particularly within an operating table, preferably in a leg of the operating table. The material used is then preferably V2A or stainless steel. Such a fixedly positioned target object is preferably used for position alignment, as is known, for example, from differential GPS.

[0029] In a further preferred embodiment, the distance between the measuring device and each of the target objects is at most 3m, preferably between 0.5m and 2.5m and particularly preferably between 1m and 2m.

[0030] Due to the short distance, i.e., the short effective range, the required signal intensity is low. This is orders of magnitude lower than, for example, in an MRI scanner or magnetic resonance imaging scanner.

[0031] In a further preferred embodiment, the measuring device has several magnetic field sensors that are spaced apart from each other and are subject to the same operating principle, and the measuring device is designed to check the position and orientation of the respective target object, as determined by the individual magnetic field sensors, against each other for plausibility and / or to improve the accuracy of position and orientation by averaging.

[0032] In this configuration, the signal is received and evaluated at several different positions. This means that two or more sensors analyze the spatial ellipse of the magnetic field of a medical target, and the result should yield at least approximately the same positional data for the corresponding medical target. This provides a verification or plausibility check of the acquisition in real time, thus increasing reliability. Additionally or alternatively, accuracy can be improved by averaging the measured values. Because multiple measurements are taken at different positions, this can also be described as a two-factor analysis, which further enhances accuracy.

[0033] In another preferred embodiment, the second target object is fixedly arranged on an endoscope.

[0034] This can advantageously improve the more frequent use of an endoscope mentioned at the beginning. According to a second aspect, the task is solved by a procedure for locating and identifying multiple medical target objects, the procedure comprising the steps - Generating an initial magnetic field with an initial time course through an initial medical target object; - Generating a second magnetic field with a second temporal profile that differs from the first temporal profile, using a second medical target object; - Detecting, using a magnetic field sensor, magnetic field lines of the first magnetic field and the second magnetic field with regard to their direction, strength and temporal progression, - Determining, by means of a processing device, the position and orientation of the respective medical target object from the direction and intensity, - Assigning, using the processing device, the determined position and orientation to one of the medical target objects based on the temporal progression; and - Outputting the position and orientation for the assigned medical target.

[0035] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0036] An embodiment of the invention is shown in the drawings and is explained in more detail in the following description. The drawings show: Fig. 1. An embodiment of a medical system for locating and identifying multiple target objects; Fig. 2. an embodiment of a method for locating and identifying multiple medical targets; and Fig. 3 an embodiment of a measuring device with several magnetic field sensors.

[0037] Fig. Figure 1 shows an embodiment of a medical system 10 for localizing and identifying multiple medical target objects 12, 14. The system 10 includes the multiple target objects 12, 14 and a measuring device 16 for localizing and identifying the multiple target objects 12, 14.

[0038] Specifically, the multiple target objects 12, 14 have a first target object 12 and a second target object 14. The first target object 12 is configured to generate a first magnetic field 20 with a first time profile 22, and the second target object 14 is configured to generate a second magnetic field 24 with a second time profile 26 that differs from the first time profile 22.

[0039] The measuring device 16 is designed to detect magnetic field lines 30, 32 of the first magnetic field 20 and the second magnetic field 24 with regard to their direction, their strength and their temporal progression by means of a magnetic field sensor 28 of the measuring device 16.

[0040] Using a processing device 34 of the measuring device 16, the position and orientation of the respective target object 12, 14 are determined from the detected direction and strength. This is possible because the shape of the magnetic field 20, 24 expected from a target object 12, 14 is known. Knowing the shape of the magnetic field 20, 24, it is possible to deduce the location of the magnetic field sensor 28 within this shape, thus allowing conclusions to be drawn about the origin of the magnetic field 20, 24, i.e., the target object 12, 14 or a reference point of the target object 12, 14 relative to the magnetic field sensor 28.

[0041] Based on the temporal appearance of the magnetic field 20, 24, the processing device 34 assigns the determined position and orientation to one of the target objects 12, 14. This is possible because the target objects 12, 14 generate their respective magnetic fields with different temporal profiles 22, 26. For example, if the first magnetic field 20 is switched on and off quickly and the second magnetic field 24 is switched on and off slowly, the magnetic fields can be distinguished based on the temporal profile 22, 26 of the resulting magnetic fields 20, 24. The magnetic fields 20, 24 can each be generated by a magnetic field coil 46, which is pulse-controlled by a control unit 48.

[0042] Finally, the processing device 34 is designed to output the position and orientation of the assigned target object 12, 14. This information can be used, in particular, to virtually display the respective target object 12, 14, for example on a screen or VR glasses. This allows the user to intuitively grasp the spatial situation, even though the user does not have a direct line of sight to the respective target object 12, 14.

[0043] In the embodiment shown here, the first medical target object 12 periodically generates the first magnetic field 20 at a first frequency, and the second medical target object 14 periodically generates the second magnetic field 24 at a second frequency. The measuring device 16 has a variable bandpass filter 36 whose center frequency can be selectively set to either the first or the second frequency. This makes it possible to separate the detection of the two magnetic fields 20 and 24, even if they temporarily overlap.

[0044] The magnetic field sensor 28 is implemented here as a component of a tablet 38, specifically as part of a gyroscope sensor 40 of the tablet 38. Furthermore, the first target object 12 is arranged here at a fixed location in space, specifically on an operating table 42, which is indicated here by a dashed line. The second target object 14 is fixedly arranged on an endoscope 44, which is also indicated by a dashed line.

[0045] Fig. Figure 2 shows an embodiment of a medical method 50 for localizing and identifying medical target objects 12, 14. The method 50 begins with the generation 52 of a first magnetic field 20 with a first temporal profile 22 by a first medical target object 12. In addition, a second magnetic field 24 with a second temporal profile 26, which differs from the first temporal profile 22, is generated 54 by a second medical target object 14.

[0046] The next step involves detecting, by means of a magnetic field sensor 28, magnetic field lines 30, 32 of the first magnetic field 2ß and the second magnetic field 24 with regard to their direction, their strength and their temporal progression 22, 26. In a further step, by means of a processing device 34, a position and orientation of the respective target object 12, 14 is determined 58 from the direction and the strength.

[0047] In the next step, the determined position and orientation are assigned to one of the target objects 12, 14 based on the time sequence using the processing device 34 (60). Finally, the position and orientation for the assigned target object 12, 14 are output (62).

[0048] Fig. Figure 3 shows an embodiment of a measuring device 16 with several magnetic field sensors 28, which are spaced apart from one another and operate on the same principle. In this embodiment, the measuring device 16 is designed to check the plausibility of the position and orientation of the respective target object 12, 14, as determined by the individual magnetic field sensors 28, against each other and / or to improve the accuracy of the position and orientation by averaging.

Claims

[1] Medical system (10) for localizing and identifying multiple medical target objects (12, 14), the system (10) comprising the multiple medical target objects (12, 14) and a measuring device (16) for localizing and identifying the multiple medical target objects (12, 14), wherein - the multiple medical targets (12, 14) have a first medical target (12) and a second medical target (14), - the first medical target object (12) is designed to generate a first magnetic field (20) with a first time course (22), - the second medical target object (14) is designed to generate a second magnetic field (24) with a second time course (26) that is different from the first time course (22), and - the measuring device (16) is designed to detect magnetic field lines (30, 32) of the first magnetic field (20) and the second magnetic field (24) with regard to their direction, strength and temporal progression by means of a magnetic field sensor (28), and to determine a position and orientation of the respective target object (12; 14) from the detected direction and strength by means of a processing device (34), to assign the determined position and orientation to one of the target objects (12; 14) from the temporal occurrence and to output the position and orientation for the assigned medical target object (12; 14). [2] Medical system according to claim 1, wherein the magnetic fields (20, 24) are each generated by a pulse-like control. [3] Medical system according to claim 1, wherein the magnetic fields are each generated by a wave-like control, in particular by a sinusoidal control. [4] Medical system according to one of the preceding claims, wherein the first medical target object (12) periodically generates the first magnetic field (20) at a first frequency, the second medical target object (14) periodically generates the second magnetic field (24) at a second frequency, and the measuring device (16) has a variable bandpass filter (36) whose center frequency can be selectively set to the first frequency and the second frequency. [5] Medical system according to claim 4, wherein each magnetic field (20, 24) is generated with a respective current which is a square wave signal or a sawtooth wave signal or a triangle wave signal or, most preferably, a sine wave signal. [6] Medical system according to one of the preceding claims, wherein the magnetic field sensor (28) is designed as a component of a tablet (38), in particular as part of a gyroscope sensor (40) of the tablet (38). [7] Medical system according to one of the preceding claims, wherein the first medical target object (12) is arranged at a fixed location in space, in particular on an operating table (42). [8] Medical system according to one of the preceding claims, wherein the distance between the measuring device (16) and each of the medical target objects (12, 14) is at most 3m, preferably between 0.5m and 2.5m and particularly preferably between 1m and 2m. [9] Medical system according to one of the preceding claims, wherein the measuring device (16) has several magnetic field sensors (28) that are spaced apart from each other and are subject to the same operating principle, and the measuring device (16) is designed to check the position and orientation of the respective medical target object (12, 14), as determined by the individual magnetic field sensors (28), against each other for plausibility and / or to improve the accuracy of position and orientation by averaging. [10] Medical system according to one of the preceding claims, wherein the second target object (14) is fixedly arranged on an endoscope (44). [11] Method (50) for localizing and identifying multiple medical targets (12, 14), the method comprising the steps: - Generating (52) a first magnetic field (20) with a first time course (22) by a first medical target object (12); - Generating (54) a second magnetic field (24) with a second time course (26) that is different from the first time course (22) by a second medical target object (14); - Detecting (56), using a magnetic field sensor (28), magnetic field lines (30, 32) of the first magnetic field (20) and the second magnetic field (24) with respect to their direction, their strength and their temporal evolution (22, 26), - Determining (58), by means of a processing device (34), a position and orientation of the respective medical target object (12; 14) from the direction and intensity, - Assigning (60), using the processing device (34), the determined position and orientation to one of the medical target objects (12, 14) based on the temporal sequence (22, 26); and - Output (62) the position and orientation for the assigned medical target (12; 14).

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