Fiducial marker system for subject movement compensation during medical treatment

• US 9,498,647 B2
• Filed: 09/25/2006
• Issued: 11/22/2016
• Est. Priority Date: 09/23/2005
• Status: Active Grant

• Current Assignee: Kantrowitz, Allen B., Mun, In K.
• Original Assignee: Kantrowitz, Allen B., Mun, In K.
• Inventors: Kantrowitz, Allen B., Mun, In K.
• Primary Examiner(s): FERNANDEZ, KATHERINE L
• Application Number:
  US11/534,759
• Publication Number:
  US 20070106152A1
• Time in Patent Office: 3,711 Days
• Field of Search: 600/427, 600/595, 340/572.4
• US Class Current: 1/1
• CPC Class Codes: A61B 2017/00694 with means correcting for movement of or for synchronisation with the body
• CPC Class Codes: A61B 2017/00699 correcting for movement caused by respiration, e.g. by triggering
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2090/397 electromagnetic other than visible, e.g. microwave
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for
• CPC Class Codes: A61B 90/39 Markers, e.g. radio-opaque or breast lesions markers
• CPC Class Codes: A61B 90/98 using electromagnetic means, e.g. transponders
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam
• CPC Class Codes: A61N 5/1067 in real time, i.e. during 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 performed using a medical device, the system comprising:

a treatment platform for supporting a subject during the medical procedure;

a first set of at least one fixed passive radiofrequency identification (RFID) tag, where said at least one fixed RFID tag is adapted to be secured in a fixed positional relationship relative to a target related to the subject;

a second set of a plurality of passive RFID tags secured to an elastomeric belt for encompassing the subject and positioned above the treatment platform, where said elastomeric belt is adapted to be secured to an exterior surface of the subject;

a plurality of RFID readers positioned to interrogate said at least one fixed RFID tag and said second set of the plurality of passive RFID tags secured to said elastomeric belt, said plurality of RFID readers configured to generate a set of output signals corresponding to respective distances between said plurality of RFID readers and each of said at least one fixed RFID tags and said plurality of passive RFID tags secured to said elastomeric belt and wherein said plurality of RFID readers are further configured to interrogate said first set and said second set of RFID tags successively at short time intervals or continuously;

a microprocessor configured to calculate based on said set of output signals displacements of said at least one fixed passive RFID tag and said second set of the plurality of passive RFID tags secured to said elastomeric belt to yield a value corresponding to subject movement that is translational, rotational, or respirational after one or more breathing cycles is made and configured to feed coordinate adjustments determined based on said value to said medical device; and

wherein said medical device is configured to continuously move during the medical procedure with respect to a position of said target in synchronicity with said microprocessor calculation corresponding to the value of subject movement, wherein said plurality of RFID readers are secured to a portion of said medical device that is configured to be continuously controlled in real-time during the medical procedure in response to the coordinate adjustments from said microprocessor without interrupting or delaying the performance of the medical procedure.

2. The system of claim 1, wherein said first set comprises at least three fixed RFID tags which define a triangle in relation to the subject, the subject encompassing the target.

3. The system of claim 1, further comprising at least one additional passive RFID tag wherein said at least one additional passive RFID tag is for implanting in an interior of the said-subject.

4. The system of claim 1, wherein said first set and said second set of RFID tags are at least four RFID tags defining a tetrahedron encompassing a target tissue.

5. The system of claim 1, wherein said plurality of RFID readers maintain a fixed position.

6. The system of claim 1, wherein said microprocessor calculates the displacements through triangulation.

7. The system of claim 1, further comprising at least one additional passive RFID tag wherein said at least one additional passive RFID tag is secured proximal to a radioactive seed or to a catheter tip during said medical procedure.

8. The system of claim 1, wherein said plurality of RFID readers has a gain adjusted until a signal is received from said plurality of passive RFID tags secured to said elastomeric belt and said at least one fixed passive RFID tag.

9. A process for subject movement compensation during a medical procedure performed using a medical device, the process comprising:

providing a plurality of passive belt radiofrequency identification (RFID) tags secured to an elastomeric belt;

attaching said elastomeric belt to encompass the subject at a position proximal to a target tissue of the subject;

attaching at least one passive body radiofrequency identification (RFID) tag to an exterior surface of the subject in opposition to said plurality of passive belt RFID tags, where said plurality of passive belt RFID tags secured to said elastomeric belt and said at least one passive body RFID tag attached to the exterior surface of the subject serve as fiducial markers;

reading the plurality of passive belt RFID tags and said at least one passive body RFID tag attached to the subject, who is resting on a treatment platform during the medical procedure, with a plurality of RFID readers positioned above the treatment platform, to compute respective distances between said plurality of RFID readers and each of said plurality of passive belt RFID tags and said at least one passive body RFID tag attached on the subject, wherein said reading is done successively at short time intervals or continuously and wherein said plurality of RFID readers generate an output signal or signals based on said computation of said respective distances;

calculating with a microprocessor a position of said target tissue based on said output signal or signals in relation to stored vectoral distances between the target and said fiducial markers, where the microprocessor further calculates displacement of said plurality of passive belt RFID tags or said at least one passive body RFID tag based on said output signal or signals to yield a value corresponding to subject movement and based on one or more previous breathing cycles a prediction of subject movement is made;

communicating, from said microprocessor to the medical device above the subject, coordinates for positioning said medical device based on the calculated position of said target tissue; and

adjusting the position of said medical device continuously during the medical procedure with respect to the position of said target tissue to maintain synchronicity with subject movement, wherein said plurality of RFID readers are secured to a portion of said medical device that is configured to move continuously during the medical procedure in response to coordinate adjustments determined based on the value corresponding to subject movement from said microprocessor without interrupting or delaying the performance of the medical procedure.

10. The process of claim 9, further comprising the step of opening a shutter in response to the communicated coordinates.

11. The process of claim 9, wherein said at least one passive body RFID tag comprises of at least three passive body RFID tags which define a triangle in relation to the subject, the subject encompassing the target tissue.

12. The process of claim 9, further comprising:

predicting coordinate data of the position of the target tissue relative to said plurality of passive belt RFID tags secured proximal to 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.

13. The process of claim 12, further comprising updating the predicted coordinate data with the output signal or signals.

14. The process of claim 9, wherein said plurality of RFID readers has a gain adjusted until a signal is received from the fiducial markers.