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EP-4326142-B1 - SYSTEM AND METHOD FOR LOCATING A MEDICAL DEVICE

EP4326142B1EP 4326142 B1EP4326142 B1EP 4326142B1EP-4326142-B1

Inventors

  • ALOMAINY, Akram Hussain Mohammed
  • THAHA, Mohamed Adhnan
  • AZIZ, Ahmed Khalid
  • JILANI, Syeda Fizzah

Dates

Publication Date
20260506
Application Date
20220420

Claims (15)

  1. A computer-implemented method for locating an endoscopic capsule (100), comprising: analysing (402) a first set of radio signals received from an endoscopic capsule at a plurality of radio signal receivers (200), wherein analysing the first set of radio signals comprises determining the quality of the radio signal received by each respective receiver of the plurality of radio signal receivers (200); based at least in part on the analysing, selecting (404) a first subset of receivers from the plurality of radio signal receivers, the first subset of receivers comprising at least three receivers, wherein selecting the first subset of receivers comprises selecting the receivers associated with the highest quality signals; estimating the location of the endoscopic capsule by performing the steps of: (a) determining (406), based on trilateration of respective radio signals of the first set of radio signals received by the first subset of receivers, a first estimated location of the endoscopic capsule; (b) determining (408), based on trilateration of a second set of radio signals received from the endoscopic capsule by the first subset of receivers, a second estimated location of the endoscopic capsule; and (c) determining (410) whether the first and second estimated locations of the endoscopic capsule are within a threshold distance of one another; if the first and second estimated locations of the endoscopic capsule are within a threshold distance of one another, outputting (412) an estimated location of the endoscopic capsule based on the first and second estimated locations; and if the first and second estimated locations of the endoscopic capsule (100) are not within a threshold distance of one another, selecting (414) a second subset of receivers from the plurality of radio signal receivers (200), the second subset of receivers comprising at least three receivers and comprising at least one receiver that was not in the first subset of receivers, and repeating steps (a)-(c) in respect of respective radio signals received from the endoscopic capsule by the second subset of receivers.
  2. The computer-implemented method of any preceding claim, wherein determining the first and/or second estimated location is based on a least squares approximation or a most likely path approximation.
  3. The computer-implemented method of claim 1 or 2, further comprising mapping the estimated location of the endoscopic capsule (100) to a location in a patient anatomy.
  4. The computer-implemented method of claim 3, further comprising verifying that the location in the patient anatomy is a plausible location for the endoscopic capsule (100).
  5. The computer-implemented method of claim 1, wherein determining the quality of the radio signal received by each respective receiver comprises determining one or more of: a signal to noise ratio of each respective radio signal; an amplitude of each respective radio signal; a signal to interference ratio of each respective radio signal; a time delay parameter of each respective radio signal; or a fluctuation frequency of each respective radio signal.
  6. The computer-implemented method of any preceding claim, wherein selecting the first subset of receivers from the plurality of radio signal receivers (200) is based at least in part on the relative location of the plurality of receivers.
  7. The computer-implemented method of any preceding claim, wherein the delay between steps (a) and (b) is 1 millisecond or less.
  8. The computer-implemented method of any preceding claim, wherein the first and second sets of radio signals comprise image and/or video feeds transmitted by the endoscopic capsule (100).
  9. The computer-implemented method of any preceding claim, wherein trilateration of the first and second sets of radio signals comprises: performing, for each respective radio signal received by each receiver of the respective subset of receivers, a path loss calculation, wherein the path loss calculation is based, at least in part, on a first radio signal parameter indicative of a path loss exponent describing the rate of change in path loss of the received radio signal as a function of distance from the endoscopic capsule (100); and/or wherein the path loss calculation is based, at least in part, on a second radio signal parameter indicative of a path loss power value at a reference distance from the endoscopic capsule.
  10. The computer-implemented method of claim 9, further comprising the steps of: (d) modifying (502, 504) the first and/or second radio signal parameter based on one or more known characteristics associated with a patient; and (e) repeating the path loss calculation using the modified first and/or second radio signal parameter.
  11. The computer-implemented method of claim 10, wherein the one or more known characteristics comprises a body mass index, BMI, value of the patient.
  12. A data processing apparatus (600) comprising a processor (602) configured to perform the method of any preceding claim.
  13. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of any of claims 1-11.
  14. A computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the method of any of claims 1-11.
  15. A system comprising: a plurality of radio signal receivers (200) configured to receive radio signals from an endoscopic capsule (100); and a data processing apparatus (600) comprising a processor (602) configured to perform the method of any of claims 1-11.

Description

Technical Field The present disclosure relates to a system and method for locating an endoscopic capsule. Background Miniaturised medical devices, such as endoscopic capsules, offer many significant benefits over traditional methods of diagnosing and treating patients. In particular, most miniaturised medical devices can be easily inserted into the human body with minimal discomfort or risk. Once inside the body, the small size of such devices offers greater versatility for performing diagnosis, drug delivery and other therapies. To take the example of an endoscopic capsule, such an endoscopic capsule can be swallowed by a patient in the same manner as an ordinary pill. This removes the need for more involved and invasive procedures associated with traditional endoscopies, where a camera on the end of a cable is inserted into the body. A capsule endoscope typically includes a camera. As the endoscopic capsule passes through the body, in particular the digestive tract, the camera can take many thousands of images. These images can be processed and can aid in diagnosis of bowel diseases and such like. There is often a need to locate and track the endoscopic capsule, for example once it has been inserted into or ingested by a patient. Most current solutions for locating the endoscopic capsule depend heavily on analysis of the images being transmitted by the endoscopic capsule. Feature extraction is typically used to determine where the endoscopic capsule is in the body. This is heavily reliant on the knowledge and experience of the physician at hand and hence is prone to human error. Some limited progress in autonomous localisation of the endoscopic capsule has been made. In particular, magnetic-based localisation, where the intensity of a magnetic field emitted by the endoscopic capsule is picked up and recorded through a large external receiving unit, has been studied. A drawback of this technology, however, is the potential for interference from other nearby devices that may be present during a procedure, as well as interference caused by prosthetic implants. To offset this variability in the quality of signals caused by external factors, it is necessary to perform the localisation procedure in a highly controlled laboratory setting. This is complex, costly and means the localisation procedures are not suitable for use in less sophisticated settings such as may be present in developing countries or where there is a shortage of suitable environments to carry out the procedure. Even in sophisticated and controlled settings, the accuracy of such techniques is heavily dependent on the quality of the endoscopic capsule magnet and the clarity of the link between the endoscopic capsule and the receiver. Additional problems with existing systems arise from the fact that they are unable to take into account the anatomical and physiological variations that occur between patients, which affect any communication link between the endoscopic capsule and the receiver, often to a significant extent. This results in large error margins and, ultimately, potentially unreliable data regarding the location of the capsule. As can be seen, existing systems and methods for locating medical devices such as capsule endoscopes suffer from significant drawbacks. It would be advantageous to provide systems and methods which address one or more of these problems, in isolation or in combination. Barbi Martina et al, "UWB RSS-Based Localization for Capsule Endoscopy Using a Multilayer Phantom and In Vivo Measurements", describes the performance of a received signal strength-based approach for 2-D and 3-D localization of a capsule endoscope in the UWB frequency band. For 2-D localization, experimental laboratory measurements using a two-layer phantom-based setup are conducted. For 3-D localization, data from an in vivo experiment are used. Localization accuracy using path loss models, under ideal and non-ideal channel estimation assumptions, is compared. Results show that, under non-ideal channel assumption, the relative localization error slightly increases for the 2-D case but not for the in vivo 3-D case. Impact of receiver selection on the localisation accuracy is also investigated for both 2-D and 3-D cases. Summary of the invention The invention to which this European patent relates is defined by a computer-implemented method according to claim 1, a data processing apparatus according to claim 12, a computer program according to claim 13, a computer-readable storage medium according to claim 14 and a system according to claim 15. Further embodiments are defined by dependent claims 2-11. Overview of the disclosure This overview introduces concepts that are described in more detail in the detailed description. It should not be used to identify essential features of the claimed subject matter, nor to limit the scope of the claimed subject matter. The scope of protection is defined by the claims. According to one aspect of the present di