System for receiving a signal from a magnetomechanical oscillator

Abstract

The system for receiving a signal from a magnetomechanical oscillator includes a main coil array that receives a response signal of the magnetomechanical oscillator and transmits an excitation signal to the magnetomechanical oscillator, and an additional coil that receives the signal of the magnetomechanical oscillator. The localizer is configured to locate the additional coil and includes a controller that controls the main coil array and the additional coil such that a receive localization signal is generated, a sensitivity provider that provides sensitivity information, and a processor that determines a position and / or orientation of the additional coil based on the provided sensitivity information and the receive localization signal. A kit is provided for upgrading a system including a main coil array by adding one or more additional coils and providing software for locating the one or more additional coils using pilot tone transmissions.

Description

[Technical field]

[0001] The present invention relates to a system for receiving a signal from a magnetomechanical oscillator, the system comprising a coil system and a localizer for determining the position of an additional coil of the system, the coil system and the localizer. Furthermore, the present invention relates to a method and a computer program for determining the position of an additional coil of the system. [Background technology]

[0002] In recent years, very small mechanical devices have been developed, for example in the form of microbots or microdevices, which can be advantageously used in applications where there are severe size constraints, such as medical applications inside the human body. Such microdevices are particularly useful as localization or sensor devices. A very advantageous type of such microdevice is the recently introduced magnetomechanical oscillator.

[0003] Such localization or sensing of magnetomechanical oscillators relies on spatially resolved detection of the magnetomechanical oscillator's response signal transmitted in response to an excitation signal. Information regarding the magnetomechanical oscillator's location is usually obtained using a receiver coil array with a known spatial sensitivity profile. In this regard, most applications require a compromise between the spatial resolution provided by the coil array and the technical effort to be spent on the coil array and the detection system. This compromise often results in a limited number of rather large detection coils. However, during short periods, such as when a thin needle must be inserted into the patient, it may be necessary to improve the resolution. In particular, when the coil array is provided close to the workspace, finer coil arrays may provide higher resolution and sensitivity and be suitable for such applications. However, the technical effort that must be spent on these finer coil arrays and the possibility that fine coil arrays may interfere with the workflow of the interventional procedure make it inconvenient to always use fine coil arrays. It is therefore desirable to provide a detection system for magnetomechanical oscillators that is more flexibly applicable to medical applications and can be easily adapted to various medical situations. Summary of the Invention [Problem to be solved by the invention]

[0004] It is therefore an object of some embodiments of the present invention to provide a system for receiving a signal from a magnetomechanical oscillator that is more flexibly applicable to medical applications and can be adapted to various medical situations, and it is further an object of some embodiments of the present application to provide a coil system, a localizer, a method and a computer program that can be used in such a system. [Means for solving the problem]

[0005] According to a first aspect of the present invention, there is provided a system for receiving a signal from a magnetomechanical oscillator, the system being configured for use in a medical application, the system comprising: a) a main coil array including a main receiving coil configured to receive an electromagnetic response signal of the magnetomechanical oscillator and a main transmitting coil configured to transmit an electromagnetic excitation signal for exciting the magnetomechanical oscillator, b) an additional coil configured to receive the electromagnetic response signal of the magnetomechanical oscillator and / or to transmit an electromagnetic excitation signal for exciting the magnetomechanical oscillator, and c) a localizer configured to identify a position of the additional coil. The localizer includes: i) a controller configured to a) control the main transmitting coil to transmit electromagnetic localization signals receivable by the additional coil, and to control the additional coil to generate received localization signals indicative of the electromagnetic localization signals received by the additional coil, and / or b) control the main receiving coil to transmit electromagnetic localization signals receivable by the main receiving coil, and to generate received localization signals indicative of the electromagnetic localization signals received by the main receiving coil; ii) a sensitivity provider configured to provide sensitivity information indicative of a) a sensitivity profile of each of the additional coil and the main transmitting coil when the main transmitting coil is controlled to transmit the electromagnetic localization signals, and / or b) a sensitivity profile of each of the additional coil and the main receiving coil when the additional coil is controlled to transmit the electromagnetic localization signals; and iii) a processor configured to determine a position and / or orientation of the additional coil based on the provided sensitivity information and the received localization signals.

[0006] The system provides additional coils for receiving the electromagnetic response signal of the magnetomechanical oscillator and / or for transmitting the electromagnetic excitation signal, so that the receiving characteristics and settings of the coil array can be adapted to various situations. Moreover, the system further comprises a localizer configured to determine the location of the additional coil based on the provided sensitivity information and the received localization signal, so that the integration of the additional coil into the existing main coil array for localization of the magnetomechanical oscillator is easy and can be performed in a short time, making the application of the system more flexible in medical environments. Thus, the system is flexibly applicable and can be adapted to various medical situations.

[0007] In general, magnetomechanical oscillators are provided in the form of or as part of milli- or microdevices that can be utilized in space-limited applications, particularly within the human body. For example, such magnetomechanical oscillators can be used as part of a catheter or needle introduced into the human body, where the magnetomechanical oscillator allows for precise localization of the catheter or needle. Furthermore, magnetomechanical oscillators can also be applied together with or as part of other interventional instruments, such as implants or other medical interventional instruments. Furthermore, magnetomechanical oscillators can be applied not only for localization, but also as sensor devices for sensing physical parameters in the magnetomechanical oscillator's environment.

[0008] In general, a magnetomechanical oscillator comprises a magnetic object that can rotate or vibrate when exposed to an exciting electromagnetic field. The rotating or vibrating magnetic object generates a signal of its own in the form of a periodically varying electromagnetic response field, which can be measured, for example, outside the body of a patient in which the magnetomechanical oscillator is implanted. In some applications, additional information can be encoded in the response signal, such as a measurement of a physical parameter in the magnetomechanical oscillator's environment or an identification of the magnetomechanical oscillator.

[0009] The main coil array refers to a coil array utilized in medical applications of a system for receiving a signal of a magnetomechanical oscillator. The main coil array comprises a main receiving coil configured to receive an electromagnetic response signal of the magnetomechanical oscillator and a transmitting coil configured to transmit an electromagnetic excitation signal for exciting the magnetomechanical oscillator. Preferably, the main coil array comprises a plurality of main receiving coils, e.g., a main receiving coil array including at least three main receiving coils for receiving the electromagnetic response signal of the magnetomechanical oscillator, thereby enabling accurate localization of the magnetomechanical oscillator. Furthermore, the main coil array may also comprise a plurality of main transmitting coils, e.g., a main transmitting coil array, for transmitting electromagnetic excitation signals to the magnetomechanical oscillator from various directions. Preferably, the main receiving coil is configured to be utilized as a main transmitting coil for transmitting an electromagnetic excitation signal, and the main transmitting coil is configured to be utilized as a main receiving coil for receiving an electromagnetic response signal from the magnetomechanical oscillator. In some embodiments of the present application, when an embodiment is applicable to both the main receiving coil and the main transmitting coil, the coils belonging to the main coil array, i.e., all the main receiving coils and all the main transmitting coils, are referred to as "main coils". In this case, each embodiment or feature described with respect to the "main coil" may be applied to at least one of the main coils, or advantageously to all of the main coils, and all embodiments referring to the main coil may be applied to the main receive coil and / or the main transmit coil.

[0010] In one embodiment, the main coil array includes a main coil that can be used as both a main receive coil and a main transmit coil, and the main coils are arranged in the form of a 3×3 or 4×4 array arrangement. A 3×3 array arrangement refers to a rectangular grid with 3×3 grid areas, in each grid area a main coil is arranged, and all nine main coils are arranged in a regular grid pattern in the main coil array. A 4×4 array arrangement is similar to the 3×3 arrangement, but 16 coils are arranged in a regular grid pattern in the main coil array instead of nine. In some embodiments, the 4×4 arrangement is preferred. The main coils of the main coil array can be arranged in other patterns, for example, in a hexagonal pattern. It is also possible to arrange the main receive coils and the main transmit coils in independent patterns. For example, the main transmit coils can be arranged in a hexagonal pattern, and the main receive coils can be arranged in a rectangular pattern. In such cases, the two arrangement patterns can overlap in the same plane, be arranged side by side, or be arranged in different planes of the region of interest. For example, a main transmit coil or a main transmit coil array may be positioned above the patient, and a main receive coil or a main receive coil array may be positioned below the patient. In general, the main coil array may include a support structure on which the main coil or at least a portion of the main coil, e.g., the main receive coil, is positioned to support one or more predetermined positions of the main coil array. Advantageously, such a support structure may be adapted to the contours of the patient or the patient support. For example, the support structure may be flexible, bendable, or generally deformable. This also allows for flexible application of the main coil array. Furthermore, in an embodiment, the main coil array is integrated into a patient support on which the patient is supported during a medical procedure.

[0011] In general, the main coil array is configured to be used in medical applications. For example, the main receiving coil and the main transmitting coil may have a biocompatible housing that allows the main receiving coil and the main transmitting coil to be placed in direct contact with the patient's tissue. Furthermore, the main coil array may be configured to meet the sanitary requirements of a medical facility. Preferably, the main coils of the main coil array, e.g. the main receiving coil and the main transmitting coil, have a diameter of 10 cm to 20 cm. In some embodiments, the main coils may have different diameters and the main transmitting coil may have a different diameter than the main receiving coil. Preferably, the main coils of the main coil array have an extension in the magnetic axis direction of less than 5 mm, more advantageously less than 2 mm, and even more advantageously less than 1 mm. In an embodiment, the main coils of the main coil array may refer to flat coils, i.e. planar coils in which all windings are provided on the same plane. In some embodiments, the main coils comprise at least two winding layers. This avoids the problem of planar coils with only one winding layer in contact with the innermost layer. It is further advantageous for the primary coils of the primary coil array to be configured for application in medical environments and situations with stringent weight restrictions and / or for the primary coils of the primary coil array to be x-ray invisible. Advantageously, the primary coils of the primary coil array are at least partially made of aluminum. Advantageously, the primary coils of the primary coil array have an inductance of less than 200 μH, more advantageously less than 50 μH. Such a small inductance allows the operating voltage to be kept small while keeping coil insulation requirements small.

[0012] Furthermore, the system comprises an additional coil configured to receive the electromagnetic response signal of the magnetomechanical oscillator and / or to transmit an electromagnetic excitation signal for exciting the magnetomechanical oscillator. The additional coil may be a separate coil, i.e., it is not usually part of the main coil array and is not used in all medical applications of the system. This coil may be added as needed, for example, when a higher spatial resolution for locating the magnetomechanical oscillator is required. In general, the additional coil may be configured for use in medical applications. For example, the additional coil may have a biocompatible housing that allows the additional coil to be placed in direct contact with the patient's tissue. Furthermore, the additional coil may be configured to meet hygiene requirements within the interventional field or general care environment. The additional coil may comprise the same characteristics as the main coil used in the main coil array described above. Alternatively, the additional coil may comprise different characteristics compared to the main coil. Furthermore, different additional coils may be provided by the system for different medical applications of the system.

[0013] According to some embodiments of the main coil array, it is advantageous that the additional coil is also configured to be applicable in medical environments and situations with strict weight restrictions and / or that the additional coil is not visible on X-rays. Likewise, it is advantageous that the additional coil is at least partially made of aluminum. It is advantageous that the diameter of the additional coil is smaller than the diameter of the main coil of the main coil array. It is advantageous that the diameter of the additional coil is adapted to its intended application. In particular, when only one additional coil is provided, the diameter of the additional coil refers substantially to the expected maximum distance between the magnetomechanical oscillator and the additional coil while the additional coil is applied. For example, when it is expected that in an interventional procedure a needle is provided up to 3 cm below the patient's skin and the additional coil is placed directly on the patient's skin, in some embodiments the additional coil may have a diameter of 3 cm. When more than one additional coil, e.g. an additional coil array, is provided, the diameter of the additional coil of the additional coil array can generally be smaller than the diameter of only one additional coil. In particular, the diameter of the additional coil of the additional coil array may be substantially 0.1 to 0.5 times the expected maximum distance between the magnetomechanical oscillator and the additional coil array while the additional coil array is applied. In both above embodiments, the diameter of the additional coil may deviate from the preferred diameter by up to twice the preferred diameter. The inventors have noticed that even in the presence of such deviation, the electromagnetic response signal of the magnetomechanical oscillator can be detected with a reasonable accuracy by the additional coil.

[0014] If the additional coil is configured only for receiving the electromagnetic response signal of the magnetomechanical oscillator, it is advantageous for the additional coil to have a higher inductance than the inductance of the main receiving coil, advantageously an inductance higher than 1 mH. This allows for an easy amplification of the received electromagnetic response signal and / or for the use of a less complex connection cable to the receiving unit for further processing of the signal if necessary. In an embodiment in which the additional coil is also configured for transmitting the electromagnetic excitation signal, the additional coil has the same inductance as the main transmitting coil, advantageously an inductance of less than 200 μH, more advantageously an inductance of less than 50 μH. The additional coil may refer to a flat, uniform planar coil, as is also advantageous for the main coil of the main coil array, but may also refer to a cylindrical coil.

[0015] The additional coil is generally configured to be placed in a region of interest, i.e., a region close to the magnetomechanical oscillator. The additional coil is configured to be attached to the region of interest of the living organism. For example, the additional coil may be configured to provide attachment means that allow such attachment to the region of interest of the living organism. Such attachment means may refer to, for example, skin adhesives, straps, tapes, etc. that can be utilized to attach an object to the skin of the living organism.

[0016] In an advantageous embodiment, the system comprises an additional coil array having two or more additional coils, advantageously having at least two additional coils. In one embodiment, the multiple additional coils are configured to be freely provided in the spatial region, i.e. the multiple additional coils do not have a fixed spatial relationship to one another and can be placed in a suitable spatial arrangement by hand, for example by a user, for each application. However, in another advantageous embodiment, the multiple additional coils may be configured to provide them with a predetermined spatial relationship to one another. For example, the additional coils may be arranged on a mounting support that supports the additional coils to be arranged in a predetermined position. For example, the mounting support may be configured such that the distance and the position of the additional coils relative to one another are fixed. However, the mounting support may also allow a degree of flexibility to arrange the additional coils in a number of different spatial arrangements, for example predetermined by the structure of the mounting support. The mounting support may also provide measuring means that allow the spatial relationship between the additional coils of the additional coil array to be measured. For example, the mounting support may refer to a folding mounting support, which has a sensor for determining the angle between different structures of the folding mounting support. This mounting support is folded to be arranged in the region of interest.

[0017] Providing a generally known mutual spatial relationship for the multiple additional coils has the advantage that in application of the system, the position of only one of the additional coils needs to be determined. Due to the known spatial relationship between all the additional coils, the positions of the other additional coils can also be directly known. This allows for rapid integration of the additional coils into the main coil array in applications where timing may be critical. Additionally or alternatively, the processor may be configured to determine the position and / or orientation of all the additional coils based on the sensitivity information and the received localization signals by directly taking into account the spatial relationship. For example, the spatial relationship may be used to determine the starting positions and / or orientations of all the additional coils, and the processor may be configured to solve equations for determining the positions and / or orientations of the interdependent additional coils based on these starting positions. This allows for a more accurate determination of the positions and / or orientations of all the additional coils.

[0018] Furthermore, the processor may be configured to determine whether an object that causes distortion of the electromagnetic field in the vicinity of the additional coil array is likely to be present in the vicinity of the additional coil array based on all the received localization signals of the additional coils, the sensitivity information, and the spatial relationship between the additional coils. Such an object, e.g. a magnetic or magnetizable object, may reduce the accuracy of determining the position and / or orientation of the additional coils as well as the position and / or orientation of the magnetomechanical oscillator. In particular, the processor may be configured to compare the determined relative positions and / or orientations of the additional coils with each other with the known mutual spatial relationship of the additional coils, i.e. with the known relative positions and / or orientations with each other. If the result of the comparison is that the deviation of the position and / or orientation of one or more additional coils from the known spatial relationship is greater than expected due to the always present noise, e.g. greater than a predetermined tolerance deviation range, the processor may be configured to determine that an object that causes distortion of the electromagnetic field is present in the region of interest. In this case, the processor may be configured to assume that the position of the object is stationary, i.e. not moving, and has a linear magnetization. Based on these assumptions, the processor may be configured to determine a correction for the presence of an object such that, when applying the correction, the determined relative positions and / or orientations of the additional coils correspond to the known spatial relationship of the additional coils. For example, the processor may utilize a dipole model to model the effect of a magnetic or magnetizable object in the region of interest. In this example, a dipole is added as a representation of the magnetic object to a model describing the electromagnetic fields of the main coil and the additional coil, the added dipole having a magnetic time delay expected for eddy currents in the magnetic or magnetizable object. The position, strength, and phase of the additional dipole in the model may then be adjusted until the position and / or orientation of the additional coil determined taking into account the dipole model results in an acceptable accuracy, i.e., a deviation from the known spatial relationship below a predefined threshold. However, the processor may also apply other methods for correcting distortions caused by the presence of a magnetic or magnetizable object.Also, although the above assumptions provide accurate results in the medical application environment while allowing an easy and computationally inexpensive determination of the correction of the distortion, other assumptions, especially more complex ones, can also be used to model the presence of a magnetic or magnetizable object. Moreover, although described above with respect to an array of additional coils, the distortion of the magnetic field can also be determined and corrected based on only one additional coil. For example, in this case, this additional coil can be placed in succession at a number of different positions and / or orientations in the region of interest having a known spatial relationship to each other. The above principles can then be applied to the determination of these successive positions and / or orientations compared to the known spatial relationship of the successive positions and / or orientations of the additional coils. In general, the processor can be configured to indicate the presence of such a magnetic or magnetizable object to a user of the system and to prompt the user to remove the object if possible. However, the processor can also be configured to correct the distortion of the magnetic field during the localization of the magnetomechanical oscillator, for example, when removal of the object is not possible, based on the determined distortion of the magnetic field. In particular, if an additional coil or an additional coil array is placed at different positions in the region of interest and the determination of the distortion is repeated for each position of the additional coil or additional coil array, such distortion and corresponding correction can be accurately determined. This easy and flexible system making available additional coils allows accurate and easy detection of distortions in the electromagnetic field that may be associated with the reception of the electromagnetic response signal of the magnetomechanical oscillator, and therefore allows correction of the distortions, more accurately determining the position of the magnetomechanical oscillator, etc.

[0019] Furthermore, the system comprises a localizer configured to determine the position of the additional coil. The localizer may advantageously be formed as part of the hardware and / or software of a computing device. The computing device may refer to any known general-purpose or dedicated computing device, for example a personal computer, a handheld computer such as a smartphone, a tablet, a laptop, a cloud computing device, etc. Advantageously, the localizer is part of the hardware and / or software of a computing device already utilized to determine the position of the magnetomechanical oscillator. However, the localizer may also be part of a dedicated computing device.

[0020] The localizer may be configured to control the main transmitting coil to transmit an electromagnetic localization signal receivable by the additional coil, and to control the additional coil to generate a received localization signal indicative of the electromagnetic localization signal received by the additional coil. Additionally or alternatively, the controller is configured to control the additional coil to transmit an electromagnetic localization signal receivable by the main receiving coil, and to control the main receiving coil to generate a received localization signal indicative of the electromagnetic localization signal received by the main receiving coil. The location of the additional coil can be determined by the additional coil receiving a signal transmitted by the main transmitting coil, or by transmitting a signal receivable by the main receiving coil. In both cases, the received localization signal is indicative of the electromagnetic localization signal received by the main receiving coil and / or the additional coil, respectively, and thus indicates the position and / or orientation in which the additional coil is located with respect to the main coil array. The electromagnetic localization signal may be any signal suitable for determining the location of the additional coil, i.e. any signal that can be received by the additional coil and / or the main receiving coil. For example, the electromagnetic localization signal may refer to an electromagnetic excitation signal used to excite a magnetomechanical oscillator. However, the electromagnetic localization signal may also refer to a signal that is used only for localizing the additional coil, and the electromagnetic localization signal may have signal characteristics that are particularly suitable for localizing the additional coil. Preferably, the electromagnetic localization signal refers to an electromagnetic pulse sequence, which pulse sequence may have different pulse patterns, for example by varying the time between two successive pulses.

[0021] The localizer may further include a sensitivity provider configured to provide sensitivity information indicative of a) a respective sensitivity profile of the additional coil and the main transmitting coil when the main transmitting coil is controlled to transmit an electromagnetic localization signal, and / or b) a respective sensitivity profile of the additional coil and the main receiving coil when the additional coil is controlled to transmit an electromagnetic localization signal. In general, when multiple additional coils are provided, the sensitivity provider may be configured to provide sensitivity information indicative of the sensitivity profile of all the additional coils. Furthermore, when multiple main receiving coils and / or multiple main transmitting coils are provided, the sensitivity provider may be configured to provide sensitivity information indicative of the respective sensitivity profile of all the main receiving coils and / or all the main transmitting coils. In particular, the sensitivity provider is configured to provide sensitivity information required to identify the position and / or orientation of the additional coil. For example, when the controller is configured to control the main transmitting coil to provide an electromagnetic localization signal, the sensitivity provider is configured to provide sensitivity information indicative of the sensitivity profile of the additional coil and the main transmitting coil. In another example, when the controller is configured to control the additional coil to transmit an electromagnetic localization signal, the sensitivity provider is configured to provide sensitivity information indicative of the sensitivity profile of the main receiving coil and the additional coil. Thus, the sensitivity provider is adapted to provide sensitivity information indicative of a sensitivity profile of the coils that transmit the electromagnetic localization signals and a sensitivity profile of the coils that receive the electromagnetic localization signals.

[0022] The sensitivity profile generally refers to the flux density of the magnetic field in a region of interest, e.g., a 3D region having a predetermined distance around the respective coil, generated by the coils being supplied with a predetermined current. The sensitivity profile of the coils may generally be frequency dependent, i.e., dependent on the frequency of the current supplied to the coils. In this case, it is beneficial for the sensitivity provider to provide such sensitivity information indicative of the sensitivity profile at the frequencies expected to be used for the electromagnetic localization signals. In general, the sensitivity profile is the same whether the coils are used as transmitting or receiving coils. Providing sensitivity information indicative of the sensitivity profile of each coil in the region of interest allows the position of the additional coils to be determined with a higher accuracy than the size, e.g., diameter, of the additional coils alone. In one embodiment, the sensitivity information may directly represent the respective sensitivity profiles. However, in a preferred embodiment, the sensitivity information has a sensitivity profile in the form of the position of the conductors in the region of interest that provide the magnetic field, i.e., the magnetic flux density, of each coil when supplied with a predetermined current. In this case, the sensitivity profile is represented by the position of the respective conductors, and thus the position is indicative of the sensitivity profile. Alternatively, the sensitivity information may refer to information regarding the position of the dipoles in the region of interest that provide the magnetic field that may represent the sensitivity profile of the respective coils.

[0023] The localizer further comprises a processor adapted to determine the position and / or orientation of the additional coil based on the sensitivity information and the received localization signal. In particular, the processor is adapted to determine the position and / or orientation of the additional coil in relation to the position and / or orientation of the coil of the main coil array. If the position and / or orientation of the coil of the main coil array is known in a global coordinate system, it is beneficial that the position and / or orientation of the additional coil is also determined in the global coordinate system based on the spatial relationship between the additional coil and the coil of the main coil array. In general, methods are known for localizing a sensor, for example providing an electromagnetic signal, using a coil array. In particular, the processor may be configured to utilize an algorithm similar to that used for localizing a magnetomechanical oscillator. For example, the processor may be configured to determine the position and / or orientation of the additional coils based on the sensitivity information and the received localization signals indicative of their respective sensitivity profiles, for example by utilizing the Biot-Savart law according to the method described in the article “Electromagnetic navigation in medicine - basic issues, advantages and shortcomings, prospects of improvement” by M. Baszynski et al., Journal of Physics: Conference Series, volume 238, pages 1-11 (2010). However, other algorithms may be utilized to determine the position and / or orientation of the additional coils.

[0024] In one embodiment, the additional coil comprises a receiving circuit for receiving the electromagnetic excitation signal transmitted by the main transmitting coil and generating an electrical signal indicative of the received electromagnetic signal, the receiving circuit being configured to operate within a certain range and not reach a saturation threshold of the receiving circuit when receiving the electromagnetic excitation signal transmitted by the main transmitting coil and generating an electrical signal indicative of the received electromagnetic excitation signal. The receiving circuit may have software and / or hardware configured to convert the electromagnetic signal received by the additional coil into an electrical signal indicative of the received electromagnetic signal. The electrical signal may include a functional relationship to the received electromagnetic signal, such as a proportional relationship or a quadratic relationship. Generally, software and / or hardware-based circuits used to convert the received electromagnetic signal into an electrical signal by the coil are known to have a threshold for the amplitude of the received electromagnetic signal, and for received electromagnetic signal amplitudes above this threshold, they cannot be distinguished from each other. In other words, the electrical signals generated for received electromagnetic signal amplitudes above the threshold do not indicate different amplitudes of the received electromagnetic signal. When receiving the electromagnetic response signal of the magnetomechanical oscillator, it is necessary to consider that the electromagnetic excitation signal for exciting the magnetomechanical oscillator needs to provide a relatively high amplitude to obtain the electromagnetic response signal from the magnetomechanical oscillator. At the same time, however, the electromagnetic response signal transmitted by the magnetomechanical oscillator is generally several orders of magnitude smaller in amplitude than the electromagnetic excitation signal. For example, the magnetic flux density of the electromagnetic excitation signal is about 1 μT to 1 mT, while the magnetic flux density of the electromagnetic response signal is about 1 pT to 100 nT. It is beneficial for a coil, such as an additional coil used to receive the electromagnetic response signal from the magnetomechanical oscillator, to be configured to receive a relatively low amplitude of the signal transmitted by the magnetomechanical oscillator. The receiving circuit may therefore be configured to receive the electromagnetic response signal at the relatively low amplitude of the magnetomechanical oscillator. In this case, the magnetomechanical oscillator will saturate when exposed to a higher amplitude electromagnetic excitation signal, for example used to locate the additional coil. However, the receiving circuit may be configured not to saturate when exposed to the electromagnetic excitation signal transmitted by the transmitting coil.For example, the receiving circuit of the additional coil may include an attenuation element configured to attenuate the received signal, advantageously only attenuating the received signal above a predetermined signal amplitude. This can reduce the saturation threshold of the receiving circuit and prevent the electromagnetic excitation signal transmitted by the transmitting coil from reaching the saturation threshold. As a non-limiting example, the attenuation element can be a voltage divider or an adjustable voltage divider comprising two resistors in series and a contact therebetween. In another example, instead of a resistor-based voltage divider, an inductive or capacitive voltage divider can be utilized to attenuate the received signal.

[0025] Advantageously, the attenuation element allows attenuation of the received signal with an attenuation factor of 100, more advantageously 1,000, and even more advantageously 1,000,000. Advantageously, the attenuation element can be of the variable attenuation element type, meaning that the attenuation factor can be adjusted between different attenuation factor values, for example in the range of 1,000 to 100,000. Without attenuation, elements typically used in the receiver circuit are configured to generate an electrical signal representative of the received electromagnetic signal over a receive amplitude range of about 4 to 5 orders of magnitude. By providing the attenuation element, the range is increased and the electromagnetic excitation signal and the response signal can be processed by the receiver circuit. Also, the receiver circuit may provide a number of different receive paths that can be automatically selected based on the amplitude of the received electromagnetic signal. Each receive path is specifically adapted to a particular amplitude range of the received electromagnetic signal. This allows maximizing the frequency with which localization measurements can be performed. This is due to the fact that the relative localization measurements can be performed at any time. This may mean that no additional time is required for the individual localization measurements, since the procedure does not have to be supplemented by additional time measurements. For example, the localization of the additional coil can be performed simultaneously with the transmission of an excitation pulse to localize the coil or device. The relative localization can be performed at any time interval.

[0026] In one embodiment, the receiving circuit comprises an adjustable attenuation element configured to adjust an attenuation factor for attenuating the received signal. In this case, it is beneficial for the receiving circuit to be configured such that an adjustment of the attenuation factor brings an impedance change in the receiving circuit below a predefined threshold. In particular, the predefined threshold is determined such that an impedance change in the receiving circuit below the threshold still results in an acceptable accuracy in determining the position and / or orientation of the additional coil. Such an impedance change in the receiving circuit leads to a change in the received current caused by the electromagnetic localization signal in the additional coil connected to the receiving circuit, and thus to an inaccurate reception of the electromagnetic localization signal. As a result, the localization of the additional coil may be inaccurate. Additionally or alternatively, the processor may be configured to compensate for the impedance change caused by the adjustable attenuation element in the receiving circuit. For example, sensitivity information of the additional coil may be determined and provided for each attenuation factor provided by the adjustable attenuation element, and the processor may be configured to take into account the sensitivity information regarding the current attenuation factor when determining the position and / or orientation of the additional coil. Furthermore, the attenuation element may also be realized as an inductance coupling that brings about an attenuation of the received signal according to the characteristics of the inductance involved.

[0027] In one embodiment, the additional coil comprises a transmitting circuit configured to generate, from a provided electrical signal, a current in the coil enabling the transmission of an electromagnetic signal, the transmitting circuit being configured to provide two transmitting paths, a first transmitting path configured to generate, from a provided electrical signal, a current in the coil enabling the transmission of an electromagnetic localization signal, and a second transmitting path configured to generate, from a provided electrical signal, a current in the coil enabling the transmission of an electromagnetic excitation signal. The transmitting circuit may comprise software and / or hardware adapted to convert an electrical signal received, for example from a computer interface, into a current applied to the additional coil to generate a transmitting signal. Preferably, the transmitting circuit and the receiving circuit are coupled to the transmitting / receiving circuit of the additional coil. Furthermore, the above-mentioned receiving circuit and / or transmitting circuit may also be provided in the coils of the main coil array, i.e. the main receiving coil and the main transmitting coil.

[0028] In one embodiment, the controller is configured to control the main transmitting coil and / or the additional coil to repeatedly transmit electromagnetic localization signals with a predetermined time interval between each electromagnetic localization signal, and to control the additional coil and / or the main receiving coil to generate a receive localization signal based on each received electromagnetic localization signal. Thus, the controller is configured to a) control the transmitting coil to repeatedly transmit electromagnetic localization signals with a predetermined time interval between each electromagnetic localization signal, and to control the additional coil to generate a receive localization signal based on each received electromagnetic localization signal, and / or b) control the additional coil to repeatedly transmit electromagnetic localization signals with a predetermined time interval between each electromagnetic localization signal, and to control the main receiving coil to generate a receive localization signal based on each received electromagnetic localization signal. The processor is configured to determine the position and / or orientation of the additional coil based on the generated receive localization signal. Repeatedly transmitting the electromagnetic localization signals with a predetermined repetition frequency, i.e. with a predetermined time interval between each electromagnetic localization signal, has the advantage that the position and / or orientation of the additional coil can be determined repeatedly over the period during which the additional coil is applied, and not just once, for example, at the beginning of an intervention procedure. In particular, in applications where at least some movement of the additional coil is expected, repeatedly determining the position and / or orientation of the additional coil after a predetermined period of time allows a more accurate determination of the position and / or orientation of the additional coil and therefore the position of the magnetomechanical oscillator. In particular, the predetermined period between the repeatedly transmitted electromagnetic localization signals, i.e. the frequency at which the localization signals are repeated, can be advantageously adapted by the controller to the respective application of the additional coil. For example, the controller can be configured to select, from a plurality of predetermined periods of time, a period that fits into the expected time scale for the respective application. In particular, a user can indicate for which application the additional coil is utilized and the controller can be configured to select the predetermined period of time based on the user's input.For example, if only slow movement on a time scale of at least a few minutes is expected in the region in which the additional coil is placed, the controller may select the predetermined period of time to be approximately one minute to ensure that the current position and / or orientation of the additional coil is accurately determined. However, for applications in which shorter time scales are expected, for example where the additional coil is placed on the patient's chest such that respiratory motion is expected, the controller may be configured to select the predetermined period of time to be within a few seconds in order to accurately track the position and / or orientation of the additional coil.

[0029] In one embodiment, the controller is configured to control the transmitting coil and / or the additional coil to continuously transmit electromagnetic localization signals and to continuously generate receive localization signals based on the received electromagnetic localization signals. Advantageously, the processor may also be configured to substantially continuously determine the position and / or orientation of the additional coil based on the continuously received localization signals. This allows for accurate tracking of the position and / or orientation of the additional coil. This is particularly desirable in applications where accurate localization is required in a rapidly changing or fluctuating environment, such as, for example, a patient's circulatory system in an interventional procedure near the patient's heart.

[0030] In one embodiment, the main transmitting coil refers to a main transmitting coil array comprising a plurality of main transmitting coils, and the controller is adapted to control the main transmitting coil array. This can be done in such a way that each coil of the main transmitting coil array transmits an electromagnetic localization signal in sequence, and the additional coil is used to generate a receive localization signal for each of the sequentially received electromagnetic localization signals. Additionally or alternatively, the additional coil refers to an additional coil array including a plurality of additional coils, and the controller is configured to control the additional coil array such that each of the additional coils of the additional coil array transmits an electromagnetic localization signal in sequence. The main receiving coil generates a receive localization signal for each of the sequentially received electromagnetic localization signals. In this case, the processor is further configured to determine the position and / or orientation of the additional coil based on each generated receive localization signal. Thus, in the case where a plurality of coils (either a plurality of transmitting coils or a plurality of additional coils) is provided in the system (where there is at least one transmitting coil and at least one additional coil), the controller is adapted to control each coil to transmit an electromagnetic localization signal in sequence. In other words, the controller is adapted to control the first coil to transmit a first electromagnetic localization signal, then control the second coil to transmit a second electromagnetic localization signal, then control the third coil to transmit a third electromagnetic localization signal, etc. Determining the location based on each of the generated received localization signals allows for more accurate location and / or orientation of the additional coils. Advantageously, in this embodiment, the transmitted electromagnetic localization signals are similar to each other and have the same signal characteristics, e.g., signal frequency, amplitude, length, etc. However, in other embodiments, the electromagnetic localization signals may be different for each coil. For example, each coil may be controlled to transmit an electromagnetic localization signal that is different from the electromagnetic localization signal transmitted from another coil. Furthermore, it is noted that in both above-mentioned embodiments, the coil receiving the localization signal may be intended as a coil array.For example, if the main transmitting coil is intended as the main transmitting coil array, the additional coil may also refer to the additional coil array, and each additional coil of the additional coil array may receive the electromagnetic localization signal transmitted in sequence. The positioning unit is adapted to determine the position and / or orientation of the additional coil array, i.e. all the additional coils, based on each of the generated received localization signals. Instead of transmitting the electromagnetic localization signals in sequence, the controller may be configured to control the main transmitting coil array or the additional coil array, respectively, to transmit electromagnetic localization signals simultaneously. In order to avoid saturation of the receiving circuit of each receiving coil, i.e. the main receiving coil or the additional coil, it is advantageous in this embodiment that the electromagnetic localization signals transmitted by the different coils have different frequencies. In one embodiment, the electromagnetic localization signal has an electromagnetic pulse sequence, which pulse sequence may have different pulse patterns, for example by varying the time between two successive pulses. It is therefore advantageous that the controller is configured to control each coil, i.e. the main transmitting coil or the additional coil, respectively, to transmit an electromagnetic localization signal with a different pulse pattern for each coil. Thus, when transmitting the electromagnetic localization signals simultaneously, not all pulses belonging to the electromagnetic localization signals are transmitted at the same time, so that not all are received by each coil at the same time, avoiding saturation. Furthermore, by utilizing different frequencies or different pulse patterns, it is also possible to encode the identity of the coil that transmitted each electromagnetic localization signal, thus allowing the controller to distinguish the received localization signals with respect to their source. This allows the position and / or orientation of the additional coils to be determined much more easily and accurately.

[0031] In one embodiment, the localizer further comprises a motion model provider, which provides a motion model indicative of the motion of the region of interest in which the additional coil is attached, and the processor further determines the current position and / or orientation of the additional coil based on the motion model. The motion model provider may be intended for a storage unit for storing one or more motion models, and the motion model provider may provide the stored one or more motion models. The motion model provider may also be capable of communicating with a storage unit for storing one or more motion models, or with a device for generating the motion models. In that case, the motion model provider may receive one or more motion models to provide the motion models. The storage unit may be any kind of memory device, a computer drive (e.g., a solid-state drive such as a flash drive), an optical disk, etc. The provided motion model indicates the motion of the region of interest in which the additional coil is attached. For example, if the additional coil is used in an intervention procedure, the additional coil is attached to the human chest, in which case the motion model may indicate the motion of the human chest region. However, the additional coil may also be attached to other regions of interest, in which case a motion model may be provided indicative of the respective motion of this region of interest. The motion model provider may be configured to select a motion model from a plurality of motion models, each of which references a different region of interest, based on, for example, knowledge of the region of interest in which the additional coil is attached. For example, a user may provide an input indicating the region of interest in which the additional coil is attached, after which the motion model provider may be configured to select and provide the motion model associated with this region of interest.

[0032] The motion model may, for example, indicate 1D, 2D, or 3D motion of the region of interest, for example, based on measurements of the motion of the region of interest, or on simulations of the motion of the region of interest. For example, the motion model may be provided as a video stream from a camera monitoring the region of interest, as a respiratory signal indicating the motion of the chest region, as an EEG signal indicating the motion of the heart, as a spline model of the various motion phases of the region of interest. In general, the motion model indicates where the region of interest is located in space with respect to time. The processor may utilize this information to determine the current position and / or orientation of the additional coil. In particular, the processor may be configured to use an estimate from the motion model indicating where the additional coil is currently located and / or oriented as a starting point for an algorithm for determining the current position and / or orientation based on the sensitivity information and the received localization signals. This allows the position and / or orientation of the additional coil to be determined more quickly and accurately. However, the processor may also be configured to utilize the predicted position and / or orientation of the additional coil derived from the motion model to validate the position and / or orientation determined based on the sensitivity information and the received localization signals. This allows for easy selection of a correct solution for the position and / or orientation of the additional coil, for example when more than one solution is provided by an algorithm for determining the position and / or orientation of the additional coil based on the sensitivity information and the localization signals. Furthermore, once the processor has determined the current position and / or orientation of the additional coil, for example based on the sensitivity information, the received localization signals, and optionally an operating model, the processor may utilize the operating model to extrapolate the position and / or orientation of the additional coil for periods when the electromagnetic localization signals are not transmitted, for example when the electromagnetic localization signals are not transmitted continuously. This allows for accurate tracking of the position and / or orientation of the additional coil even in embodiments where a continuous electromagnetic localization signal is not present.

[0033] In one embodiment, the additional coil further comprises an accelerometer, the accelerometer measures the acceleration of the additional coil, and the processor determines the current position and / or orientation of the additional coil further based on the measured acceleration of the additional coil. The accelerometer may be any known accelerometer providing a measurement of acceleration in one or more directions. For example, the accelerometer contemplates a single-axis or multi-axis accelerometer adapted to measure both the magnitude and the direction of the acceleration of the additional coil. Furthermore, the accelerometer includes or refers to an angular accelerometer and / or an angular velocity sensor, such as a gyroscope, for measuring rotational acceleration. In an advantageous embodiment, the accelerometer refers to a microelectromagnetic system accelerometer. As mentioned above with respect to providing a motion model, the acceleration measurement also provides information indicative of the movement of the additional coil, and thus the position and / or orientation of the additional coil can be more accurately determined. For example, the processor may be adapted to determine the current position and / or orientation of the additional coil using the measured acceleration after a first position of the additional coil has been determined, for example based on the sensed information and the received localization signal, for example in the absence of a continuous electromagnetic localization signal. The measured acceleration may also allow for determining an expected position and / or orientation of the additional coil, which the processor may be configured to use as a starting point for an algorithm for determining the position and / or orientation of the additional coil based on the sensitivity information and the received localization signals. The processor may also be configured to consider the acceleration measurements as a motion model or to utilize the acceleration measurements to generate a motion model indicative of the movement of the additional coil. The processor may then utilize the motion model as described above. Generally, also in this embodiment, the provision of an additional accelerometer allows for a more accurate determination of the current position and / or orientation of the additional coil, and therefore the position of the magnetomechanical oscillator.

[0034] The processor may further be adapted to determine whether the measured acceleration exceeds a predefined acceleration threshold, and if the measured acceleration exceeds the predefined acceleration threshold, the controller may be adapted to control the coils, i.e. the main transmitting coil and / or the additional coil, to transmit the electromagnetic localization signal again. In particular, if the measured acceleration exceeds the predefined acceleration threshold, it may be expected that the position and / or orientation of the additional coil has changed in a way that is difficult to determine simply based on the measured acceleration, so that it is advantageous to determine the position and / or orientation by performing the localization of the additional coil based on the electromagnetic localization signal again in order to obtain an accurate acceleration. The predefined acceleration threshold may be determined in advance depending on the application of the additional coil, for example based on the experience of a user of the system, or it may generally be intended as an acceleration value that is known to indicate a position change outside a safety margin that may be provided by the user. Furthermore, in an embodiment, the processor may be configured to integrate the acceleration signal once to generate a velocity signal and / or to integrate the acceleration signal twice to generate a position signal. Based on these integration results, a threshold value for determining whether a new determination of the position and / or orientation is necessary, for example by performing the localization of the additional coil based on the electromagnetic localization signal again, may also be determined as described above.

[0035] In one embodiment, the system comprises two or more additional coils, and the processor is adapted to successively determine the positions and / or orientations of the additional coils by utilizing the already determined positions and / or orientations of the additional coils. In this embodiment, the system advantageously comprises an additional coil array with at least two additional coils. By sequentially determining the positions and / or orientations of the additional coils by utilizing the already determined positions and / or orientations of the additional coils, the positions and / or orientations of all the additional coils can be determined more accurately. In an advantageous example, the processor is adapted to use a computational model that allows to model the signals transmitted and received by the main coils, i.e. the main receiving coil and the main transmitting coil, and the signals further transmitted and received by the additional coils. Using this computational model, the processor may be adapted to correct the obtained position and / or orientation of the first additional coil until the virtual receive localization signals modeled by the computational model are optimized with respect to the actually measured receive localization signals. Then, the corresponding position and / or orientation of the first additional coil is fixed in the computational model with respect to the position and / or orientation of the main coil. Using this updated computational model, the next additional coil is processed in a similar manner, then the third, and so on until all additional coils have been processed. Based on the positions and / or orientations determined during this process, the computational model can be applied again to the first coil and subsequent coils. This is repeated until the difference between the calculated receive localization signals and the actual measured receive localization signals is below a predetermined threshold, e.g., minimized, resulting in an iterative determination of the positions and / or orientations of all additional coils.

[0036] In one embodiment, the electromagnetic localization signal has an amplitude that does not saturate the receiving circuit of the additional coil and / or the main receiving coil, respectively, and the receiving circuit is configured to generate a receiving localization signal based on the received electromagnetic localization signal. It is generally known that any receiving circuit has a saturation threshold above which the generated receiving localization signal is not indicative of the amplitude of the received electromagnetic localization signal. It is therefore beneficial to avoid saturation of the receiving circuit of the additional coil and / or the main receiving coil, respectively. The controller may therefore be configured to control the main transmitting coil and / or the additional coil to transmit an electromagnetic localization signal having an amplitude that is known not to saturate the receiving circuit of the additional coil and / or the main receiving coil. However, as mentioned above, saturation of the receiving circuit can also be avoided by having the receiving circuit appropriately adjusted.

[0037] In one embodiment, the electromagnetic localization signal means a signal having signal characteristics outside the signal characteristic range utilized for exciting the magnetomechanical oscillator. Thus, the electromagnetic localization signal does not intend the electromagnetic excitation signal utilized for exciting the magnetomechanical oscillator. The signal characteristic means any characteristic of the signal, for example, frequency, amplitude, pulse sequence, etc. Advantageously, the electromagnetic localization signal includes a frequency different from the frequency of the electromagnetic excitation signal. The electromagnetic localization signal is provided to enable computational modeling of the received localization signal based on a computational model of the main coil array and the additional coil. In this case, it is advantageous for the electromagnetic localization signal to include a frequency or frequency range that does not result in an influence of the patient on the localization signal. The frequency or frequency range of the electromagnetic localization signal is less than 10 MHz, more preferably less than 1 MHz, even more preferably less than 100 kHz. The processor is advantageously adapted to model the calculated received localization signal and compare this signal with the measured and received localization signal in order to determine the position and / or orientation of the additional coil, for example by subtracting the calculated received localization signal, optionally scaled respectively, from the actually measured received localization signal. In this, as well as other embodiments, the processor may be configured to take into account the patient's influence on the electromagnetic localization signal, e.g., when determining the position and / or orientation of the additional coil, in a manner similar to that described above for magnetic or magnetizable objects.

[0038] In one embodiment, the electromagnetic localization signal may also mean the electromagnetic excitation signal, which in particular allows the position and / or orientation of the additional coil to be accurately determined for all periods during which the magnetomechanical oscillator is also excited and thus the localization of the magnetomechanical oscillator is determined, so that the position and / or orientation of the additional coil is only determined if necessary.

[0039] In one embodiment, the additional coil comprises a local energy storage element or device, for example a battery. This embodiment has the advantage that it is not necessary to provide the additional coil with a wired connection to a power source, which may be inconvenient, for example in the region of interest during an intervention procedure. In one embodiment, the additional coil comprises a local energy storage element configured to be charged by an electromagnetic charging signal, and the controller is configured to control the transmitting coil to transmit an electromagnetic charging signal to the additional coil configured to charge the local energy storage element of the additional coil. In this embodiment, powerful batteries that may increase the size or weight of the additional coil can be avoided. The local energy storage element may include a battery that has a short battery life, for example of a few minutes. After this time has elapsed, the controller is configured to control the main transmitting coil to transmit an electromagnetic charging signal to charge the battery again. By electromagnetic charging signal is meant an electromagnetic localization signal that allows also the local energy storage element to be charged during the localization process. In general, methods are known in the art for charging an energy storage element without the aid of a wired connection, i.e. by the aid of an electromagnetic signal. However, in another embodiment, the additional coil may also comprise a local energy storage element, such as a battery, that is not charged by the additional electromagnetic signal.

[0040] If the additional coil comprises a local energy storage element and thus has no wired connection to a power source, it may be beneficial for the received signal, i.e. an electrical signal indicative of the received electromagnetic signal, to also be provided to the localizer using a wireless connection. For example, Bluetooth, WiFi, or other known wireless communication may be used. Furthermore, the additional coil may be wirelessly connected to the localizer for transmitting the electromagnetic signal, or to any other controller configured to control the transmission of the signal for the additional coil.

[0041] Also, if the additional coil includes a local energy storage element such as a battery, it is beneficial for the additional coil to be adapted to provide a sleep mode in which it consumes less energy than in the normal mode, preferably substantially no energy. The controller may be configured to control the additional coil to enter the sleep mode if the additional coil is not currently used during the application, i.e. if no electromagnetic signal is currently provided to be received by the additional coil. The controller may be configured to wake up the additional coil, i.e. to exit the sleep mode and change it to the normal operating mode. However, the additional coil may comprise a sleep mode circuit adapted to control the additional coil to change between the sleep mode and the normal mode. For example, the sleep mode circuit may be configured to react based on the reception of a predetermined signal to change from the normal operating mode to the sleep mode or from the sleep mode to the normal operating mode. The controller may then be configured to control the main transmitting coil to transmit a respective predetermined signal to the additional coil. However, the sleep mode related circuit may be configured to automatically change from the normal operating mode to the sleep mode, for example, if no electromagnetic localization signal or response signal has been received by the additional coil for a predetermined period of time.

[0042] In one embodiment, the additional coil comprises an LC circuit, the resonant frequency of the LC circuit being within the frequency range of the electromagnetic excitation signal of the magnetomechanical oscillator. In general, the LC circuit consists of an inductor and a capacitor connected to each other. Such an LC circuit can therefore function as an electric resonator having a predetermined resonant frequency. When the LC circuit is arranged as part of the additional coil near the magnetomechanical oscillator, the LC circuit amplifies the electromagnetic excitation signal near the magnetomechanical oscillator, which leads to an increase in the excitation of the magnetomechanical oscillator. Such an increase in the excitation of the magnetomechanical oscillator also leads to a stronger signal provided by the magnetomechanical oscillator, making it much easier to locate the magnetomechanical oscillator. Furthermore, this signal provided by the excitation of the magnetomechanical oscillator is amplified again by the LC circuit, providing an even stronger signal. The system can further comprise an LC circuit position provider adapted to provide a position of the LC circuit. For example, the position of the LC circuit can be fixed relative to the additional coil, such that the position of the LC circuit can be provided in relation to the position and / or orientation of the additional coil, or based on the known position and / or known orientation of the additional coil. However, the system may be configured to determine the position of the LC circuit, for example using the same technique as described above for the position of the additional coil. In this case, the localization of the magnetomechanical oscillator may be performed further based on the known position of the LC circuit. Preferably, the additional coil refers to the inductor of the LC circuit, and by providing a capacitor connected to the additional coil, the capacitor forms an LC circuit with the additional coil. Optionally, the additional inductor may be provided in the LC circuit, and may advantageously comprise a soft magnetic core. This improves the quality factor of the LC circuit. Advantageously, the LC circuit may be used together with a local energy storage element to maximize the energy transferred to the local energy storage element. However, as described above, the presence of the LC circuit may affect the electromagnetic signals transmitted and received by the additional coil, so it is beneficial if the controller is configured to control the additional coil such that the LC circuit is only utilized during energy transfer, and preferably not during localization of the additional coil and / or the magnetomechanical oscillator.

[0043] In a further aspect of the present invention, a medical coil system for receiving a signal from a magnetomechanical oscillator is provided, the medical coil system being used in a medical application, the medical coil system comprising: a) a main coil array including a main receiving coil for receiving an electromagnetic response signal of the magnetomechanical oscillator, and a main transmitting coil for transmitting an electromagnetic excitation signal for exciting the magnetomechanical oscillator, and b) an additional coil, the additional coil for receiving the electromagnetic response signal of the magnetomechanical oscillator and / or transmitting an electromagnetic excitation signal for exciting the magnetomechanical oscillator. In particular, the medical coil system is adapted to be controlled and used together with a localizer as described above. Furthermore, the coils of the medical coil system, i.e. the main coil and the additional coil, may be configured with respect to a system for receiving an electromagnetic response signal of the magnetomechanical oscillator as described above. The medical coil system may therefore be considered as part of the above system.

[0044] In a further aspect of the invention, a localizer is provided, the localizer configured to be used with a main coil array including a main receiving coil configured to receive an electromagnetic response signal of a magnetomechanical oscillator, and a main transmitting coil configured to transmit an electromagnetic excitation signal for exciting the magnetomechanical oscillator, and an additional coil configured to receive the electromagnetic response signal of the magnetomechanical oscillator. The localizer is configured to locate the additional coil, the localizer including: i) a controller configured to a) control the main transmitting coil to transmit electromagnetic localization signals receivable by the additional coil, and to control the additional coil to generate received localization signals indicative of the electromagnetic localization signals received by the additional coil, and / or b) control the main receiving coil to transmit electromagnetic localization signals receivable by the main receiving coil, and to generate received localization signals indicative of the electromagnetic localization signals received by the main receiving coil; ii) a sensitivity provider configured to provide sensitivity information indicative of a) a sensitivity profile of each of the additional coil and the main transmitting coil when the main transmitting coil is controlled to transmit the electromagnetic localization signals, and / or b) a sensitivity profile of each of the additional coil and the main receiving coil when the additional coil is controlled to transmit the electromagnetic localization signals; and iii) a processor configured to determine a position and / or orientation of the additional coil based on the provided sensitivity information and the received localization signals.

[0045] In a further aspect of the invention, a method is provided for use with a main coil array including a main receiving coil configured to receive an electromagnetic response signal of a magnetomechanical oscillator, and a main transmitting coil configured to transmit an electromagnetic excitation signal for exciting the magnetomechanical oscillator, together with an additional coil configured to receive the electromagnetic response signal of the magnetomechanical oscillator. The localizer is configured to locate the additional coil, the method comprising the steps of: i) a) controlling the main transmitting coil to transmit an electromagnetic localization signal receivable by the additional coil, and controlling the additional coil to generate a received localization signal indicative of the electromagnetic localization signal received by the additional coil, and / or b) controlling the additional coil to transmit an electromagnetic localization signal receivable by the main receiving coil, and controlling the main receiving coil to generate a received localization signal indicative of the electromagnetic localization signal received by the main receiving coil; ii) a) providing sensitivity information indicative of a sensitivity profile of each of the additional coil and the main transmitting coil when the main transmitting coil is controlled to transmit the electromagnetic localization signal, and / or b) of a sensitivity profile of each of the additional coil and the main receiving coil when the additional coil is controlled to transmit the electromagnetic localization signal; and iii) determining a position and / or orientation of the additional coil based on the provided sensitivity information and the received localization signal.

[0046] In a further aspect of the invention, a computer program product for determining the position of a coil is disclosed, the computer program product having dedicated program code for causing a processor of a localizer according to the present embodiments to execute one or more of the methods described herein. The computer program product may be realized as a tangible medium or as a file downloadable from a server. In some embodiments, the computer program product is executed directly on the processor.

[0047] A further aspect of the invention provides a kit for use with an existing system including a main coil array, the main coil array including a main receiving coil for receiving an electromagnetic response signal of a magnetomechanical oscillator, the main coil array further including a main transmitting coil for transmitting an electromagnetic excitation signal for exciting the magnetomechanical oscillator. The kit includes at least one moving additional coil configured to be positioned in a region of interest with respect to the magnetomechanical oscillator, the moving additional coil further configured to transmit an additional electromagnetic excitation signal for exciting the magnetomechanical oscillator and / or to receive the electromagnetic response signal of the magnetomechanical oscillator. The kit further includes computer program code configured to be executed on the circuitry of a processor, the computer program code configured to cause at least one of the main transmitting coil and the at least one moving additional coil to transmit an electromagnetic localization signal and to provide a received localization signal from the at least one moving additional coil and the at least one of the main receiving coil, and further configured to cause the processor to determine at least one of a position and an orientation of the at least one moving additional coil from the received localization signal.

[0048] In some embodiments, the electromagnetic location signal is a pilot tone signal.

[0049] In some embodiments, the program code may be further configured to cause the processor to determine sensitivity information of the at least one additional coil to the electromagnetic response signal based at least in part on one or more structural characteristics of the at least one movable additional coil and based on at least one position and orientation of the at least one movable additional coil.

[0050] In some embodiments, the electromagnetic excitation signal is repeatedly transmitted and the program code is executable to repeatedly transmit the electromagnetic localization signal prior to the repeated transmission of the electromagnetic excitation signal.

[0051] It is to be understood that the system, the coil system, the localizer, the method, the computer program product and the kit may have similar and / or identical preferred embodiments, in particular as set out in the dependent claims.

[0052] The present application has a number of technical advantages. Some embodiments of the present application have the advantage that location signals can be determined with greater accuracy.

[0053] In some embodiments, by using the localization signal and the current structure, sensitivity information is increased, allowing the electromechanical device to locate and determine different parts of a subject or object with greater sensitivity and accuracy.

[0054] In some embodiments, the system provides additional coils for receiving the electromagnetic response signal of the magnetomechanical oscillator and / or for transmitting the electromagnetic excitation signal, so that the receiving characteristics and settings of the coil array can be adapted to various situations. Thus, the present invention is easily adaptable. This is a further technical advantage of some embodiments of the present application.

[0055] In some embodiments, a further advantage is that deviations in the electromagnetic response signal of the magnetomechanical oscillator can be detected by the main coil or the additional coil with suitable accuracy to mitigate undesirable effects such as noise.

[0056] In some embodiments, the frequency at which localization measurements can be performed may be maximized, which is a further technical advantage of the present application in accordance with some embodiments.

[0057] In some embodiments, repeatedly transmitting the electromagnetic localization signals at a predefined repetition frequency, i.e. with a predefined time interval between each electromagnetic localization signal, has the advantage that the position and / or orientation of the additional coil can be determined not just once, but repeatedly over the period that the additional coil is applied, which is a further technical advantage of the present application according to some embodiments.

[0058] The above advantages are not limiting and further technical advantages may be envisaged.

[0059] It is to be understood that embodiments of the invention can also be formed by any combination of the features of the dependent claims or the above embodiments with the independent claims.

[0060] These and other aspects of the invention will be elucidated and elucidated with reference to the embodiments described hereinafter. [Brief description of the drawings]

[0061] [Figure 1] FIG. 1 illustrates, in a schematic and exemplary manner, one embodiment of a system for determining the position of a magnetomechanical oscillator. [Diagram 2] FIG. 2 shows, diagrammatically and exemplarily, a flow chart of a method for determining the position of an additional coil in a system according to an embodiment of the invention. [Diagram 3] FIG. 3 shows a schematic and exemplary embodiment of a transmit / receive circuit for an additional coil. [Figure 4] FIG. 4 illustrates, in a schematic and exemplary manner, one embodiment of a pilot tone generation circuit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] FIG. 1 shows, in a schematic and exemplary manner, an embodiment of a system 100 for receiving signals from a magnetomechanical oscillator. In the example shown in FIG. 1, the system 100 is applied to an intervention procedure in which a magnetomechanical oscillator (not shown in FIG. 1) is used in the body of a patient 140 to determine the position of an intervention device, such as a catheter or needle. The system 100 comprises a main coil array, which in this example comprises main receive coils 111, 112, 113, and a main transmit coil 110. The main transmit coil 110 is configured to transmit an electromagnetic excitation signal for exciting a magnetomechanical oscillator provided in the body of the patient 140. The main receive coils 111, 112, 113 of the main receive coil array are configured to receive an electromagnetic response signal provided by the excited magnetomechanical oscillator. Based on the magnetomechanical oscillator signal received by the main receive coils 111, 112, 113, the position of the magnetomechanical oscillator in the body of the patient 140 can be determined. Furthermore, the electromagnetic response signal of the magnetomechanical oscillator may further encode additional information, for example, an identification of the magnetomechanical oscillator or sensed information indicative of a sensed physical parameter in the magnetomechanical oscillator's environment, which can also be determined using the magnetomechanical oscillator's electromagnetic response signal received by the main receiving coils 111, 112, 113.

[0063] The main coils 110, 111, 112, 113 of the main coil array may refer to, for example, aluminum planar coils with a diameter of 10 cm to 20 cm. The main coils 110, 111, 112, 113 may have an inductance of less than 200 μH. Such a small inductance allows the operating voltage to be kept small, and also the coil insulation requirements to be kept small. However, other realizations of the main coils 110, 111, 112, 113 may be appropriate based on the intended application of the main coil array.

[0064] To allow more accurate reception of signals from the magnetomechanical oscillator during an intervention procedure, an additional (moving) coil array 120 can be provided in the region of interest of the patient 140 as part of the system 100. In this example, the additional (moving) coil array 120 comprises additional coils 121, 122, 123, which can also be considered as moving coils as part of a moving coil array and can be placed on the chest of the patient 140. The additional coils 121, 122, 123 of the additional (moving) coil array 120 are also configured to receive electromagnetic response signals of the magnetomechanical oscillator and / or to transmit electromagnetic excitation signals for exciting the magnetomechanical oscillator provided in the body of the patient 140. In the example shown in FIG. 1, the additional coils 121, 122, 123 are arranged on a mounting support 124 that can be used to mount the additional (moving) coil array 120 in the region of interest of the patient 140. In particular, the mounting support 124 allows the additional coils 121, 122, 123 to be positioned in a known spatial relationship to one another, e.g., a spatial relationship determined by the structure of the mounting support 124. However, in other embodiments, the mounting support 124 can be omitted and the additional coils 121, 122, 123 can be separate movable coils that can be freely positioned within the region of interest of the patient 140, e.g., by a physician performing an interventional procedure.

[0065] The additional coils 121, 122, 123 of the additional coil array 120 may refer to planar coils, for example made of aluminum. The diameter of the additional coils 121, 122, 123 is advantageously smaller than the diameter of the main coils 110, 111, 112, 113, and the additional coils 121, 122, 123 may also have an inductance of less than 200 μH. However, other realizations of the additional coils 122, 123, 113 may also be appropriate, based on the intended application of the additional coil array. In particular, the system 100 may have different additional coils for different medical applications. In particular, different additional coils may be provided, with a diameter adapted to the maximum distance between the respective additional coil and the magnetomechanical oscillator, which is expected for the respective medical application.

[0066] Furthermore, the system 100 comprises a localizer 130 configured to determine the positions of the additional coils 121, 122, 123 of the additional coil array 120. The localizer may be implemented as part of the hardware and / or software of any known computing device. For example, the localizer 130 may be provided as a standalone device or as part of the hardware and / or software of a computing device that also provides other functions. Advantageously, the localizer 130 may be provided as part of the hardware and / or software of a computing device that is already used to determine the position of the magnetomechanical oscillator based on the electromagnetic response signal of the excited magnetomechanical oscillator received by the main coil array and the additional coil array 120. The localizer 130 may be connected to the main coil array and the additional coil array 120 in a wired or wireless manner, as indicated by the connecting lines 114 and 125. The localizer 130 comprises a sensitivity provider 131, a controller 132, optionally a motion model provider 133, and a processor 134.

[0067] The sensitivity provider 131 is configured to provide sensitivity information indicative of the sensitivity profile of the additional coils 121, 122, 123 and / or the main receiving coils 111, 112, 113 and / or the main transmitting coil 110. In particular, the sensitivity provider 131 is configured to provide the sensitivity information necessary to determine the position and / or orientation of the additional coils 121, 122, 123. Generally, the sensitivity information indicative of the sensitivity profile of all coils involved in transmitting and receiving the electromagnetic localization signal is taken into account, so that it is preferable that the sensitivity provider 131 is configured to provide sensitivity information indicative of the sensitivity profile of each involved coil. For example, if the main transmitting coil 110 is controlled to transmit an electromagnetic localization signal and the additional coils 121, 122, 123 are controlled to receive an electromagnetic localization signal, the sensitivity provider 131 is configured to provide sensitivity information indicative of the sensitivity profile of the main transmitting coil 110 and the additional coils 121, 122, 123. In general, it is beneficial if the sensitivity information of each of the coils 110, 111, 112, 113, 121, 122, 123 is known and stored in a storage unit, such as, for example, any type of memory device, a computer drive (e.g., a solid-state drive such as a flash drive), an optical disk, a remote server, or the like. The sensitivity provider 131 may then be configured to select the respective sensitivity information from the storage unit. The sensitivity information of these coils 110, 111, 112, 113, 121, 122, 123 may be determined, for example, during a calibration procedure of the system 100 prior to an intervention procedure, or may be provided, for example, by the manufacturer of the system 100. For example, the sensitivity profile of each coil may be determined by utilizing a virtual simulation model, optionally in combination with actual measurements of the magnetic field of the coils. The simulation model may be provided by virtually providing a conductor for each coil in the simulation model and simulating the magnetic field of the virtual coil conductor using the Biot-Savart law. To calibrate and / or verify the simulated magnetic field, measurements of the magnetic field, in particular measurements of the magnetic flux density of the magnetic field, may optionally be performed at several points around the actual coil.These measurements can be used to calibrate the simulation model of the coil so that the simulated magnetic field corresponds to the magnetic field actually measured at the respective points. This improves the accuracy of the simulation model and allows to take into account deviations of the actual coil from the specifications, which may be due to, for example, manufacturing inaccuracies. However, other known methods for determining the sensitivity profile of the coil can also be used to provide the sensitivity information. The sensitivity information may refer to the respective sensitivity profile itself or to other measures of the sensitivity profile. For example, the sensitivity information may refer to the simulation model of the coil, for example the position and orientation of the virtual conductors in the simulation model, since the sensitivity profile can be derived directly from these using known physical laws.

[0068] In that case, the controller 132 may be configured to control the main transmitting coil 110 to transmit electromagnetic localization signals receivable by the additional coils 121, 122, 123, and further to control the additional coils 121, 122, 123 to generate receive localization signals indicative of the electromagnetic localization signals received by the additional coils 121, 122, 123. Additionally or alternatively, the controller may be configured to control the additional coils 121, 122, 123 to transmit electromagnetic localization signals receivable by the main receiving coils 111, 112, 113, and to control the main receiving coils 111, 112, 113 to generate receive localization signals indicative of the electromagnetic localization signals received by the main receiving coils 111, 112, 113. In general, receive localization signals may refer to electrical signals generated by receiving circuitry provided as part of each additional coil 121, 122, 123 or as part of the main receiving coils 111, 112, 113, respectively. Advantageously, the additional coils 121, 122, 123 have a receiver circuit configured such that the additional coils 121, 122, 123 do not reach a saturation threshold of the receiver circuit when receiving the electromagnetic excitation signal transmitted by the main transmission coil 110. Such a receiver circuit can be realized, for example, by providing a respective damping mechanism including an element, for example a damping element, enabling damping of the received signal in the receiver circuit. Thereby, also for the electromagnetic excitation signal transmitted by the main transmission coil 110, each additional coil 121, 122, 123 can generate a received localization signal indicative of the amplitude of the received electromagnetic localization signal. A more detailed example of such a receiver circuit is described below with reference to FIG. 3.

[0069] If the received localization signal is generated by the additional coils 121, 122, 123, the processor 134 is configured to determine the position and / or orientation of the additional coils 121, 122, 123 of the additional coil array 120 based on the provided sensitivity information of the additional coils 121, 122, 123 and the main transmitting coil 110 and on the received localization signal. If the received localization signal is generated by the main receiving coils 111, 112, 113, the processor is configured to determine the position and / or orientation of the additional coils 121, 122, 123 based on the sensitivity information of the main receiving coils 111, 112, 113 and the additional coils 121, 122, 123. In general, the determination of the position and / or orientation of the additional coils 121, 122, 123 can be based on known coil localization algorithms and / or algorithms similar to those used for localization of magnetomechanical oscillators. For example, in an advantageous embodiment, a computational model is provided to determine the position and / or orientation of the additional coils 121, 122, 123. Advantageously, the processor 134 is configured to apply the computational model, which includes sensitivity information provided, for example, in the form of the position and / or orientation of all conductors that can represent the coil magnetic field generated by each coil when a known current is supplied. However, it is also possible to directly incorporate the sensitivity information into the computational model as a sensitivity profile of each coil. Based on the sensitivity information incorporated into the computational model of the coils and known physical laws, a virtually received localization signal can be simulated depending on the relative position and / or orientation of the coils involved in the localization process. Optionally, further influences can be taken into account to improve the accuracy of the computational model. For example, the transmission and / or reception circuitry of the respective coil can also be incorporated into the computational model, and its influence on the virtual received localization signal can be simulated. The simulated received localization signal can then be compared with the actually measured received localization signal.By varying the relative position and / or orientation of the involved coils, the relative position and / or orientation of the respective coils that minimizes the difference between the virtual and the measured receive localization signals can be determined in the computational model as the actual position and / or orientation of the respective coils. Thus, the determination of the position and / or orientation of the respective coils can be considered as an optimization problem and can be solved using known optimization algorithms, for example iterative or direct solvers. If information about the position and / or orientation of the respective coils, for example the main coil and / or the additional coils, is available in advance, this position information can be further taken into account in the computational model, for example as a starting point for the optimization process. To further increase the accuracy of the computational model and the optimization process, further influences on the receive localization signals can be considered, in particular those that result in deviations from the expected receive localization signals. It is advantageous if the influence on the accuracy of the receive localization signals is considered as an error function. For example, in some commonly used amplifiers, the actual amplification cannot be predicted precisely because it is within a certain error range. Therefore, it is necessary to consider possible errors caused by such amplifiers. All identified contributions to the expected error of the received localization signal are provided in the form of an error function, along with respective weights that can be used to weight the contribution of each term in the error function. The error function can then be incorporated into an optimization process using known methods and algorithms. The results of the optimization are provided by the processor 134 as the positions and / or orientations of the additional coils (and, optionally, the position and / or orientation of the main coils, if not already known). In general, other known algorithms that enable the processor 134 to determine the positions and / or orientations of the electromagnetic signal sources can also be used.

[0070] In an embodiment in which multiple additional coils are provided, as shown in the embodiment of Fig. 1, the position and / or orientation of each additional coil 121, 122, 123 is advantageously determined by the processor 134 based on a known position and / or orientation of at least one of the additional coils 121, 122, 123, respectively. Furthermore, in the embodiment shown in Fig. 1, the known spatial relationship between the additional coils 121, 122, 123 provided by the mounting support 124 may be advantageously utilized by the processor 134 to determine the positions and / or orientations of the additional coils 121, 122, 123. For example, the processor 134 may be configured to first determine the position and / or orientation of only one of the additional coils, e.g., the additional coil 121, based on the sensitivity information and the received localization signals, and to determine the position and / or orientation of these additional coils based on the known spatial relationship of the additional coils 122, 123 to the position and / or orientation of the additional coils 121. However, the processor 134 may be configured to utilize the spatial information provided by the mounting support 124 in other ways, for example to validate the results of position and / or orientation determinations based on the sensitivity profiles and received localization signals, or as a starting point for optimization algorithms, as described above.

[0071] The localizer 130 further comprises a motion model provider 133. The motion model provider 133 may be configured to provide a motion model of the region of interest to which the additional coil array 120 is attached. In the example shown in FIG. 1, the additional coil array 120 is attached to the chest of the patient 140. The motion model provider 133 may therefore be configured in this case to provide a motion model of the human chest. In general, the motion model provided by the motion model provider 133 may be a generic motion model of the region of interest. For example, in the example shown in FIG. 1, this may be a generic model of human chest motion, obtained by averaging chest motions measured from various people. However, the provided motion model may also be a specific motion model, in particular a motion model specific to the patient 140. For example, in the embodiment shown in FIG. 1, the motion model may mean a motion model specific to the patient 140, which may be determined based on measurements of past or current chest motions of the patient 140. In an advantageous embodiment, a motion sensor is attached to the area of ​​interest of the patient 140, in FIG. 1 the chest of the patient 140, and the measurement signals provided by the motion sensor are directly used as a motion model and provided by the motion model provider 133.

[0072] If a motion model is provided by the motion model provider 133, the processor 134 may be further configured to determine the position and / or orientation of the additional coils 121, 122, 123 based on the motion model. In particular, the processor 134 may be configured to estimate the current position and / or orientation of the additional coils 121, 122, 123 based on the motion model and to use this estimated position and / or orientation as a starting point for an algorithm for determining the current position and / or orientation of the additional coils 121, 122, 123, e.g., as described above, as a starting point for a computational model. However, the processor 134 may also be configured to utilize the motion model to estimate the position and / or orientation of the additional coils 121, 122, 123 during periods when no electromagnetic localization signal is provided for determining the position of the additional coils 121, 122, 123. Thus, based on the motion model, the current position of the additional coils 121, 122, 123 can be accurately tracked even when no continuous electromagnetic localization signal is provided.

[0073] After the position and / or orientation of the additional coils 121, 122, 123 are determined, the determined position and / or orientation may be utilized in an algorithm for determining the position of the magnetomechanical oscillator, for example, during an interventional procedure. Furthermore, the processor 134 may be configured to provide the determined position and / or orientation to a user of the system 100, for example, a physician, for example, via a display device. This allows verification of the results. Furthermore, the determined position and / or orientation may be integrated into the medical procedure framework, for example, displayed on a display in association with an anatomical image of the patient 140, such that the additional coils 121, 122, 123 can also be utilized as markers on the patient 140. For example, the movement of the region of interest of the patient 140 may also be derived from changes in the position and / or orientation of the additional coils 121, 122, 123.

[0074] Fig. 2 shows, in a schematic and exemplary manner, a method for locating additional coils in a system such as the system 100 shown in Fig. 1. In particular, the method 200 includes a first operation 210 of providing sensitivity information of the additional coils 121, 122, 123 and / or the main receiving coils 111, 112, 113 and / or the main transmitting coil 110, as described above. In a further operation 220, the method 200 may include controlling the main transmitting coil 110 to transmit electromagnetic localization signals receivable by the additional coils 121, 122, 123, and controlling the additional coils 121, 122, 123 to generate received localization signals indicative of the electromagnetic localization signals received by the additional coils 121, 122, 123. Additionally or alternatively, in operation 220, method 200 may also include controlling the additional coils 121, 122, 123 to transmit electromagnetic localization signals that can be received by the main receive coils 111, 112, 113, and controlling the main receive coils 111, 112, 113 to generate receive localization signals indicative of the electromagnetic localization signals received by the main receive coils 111, 112, 113. In general, operations 210 and 220 may be performed in any order and may also be performed simultaneously. Furthermore, method 200 includes operation 230 of determining a position and / or orientation of the additional coils 121, 122, 123 based on sensitivity information of the additional coils 121, 122, 123 and the main transmit coil 110 and the receive localization signals, if the receive localization signals are generated by the additional coils 121, 122, 123. Additionally or alternatively, operation 230 may include determining the position and / or orientation of the additional coils 121, 122, 123 based on sensitivity information of the main receive coils 111, 112, 113 and the additional coils 121, 122, 123 and the receive positioning signal if the receive positioning signal is generated by the main receive coils 111, 112, 113. In general, the position and / or orientation of the additional coils 121, 122, 123 may be determined according to any of the principles discussed above with respect to FIG.

[0075] Fig. 3 shows a schematic and exemplary embodiment of a transmit / receive circuit 300 of the additional coil 310. By transmit / receive circuit 300 is meant a combination of a receive circuit for receiving an electromagnetic signal and generating an electrical signal representative of the received electromagnetic signal, and a transmit circuit for generating from the supplied electrical signal an electric current which, when supplied to the additional coil 310, results in the transmission of an electromagnetic signal. The exemplary transmit / receive circuit 300 shown in Fig. 3 comprises a computer interface 320 which can supply an electric signal, for example from the controller 134 of Fig. 1, for controlling the transmit / receive circuit and / or the additional coil 310 or for receiving and further processing an electric signal representative of the electromagnetic signal received by the additional coil 310. Each connection line between two components of the transmit / receive circuit 300 can be considered as one or more data lines for transmitting an electric signal, i.e. an electric current, between the different components. A first electric signal is supplied from the computer interface 320 to an amplifier 321, which can be realized as an H-bridge, i.e. a full bridge. The output signal of the amplifier 321 is then fed to a transformer 330, which feeds the further coil 310 to provide a base signal, which may for example be an electromagnetic excitation signal. The transformer 330 may be considered as an interface between the further coil 310 and further parts of the transmit / receive circuit used to modify the received or fed electrical signal, so that the further coil 310 can be used to receive / transmit an electromagnetic localization signal, to receive an electromagnetic response signal of a magnetomechanical oscillator and / or to transmit an electromagnetic excitation signal.

[0076] In some embodiments, the electrical signal transmitted or received from the additional coil 310 passes through a first inductance 331 of the transformer 330 and is thus coupled to other inductances 332, 333 of the transformer 330. The transformer 330 in this example therefore enables inductive coupling between the additional coil 310 and other parts of the transmit / receive circuit 300. However, in other embodiments, other electrical couplings, for example capacitive or resistive couplings, may also be utilized.

[0077] A further part of the transmission / reception circuit 300 can be considered as a transmission circuit for transmitting an electromagnetic localization signal. In this part of the circuit, an electrical signal resulting in the electromagnetic localization signal is provided by the computer interface 320 to a circuit element 340 comprising a logical AND gate 341 and three resistors R1, R2, R3. The resistors R1, R2, R3 control, based on the electrical signal received by the circuit element 340, which current is provided to the second inductance 332 of the transformer 330 and thus how the base signal should be modified to result in the electromagnetic localization signal transmitted by the additional coil 310. In general, it is advantageous for the resistors R1, R2, R3 to have a higher impedance compared to the impedance of the second inductance 332 at the desired frequency, so that a relatively weak coupling with the first inductance 331 is achieved.

[0078] The third part of the transmit / receive circuit 300 can be considered as a receive circuit that allows the reception of an electromagnetic localization signal without exceeding the saturation threshold of the receive circuit. In this part, a third inductance 333 of the transformer 330 allows the reception of an electric signal representative of the electromagnetic signal received by the additional coil 310 through inductive coupling with the first inductance 331. The electric signal separated from the additional coil 310 by the third inductance 333 can be fed directly to a low noise amplifier (LNA) 351, which is part of the circuit element 350. Alternatively or additionally, the separated electric signal can be fed first to an attenuation element 352, here realized as a potentiometer, which is also part of the circuit element 350, and then to the LNA 351 and thereafter to the computer interface 320 via the analog / digital converter 322. Which of the two paths is used for the separated, i.e. received, signal can be determined by controlling a switch shown as part of the attenuation element 352. These two paths thus allow two different attenuation factors, i.e. two different amplifications, of the received signal to be realized. In general, an adjustable attenuation element may be provided, allowing for more than two attenuation factors, thus allowing for even greater precision and flexibility of the additional coil 310. Here, the LNA may comprise a junction-gate field-effect transistor (JFET) (common source amplifier) ​​input stage and a low noise op-amp for further amplification. However, in various embodiments, other amplifiers (e.g., those with silicon bipolar input stages) may be used.

[0079] Generally, the switches shown in this exemplary transmit / receive circuit 300 refer to well-known computer-controllable switches. They can be realized, for example, as mechanical or semiconductor relays. Optionally, the LNA 351 can be configured to control a further switch 353 capable of shorting the inductance 331. This can be advantageous if the LNA 351 needs to be protected during the transmission of the electromagnetic signal. Furthermore, due to the small current consumed, a slow rise in the current in the additional coil 310 due to the inductance 331 can be prevented. Generally, it is advantageous if the first inductance 331 has a much higher inductance than the inductances of the second and third inductances 332, 333, more advantageously at least ten times higher. This also allows for a moderate protection of the LNA 351 without using the optional switch 353.

[0080] In general, tracking of magnetomechanical oscillators relies on spatially resolved detection of the magnetomechanical oscillator's response to, for example, a series of excitation pulses. The spatial information is usually obtained using an array of main receiving coils with a known spatial sensitivity profile. For general-purpose applications, a compromise between spatial resolution and the technical effort of the main coil array and detection system may result in a limited number of rather large main coils, but some applications may require higher resolution over short periods of time (e.g., when inserting a needle into a patient). Finer coil arrays provide higher resolution and sensitivity, especially if the coil arrays are close to the workspace. However, it is inconvenient to always place them in the workspace as they may interfere with the workflow of the procedure.

[0081] In order to provide a more flexible system for receiving the signals of the magnetomechanical oscillator, it is proposed, for example, to provide a set of additional coils. The additional coils may be physically connected to one or more of the main coils or the main coil array. Advantageously, each additional coil comprises at least signal receiving means, i.e. receiving circuits, configured not to saturate during the weakest excitation signal transmitted by the main transmitting coil. The sensitivity encoding allows the position and orientation of the additional coil to be estimated from the signals detected from the electromagnetic localization signals transmitted using the main coil array, i.e. received localization signals. The determined position and / or orientation of the additional coils can then be incorporated into the position and characteristic reconstruction computational model of the reconstruction algorithm used to localize the magnetomechanical oscillator. Furthermore, if necessary, the main transmitting coil can be controlled to utilize a low-power transmission mode in order to improve the determination of the position and orientation. In this case, the low-power transmission mode comprises transmitting a pilot tone signal as an electromagnetic localization signal having an amplitude low enough not to saturate the receiving circuit of the additional coil. In general, the additional coils may be provided as wireless coils or with a wired connection interface. In the latter case, it is advantageous if the additional coil is also provided with a transmitting function, i.e. a transmitting circuit, for example for transmitting an excitation signal or an electromagnetic localization signal. The additional coil may be provided in the patient's region of interest and thus may move during tracking of the position of the magnetomechanical oscillator, so that the position and / or orientation information is preferably upgraded at a sufficiently high frequency. To reduce the need to frequently solve the complete coil localization problem, a motion model describing the expected movements may be used.

[0082] The reconstruction to determine the position and / or orientation is performed by a common model-based reconstruction algorithm known for locating the source of an electromagnetic signal. This algorithm is based on sensitivity information of each additional coil, which has advantageously been recorded and / or obtained beforehand during a calibration operation. The calibration operation may be performed in conjunction with each measurement pulse. In a simple embodiment, all main transmission coils can transmit a "pilot tone" as an electromagnetic localization signal, meaning a constant signal outside the normal operating band of the main coils, i.e. outside the band of the electromagnetic excitation signal normally used. This pilot tone can be transmitted in turn by all main transmission coils and recorded by at least the additional coils, and can be transmitted before each measurement pulse (so that the "calibration" is performed before each measurement). This allows maximizing the position accuracy (reducing errors due to movement) since the time delay between the calibration and the measurement is minimized. This can be done at all times, even during the signal reception of the magnetomechanical oscillator. Using this information, a common reconstruction algorithm, for example utilized by a processor, can position and orient the additional coils, obtaining accurate results due to the high signal-to-noise ratio. The pilot tone can be transmitted by one or more moving coils in the fixed array. An example of a procedure is as follows.

[0083] Transmit a pilot tone / calibration magnetic signal (can be performed by one or more moving coils in a fixed array).

[0084] Transmit the measurement signal (any coil combination including a moving coil).

[0085] Receives pilot tone / calibration signals (for any coil combination) and generates a corresponding electrical calibration signal.

[0086] It receives the sensor response (any coil combination including a moving coil) and produces a corresponding electrical sensor signal.

[0087] The calibration signal is processed to obtain calibration information (ie, a sensitivity profile from a sensitivity provider).

[0088] The calibration signal is used in processing the electrical sensor signal to determine the sensor position.

[0089] In some embodiments, an upgrade kit may be provided for use with an existing system, including with a system comprising a main coil array, as described above, the main coil array comprising a main receiving coil configured to receive an electromagnetic response signal of an electromechanical oscillator, the main coil array further comprising a main transmitting coil configured to transmit an electromagnetic excitation signal for exciting the magnetomechanical oscillator. Such a kit may include at least one moving additional coil configured to be placed in a region of interest with respect to the magnetomechanical oscillator. The moving additional coil is further configured to transmit an additional electromagnetic excitation signal for exciting the magnetomechanical oscillator and / or to receive an electromagnetic response signal of the magnetomechanical oscillator. The upgrade kit may further comprise at least one non-transitory tangible medium having stored thereon program code executable to cause at least one of the main transmitting coil and the at least one moving additional coil to transmit an electromagnetic localization signal, and to provide a received localization signal from at least one of the at least one moving additional coil and the main receiving coil. The program code is further executable to cause the processor to determine at least one of a position and an orientation of the at least one moving additional coil from the received localization signal.

[0090] In some embodiments, the program code may be executed by a processor that may be included in a system (e.g., system 100) that receives a signal from the magnetomechanical oscillator. In some embodiments, the processor may be formed as a part of a computing device. The computing device may be intended to be any known general-purpose or dedicated computing device. For example, it may be a personal computer; a handheld computing device such as a smartphone, tablet, laptop; a cloud computing device, etc. The computing device may be one that is already utilized to identify the location of the magnetomechanical oscillator, or it may be a separate computing device. Here, the electromagnetic localization signal may be a pilot tone signal as described above. In some embodiments, the at least one non-transitory tangible medium may further store information about one or more structural characteristics of the at least one moving additional coil, the one or more structural characteristics including at least one of a diameter and a number of turns of the at least one moving additional coil. In some embodiments, the program code may further be configured to cause the processor to determine sensitivity information of the at least one additional coil to the electromagnetic response signal based at least in part on the one or more structural characteristics of the at least one moving additional coil and based on at least one position and orientation of the at least one moving additional coil. In some embodiments, the electromagnetic excitation signal is repeatedly transmitted and the program code is executable to repeatedly transmit the electromagnetic localization signal prior to the repeated transmission of the electromagnetic excitation signal.

[0091] Further, an additional algorithm may be applied by the processor to mitigate the effects of metal in the surrounding environment as part of the position and / or orientation determination. Additionally, the processor may be configured to further reconstruct the position and / or orientation of the second additional coil using the known position and / or orientation of the first additional coil in a computational model-based reconstruction algorithm. An advantage of this approach is that the field of view of the system can be gradually expanded.

[0092] Moreover, it is beneficial to extend the field of view of the system by incorporating an accelerometer in each additional coil. Moreover, instead of using a pilot tone as described above, in other embodiments, an excitation signal can also be used to locate the additional coil. In this embodiment, it is preferable that the main transmitting coil is configured to provide a low transmission amplitude. Alternatively or additionally, the additional coil advantageously has a switchable attenuator as part of the receive path of the receive circuit of the additional coil. To avoid saturation of the receive circuit of the additional coil, a pilot tone with an adjustable power level can be used as an electromagnetic localization signal. The flexibility of the system is greatest if the additional coil can be configured as a transmit coil. This can be easily achieved by hardwiring the additional coil to a power source. Alternatively, the additional coil can be provided with a battery as a power storage device. Battery-powered additional coils are very convenient to incorporate high-frequency means for transmitting the receive signal. The main transmitting coil can also be used to transmit power to the additional coil to charge a local energy storage device of the additional coil, for example a battery or a double layer capacitor. The additional coil can also be provided with an LC resonant circuit. The resonant circuit can be made to approximately tune to the transmit frequency of the magnetomechanical oscillator, allowing the transmit and receive fields to be locally enhanced.

[0093] The devices using pilot tones disclosed herein can provide many benefits and advantages, the uses of which are not limited to those described herein. For example, pilot tones can be used for purposes such as compensation for drift in the receiving coil, compensation for drift in the amplifier. In some cases, the drift may be gain drift, and the amplifier 321 and / or low noise amplifier (LNA) 351 may be utilized. It is generally known that LNA drift can be compensated for in the LNA by appropriate feedback, and can be used to boost the received signal to a sufficient level above the noise floor, making the amplifier available for additional processing. However, this inherently causes noise and power consumption (power penalty) that are undesirable in this type of system. By using the pilot tone structure, these adverse effects can be minimized or avoided altogether. Furthermore, the structure and pilot tones allow for detection of the presence of obstructions near the coil, such as the main coil or the additional coil, or a combination of the two (e.g., obstructions that may be caused by the presence of metal in the environment). This allows for reducing or minimizing risk to the patient (e.g., in cardiac surgery), increasing signal reliability, reducing noise, etc. Furthermore, the presence of metal in the region not only changes the gain in the coil, but also changes the spectral response of the coil. By utilizing the pilot tone structure, it is possible to separate generally undesirable signals, such as noise signals, from desired signals, such as the response signal. For example, in the above example, the signal generated from metal near the coil can be distinguished from the gain change of the low noise amplifier (LNA) 351.

[0094] Furthermore, the inventors have surprisingly determined that it is possible to generate pulses of sufficiently high intensity that they can be used and detected by other coils, such as array coils. This can be done so that the received signals, such as the self-received signals, are not saturated. In some advantageous embodiments, this allows the coils to be permanently localized relative to one another, where the coils can be main coils, additional coils, or any combination thereof. In some advantageous embodiments, it is further desirable to filter the pulses before performing the coupling to the coils. Preferably, the pulses are low pass filtered as known in the art. This allows the generation of pulses of sufficient intensity to be measured by other coils without saturating their own receiving operation. In some embodiments, the other coils are additional coils. In other embodiments, they are main coils in the array.

[0095] In some embodiments, a complementary metal-oxide-semiconductor (CMOS) device may be used for the pilot tone generation, and various types of CMOS devices may be used, such as RF CMOS devices. In some embodiments, a CMOS output logic gate may be used for the pilot tone generation. For example, the CMOS gate may connect the output to a stable ground. This may prevent the voltage potential at the power supply (e.g., Vcc) at a given resistor from dropping. Advantageously, this configuration may provide stability to the system. In some cases, it may only be necessary to stabilize Vcc to a stable level for the entire system to be stable. In general, this may be achieved using a voltage regulator that is simple in design and cost-effective. Thus, this may provide an additional benefit of being cost-effective. In some embodiments, a voltage regulator may also be utilized, and the regulator may be one that exhibits low temperature drift.

[0096] FIG. 4 illustrates, in a schematic and exemplary manner, one embodiment of a pilot tone generation circuit 400 configured to generate a pilot tone signal that may be used as an electromagnetic location signal as described above. The pilot tone generation circuit 400 comprises a voltage regulator 410, a CMOS output stage device 420, an optional low pass filter (LPF) 430, a resistor R440, and a coupling transformer 450. The voltage regulator has an input 405. The input 405 receives a power supply voltage and generates a regulated supply voltage Vcc in response thereto. The voltage regulator 410 may be a high-precision voltage regulator. A capacitor C at the output of the voltage regulator 410 may reduce noise and stabilize the regulated supply voltage Vcc. The CMOS output stage device 420 has an input 415 that receives a pilot tone input signal. The pilot tone input signal may be, for example, a digital signal that includes a pulse sequence unique to each coil that transmits a pilot tone signal. Advantageously, the transistors of the CMOS output stage device 420 have an on-resistance that is much smaller (e.g., by an order of magnitude or more) than the resistance of resistor R440. A coupling transformer 450 couples the pilot tone output signal to the transmit and receive coil system.

[0097] Because pilot tones have different uses, in some embodiments, circuit 400 may be modified to implement different selectable current levels. In some embodiments, actual pilot tone signals and control signals are used to allow selection of different current levels. In that case, the circuit includes different outputs with different output resistors, which are coupled in parallel. A digital control signal (e.g., a 2-bit word) selects the appropriate output stage.

[0098] In the above embodiment, the system comprises an additional coil array including three additional coils, but in other embodiments, the system may comprise any number of additional coils, for example only one additional coil, or multiple additional coils. Furthermore, in the above embodiment, the system comprises only one main transmitting coil, but in other embodiments, the system may comprise more than one main transmitting coil, in particular multiple main transmitting coils, in which case the same principles as detailed above are also applicable. Furthermore, in the above embodiment, the system comprises a main receiving coil array including three main receiving coils, but in other embodiments, the system may comprise any number of main receiving coils, for example one main receiving coil, or multiple main receiving coils. In particular, in the above embodiment, the system comprises a main transmitting coil that is used only for transmitting electromagnetic signals and a main receiving coil that is used only for receiving electromagnetic signals, but in other embodiments, each main coil of the system may be adaptable to be utilized as both a main transmitting coil and a main receiving coil.

[0099] While in the above embodiments the transmit / receive circuitry has been described as part of the additional coil, in other embodiments the same or similar transmit / receive circuitry may be provided as part of the main coil or main coil array. Furthermore, while in the above embodiments the combination of the receive circuitry and the transmit circuitry has been described as the transmit / receive circuitry, in other embodiments only a portion of the transmit / receive circuitry may be provided in the additional coil and / or the main coil, for example only the receive circuitry may be provided.

[0100] Other variations of the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention from the drawings, the disclosure, and the appended claims. In the claims, the terms "comprises" and "including" do not exclude other elements or steps, and singular elements do not exclude a plurality.

[0101] A single unit or device may fulfill the functions of several items recited in the claims. The mere fact that several measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0102] The procedures performed by one or more units or devices, such as providing sensitivity information, providing a motion model, controlling the coils, determining the position and / or orientation of additional coils, may also be performed by any number of other units or devices. These processes may be implemented via program code of a computer program that may be stored in a memory and executed by a processor and / or stored as dedicated hardware.

[0103] The computer program may be stored and / or distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, or may be distributed in other forms, such as via the Internet, other wired or wireless telecommunications systems, or a cloud system.

[0104] Any reference signs in the claims should not be construed as limiting the scope. While the invention has been illustrated and described in detail in the drawings and above, such illustrations and descriptions are to be considered as illustrative or exemplary and not limiting. The invention is not limited to the disclosed embodiments. From the drawings, the disclosure, and the appended claims, other variations of the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention.

[0105] Disclosed herein is a system for receiving a signal from a magnetomechanical oscillator. The system comprises a main coil array configured to receive a response signal of the magnetomechanical oscillator and send an excitation signal to the magnetomechanical oscillator, and an additional coil for receiving the signal of the magnetomechanical oscillator. A localizer is configured to identify a position of the additional coil and includes a controller for controlling the main coil array and the additional coil such that a receive localization signal is generated, a sensitivity provider for providing sensitivity information, and a processor for determining a position and / or orientation of the additional coil based on the provided sensitivity information and the receive localization signal. The system is flexibly applicable and can be easily adapted to various medical situations.

Claims

1. 1. A system for receiving a signal from a magnetomechanical oscillator, the system comprising: a main coil array including at least one main transmit coil for transmitting an electromagnetic excitation signal for exciting the magnetomechanical oscillator; a main receiving coil for receiving an electromagnetic response signal of the magnetomechanical oscillator; At least one additional coil, said additional coil comprising: (1) receiving the electromagnetic response signal of the magnetomechanical oscillator; or (2) transmitting the electromagnetic excitation signal to excite the magnetomechanical oscillator; at least one additional coil, the main coil array and the additional coil forming a medical coil system for receiving signals from the magnetomechanical oscillator; a controller that controls at least one of the main transmitting coil and the additional coils to transmit an electromagnetic location signal, the controller further controlling the additional coil to generate a receive location signal indicative of the electromagnetic location signal received by the additional coil when the main transmitting coil transmits the electromagnetic location signal, and to control the main receiving coil to generate a receive location signal indicative of the electromagnetic location signal received by the main receiving coil when the additional coil transmits the electromagnetic location signal; a processor that determines at least one of a position or an orientation of the additional coil based on the received localization signals and sensitivity information; The system, wherein the sensitivity information indicates at least one of: (1) a sensitivity profile of each of the additional coils and the main transmitting coil when the main transmitting coil transmits the electromagnetic localization signal; or (2) a sensitivity profile of each of the additional coils and the main receiving coil when the additional coil transmits the electromagnetic localization signal.

2. 2. The system of claim 1, wherein the additional coil includes a receiver circuit that receives an electromagnetic signal and generates an electrical signal indicative of the received electromagnetic signal, the receiver circuit having a saturation threshold, the saturation threshold of the receiver circuit not being reached when the receiver circuit receives the electromagnetic excitation signal transmitted by the main transmit coil and generates an electrical signal indicative of the electromagnetic excitation signal.

3. 3. The system of claim 1, wherein the controller controls at least one of the main transmitting coil and the additional coils to transmit the electromagnetic localization signals repeatedly with a predetermined period between transmissions of the electromagnetic localization signals, and further controls at least one of the additional coil and the main receiving coil to generate the receive localization signals based on the electromagnetic localization signals received from the transmissions of the electromagnetic localization signals, and the processor determines at least one of the position and the orientation of the additional coil based on the receive localization signals generated from the transmissions of the electromagnetic localization signals.

4. 4. The system of claim 1, wherein at least one of the at least one main transmitting coil and the at least one additional coil generates and transmits a pilot tone signal as the electromagnetic localization signal.

5. 5. The system of claim 4, wherein the at least one of the at least one main transmit coil and the at least one additional coil includes a CMOS output logic circuit that generates the pilot tone signal.

6. (1) the at least one main transmitting coil includes a main transmitting coil array having a plurality of main transmitting coils, and the controller controls the main transmitting coil array such that the plurality of main transmitting coils of the main transmitting coil array transmit electromagnetic location signals in sequence, and further controls the additional coils to generate receive location signals for at least some of the electromagnetic location signals received in sequence; or (2) the at least one additional coil includes an additional coil array having a plurality of additional coils, and the controller controls the additional coil array such that the plurality of additional coils of the additional coil array transmit electromagnetic location signals in sequence, and further controls the main receiving coil to generate receive location signals for at least some of the electromagnetic location signals received in sequence. The system of claim 1 , wherein the processor is further configured to determine at least one of a position and an orientation of the additional coil based on the generated received localization signals.

7. 7. The system of claim 1, wherein the additional coil further comprises an accelerometer that measures an acceleration of the additional coil, and the processor determines at least one of a current position and orientation of the additional coil further based on the measured acceleration of the additional coil.

8. 8. The system of claim 1, wherein the electromagnetic localization signal has signal characteristics outside a range of signal characteristics utilized for the excitation of the magnetomechanical oscillator.

9. 9. The system of claim 1, wherein the additional coil includes a local energy storage element, the local energy storage element being charged by an electromagnetic charging signal, and the controller controls the main transmitting coil to transmit the electromagnetic charging signal to the additional coil.

10. 10. The system of claim 1, wherein the system comprises an LC circuit, the LC circuit including the additional coil, the resonant frequency of the LC circuit being within a frequency range of the electromagnetic excitation signal.

11. 1. A coil system for receiving a signal from a magnetomechanical oscillator, the coil system comprising: a main coil array including a main receiving coil for receiving an electromagnetic response signal of the magnetomechanical oscillator, and a main transmitting coil for transmitting an electromagnetic excitation signal for exciting the magnetomechanical oscillator; and an additional coil, the additional coil (1) for receiving an electromagnetic response signal of the magnetomechanical oscillator or for transmitting an electromagnetic excitation signal for exciting the magnetomechanical oscillator.

12. (1) a main coil array including a main receiving coil for receiving an electromagnetic signal of a magnetomechanical oscillator, the main coil array further including a main transmitting coil for transmitting an electromagnetic excitation signal for exciting the magnetomechanical oscillator; (2) an additional coil for receiving an electromagnetic response signal of the magnetomechanical oscillator; a system for use with said additional coil, said system determining a position of said additional coil; The system comprises: a controller that controls at least one of the main transmitting coil and the additional coils to transmit an electromagnetic location signal, the controller further controlling the additional coil to generate a receive location signal indicative of the electromagnetic location signal received by the additional coil when the main transmitting coil transmits the electromagnetic location signal, and to control the main receiving coil to generate a receive location signal indicative of the electromagnetic location signal received by the main receiving coil when the additional coil transmits the electromagnetic location signal; a processor that determines at least one of a position and an orientation of the additional coil based on the received localization signals and sensitivity information; The system, wherein the sensitivity information indicates at least one of: (1) a sensitivity profile of each of the additional coils and the main transmitting coil when the main transmitting coil transmits the electromagnetic localization signal; or (2) a sensitivity profile of the additional coils and the main receiving coil when the additional coil transmits the electromagnetic localization signal.

13. 1. A computer-implemented method of operation of a system, the system including: (1) a main coil array including a main receiving coil for receiving an electromagnetic signal of a magnetomechanical oscillator, the main coil array further including a main transmitting coil for transmitting an electromagnetic excitation signal for exciting the magnetomechanical oscillator; and (2) an additional coil for receiving an electromagnetic response signal of the magnetomechanical oscillator, the system locating a position of the additional coil, the method comprising: controlling at least one of the main transmitting coil and the additional coil to transmit an electromagnetic localization signal; controlling the additional coils to generate received location signals indicative of the electromagnetic location signals received by the additional coils when the main transmitting coil transmits the electromagnetic location signals; controlling the main receiving coil to generate a receive location signal indicative of the electromagnetic location signal received by the main receiving coil when the additional coil transmits the electromagnetic location signal; providing sensitivity information indicative of at least one of: (1) a respective sensitivity profile of the additional coil and the main transmitting coil when the main transmitting coil transmits the electromagnetic localization signal; and (2) a respective sensitivity profile of the additional coil and the main receiving coil when the additional coil transmits the electromagnetic localization signal; determining at least one of a position and an orientation of the additional coil based on the provided sensitivity information and the received localization signals; A method comprising:

14. A computer program for determining a coil position, said computer program comprising program code means for causing a processor to carry out the method of claim 13 and / or for operating on a system according to claims 1 to 12.

15. 1. A kit for use with a system including a main coil array, the main coil array including a main receive coil for receiving an electromagnetic response signal of a magnetomechanical oscillator, the main coil array further including a main transmit coil for transmitting an electromagnetic excitation signal for exciting the magnetomechanical oscillator, the kit comprising: at least one additional moving coil arranged in a region of interest with respect to the magnetomechanical oscillator, the additional moving coil (1) transmitting an additional electromagnetic excitation signal for exciting the magnetomechanical oscillator or (2) receiving the electromagnetic response signal of the magnetomechanical oscillator; and a computer program product executable to cause at least one of the main transmitting coil and the at least one movable additional coil to transmit electromagnetic localization signals and to provide received localization signals from the at least one movable additional coil and the at least one main receiving coil, the computer program product being further executable to cause a processor to determine at least one of a position and an orientation of the at least one movable additional coil from the received localization signals.

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