Fiducial marker system for subject movement compensation during medical treatment

{
  "publication_number": "US2007106152A1",
  "country": "US",
  "kind": "A1",
  "title": "Fiducial marker system for subject movement compensation during medical treatment",
  "abstract": "A system is provided for subject movement compensation during a medical procedure. The system uses passive radiofrequency identification tags associated with a subject, and at least one active RFID reader is positioned to interrogate the position of at least three such passive radiofrequency identification tags so as to triangulate the geometric position of a subject body tissue. The reader generates an output signal corresponding to a distance between said reader and a tag. A microprocessor calculates a displacement of a tag relative to the reader from said output signal to yield a value corresponding to subject movement. A medical device operates in synchronicity with the calculation corresponding to subject movement to compensate for subject movement during a treatment process in essentially real time. A process for subject movement compensation during a medical procedure is also provided.",
  "claims": [
    "1. A system for subject movement compensation during a medical procedure comprising: at least one passive radiofrequency identification tag secured to a subject; at least one active RFID reader positioned to interrogate said at least one passive radiofrequency identification tag with the proviso that there are at least three total of said tag and said reader, said at least one reader generating an output signal corresponding to a distance between said reader and said at least one tag; a microprocessor calculating a displacement of said tag from said output signal to yield a value corresponding to subject movement; and a medical device operating in synchronicity with the calculation corresponding to subject movement.",
    "2. The system of claim 1, wherein said at least one tag is at least three tags defining a triangle defining a target tissue.",
    "3. The system of claim 1, wherein said at least one tag is implanted.",
    "4. The system of claim 1, wherein said at least one tag is secured to an elastomeric belt encompassing the subject.",
    "5. The system of claim 1, wherein said at least one tag includes at least four tags defining a tetrahedron encompassing a target tissue.",
    "6. The system of claim 1, wherein said at least one reader is two or more active radiofrequency readers.",
    "7. The system of claim 1, wherein said at least one reader maintains a fixed position.",
    "8. The system of claim 1, wherein said at least one reader is secured to a moveable portion of said medical device.",
    "9. The system of claim 1, wherein said microprocessor calculates the displacement through triangulation.",
    "10. The system of claim 1, said at least one tag is secured proximal to a radioactive seed or a catheter tip.",
    "11. The process for subject movement compensation during a medical procedure comprising: scanning a subject to compute a vectoral distance between a passive radiofrequency identification tag secured to said subject and a target tissue within said subject; storing the vectoral distance in a digital memory accessible by a microprocessor; activating a radiofrequency reader to generate an output signal corresponding to a distance between said tag and said reader; computing with said microprocessor a position of the target tissue based on the output signal; and communicating from said microprocessor to a medical device coordinates of the target tissue.",
    "12. The process of claim 11, further comprising the step of moving said medical device in response to the communicated coordinates.",
    "13. The process of claim 11, further comprising a shutter in response to the communicated coordinates.",
    "14. The process of claim 11, where at least three of said tags are present and define a triangle encompassing the target tissue.",
    "15. The process of claim 11, further comprising: predicting coordinate data of the position of the tissue based on the period and chest cavity expansion associated with a prior respiratory cycle; and feeding to said medical device said predicted coordinate data.",
    "16. The process of claim 15, updating the predicated coordinate data with the output signal."
  ],
  "description_excerpt": "The present invention in general relates to non-optical fiducial markers deployed as part of a system for subject movement during a medical treatment and in particular, to a fiducial marker system that compensates for subject movement in real time.\n\nThe delivery of high intensity radiation to cancerous body tissue with a highly focused delivery is complicated by subject movement during the radiation administration session. While bolting a subject skull into a frame has proven to be partially successful, cervical flexion and respiration still contributes to radiation delivery defocus. While anesthesia has proven partly successful in compensating for cervical flexion and respiration, the difficulties and possible complications associated with anesthesia make this an unattractive option.\n\nTreatment of a lesion located in the thoracic or abdominal cavity exacerbates the problem associated with patient movement. With a diaphragm traveling about 10 cm in an adult human, dynamic positional change of organs is observed during a respiration cycle. The result of organ movement is a radiation delivery defocus with tissue surrounding a lesion being subjected to unintended dosing.\n\nPrior art attempts to address physiological movement during radiation dosing have met with limited success. Typical of these systems is the establishment of a camera array around the three-dimensional subject volume. A series of blinking lights secured to subject skin are tracked by the cameras and through geometric triangulation, the location of a surgical tool, catheter tip, or fiducial marker is noted.",
  "cpc": [
    "A61N 5/1049",
    "A61B 2017/00694",
    "A61B 2017/00699",
    "A61B 2034/2051",
    "A61B 2090/397",
    "A61B 34/20",
    "A61B 90/36",
    "A61B 90/39",
    "A61B 90/98",
    "A61N 5/1067"
  ],
  "ipc": [
    "A61B 5/05",
    "G08B 13/14",
    "A61N 5/10"
  ],
  "inventors": [
    "Allen Kantrowitz",
    "In Mun"
  ],
  "filing_date": "2006-09-25",
  "publication_date": "2007-05-10",
  "priority_date": "2005-09-23",
  "application_number": "US-53475906-A",
  "family_id": "38004726",
  "cited_by_count": 111,
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