Tag and detection device

• US 6,026,818 A
• Filed: 03/02/1998
• Issued: 02/22/2000
• Est. Priority Date: 03/02/1998
• Status: Expired due to Term

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Blair-Port, Ltd.
• Inventors: Blair, William, Port, Jeff
• Primary Examiner(s): GILBERT, SAMUEL G
• Application Number:
  US09/033,340
• Time in Patent Office: 722 Days
• Field of Search: 128/897-899, 604/362, 324/260
• US Class Current: 128/899
• CPC Class Codes: A61B 2090/0804 Counting number of instruments used; Instrument detectors
• CPC Class Codes: A61B 90/39 Markers, e.g. radio-opaque or breast lesions markers
• CPC Class Codes: A61F 13/44 with radio-opaque material or signalling means for residual material

Abstract

A method and device for the detection of unwanted objects in surgical sites, including a medically inert detection tag which is affixed to objects such as medical sponges or other items used in body cavities during surgery. The detection tag is of minimal size with a length of about 8 mm in the shape of a bead (ovate or circular) of a medically inert hard material such as plastic or glass, with a single signal emitter such as a miniature ferrite rod and coil and capacitor element imbedded therein. Alternatively, the tag includes a flexible thread composed of a single loop wire and capacitor element, within a protective flexible elongate casing which is sewn or woven into the fabric of the sponge. A detection device is utilized to locate the tag by pulsed emission of a wide band transmission signal. The tag resonates with a radiated signal, in response to the wide band transmission, at its own single non-predetermined frequency, within the wide band range. With the pulsed emissions, the return signals build up in intensity at a single (though not predefined) detectable frequency over ambient noise whereby utilizable small, economical tags readily provide recognizable detection signals.

Claims

1. A device for the electronic detection of an object within a defined area, said device comprising at least one minimally sized, low Q detection tag element for affixation to said object, without impeding operative use of the object, wherein said tag element comprises a single electronic signal emitter contained within protective means for electrically insulating said tag element;

said device further comprising an electronically operable interrogation and detection member adapted to locate the tag element within a predetermined distance therefrom, wherein the interrogation and detection member comprises means for the emission of pulsed wide band transmission signals which includes, within the wide band, a signal which activates the single signal emitter to provide a response signal, and means for the reception and analysis of said response signal;

wherein multiple pulsed signals cause increasing intensity of the return signals of the minimally sized tag element to build up in intensity at a single detectable frequency over ambient electronic noise levels to permit detection of the tag element and the object to which the tag element is attached.

2. The device of claim 1, wherein the tag element comprises a bead configuration with a length of up to 12 mm and wherein the tag comprises a single response signal emitter encapsulated within an electrically insulative bio-inert hard plastic.

3. The device of claim 2, wherein the single response signal emitter comprises a ferrite rod and a coil wire therearound with means for providing a capacitance.

4. The device of claim 3, wherein the single response signal emitter further comprises a protective diode adapted to prevent accidental burn-out thereof resulting from electrical equipment being brought into proximity therewith.

5. The device of claim 3, wherein the tags are configured with three orthogonal tank windings, comprising horizontal and vertical tank and center tank circuits.

6. The device of claim 2, wherein said bead configuration comprises means for attachment to the object.

7. The device of claim 6, wherein a defined area is a surgical site, said object is a surgical sponge and said means for attachment comprises flexible threads anchored in the bead and adapted for attachment to the threads of the sponge.

8. The device of claim 6, wherein said object is a laparotomy sponge and said means for attachment comprises a rivet attachment member and an eyelet member whereby the tag is attached to a marker loop of the laparotomy sponge.

9. The device of claim 1, wherein the single response signal emitter comprises an electrically insulative flexible thread element comprising a single loop wire with multiple turns with means for providing a capacitance, within a flexible casing.

10. The-device of claim 1, wherein the interrogation and detection member comprises a single removable loop antenna attached to a handle, said handle having contained therein electronic means for said pulsed wideband transmission and electronic means for detecting and analyzing said response signals.

11. The device of claim 10, wherein said interrogation means comprises an untuned transmitter.

12. A method for the electronic detection of a foreign object used during surgery but not intended to remain in a human body cavity after surgery;

said method comprises the steps of;

a) attachably providing the foreign object used in surgery, with at least one low Q tag element which does not interfere with utilization of the foreign object, wherein said tag element contains means which respond to an emitted wideband signal, with a single, non-predetermined, response signal;

b) after surgery, scanning a surgical site with interrogation means for scanning wherein said means for scanning emits a pulsed signal which includes a frequency at which the tag element responds with a single response signal for each pulse;

with said pulsed signal being of sufficient duration to cause the return signals from the tag element, in response to each of the interrogation pulses, to become cumulatively increased in intensity, for reliable detection by detection means, as a peak signal distinguishable from background noise, for detection of the tag and object attached thereto.

13. An apparatus for electronic detection of an object within a defined area, said apparatus comprising:

a transmitter that emits a pulsed wideband interrogation signal;

a low Q tag element affixed to an object, said tag element including a tag circuit that responds to each pulse of said pulsed wideband interrogation signal with a small narrowband return signal having a specific, but not predetermined frequency, said tag element being minimally sized and being so affixed relative to said object as to not interfere with the intended use of the object in a defined area;

a wideband receiver circuit that receives said small narrowband return signals, said receiver circuit comprising means for optimal reception within a predetermined distance from said tag element; and

a signal processor, coupled to said wideband receiver circuit, that transforms said small narrowband return signals into a resulting narrowband return signal having sufficient strength to be distinguishable from ambient noise.

14. The apparatus of claim 13, wherein said tag circuit includes a ferrite rod, a coil wound around said ferrite rod, and a capacitive element coupled to said coil.

15. The apparatus of claim 13, wherein said tag circuit is encased in a protective casing configured in the shape of a bead, and wherein said bead has an overall length of between 5 to 12 millimeters.

16. The apparatus of claim 13, wherein said predetermined distance within which said wideband receiver circuit is adapted for optimal reception is between 12 to 18 inches from said tag element.

17. The apparatus of claim 13, wherein said signal processor comprises a boxcar integrator.

18. A method for the electronic detection of a foreign object used in a surgical site, said method comprising the steps of:

providing a minimally sized, passive device configured to emit a small narrowband response signal, characterized by a specific, but not predetermined response frequency, in response to an excitation signal including a specific, but not predetermined excitation frequency;

attaching said passive device to said foreign object so as to not interfere with the intended use of said foreign object in the surgical site;

using said foreign object in the surgical site;

scanning the surgical site with a plurality of pulses of a wideband interrogation signal that includes said specific, but not predetermined excitation frequency, said plurality of pulses being of sufficient duration and interval so as to cause said passive device to emit a plurality small narrowband response signals of increasing intensity;

utilizing a wideband receiver to receive said plurality small narrowband response signals; and

transforming said plurality of small narrowband response signals into a resulting response signal of sufficient strength to be distinguished from ambient noise.