WO2025210197A1

WO2025210197A1 - Transcranial magnetic stimulation treatment device

Info

Publication number: WO2025210197A1
Application number: PCT/EP2025/059198
Authority: WO
Inventors: Wilbert OSMOND; Stasys HIOB; Allan Dunbar
Original assignee: Neurocare Group AG
Current assignee: Neurocare Group AG
Priority date: 2024-04-03
Filing date: 2025-04-03
Publication date: 2025-10-09
Anticipated expiration: 2026-10-03
Also published as: DE102024109366A1

Abstract

Transcranial magnetic stimulation treatment device A transcranial magnetic stimulation treatment device (10) comprises a magnetic-field generation means (12) and a pose determination device (14) comprising a stereo image capture device (16), a multitude of markers (18) and an image processing device (20), wherein the stereo image capture device (16) is configured and arranged to capture stereo image data of a scene, the multitude of markers (18) is visibly arranged on and assigned to the magnetic-field generation means (12) and/or a head (24) of a patient, and the image processing device (20) is configured to process the stereo image data into position and/or pose data of each marker (18) visible to the stereo image capture device (16) and/or into pose data of the magnetic-field generation means (12) and/or the head (24) of the patient. A method of determining a treatment pose for a transcranial magnetic stimulation treatment device according to any of the previous claims, wherein, in a first step, stereo image data is captured of said head (24), on which a multitude of markers (18) is visibly arranged, in a second step, head shape data describing a shape of said head (24) is estimated from the stereo image data, in a third step, at least one treatment pose is determined relative to said head shape data and in a fourth step, said head shape data and/or treatment pose is stored in a data storage means (22).

Description

DESCRIPTION

Transcranial magnetic stimulation treatment device

The invention relates to a transcranial magnetic stimulation treatment device comprising a magnetic-field generation means and a pose determination device. The invention further relates to a method of determining a treatment pose for such a transcranial magnetic stimulation treatment device as well as a computer program product for performing said method on said device.

Transcranial magnetic stimulation is a form of therapy in which shaped magnetic fields are introduced into a patient’s head to stimulate nerves or groups of nerves within the brain. The magnetic fields are to be applied to particular predetermined areas of the brain which requires precise positioning of the magnetic-field generation means relative to the head of the patient. Both the position as well as the spatial orientation is relevant for correct application of the magnetic fields. To simplify reasoning about these issues, the combination of an object’s position and orientation is referred to as a “pose”.

Currently, during setup of a transcranial magnetic stimulation session, a variety of parameters need to be determined and/or calibrated. Importantly, the position at which the stimulation is planned to take place needs to be determined on the head of each patient. Since each head has a different shape, this is an individual determination to be carried out in each session for each patient. This determination requires skill on the part of the practitioner and a certain amount of time during each session.

Furthermore, during the treatment, neither the head nor the magnetic-field generation means are fixed in position. Thus, positioning errors may occur and accumulate over the course of the session. Since magnetic field intensity falls off with the cube of distance, small distance errors may impact treatment in relevant ways.

Current approaches to mitigating the problems relating to precision of determining treatment parameters and maintaining the arrangement of magnetic-field generation means and head during the treatment generally involve very complex solutions. Some approaches seek to eliminate the human element by fixating the head of the patient and/or positioning the magnetic-field generation means by means of robotic arms or similar devices.

The invention seeks to mitigate the above-mentioned problems and to simplify determination of treatment parameters as well as to improve treatment quality.

To solve this problem, a device, a method, a computer program and a computer- readable medium according to the independent claims are proposed. Advantageous embodiments are the subject of the dependent claims.

In particular, the problem is solved by a transcranial magnetic stimulation treatment device comprising a magnetic-field generation means and a pose determination device comprising a stereo image capture device, a multitude of markers and an image processing device, wherein the stereo image capture device is configured and arranged to capture stereo image data of a scene, the multitude of markers is visibly arranged on and assigned to the magnetic-field generation means and/or a head of a patient, and the image processing device is configured to process the stereo image data into position and/or pose data of each marker visible to the stereo image capture device and/or into pose data of the magnetic-field generation means and/or the head of the patient.

Recognition of the markers improves the precision of determining the pose of the magnetic-field generation means and the head of the patient, in particular relative to each other. This enables more precise determination of the preferred treatment parameters.

In some embodiments, the stereo image capture device comprises an optical polarizer device arranged as a filter for the image to be captured.

Such an optical polarizer device may reduce glare and reflections within the scene that is captured. Thus, the images captured show the features of the scene, in particular features of the markers, more clearly.

In some embodiments, where the pose of the markers on the head of a patient may be determined, the patient or the head of the patient is arranged to be rotatable relative to the stereo image capture device such that images of all sides of the head may be captured by the stereo image capture device.

This may be achieved for example by putting the patient in a rotatable chair and rotating the entire patient. It is a very convenient way to capture the entirety of the surfaces of the head, making later determination of the shape of the head more accurate.

In some embodiments, where the pose of markers on the head of the patient is to be determined, a mirror is arranged such that at least a section of surface areas of the head facing away from the stereo image capture device are visible to the stereo image capture device through the mirror.

As with the previous claims, capturing more markers makes the determination of the shape of the head more accurate. Adding a mirror to the setup is an easy and cost- effective way to allow the stereo image capture device to see more markers.

In some embodiments, the transcranial magnetic stimulation treatment device comprises a head shape estimation device configured to estimate head shape data describing a shape of the head of the patient from the position and/or pose data.

The head shape estimation device takes the position and/or pose data of the markers and transforms that the data into a digital model of the head. That model can later be used to determine and verify a treatment or stimulation position. Furthermore, the model may later be used to display relevant information on a digital representation of the head.

In some embodiments, the transcranial magnetic stimulation treatment device comprises a stimulation position verification device configured to estimate and/or detect a stimulation position based on said head shape data.

The stimulation position verification device that allows for improved quality control and may improve instructions given to the operator regarding the position of the magnetic- field generation means.

In some embodiments the transcranial magnetic stimulation treatment device may comprise a data storage means for storing the head shape data and/or the stimulation position. In this way, the head shape estimation as well as the determination of the treatment of stimulation position only needs to be carried out once. For further treatment sessions, the stored data may be reused.

In some embodiments, the image processing device comprises a deep learning unit for detecting markers in the stereo image data and/or for detecting a face map in the stereo image data.

Deep learning units have proven to be far superior to other models for pattern detection and pose determination in stereo image data. Detecting the position of a face on a head is relevant for advising an operator on a treatment or stimulation position since a face is easily recognizable for human operators.

In some embodiments, the pose determination device is configured to re-determine the pose of the magnetic-field generation means and/or the head of the patient in arbitrary intervals, in particular intervals equivalent to a frame interval of the stereo image capture device.

The exact position of the magnetic-field generation means is relevant for the treatment quality. Since magnetic field density falls off quickly with distance, it is particularly relevant that the magnetic-field generation means be positioned correctly. By regularly verifying that the operator positions the magnetic-field generator device correctly, the treatment quality is thus improved. Updating the actual position data every camera frame allows for smooth interpretation of the data and for smooth display of visual cues.

In some embodiments, a display device for displaying pose data of the magnetic-field generation means and/or stimulation point position data and/or quality control parameters is provided.

By means of such a device, an operator may receive immediate feedback to the treatment currently in effect.

In some embodiments, the display device may be configured to display the pose data as augmented reality and/or configured to display navigational prompts and/or cues derived from deviations of the magnetic-field generation means pose from a target pose. Giving visual 3D cues is the easiest way to guide an operator to correctly position the magnetic-field generation device. However, navigational prompts and cues are often sufficient to achieve highly accurate positioning.

In some embodiments, the markers have a low-reflectance surface.

Having a low amount of any kind of reflection improves detection of the markers as there are fewer reflections that may confuse e.g. the pose determination device. In particular, intense reflections may obscure parts of the pattern of the markers.

In some embodiments, the transcranial magnetic stimulation treatment device comprises a sensor for measuring at least one biological parameter, wherein the sensor is connected to a control device, in particular via a real-time link, and wherein the control device is configured to analyze sensor measured sensor data, in particular in real-time.

It is thus possible for the magnetic stimulation to be effected in response to biological parameters. Also, a position of the magnetic-field generation means may be verified by determining whether a magnetic stimulation via the magnetic-field generation means effects a reaction in the measured sensor data.

The problem is further solved by a method of determining treatment pose for any of the transcranial magnetic stimulation treatment devices described above, wherein, in a first step, stereo image data is captured of said head), on which a multitude of markers is visibly arranged; in a second step, head shape data describing a shape of said head is estimated from the stereo image data, in a third step at least one treatment pose is determined relative to said head shape data and in a fourth step, said head shape data and/or treatment pose are stored in a data storage means.

This method, carried out for example on any of the transcranial magnetic stimulation treatment devices above, allows for the preparation of all necessary data for carrying out a treatment session. The stored data may be used in all future treatment sessions so that the usual steps of determining a treatment or stimulation pose do not need to be repeated in every session. Thus, treatment efficiency is increased and the patient is not subjected to the same calibration steps in every session. In some embodiments, in a fifth step, said head shape data and/or treatment pose is retrieved from the storage means and in a sixth step, the retrieved head shape data and/or treatment pose are used to verify a correct position of the magnetic-field generation means during use or operation of the device, for example during a treatment session.

Thus, in a treatment session, an operator may start treating the patient immediately, receiving feedback regarding the correct position of the magnetic-field generation means. Thus, treatment sessions become more efficient and effective.

In some embodiments, in a seventh step, pose data of the magnetic-field generation means and/or stimulation point position data and/or quality control parameters are displayed.

Thus, an operator may receive immediate feedback to the treatment currently in effect.

In some embodiments, in an eighth step, at least one vital parameter of the patient is determined from a series of captured images.

Such a vital parameter may be, for example, a pulse of the patient. No separate device for determining said vital parameter would thus be necessary, leaving the patient unencumbered for treatment.

The problem is also solved by a computer program comprising instructions which, when the program is executed by a computer, cause the device to carry out the methods of any of the method claims.

The problem is also solved by a computer-readable data carrier having stored thereon said computer program product.

Further features and advantages of the present disclosure will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

Fig. 1 is a schematic diagram illustrating a transcranial magnetic stimulation treatment device, according to the present invention. It will be noted that throughout the appended drawings, like features are identified by like reference numerals. Different views may employ different scales even if they show the same elements. Directions, such as “left", “right", “top" and “bottom" are to be understood relative to each figure and may, in different figures, specify different directions.

Designations such as “first”, “second” or “third” are used in this document to distinguish similar but different items. They do not necessarily designate a hierarchy or sequence.

The transcranial magnetic stimulation treatment device 10 shown in Fig. 1 comprises a magnetic field generation means 12 and a pose determination device 14. The pose determination device 14 comprises a stereo image capture device, for example a stereo camera 16, a multitude of markers 18 and an image processing device 20. The transcranial magnetic stimulation treatment device 10 may further comprise a storage means, which is embodied by a cloud storage 22 in this embodiment.

The transcranial magnetic stimulation treatment device 10 may in particular be operated in two distinct modes. A first mode is employed to estimate a shape of a head 24 of a patient. A second mode is employed during treatment, in particular to track the pose of the magnetic field generation means 12 and the head 24. In particular, during the second mode, the relative position and orientation of the magnetic field generation means 12 relative to the head 24 may be determined to estimate the quality of the treatment.

During operation according to the first mode, the head 24 of the patient is equipped with a cap 26, on which a multitude of markers 18 is arranged in a predetermined arrangement. Each of the markers 18 comprises a unique pattern. The markers 18 may be printed on the cap 26 or may be arranged on separate devices, e.g. stickers, to be adhered to the 26 at predetermined positions.

To determine the shape of the head 24, the stereo camera 16 is configured and arranged to capture stereo image data of a scene, in which the head 24 with the cap 26 is visible. The stereo camera 16 may capture single stereo images, may be triggered to capture or may continuously capture stereo images which are then represented as stereo image data, comprising a left and right image. The stereo image data may also be used e.g. to display the images.

The stereo image data is made available to the image processing device 20. The image processing device 20 is configured to apply image processing methods to find locations of the markers 18 within the stereo image data. From the difference in location of each marker 18 between the left and right image, a pose, comprising a distance and direction relative to the stereo camera 16 may be determined. Further methods for determining distance and direction relative to a stereo camera 16 from stereo image data are well known from the field of stereo vision.

Since the stereo camera 16 only sees one side of the head 24 and the cap 26 at a time, further images need to be captured from different viewpoints relative to the head 24 in order to be able to estimate a complete shape. One method for obtaining different viewpoints is to let the patient rotate about a body axis by 360° while capturing further stereo images in regular intervals. Another method for obtaining different viewpoints comprises arranging a mirror such that the stereo camera 16 can see those sections of the head 24 via the mirror that it cannot see directly.

For each of the stereo images captured, the image processing device 20 processes the stereo image data into position data for each marker 18 visible in each image. In this way, a multitude of positions of points located on the surface of the head 24 is obtained. Since the shape of human heads 24 follows certain biological rules, the shape of the head 24 between the points may be estimated following said rules.

In a further step, the image processing device 20 processes the stereo image data to determine the location of a face on the head 24. The shape of the head 24 and the location of the face within that shape are then stored in the storage means 22, e.g. for use during the second mode.

During operation according to the second mode, the pose of the head 24 and the magnetic-field generation means 12 are to be tracked by the pose determination device. To this end, the magnetic-field generation means 12 is equipped with markers 18. The stereo camera 16 regularly captures images of the magnetic-field generation means 12 and the head 24 and transfers the stereo image data to the image processing device 20 as input images. The image processing device 20 determines the pose of the magnetic-field generation means 12 by recognizing the markers 18 as described above for the markers 18 on the cap 26.

One possible method of determining a treatment pose is described hereinafter. When determining a treatment pose, in particular when operating according to the second mode, an operator may move the magnetic-field generation device 12 over an area of the head 24 which is suspected to contain the treatment area. By applying a magnetic field and observing a reaction of the patient or lack thereof, the treatment pose is determined. Once the treatment pose has been determined, the pose of the magnetic- field generation device 12 may be stored as stimulation position data, for example together with the head shape data, for reference in future treatment sessions.

In some embodiments, the transcranial magnetic stimulation treatment device 10 may comprise an input device, for example, a button, a foot button or a voice control so that the operator may operate the transcranial magnetic stimulation treatment device 10 to store the current pose of the magnetic-field generation device 12 as a treatment or stimulation position.

The pose determination device 14 may load the head shape data and/or the stimulation position and orientation data from the storage means 22. In this way, a patient would only need to go through the process of head shape estimation and treatment/stimulation position and orientation determination once. Thus, treatment will be faster, more efficient and more comfortable for the patient. In some embodiments, the treatment pose may be adjusted during a treatment session and the adjusted treatment pose data stored in the storage means 22.

The pose determination device 20 may furthermore comprise a treatment support device comprising a display device 28. The pose determination device 14 may be provided with treatment pose data describing a preferred treatment pose for the magnetic-field generation means 12 relative to the head 24. The treatment support device may then compare the poses determined by the pose determination device 24 for the magnetic-field generation means 12 and the head 24 and display advice and/or instructions for an operator on how to improve treatment quality. Furthermore, pose data of the magnetic-field generation means, stimulation point position data and/or quality control parameters may be displayed.

In some embodiments, the advice and/or instructions may be displayed as an augmented reality image.

Furthermore, the treatment support device may track the poses of the magnetic-field generation means 12 and the head 24 over an entire treatment session and, from the data collected, estimate a quality of the treatment effected during the session.

In various embodiments, the markers 18, to be well visible and detectable in the stereo image data, may, for example have a low reflectance and/or a low specular reflectance. In some embodiments, the markers 18 may have a reflectance of less than 40% and/or a low specular reflectance of less than 80 Gloss Units. In various embodiments, the markers 18 may, for example, include patterns of light and dark areas and/or may each have a unique pattern. Furthermore, it could be advantageous if the markers 18 would not comprise a pattern that is symmetric, in particular symmetric along a horizontal direction. This is especially true when a mirror is used to determine the head shape data. When choosing a size of the markers, it may be advantageous to choose a size at which individual features of the marker 18 are larger than the resolution of the stereo camera 16 up to an imaging distance of 2m. More specifically, the individual features of the markers 18 should be, independently of their distance, in the field of vision of the stereo camera 16 and be represented by at least one pixel in the final image.

In some embodiments, each of the markers 18 shows a unique pattern. In some embodiments, the number of markers 18 arranged on the magnetic-field generation means 12 is 3, 4, 5, 6, 7, 8, 9 or more. The same or a different number of markers 18 may be arranged on the cap 26. In some embodiments, the markers 18 may be printed on the cap 26 and/or the magnetic-field generation device 12. In some embodiments, the markers 18 may be applied to the cap 26 and/or the magnetic-field generation means 12 as one or more stickers, in particular as rigid markers 18.

In some embodiments, the patient may or may not wear the cap 26. If the patient does not wear the cap 26, the image processing device 20 may determine the pose of the head 24, for example, by finding the pose of the face of the patient in the stereo image data.

In some embodiments, the image processing device 20 may be configured to recognize, from a series of input images, at least one vital parameter of the patient. Such a vital parameter may be, for example, a pulse of the patient. Such parameters may, for example, be relevant for application of neuro-cardiac guided functional localization.

Throughout this document, the word “pose” relating to an object is to be understood as the combination of the object's position and orientation.

The storage means may be a cloud storage 22 as shown in the embodiments. However, any other storage means such as a NAS, a local hard drive, a mobile storage device or an SSD, may be used to store the data.

Each of the devices described herein, in particular the pose determination device 14, image processing device 20, the head shape estimation device and/or the deep learning unit may be implemented, in its entirety or in part, as a computer program to be executed on a computer, e.g. a microcontroller or PC, as appropriate. Multiple devices described herein may be implemented as a common computer program, regrouping all those devices’ functions.

The expressions “seen by the stereo image capture device”, “visible to the stereo image capture device” or “visible to the stereo camera 16” are to be understood to mean any objects in the scene which influence the captured stereo image data.

Independent of the grammatical term usage, individuals with male, female or other gender identities are included within the term.

In some embodiments, the stereo image capture device 16 of the transcranial magnetic stimulation treatment device 10 may comprise an optical polarizer device arranged as a filter for the image to be captured.

In some embodiments, where the pose of markers 18 on the head 24 of a patient is to be determined, the patient is arranged to be rotatable relative to the stereo image capture device 16 such that images of all sides of the head 24 may be captured by the stereo image capture device 16.

In some embodiments, the method comprises a fifth step, in which said head shape data and/or treatment pose is retrieved from the data storage means 22 and a sixth step, in which the retrieved head shape data and/or treatment pose are used to verify a correct position of the magnetic-field generation means 12 relative to the head 24 without the markers 18 during use or operation of the transcranial magnetic stimulation device 10, for example during a treatment session.

In some embodiments, the transcranial magnetic stimulation treatment device may comprise a sensor for measuring at least one biological parameter and may be configured to verify a biological effect is provoked by the magnetic-field generation means 12. Analysis of the sensor data may serve to determine whether a magnetic field generated by the magnetic-field generation means 12 is arranged correctly and/or provides a magnetic field of a desirable intensity.

This may be carried out as one or more verification steps comprised in the method of determining a treatment pose. The verification step may comprise three substeps: selecting a magnetic field strength to be applied by the magnetic-field generation means 12; measuring a change of the biological effect and verifying whether the measured change is in line with a desired effect.

The sensor data may, in some embodiments, be used for triggering a pulse of the magnetic-field generation means 12 during operation in response to a recognized variation of the biological parameter.

To achieve these ends, the sensor may, for example, comprise one or more of the following: An electroencephalogram (EEG) sensor, an electrocardiogram (ECG) sensor, a heart rate sensor, an electromyogram (EMG) sensor, a plethysmography sensor, a pupillometry sensor, a pneumography sensor, a galvanic skin response sensor (GSR), an electrodermal activity sensor (EDA). The measured data output by these sensors, also referred to as sensor data, may be fairly complex. In some embodiments, a control device for controlling a magnetic-field output of the magnetic-field generation means 12 may thus be provided for analyzing the sensor data, and for controlling the magnetic-field output in response to the sensor data. To this end, it may be useful for communication between the sensor and the control device to be near real-time so that sufficient time remains for the analysis and the controlling of the magnetic field output before the measured biological parameter changes too much so that the result of the analysis is no longer applicable. In some embodiments, such communication and/or control device may provide real-time conditions.

LIST OF REFERENCES

10 transcranial magnetic stimulation treatment device

12 magnetic-field generation means 14 pose determination device

16 stereo camera (stereo image capture device)

18 marker

20 image processing device

22 cloud storage (storage means) 24 head (of the patient)

26 cap

28 display device

Claims

1 . A transcranial magnetic stimulation treatment device (10) comprising a magnetic-field generation means (12) and a pose determination device (14) comprising a stereo image capture device (16), a multitude of markers (18) and an image processing device(20), wherein the stereo image capture device (16) is configured and arranged to capture stereo image data of a scene, the multitude of markers (18) is visibly arranged on and assigned to the magnetic-field generation means (12) and/or a head (24) of a patient, and the image processing device (20) is configured to process the stereo image data into position and/or pose data of each marker (18) visible to the stereo image capture device (16) and/or into pose data of the magnetic-field generation means (12) and/or the head (24) of the patient.

2. Transcranial magnetic stimulation treatment device according to any of the previous claims, characterized in that, where the pose of markers (18) on the head (24) of a patient is to be determined, the patient is arranged to be rotatable relative to the stereo image capture device (16) such that images of all sides of the head (24) may be captured by the stereo image capture device (16).

3. Transcranial magnetic stimulation treatment device according to any of the previous claims, characterized in that, where the pose of markers (18) on the head (24) of a patient is to be determined, a mirror is arranged such that at least a section of surface areas of the head (24) facing away from the stereo image capture device (16) are visible to the stereo image capture device (16) through the mirror.

4. Transcranial magnetic stimulation treatment device according to any of the previous claims, characterized by a head shape estimation device configured to estimate head shape data describing a shape of the head (24) of the patient from the position and/or pose data.

5. Transcranial magnetic stimulation treatment device according to claim 4, characterized by a stimulation position verification device configured to estimate and/or detect a stimulation position based on said head shape data.

6. Transcranial magnetic stimulation treatment device according to claim 4 or 5, characterized by a data storage means (22) for storing the shape data and/or the stimulation position.

7. Transcranial magnetic stimulation treatment device according to any of the previous claims, characterized in that the image processing device (20) comprises a deep learning unit for detecting markers in the stereo image data and/or for detecting a face map in the stereo image data.

8. Transcranial magnetic stimulation treatment device according to any of the previous claims, characterized in that the pose determination device (14) is configured to re-determine the pose of the magnetic-field generation means (12) and/or the head (24) of the patient in arbitrary intervals, in particular intervals equivalent to a frame interval of the stereo image capture device (16).

9. Transcranial magnetic stimulation treatment device according to any of the previous claims, characterized by a display device (28) for displaying pose data of the magnetic-field generation means (12) and/or stimulation point position data and/or quality control parameters.

10. Transcranial magnetic stimulation treatment device according to claim 9, characterized in that the display device (28) is configured to display the pose data as augmented reality and/or configured to display navigational prompts and/or cues derived from deviations of the magnetic-field generation means (12) pose from a target pose.

1 1 . Transcranial magnetic stimulation treatment device according to any of the previous claims, characterized in that the markers (18) have a low-reflecting surface.

12. Transcranial magnetic stimulation treatment device according to any of the previous claims, characterized in that the transcranial magnetic stimulation treatment device comprises a sensor for measuring at least one biological parameter, wherein the sensor is connected to a control device, in particular via a real-time link, and wherein the control device is configured to analyze sensor measured sensor data, in particular in real-time.

13. Method of determining a treatment pose for a transcranial magnetic stimulation treatment device according to any of the previous claims, wherein, in a first step, stereo image data is captured of said head (24), on which a multitude of markers (18) is visibly arranged, in a second step, head shape data describing a shape of said head (24) is estimated from the stereo image data, in a third step, at least one treatment pose is determined relative to said head shape data and in a fourth step, said head shape data and/or treatment pose is stored in a data storage means (22).

14. The method according to claim 13, characterized by a fifth step, in which said head shape data and/or treatment pose is retrieved from the data storage means (22) and a sixth step, in which the retrieved head shape data and/or treatment pose are used to verify a correct position of the magnetic-field generation means (12) relative to the head (24) without the markers (18) during use of the transcranial magnetic treatment device.

15. The method according to any one of claims 13 and 14, characterized by a seventh step, in which pose data of the magnetic-field generation means (12) and/or stimulation point position data and/or quality control parameters are displayed.

16. The method according to any of the claims 13 to 15, characterized by an eighth step, in which at least one vital parameter of the patient is determined from a series of captured images.

17. A computer program comprising instructions to cause the device of any of the claims 1 to 13 to execute the steps of the method of any of the claims 14 to 16.

18. A computer-readable medium having stored thereon the computer program of claim 17.