Location tracking system

Abstract

The present invention relates to a tracking system and a location method for precisely tracking and real-time locating signal emission sources within a patient's body. [Solution] A signal tracking system comprising: one fixed element (12) fixed to a rigid body part of a patient surrounding a target body part, the fixed element (12) further comprising a mapping element (16); one tracker element fixed to the fixed element (12) for tracking an internal tracker in real time; and a control unit having a memory for storing an internal reference and an image showing a target body part and one fixed element (12), wherein the control unit is designed to define at least one 3D frame position associated with at least one fixed element (12) within the internal reference and to precisely locate each point of the target body part.

Description

Technical Field

[0001] The present invention relates to a tracking system and a positioning method for precisely tracking a signal emission source in a patient's body and performing real-time positioning.

Background Art

[0002] In modern medicine, it is becoming increasingly important to be able to precisely position in real time a device that emits a signal inserted into a patient's body in order to perform some surgical procedures or some precise and targeted drug deliveries.

[0003] This applies, for example, to gene therapy or cell transplantation, improvement of tumor resection, and local delivery of drugs active against tumors. As an example, it is well known that in order to reach a difficult deep brain tumor, a surgeon requires a system that can locate a millimeter-sized device and precisely reach the surgical site in real time. Furthermore, the already complex medical environment requires a tracking system that is "user-friendly", i.e., minimally invasive, reproducible, and applicable to patients.

[0004] Furthermore, due to both the desire to reduce side effects on the patient (caused by, for example, anesthesia and openings in the body such as the skull) and the accuracy requirements, less invasive procedures are increasingly demanded. Regarding a specific example of the skull, a skull opening creates a cerebrospinal fluid leak, inducing a brain displacement (potentially up to several centimeters), and altering the target surgical site (target body site) obtained from preoperative imaging techniques. Therefore, it is meaningful to find a solution to replace a large skull opening.

[0005] Reduced invasiveness can be achieved by reducing the size of the cranial opening(s), or even by not making an opening at all. However, in the case of signal-emitting sources located within the brain, this causes the signals to cross over the cranial layers. The performance of the localization system is directly affected by these layers, which increase both the depth and attenuation along the signal pathway. This can be said for any potential target body part.

[0006] Restricting or reducing body openings, therefore, leads to the search for signals emitted from within the patient's body that can be accurately read from outside the body.

[0007] Among known signal tracking techniques, magnetic field techniques offer positional accuracy of approximately millimeters, which is unsuitable for locating microdevices, which are becoming increasingly common. Electromagnetic radio frequency (EMRF) wave techniques are limited by their centimeter-level positional accuracy, which does not meet the requirements of microdevices. EM optical wave techniques suffer strong absorption in human tissue, thus significantly limiting surgical depth and adding invasiveness to bypass bone layers. EM very high frequency (EMVHF) waves exceeding the maximum dose are known to have adverse effects on human tissue. Magnetic resonance imaging (MRI) techniques are limited by their inherent trade-off between temporal and spatial resolution. The use of MRI further prohibits the use of magnetic materials and significantly reduces the number of implantable systems. While ultrasound suffers from some attenuation in tissue layers and reflection at interfaces, their limitations are far less significant than those associated with electromagnetic techniques.

[0008] With regard to technological advancements, the ability to locate sub-millimeter devices, such as robots or catheter terminals, in real time during surgical procedures while maintaining accuracy even under high disturbances is becoming increasingly important. In this regard, tracking systems should meet several criteria: being safe for the human body, minimally invasive, exhibiting the best possible localization accuracy, being able to operate throughout the body, especially inside the brain, functioning in real time, being as small as possible, and consuming the least amount of energy.

[0009] In current neuronavigation, for example, surgeons use a well-known reference external 3D frame, assuming that the brain does not move relative to this external 3D frame. This external 3D frame is a large, cage-like structure that is screwed inside the patient's skull and surrounds the entire head. This large external 3D frame is very bulky and heavy, forcing the patient to remain motionless for a very long time. Therefore, it is very uncomfortable to endure. It is also difficult to keep fixed to the patient for extended periods. It also causes some steric obstruction that can restrict the surgeon's free movement during surgery. Nevertheless, this external 3D frame allows surgeons to have a reference point that appears in both MRI and CT images, enabling alignment of all images.

[0010] In this application, a 3D frame is defined as a coordinate system whose origin, orientation, and scale are specified by a set of reference points. Its position is determined mathematically (by numerical coordinate values) and physically (by signals sent by conventional markers).

[0011] The objective of the present invention is to provide a method for aligning different images obtained by different imaging techniques in a safe, accurate, and comfortable manner for both the surgeon and the patient. [Overview of the project]

[0012] The present invention therefore relates to a signal tracking system configured to track an internal tracker located within a target body part of a patient, wherein the system -At least one fixation element designed to be fixed to a rigid body part of a patient, wherein the rigid body part at least partially surrounds a target body part, and the fixation element further comprises a mapping element. - A tracker element configured to be fixed to a fixed element, wherein at least one sensor element is designed to track an internal tracker in real time, and at least one tracker element, - A control unit configured to collect tracking information in real time from at least one tracker element, wherein the control unit Internal standards and, ○ At least one unique pre-established image showing at least a portion of the target body part of the patient or an element located within the aforementioned target body part, wherein the unique pre-established image further shows at least one fixed element and at least one mapping element, A control unit further equipped with memory designed to store, Equipped with, The control unit is designed to define at least one 3D frame position associated with at least one fixed element within internal standards, and to precisely locate each point of the target body part relative to the 3D frame position. The internal criteria are defined within a unique, pre-established image showing at least a portion of the patient's target body part or an element located within the aforementioned target body part. The control unit is further designed to precisely locate internal trackers within a target body part in real time, within an internal reference, for at least one 3D frame position.

[0013] Thus, the solution makes it possible to achieve the objectives described above. In particular, it enables the registration of ultrasound tracking information into medical images within a single internal standard. This further minimizes registration errors through the automatic detection of implants in the aforementioned images.

[0014] The system according to the present invention has the following features, which can be taken separately from each other or combined with each other: -Memory is, Internal standards and, ○ At least one first pre-established image showing the target area of ​​the patient, ○ At least one second pre-established image showing a rigid body part to which at least one fixed element and at least one mapping element are fixed, Further designed to preserve, The internal criteria are defined in a first pre-established image showing at least a portion of the patient's target body part or an element located within the aforementioned target body part. The control unit is designed to define at least one 3D frame position associated with at least one fixed element within an internal reference, and to align at least one first and second pre-established image within the internal reference in order to precisely locate each point of the target body part relative to the 3D frame position. The control unit is further designed to precisely locate internal trackers within a target body part in real time within an internal reference for at least one 3D frame position. - At least one tracker element must be configured to be detachably attached to a fixed element. - At least one restraint element is designed to be fixed inside a rigid body part of the patient, and at least one tracker element is also fixed to a restraint element inside a rigid body part. - The system comprises at least three tracker elements regularly distributed around the target body part. -At least one fixed element, mapping element, and tracker element are all CT compatible, and at least one second image is a CT image. -Both the fixed and mapping elements are MRI compatible, and at least one first image is an MRI image. - The internal tracker is a signal emission source. - The internal tracker is a secondary source designed to reflect signals emitted by the primary source. - The primary source of supply is located outside the subject's body. - The primary source must be at least one tracker element. - The internal tracker is a contrast agent dispensed by a microdevice. - The internal tracker is part of the microdevice. It may have one or more of these.

[0015] The present invention also relates to a signal tracking method configured to position an internal tracker located within a target body part within an internal reference using a tracking system described in any one of the prior claims, wherein the method comprises the following steps in chronological order of the discussion: - The step of fixing at least one mapping element to a rigid body part of the patient using at least one fixing element, - A step of establishing at least one unique image showing at least a portion of a target body part of a patient or an element located within the aforementioned target body part, wherein the aforementioned image further shows at least one fixed element and at least one mapping element, - The step of saving at least one unique image to the control unit's memory, - The step of aligning at least one unique image with an internal reference, - The steps include using a control unit to detect the position of at least one mapping element in order to determine the 3D frame position of each fixed element relative to an internal reference, - If necessary, the step of fixing the tracker element to a fixed element, - Starting the signal emission of the internal tracker, and - Using the control unit to track and locate the internal tracker in real time, and including.

[0016] The method may include the following steps taken separately from each other or in combination with each other: - The method has the following steps in the chronological order of the discussion: - Establishing at least one first image showing the target body part of the patient and storing it in the memory of the control unit, and - Fixing at least one mapping element to the hard body part of the patient using at least one fixing element, and - Establishing at least one second image showing the hard body part to which at least one fixing element and at least one mapping element are fixed, and - Using the control unit to align at least one first and second image with respect to an internal reference, and - Using the control unit to detect the position of at least one mapping element in order to determine the 3D frame position of each fixing element with respect to the internal reference, and - If necessary, fixing the tracker element to the fixing element, and - Starting the signal emission of the internal tracker, and - Using the control unit to track and locate the internal tracker in real time, and including, - The method may further include two other steps that are performed after the step of fixing at least one mapping element to the hard body part of the patient using at least one fixing element: - Establishing at least one new first image showing the target body part of the patient and replacing the previous image in the memory of the control unit, and - Establishing at least one new second image showing the hard body part of the patient and replacing the previous image in the memory of the control unit, and may further include. - The final step may include visualizing the internal tracker in real time, either within a first pre-established image or on an image acquired in real time. [Brief explanation of the drawing]

[0017] [Figure 1] This is a perspective view of a system showing several fixed and sensor elements that are regularly attached to the human head around a target body part and communicate with a control unit. [Figure 2] This is a perspective view of the sensor element according to the present invention. [Figure 3] This is a perspective view of the fixed element according to the present invention. [Figure 4] This is a perspective view of the mapping element according to the present invention. [Figure 5] This is a perspective view of the fixed and mapping elements attached to a human skull. [Figure 6] This is a schematic diagram of the tracking method according to the present invention. [Modes for carrying out the invention]

[0018] For surgical procedures involving implantable or introduceable devices of millimeter or sub-millimeter size, such as neurosurgery using implantable microrobot systems or cardiac surgery using catheters, the devices need to be registered in medical images used for surgical planning and / or real-time monitoring of the surgery.

[0019] In other words, the device must be monitored. This can be achieved using the signal tracking system 10 of the present invention.

[0020] From a clinical standpoint, patients require a dedicated external 3D frame system that is attached around the body part being operated on, specifically, around the head in certain cases of neurosurgery. This external 3D frame system is essential for tracking millimeter- or sub-millimeter devices, such as microrobots operating within the brain. Therefore, the signal tracking system 10 according to the present invention is - At least one fixation element 12 designed to be fixed to a rigid body part 14 of the patient, for example, the skull, - At least one mapping element 16, - At least one tracker element 18, - Control unit 20 It is equipped with.

[0021] As shown in Figure 1, to maximize efficiency, the tracking system 10 requires several tracker elements 18 distributed around a target body part 22 to create an external 3D frame system. The tracker elements 18 are distributed around the target body part 22 to allow the surgeon to operate with a sufficiently large workspace. In that respect, several tracker elements 18 are fixed to the patient's rigid body parts 14 around the aforementioned target body part 22. In the embodiment currently described, the target body part 22 is the patient's brain, and several tracker elements 18 need to be screwed into the skull. In the embodiment described, each tracker element 18 comprises at least one tracker head 18a and one tracker fixing rod 18b (see Figure 2). Each tracker head 18a comprises at least one ultrasonic transducer. Thus, similar to a GPS system, several tracker elements 18 are regularly distributed around the target head, forming satellite-like implants.

[0022] Each tracker head 18a further communicates continuously with the control unit 20 in real time. Thus, the signal being measured is continuously transmitted to the control unit 20 in real time by each tracker element 18.

[0023] As shown in Figure 2, in some embodiments, each tracker fixing rod 18b has a male thread designed to cooperate with a female thread 24 formed inside each fixing element 12 (see Figure 3). To fix each tracker element 18 to the rigid body part 14 of the target, the tracking system 10 comprises an equal number of fixing elements 12. An example of a fixing element 12 is shown in Figure 3. The fixing elements 12 are made of a well-known biocompatible and inert material such as PEEK, silicone, or titanium. Each fixing element 12 allows the tracker element 18 and mapping element 16 to be securely fixed to the patient's skull. In some embodiments, the tracker element 18 is detachably fixed to the fixing element 12, and in some other embodiments, they are part of the same piece. In any case, fixing the tracker element 18 to the rigid body part 14 requires opening the patient's body, in particular the patient's scalp, which is vascularized tissue and therefore limits the number of incisions. Furthermore, each time tissue is exposed, the risk of infection increases, especially in neurosurgery, where the surgical time is long. Therefore, it is important to quickly fix the fixation elements 12 with minimal tissue exposure. In some alternative embodiments, adhesion of the fixation elements 12 may be an alternative to screwing them to a rigid body part 14. Depending on the embodiment, the tracker elements 18 may be fixed above or below the patient's skin, and in some embodiments, the fixation elements 12 are fixed inside the patient's rigid body part 14, and at least one tracker element 18 is also fixed inside the rigid body part 14, and therefore below the skin. This requires making small holes inside the rigid body part 14, but improves safety because the skin can be closed.

[0024] Depending on the embodiment, the following two types of fixing elements 12 are possible: - A rigid body part 14 (or a part thereof) remains between the target body part 22 and the tracker element 18, meaning that a fixing element 12 is fixed to the rigid body part 14 or inside it (in the shown embodiment, this means that the fixing element 12 is screwed or glued to the skull), or - The fixing element 12 penetrates and is fixed through a rigid body part 14, meaning that the fixing element 12 tunnels through the rigid body part 14 and pushes the tracker element 18 into direct contact with the target body part 14 (in the shown embodiment, this means that the fixing element 12 penetrates the skull and is screwed in, so that the tracker element 18 is in direct contact with the brain).

[0025] The direct contact embodiment allows for limiting the attenuation of the tracked signal because the tracker element 18 is not separated from the target body part 22 by a rigid body part 14 (in this case, the target brain and skull, respectively). In this embodiment and the embodiment in which the fixation element 12 is fixed inside the rigid body part 14, a semi-trepanation hole with a diameter of approximately 1 cm (maximum 2 cm) is made by a surgeon. However, this act requires a neuroanesthetic to manage undesirable events such as massive bleeding or partial skull collapse. In the non-direct contact embodiment, the dimensions of the fixation element 12 are limited by the shape of the rigid body part 14, in this case the circular shape of the skull. In the embodiment in which the fixation element 12 is fixed inside the rigid body part 14, a semi-trepanation hole of the same type with a diameter of approximately 1 cm (maximum 2 cm) is made by a surgeon, and the same constraints and risks as in the direct contact embodiment exist. However, as already stated, this embodiment allows for closing the skin over the fixation element 12 and the tracker element 18, thus improving safety. In embodiments in which the fixing element 12 is fixed to a rigid body part 14, in the case of the skull, each fixing element 12 must be in contact with the skull and cannot be fixed to a point with a large curvature.

[0026] The size of the fixation element 12 is minimized to reduce the size of the screw and thus the stress on the patient. The dimensions of the fixation element 12 should be suitable for local anesthesia and therefore have a diameter of 2 cm and a height of 1 cm, especially if the fixation element 12 must be fixed (or embedded) inside a rigid body part 14.

[0027] As already mentioned, in order to perform surgical procedures involving millimeter- or sub-millimeter implantable or introduceable devices, the devices need to be registered in medical images used for surgical planning and / or real-time monitoring of the surgery. For example, to obtain medical images for a microrobot operating in the brain of a target, a surgeon typically plans and follows the surgery on MRI and / or CT images. A computed tomography (CT) scanner consists of an X-ray tube coupled to scintillation detectors mounted opposite each other on a rotating gantry. A CT scan provides image slices of target tissue through pre-planned translation and rotation of a sensor array.

[0028] Magnetic resonance imaging (MRI) uses signals emitted by hydrogen (protons) moving within the human body. Due to their electric charge, their spins generate a detectable magnetic field. An MRI measurement consists of three steps: - A superconducting magnet generates a steady external magnetic field that aligns a few mobile protons per million and brings them to a low-energy state. - The transmitting coil generates RF radiation. - After the RF radiation stops, the protons relax and emit photons at their resonant frequencies. - Steps to measure the relaxation time constant and obtain an MRI image. It consists of.

[0029] In some cases, for example in an emergency, the surgeon can acquire at least one unique image showing at least a portion of the patient's target body part 22 or an element located within the aforementioned target body part 20, as well as at least one fixed element 12 and at least one mapping element 16. The control unit 20 can then define at least one 3D frame position associated with at least one fixed element 12 within a coordinate system (or internal reference R), thereby precisely positioning each point of the target body part 22 relative to the 3D frame position.

[0030] Due to the different physiological properties of the tissues of the rigid body part 14 and the target body part 22, surgeons spend most of their time planning surgery on both MRI and CT images (MRI images are used for the soft target body part 22, and CT images are used for the rigid body part 14). These different images can be aligned in a multimodal registration process. According to those skilled in the art, the objective of the image registration process is to find the optimal transformation that best aligns the structure of the subject in the different images (the target body part 22, the rigid body part 14, and the external 3D frame formed by the fixation element 12). With respect to the present invention, the registration process aligns at least one first image (e.g., an MRI image) showing the target body part 22 with at least one second image (e.g., a CT image) showing the rigid body part 14 to which the fixation element 12 is fixed.

[0031] In some alternative embodiments, the registration process first aligns at least one first image with an image showing a rigid body part 14 to which the fixing element 12 is attached. The registration process then aligns two of the aforementioned images with at least one second image showing a rigid body part 14 to which the fixing element 12 is attached.

[0032] As is well known to those skilled in the art, the registration process is an algorithm that converges through multiple iterations toward a maximum similarity measurement and aligns at least two images within a coordinate system (or internal reference R) found using prior geometric transformations known in the prior art. The registration process algorithm uses image information to establish a specific measurement called similarity. These algorithms are typically based on voxel intensity, gradient intensity, frequency study (Fourier space), or statistical information about intensity or features (edges, contours, etc.) in the images being aligned. Thus, the internal reference R is defined within a pre-established image showing at least a portion of the patient's target body part 22 or an element located within the aforementioned target body part 20.

[0033] The present invention therefore makes it possible to define an internal reference on a first 3D image of a target body part 22, which is set as a reference and defines / includes an internal reference R.

[0034] The objective of the registration process during surgery is to establish a 3D transformation between an external 3D frame and an internal 3D frame, which represents the 3D frame of the target body part 22. According to the present invention, as already stated, several fixation elements 12 fixed to the rigid body part 14 of the target form the external 3D frame. This means that in order to proceed with the registration process, each fixation element 12 must be precisely detected and its precise position must be obtained within a predetermined reference R. This reference R can be, for example, the rigid body part 14, or any other element present in one of the images. It can also be an external element defined independently of what is seen in the image. This internal reference R is stored in the memory 26 of the control unit 20. The memory 26 of the control unit 20 also - At least one first image (internal 3D frame) showing the patient's target area 22 and - At least one second image (external 3D frame) showing a rigid body part 14 to which the fixed element 12 and mapping element 16 are fixed, - Any further images that may be used to obtain clear and precise alignment Save it.

[0035] The control unit 20 is designed to execute a registration process algorithm, thereby aligning all images within an internal reference R, and then positioning each point of the target body part 22 within the aforementioned internal reference R.

[0036] This image alignment further enables the control unit 20 to establish a 3D frame position within an internal reference R for each fixed element 12. Once the control unit 20 aligns the external and internal 3D frames, each 3D frame position is therefore defined within the internal reference R as any point on the target body part 10. The 3D frame position of each fixed element 12 is therefore clearly established relative to the target body part 10. To enable the direct establishment of the 3D frame position within the internal reference R, or to enable the execution of the registration process algorithm, each fixed element 12 comprises a mapping element 16. As shown in Figure 4, the mapping element 16 comprises a mapping head 16a and a connecting rod 16b. In the shown embodiment, the mapping element 16 may be detachably fixed to the fixed element 12. In other embodiments not shown, the mapping element 16 is formed integrally with the fixed element 12. In the shown embodiment, each connecting rod 16b has a male thread designed to cooperate with a female thread 24 formed inside each fixed element 12 (see Figure 3). The connecting rod 16b therefore cooperates with the fixing element 12 to secure the mapping element 16 to the fixing element 12. Several other embodiments not shown may be assumed.

[0037] As seen in Figure 4, the mapping head 16a exhibits a specific shape that allows for easy recognition and localization of the mapping head 16a and, therefore, the fixed element 12 to which it is connected. The head 16a of the mapping element 16 is therefore a reference point for the 3D square.

[0038] In some embodiments, both the mapping element 16 and the tracker element 18 are CT compatible.

[0039] Once each fixed element 12 and the points of the target body part 10 are precisely located within the internal reference R, the control unit 20 and tracker elements 18 precisely locate any internal tracker 28, such as a signal emitter located within the target body part 22, within the internal reference R in real time. More precisely, once at least one fixed element 12 is detected in the target body part image, this makes it possible to obtain the 3D position of this fixed element 12 within the internal reference R. Since each tracker element 18 is attached to each fixed element 12, it becomes possible to directly know their 3D positions within the internal reference R. Therefore, any internal tracker 28 can be directly tracked within the internal reference R.

[0040] This allows for more direct, reliable, and efficient tracking, in contrast to other systems that require the establishment of at least two criteria: one relating to the patient and another to the system itself.

[0041] The internal tracker 28 may also be a signal sensor configured to sense several signals emitted by the tracker element 18. In this application, the term “sensor” is understood to mean a receiver. In some embodiments, the internal tracker 28 may be a contrast agent dropped by a microdevice. The contrast agent may be any microscopic elements about 1 micron in size that are highly reflective of ultrasound, such as microbubbles. In some embodiments, the internal tracker 28 may be part of a microdevice that can be operated from outside the patient’s body.

[0042] If the internal tracker 28 is a signal emitter, it can be a primary source (active implantable device) or a secondary source. The secondary source is designed to reflect signals emitted by another primary source. This secondary source can be a passive implantable device, such as a passive microtracker. If the signal emitter is a secondary source, the primary source can be outside the patient's body, and more specifically, the primary source can be one of several tracker elements 18 fixed around a target body part 22. In this case, the primary source transmits a signal into the target body part 22, and the signal source reflects this signal back to a tracker element 18 fixed to a rigid body part 14. In the specific case where the tracker element 18 is an ultrasound transducer, one of them fixed to a rigid body part 14 of the patient (e.g., the skull) transmits ultrasound into the target body part 22 (e.g., the patient's brain). In either case, the signal emitter emits waves that travel toward the rigid body part 14 into which one or more further tracker elements 18 are implanted. The time of flight between the initial transmission and reception is used to obtain the distance the wave has traveled. Using several tracker elements 18 involving at least three, it becomes possible to obtain the 3D position of the signal emitter relative to the tracker elements 18.

[0043] If the internal tracker 28 is a sensor, it functions in a similar manner, and the time of flight between the initial transmission and reception from the tracker element 18 is used to obtain the distance the wave has traveled. Using several tracker elements 18 involving at least three, it becomes possible to obtain the 3D position of the internal tracker 28 relative to the tracker elements 18.

[0044] It is well known to those skilled in the art that most tracker elements 18 (e.g., ultrasound transducers), by their composition, are CT image compatible but not MRI image compatible. This significantly limits the use of such systems in clinical settings where MRI is increasingly becoming MRI-based to allow surgeons to check the condition of target body parts 22 during surgery.

[0045] However, since the memory 26 of the control unit 20 stores accurate images of the rigid body part 14 and the target body part 22 aligned with an external 3D frame including the fixation elements 12, the position of the internal tracker 28 is therefore translated in real time into the image shown to the surgeon on the screen during surgery by the control unit 20. The surgeon can therefore precisely visualize the internal tracker 28 within the patient's target body part 22.

[0046] The tracking system 10 according to the present invention enables a surgeon to perform a signal localization method as shown in Figure 6. This method allows an internal tracker 28 located within a target body part 22 of a patient to be localized within an internal reference R. When only one unique image is required, the method is performed in the following steps in chronological order of the discussion: - A step of fixing at least one mapping element 16 to a rigid body part 14 of the patient using at least one fixing element 12, - A step of establishing at least one unique image showing at least a portion of the patient's target body part 22 or an element located within the aforementioned target body part 22, wherein the aforementioned image further shows at least one fixed element 12 and at least one mapping element 16. - A step of saving at least one unique image to the memory 26 of the control unit 20, - A step of aligning at least one eigenimage with an internal reference R, - In order to determine the 3D frame position of each fixed element 12 with respect to an internal reference R, the control unit 20 is used to detect the position of at least one mapping element 16. - If necessary, the step of fixing the tracker element 18 to the fixed element 12, - Step 28 to start emitting a signal, - A step of tracking and locating the internal tracker 28 in real time using the control unit 20. Includes.

[0047] If the quality of the unique image is sufficiently good, the method may include visualizing the internal tracker 28 in real time within at least one unique, pre-established image. The internal tracker may also be visualized on a real-time acquired image. This real-time acquired image may be acquired by an external means, such as an ultrasound probe.

[0048] If more than one image is required, the method involves the following steps in chronological order of the argument: - A step of establishing at least one first image showing a target body part 22 of the patient using MRI images and storing it in the memory 26 of the control unit 20. -In some cases, the step of establishing at least one further image showing the patient's hard body part 14 using a CT image and saving it to the memory 26 of the control unit 20, -Steps to design the preoperative plan when defining robotic surgery, - A step of fixing at least one mapping element 16 to a rigid body part 14 of the patient using at least one fixing element 12, - A step of establishing at least one second image showing a rigid body part 14, wherein at least one fixed element 12 and at least one mapping element 16 are fixed, and if the tracker element 18 and the fixed element 12 are manufactured as a single unit, the tracker element 18 is fixed. - Using the control unit 20, align at least one first, second, and third image with respect to an internal reference R. - In order to determine the 3D frame position of each fixed element 12 with respect to an internal reference R, the control unit 20 is used to detect the position of at least one mapping element 16. -In some cases, if the tracker element 18 is detachable from the fixed element, the step is to fix the tracker element 18 to the fixed element 12. - Step 28 to start emitting a signal, - A step of tracking and locating the internal tracker 28 in real time using the control unit 20, - A step of visualizing the internal tracker 28 in real time, either within at least one pre-established image or on an image acquired in real time. This includes the acquisition of real-time images by external means, such as an ultrasonic probe.

[0049] More precisely, after the placement of the fixed element 12, new CT and MRI images are acquired and registered in the memory 26 of the control unit 20 with the images acquired before the placement of the fixed element 12. In these new images, the fixed element 12 is detected and localized by the mapping head 16a of the mapping element 16 fixed to the fixed element 12. This allows the control unit 20 to achieve registration between ultrasound tracking and brain images. Since most sensor elements 18 are not MRI compatible, in some embodiments, the sensor element 18 is fixed to the fixed element 12 after the MRI image has been established. Thus, after the registration process, the mapping element 16 is removed from the fixed element 12 (if removable) and replaced with the sensor element 18. If the fixed element 12 and the mapping element 16 form an inseparable element, the tracker element 18 is simply fixed to the fixed element 12. And if the tracker element 18 and the fixed element 12 are made from the same piece, they are both fixed together to a rigid body part 10. Depending on the embodiment, this implies that the tracker element 18 is MRI compatible.

[0050] In addition to the registration concept, implants can be used to estimate geometric errors from MRI images, as well as registration errors between CT and MRI images.

[0051] After the step of fixing the fixing element 12 to the rigid body part 14, - The patient's skin is closed with sutures, or - The fixing element 12 is small enough (about 2-6 mm) to be simply covered with a bandage.

[0052] As shown in Figures 1 and 5, the tracking system 10 is small, non-invasive, harmless to the target body, and provides sub-millimeter accuracy to depths of 100 mm to 500 mm within the target body part 22 (e.g., the brain) of the target, at frequencies higher than 20 Hz, for example.

[0053] The tracking system 10 and localization method according to the present invention improve the comfort and safety of deep surgical interventions. For example, it allows for local anesthesia per fixation element 12 instead of heavy general anesthesia.

[0054] Another crucial element is error limitation, and the tracking system according to the present invention makes it possible to avoid manual setting of the position of the fixed element 12. Furthermore, using the sensor element 18, the internal tracker 28 is directly detected as soon as a signal is emitted or sensed.

[0055] Finally, the tracking system 10 according to the present invention eliminates the need for device-related adjustments and thus reduces the risk of human interference through manual settings (3D frame-based system). It also cancels the need for periodic verification of image guidance and does not rely on the coordination of the surgeon's vision and hands.

[0056] More precisely, one of the main technical advantages is the creation of a single reference point, one attached to the patient rather than, for example, the operating room. This allows for patient movement without losing the alignment achieved by the invention, in contrast to other systems where this alignment is lost as soon as the patient's body moves relative to an external reference point located in the operating room.

Claims

[Claim 1] A signal tracking system (10) configured to track an internal tracker (28) located within a target body part (22) of a patient, wherein the tracking system (10) - At least one fixation element (12) designed to be fixed to a rigid body part (14) of the patient, wherein the rigid body part (14) at least partially surrounds the target body part (22), and the at least one fixation element (12) further comprises at least one mapping element (16), - At least one tracker element (18) configured to be fixed to at least one fixed element (12), wherein the at least one tracker element (18) is designed to track the internal tracker (28) in real time, - A control unit (20) configured to collect tracking information in real time from at least one tracker element (18), wherein the control unit (20) ○ Internal coordinate system, that is, internal reference (R), ○ At least one unique pre-established image showing at least a portion of the patient's target body part (22) or an element located within the target body part (22), wherein the unique pre-established image further shows the at least one fixed element (12) and the at least one mapping element (16), A control unit (20) further includes a memory (26) designed to store data, Equipped with, The internal reference (R) is included in or defined within a unique, pre-established image showing at least a portion of the patient's target body part (22) or an element located within the target body part (22), and the internal reference (R) is attached to the patient. The control unit (20) is designed to define at least one position of the 3D frame formed by the at least one fixed element (12) using the internal reference (R) as a reference, the fixed element (12) is fixed to the patient's rigid body part (14), the position and orientation of the 3D frame is determined by the spatial coordinates of the fixed element (12) as identified in the unique pre-established image, and the control unit (20) is designed to locate each point of the target body part (22) relative to at least one position of the 3D frame. The control unit (20) is further configured to process tracking information in real time to determine the position of an internal tracker (28) within the internal reference (R), the position being calculated relative to the position in the 3D frame, and the control unit (20) is further configured to update the positioning of the internal tracker (28) within the target body part (22) relative to the position in the 3D frame in real time, the tracking system (10).

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