WO 2021/005582 PCT/IB2020/056571

1

TITLE

System for the magnetic localization and locomotion of an endoscopic capsule

DESCRIPTION Field of the invention

The present invention relates to the sector of capsular endoluminal procedures for diagnosis and treatment.

In particular, the invention relates to a system for the magnetic localization and locomotion of an endoscopic capsule in a gastrointestinal tract.

Description of the prior art

Traditional endoscopy systems are manually pushed and pulled from the outside through the natural sphincters within the gastrointestinal system. The tip of the device therefore moves under the action of forces transmitted throughout the device .

The magnetic guided endoscopic systems, on the other hand, are moved by the tip of the device under the action of magnetic interactions. In particular, the endoscopic system is composed of a robotic platform which supports in its terminal part one or more sources of permanent magnetic field, and a capsular system, wired or not, containing an internal source of permanent magnetic field. The force required for advancement is therefore transmitted from the tip to the tail as opposed to traditional systems. This paradigm shift in the mode of locomotion resulted in the need for a localization system to accurately and repeatably identify the position and orientation of the tip of the endoscopic system within the anatomical district concerned.

In fact, if in the case of traditional endoscopic systems the definition of the position and orientation of the tip with respect to a global system (external to the lumen) is of negligible importance since the system is free to move forward and backward along a trajectory defined by its anatomy of the lumen, in a magnetic guide system it is of fundamental importance for the correct positioning of the external magnetic field source in the free space.

Numerous localization systems have been developed capable of defining the pose of an object within an anatomical district. The main ones exploit magnetic and electromagnetic systems, radio frequency systems and optical systems. However, the radio frequency and optical systems, although compatible with magnetic locomotion, do not guarantee sufficient precision to allow correct locomotion of the capsular system. Instead, usually, magnetic and electromagnetic systems manage to guarantee good precision in the volume of interest but are influenced by magnetic interference, such as the presence of metallic materials or the presence of other strong magnetic sources. In this case, it is therefore not possible to combine magnetic locomotion and localization at the same time.

In the document "Enhanced real-time pose estimation for closed-loop robotic manipulation of magnetically actuated capsule endoscopes" on behalf of A. Taddese et al . a method for the magnetic localization of an endoscopic capsule is described which is based on a hybrid use of both static (permanent magnets) and alternating (solenoids) magnetic field sources, ensuring a significant reduction of interference with the magnetic locomotion of the capsule itself .

However, this method requires 6 mono-axial sensors on board the capsule, resulting in a greater encumbrance within a necessarily small space.

In addition, the identification of the capsule installation requires at least one permanent magnetic field source .

The method mentioned above is also described in US2019104994, together with the localization system that implements this method.

Summary of the invention

It is therefore a feature of the present invention to provide a system for the magnetic localization and locomotion of a medical device which allows to reduce the components present on board the medical device itself. It is also a feature of the present invention to provide such a system that allows to identify the pose of the medical device even without the use of a static magnetic field source or without being within its working field.

It is a further feature of the present invention to provide such a system which allows to improve the triangulation of the medical device, reducing the influence of the detection noise on the localization.

It is still a feature of the present invention to provide such a system that allows the creation of an autonomous or semi-autonomous system for guiding the medical device within the anatomical district of interest.

These and other objects are achieved by a system for the magnetic localization and locomotion of a medical device according to claims from 1 to 11.

Brief description of the drawings

Further characteristic and/or advantages of the present invention are more bright with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings in which:

— Fig. 1 shows a possible embodiment of the system for the magnetic localization and locomotion of a medical device, according to the present invention;

Fig. 2 shows in detail the magnetic fields obtained by the alternating magnetic field source of the embodiment of Fig. 1.

Description of a preferred exemplary embodiment

With reference to Figs. 1 and 2, in a preferred exemplary embodiment, the system 100 according to the present invention is adapted to carry out the magnetic localization and locomotion of an endoscopic capsule 200 in the gastrointestinal tract of a patient 10.

In this exemplary embodiment, the system 100 comprises a plurality of external magnetic field sources, and in particular :

— an external permanent magnet 110, which is adapted to generate a static magnetic field having frequency j = 0;

— four solenoids 120, arranged to generate alternate electromagnetic fields having respective frequencies

The permanent magnet 110 is moved by a robotic arm 105.

The system 100 also comprises a endoscopic capsule 100 comprising in turn a magnetic field sensor, arranged to carry out a measurement of the components along three orthogonal axes of the magnetic field vector generated by the external magnetic field sources 110 and 120, and an accelerometer, arranged to carry out a measurement of the accelerations of the endoscopic capsule 200. The system then comprises a control unit arranged to carry out an identification of the position and of the orientation of the endoscopic capsule 200 with respect to a reference system S.

In particular, the control unit, for identifying the position of the capsule 200, is arranged to:

— receive from the magnetic field sensor the measurement of the components along three orthogonal axes of the magnetic field vector generated by the external magnetic field sources

110 and 120;

— calculate the individual magnetic fields generated by such external magnetic field sources 110 and 120 for estimating the distance d _j , with i = 1, ...,5, of the capsule 200 from the source 110,120 themselves ;

— carry out a triangulation of the estimated distances d _j for identifying the position of the capsule 200 with respect to the reference system S .

Furthermore, the control unit, for increasing the precision of the triangulation, can be arranged to:

— carry out an optimization of the triangulation, approximating the lines of the magnetic fields determined by the magnetic field sensor according to an ellipsoidal and/or a spheroidal mathematical model weighted on the basis of the derivative with respect to the measured magnetic fields;

— to define an optimal position of the capsule 200 weighted on the basis of the estimate of the error between the magnetic fields determined and the magnetic fields estimated according to the ellipsoidal and/or spheroidal models;

— carry out an optimization of the triangulation on the basis of the magnetic field model.

With respect to the prior art, therefore, it is possible to identify the position of the capsule 200 by using a single triaxial magnetic field sensor or, alternatively, 3 mono axial sensors, instead of 6 mono axial sensors, with consequent reduction of the encumbrance inside the capsule itself .

It should be noted that triangulation by the control unit could also take place with only two solenoids 120, given that the frequencies of the generated magnetic fields are different from each other and different from 0. In this case, the external permanent magnet 110, which generates a static magnetic field at a frequency = 0, would be necessary both for handling the capsule 200, both to provide to the magnetic field sensor a third magnetic field, at a frequency different from that of the solenoids, essential for triangulating the position of the capsule 200.

Furthermore, the control unit, for identifying the orientation of the capsule 200, is arranged to:

— receive from the accelerometer the measurement of the accelerations of the endoscopic capsule 200;

— estimate the roll and pitch angles of the endoscopic capsule 200 on the basis of the measurement of the accelerations received by the accelerometer;

— estimate the magnetic field vector B _s generated by the external magnetic field sources 110 and 120 calculated considering the position of the endoscopic capsule 200 with respect to the external magnetic field sources 110 and 120;

— define the magnetic field vector B _m determined by the magnetic field sensor;

— calculate the derivatives B _s ' and B _m ' as projections of the magnetic field vectors B _s and B _m in a plane orthogonal to the gravitational vector;

— calculate the yaw angle of the endoscopic capsule 200 as arcsine of the ratio between the vector product of B _s ' and B _m ' and the product of the norm of the vectors B _s ' and B _m ' . In a possible variant embodiment, a carriage can be provided arranged to move the solenoids 120 to follow the movement of the endoscopic capsule 200 in the patient's body 10.

The foregoing description some exemplary specific embodiments will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt in various applications the specific exemplary embodiments without further research and without parting from the invention, and, accordingly, it is meant that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention, it is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation .