METHOD AND APPARATUS TO DETECT TRANSPONDER TAGGED OBJECTS, FOR EXAMPLE DURING MEDICAL PROCEDURES

• US 20100109848A1
• Filed: 10/27/2009
• Published: 05/06/2010
• Est. Priority Date: 10/28/2008
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: RF Surgical Systems, Incorporated (Medtronic Plc)
• Inventors: Blair, William A., Poirier, David A., Barnes, Bruce E.
• Granted Patent: US 8,264,342 B2
• Time in Patent Office: Days
• US Class Current: 340/10.200
• CPC Class Codes: A61B 90/90 Identification means for patients or instruments, e.g. tags
• CPC Class Codes: A61B 90/98 using electromagnetic means, e.g. transponders
• CPC Class Codes: A61G 13/10 Parts, details or accessories surgical drape sheets A61B46/00
• CPC Class Codes: A61G 13/1265 having inflatable chambers
• CPC Class Codes: A61G 13/127 having chambers filled with liquid or gel
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions
• CPC Class Codes: G06K 7/10128 the step consisting of detection of the presence of one or more record carriers in the vicinity of the interrogation device
• CPC Class Codes: H01Q 21/00 Antenna arrays or systems arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system H01Q3/00
• CPC Class Codes: H01Q 5/00 Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements combinations of separate active antenna units operating in different wavebands and connected to a common feeder system H01Q21/30
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

The presence or absence of objects (e.g., medical implements, medical supplies) tagged with transponders may be determined in an environment in which medical procedures (e.g., surgery) are performed via an interrogation and detection system which includes a controller and a plurality of antennas positioned along a patient support structure. The antennas may, for example, be positioned along an operating table, bed, a mattress or pad or a sheet and may be radiolucent. Respective antennas may successively be activated to transmit interrogation signals. Multiple antennas may be monitored for responses from transponders to the interrogation signals. For example, all antennas other than the antenna that transmitted the most recent interrogation signal may be monitored.

Claims

1. An apparatus to detect transponder tagged objects which are used in performing medical procedures, the apparatus comprising:

a plurality of antennas, at least some of the antennas spaced at intervals along at least a portion of a length of a patient support structure that is sized to support a patient; and

a control system communicatively coupled to the antennas and configured to successively transmit an interrogation signal via respective ones of at least two of the antennas and to monitor at least the other ones of the antennas for a response to the interrogation signal in a period following the transmission of the interrogation signal and preceding a transmission of another interrogation signal.

2. The apparatus of claim 1 wherein the plurality of antennas includes at least three antennas and each of the antennas includes a respective antenna coils, a portion a projected area of each successive one of the antenna coils along the portion of the length of the patient support structure overlapping a portion of a projected area of at least one neighboring one of the antenna coils.

3. The apparatus of claim 1 wherein the plurality of antennas includes at least six antennas.

4. The apparatus of claim 1 wherein the control system is configured to successively transmit an interrogation signal from all of the antennas in the plurality of antennas, one at a time, and to monitor all of the antennas in the plurality of antennas for a response to each of the interrogation signals.

5. The apparatus of claim 1 wherein the control system is configured to successively transmit an interrogation signal from all of the antennas in the plurality of antennas, one at a time, and to monitor all of the antennas in the plurality of antennas for a response to each of the interrogation signals except the antenna from which a most recent interrogation signal was transmitted.

6. The apparatus of claim 1 wherein the control system is configured to monitor a level of noise, successively transmit an interrogation signal from each the antennas, one at a time, and to monitor all of the antennas for a response to the interrogation signal, determine which of the antennas receives a strongest one of the responses to the interrogation signal, determine a noise estimation based on the monitored level of noise, and subtract the noise estimation from the strongest one of the responses to distinguish a signal portion of the response signal from a noise portion of the response signal.

7. The apparatus of claim 6 wherein the control system is configured to determine the noise estimation as an average based on the monitored level of noise on all antennas except the antenna that received the strongest one of the responses to the interrogation signals.

8. The apparatus of claim 1 wherein the control system is configured to measure a level of ambient noise detected via a plurality of the antennas during a noise detection portion of a cycle, the noise detection portion temporally spaced from any preceding interrogation portions of the cycle such that transponders, if any, are not responding to any electromagnetic interrogation signals transmitted during any preceding interrogation portions of the cycle;

determine a set of noise cancellation factors for each of a number of antenna channels;

determine a sample averaging time for sampling noise based on the measured level of ambient noise;

determine a sample averaging time for sampling responses to interrogation signals based on the measured level of ambient noise;

average noise corrected samples of noise sampled for the determined noise sample averaging time during the noise detection portion of the cycle;

transmit a number of electromagnetic interrogation signals via one of the antennas during an interrogation portion of the cycle that follows the noise detection portion;

average noise corrected samples of responses sampled for the determined signal averaging time during the interrogation portion of the cycle in a period while no electromagnetic interrogations signals are being transmitted by any of the antennas, the period spaced temporally sufficiently closely to the transmission of the electromagnetic interrogations signals that the transponders, if any, are still responding to the electromagnetic interrogation signals; and

compare averaged noise corrected samples of responses to the interrogation signals to at least one transponder detection threshold.

9. The apparatus of claim 8 wherein the control system is further configured to iterate through each of the antennas if averaged noise corrected samples of responses to interrogations signals does not satisfy the at least one transponder detection threshold.

10. The apparatus of claim 8 wherein the control system is further configured provide a notification of detection of a transponder if the averaged noise corrected samples of responses to interrogations signals does satisfies the at least one transponder detection threshold an N^th time, where N is greater than 1.

11. The apparatus of claim 8 wherein the control system is further configured to compare at least one noise level measured from before a first interrogation portion of the cycle a noise level measured after the first interrogation portion of the cycle;

and increase the sample averaging time for sampling responses to interrogation signals if a result of the comparison indicates a variation in excess of a variation threshold.

12. The apparatus of claim 8 wherein the control system is further configured to determine the set of noise cancellation factors for each of the number of antenna channels by, for each respective antenna channel averaging the measured levels of ambient noise received on all the antenna channels other than the respective antenna channel for which the noise cancellation factor is being determined.

13. The apparatus of claim 1 wherein the antennas are radiolucent, and further comprising

the patient support structure selected from the group consisting of:

an operating table, a patient bed, a mattress, a pad and a sheet.

14. A method to detect transponder tagged objects which are used during medical procedures, the method comprising:

for each of at least three antennas spaced at intervals along at least a portion of a length of a patient support structure,

successively transmitting a number of interrogation signals via respective ones of the antennas; and

monitoring at least the other ones of the antennas for a response to the interrogation signals in a period following the transmission of the interrogation signal and before transmitting another number of interrogation signals via a next one of the antennas.

15. The method of claim 14 wherein successively transmitting a number of interrogation signals via respective ones of the antennas includes transmitting the interrogation signals from all of the antennas, one at a time, and wherein monitoring at least the other ones of the antennas for a response to the interrogation signals includes monitoring all of the antennas in the plurality of antennas for a response to each of the interrogation signals.

16. The method of claim 14 wherein successively transmitting a number of interrogation signals via respective ones of the antennas includes transmitting the interrogation signals from all of the antennas in the plurality of antennas, one at a time, and wherein monitoring at least the other ones of the antenna for a response to the interrogation signals includes monitoring all of the antennas except the antenna from which a most recent interrogation signal was transmitted for a response to the most recent interrogation signal.

17. The method of claim 14, further comprising:

measuring a level of ambient noise detected via a plurality of the antennas during a noise detection portion of a cycle, the noise detection portion temporally spaced from any preceding interrogation portions of the cycle such that transponders, if any, are not responding to any electromagnetic interrogation signals transmitted during any preceding interrogation portions of the cycle;

determining a set of noise cancellation factors for each of a number of antenna channels;

determining a sample averaging time for sampling noise based on the measured level of ambient noise;

determining a sample averaging time for sampling responses to interrogation signals based on the measured level of ambient noise;

averaging noise corrected samples of noise sampled for the determined noise sample averaging time during the noise detection portion of the cycle; and

wherein successively transmitting a number of interrogation signals via respective ones of the antennas includes transmitting the number of electromagnetic interrogation signals via one of the antennas during an interrogation portion of the cycle that follows the noise detection portion; and

monitoring at least the other ones of the antennas for a response to the interrogations signals in a period following transmission of the interrogation signal includes averaging noise corrected samples of responses sampled for the determined signal averaging time during the interrogation portion of the cycle in a period while no electromagnetic interrogations signals are being transmitted by any of the antennas, the period spaced temporally sufficiently closely to the transmission of the electromagnetic interrogations signals that the transponders, if any, are still responding to the electromagnetic interrogation signals.

18. The method of claim 17, further comprising:

comparing averaged noise corrected samples of responses to the interrogation signals to at least one transponder detection threshold; and

iterating through each of the antennas if averaged noise corrected samples of responses to interrogations signals does not satisfy the at least one transponder detection threshold.

19. The method of claim 18, further comprising:

providing a notification of detection of a transponder if the averaged noise corrected samples of responses to interrogations signals does satisfies the at least one transponder detection threshold an N^th time, where N is greater than 1.

20. The method of claim 17, further comprising:

comparing at least one noise level measured from before a first interrogation portion of the cycle a noise level measured after the first interrogation portion of the cycle; and

increasing the sample averaging time for sampling responses to interrogation signals if a result of the comparison indicates a variation in excess of a variation threshold.

21. The method of claim 17 wherein determining the set of noise cancellation factors for each of the number of antenna channels includes, for each respective antenna channel averaging the measured levels of ambient noise received on all the antenna channels other than the respective antenna channel for which the noise cancellation factor is being determined.

22. The method of claim 14 wherein the successively transmitting a number of interrogation signals includes successively transmitting the interrogations signals at a number of different frequencies at a number of different times.

23. An apparatus to detect transponder tagged objects which are used in performing medical procedures, the apparatus comprising:

a patient support structure that is sized to support a patient; and

at least three antennas positioned along at least a portion of a length of the patient support structure, each of the antennas positioned along the length of the patient support structure radiolucent to X-ray frequency electromagnetic energy, and each of the antennas having a respective range, the ranges of the antennas in each neighboring pair of antennas at least partially overlapping.

24. The apparatus of claim 23 wherein the patient support structure is elongated having a longitudinal axis and the antennas are coil antennas, at least some of the coil antennas arranged successively along the longitudinal axis.

25. The apparatus of claim 24 wherein a portion of each successive one of the antenna coils is arranged successively along the longitudinal axis of the surgical table with a projected area that overlaps a portion of a projected area of at least one neighboring one of the antenna coils.

26. The apparatus of claim 23 wherein the patient support structure has at least one X-ray film receiving receptacle and the antennas are positioned between a patient support surface of the patient support structure and the at least one X-ray film receiving receptacle.

27. The apparatus of claim 26 wherein the antennas each comprise a respective stripe-line aluminum coil having a number of windings, each stripe-line aluminum coil has a thickness that is not greater than 200 microns.

28. The apparatus of claim 27 wherein each stripe-line aluminum coil has a thickness that is not greater than 100 microns.

29. The apparatus of claim 23 wherein the antennas are carried by the patient support structure on, in or under a patient support surface, and further comprising

at least one pad that overlies at least one of the antennas.

30. The apparatus of claim 23, further comprising

a control system communicatively coupled to the antennas and configured to successively transmit an interrogation signal via respective ones of the antennas and to monitor at least the other ones of the antennas for a response to the interrogation signal in a period following the transmission of the interrogation signal and preceding a transmission of another interrogation signal.

31. The apparatus of claim 30, further comprising

a pedestal that supports the patient support structure, wherein the control system is at least partially housed in the pedestal.

32. The apparatus of claim 30, further comprising

at least one antenna port carried by the patient support structure, the at least one antenna port communicatively coupled to at least one of the antennas and communicatively coupleable to the control system.

33. The apparatus of claim 30, further comprising

at least one visual indicator carried by the patient support structure, the at least one visual indicator communicatively coupled to the control system and operable thereby to produce visual indications indicative of responses to the interrogation signals;

and

at least one user switch carried by the patient support structure, the at least one switch communicatively coupled to the control system and operable thereby to control at least one aspect of an operation of the control system.

34. The apparatus of claim 23 wherein the patient support structure is at least one of a pad or a mattress that carries the antennas on at least one of an exterior or an interior thereof, and the at least one of the pad or the mattress including at least one communications interface to provide selectively decoupleable communicative coupling with at least some of the antennas.

35. The apparatus of claim 34 wherein the at least one of the pad or the mattress has a compliant inner portion and an outer cover that at least partially surrounds the compliant inner portion and which is impervious to bodily fluids, the compliant inner portion and the outer cover comprising radiolucent materials that can withstand multiple sterilization cycles.

36. The apparatus of claim 23 wherein the patient support structure is a sheet that carries the antennas on at least one of an exterior or an interior thereof, the sheet including at least one communications interface that provides communicative coupling with at least some of the antennas.

37. The apparatus of claim 23, further comprising:

a number of sensors carried by the patient support structure, the sensors responsive to a respective force exerted by a respective portion of the patient.

38. The apparatus of claim 37 wherein each of the sensors is communicatively coupled to provide a signal indicative of the respective force exerted by the respective portion of the patient.

39. The apparatus of claim 23, further comprising:

a gel carried by the patient support structure at least at a number of locations that correspond to a number of defined locations of the patient when the patient is supported by the patient support structure.

40. A system comprising:

a transponder tag coupled to a medical supply item, the transponder tag configured to wirelessly receive electromagnetic energy in the form of a number of interrogation signals and to emit a response to the interrogation signal by radiating electromagnetic energy;

an array of antennas located in a medical procedure environment in which medical procedures are performed; and

a controller communicatively coupled to the array of antennas and configured to perform a transponder detection cycle that includes a number of noise detection portions and a number of interrogation portions temporally spaced from the noise detection portions, during which the controller;

monitors at least two of the antennas of the array of antennas for an ambient noise in the medical procedure environment during the noise detection portions of the transponder detection cycle, the noise detection portions spaced sufficiently from the interrogation portions that the transponder is not emitting a response detectable by the controller to any previous interrogation signals;

emits a number of interrogation signals from each of at least two of the antennas of the array of antennas, successively, during a number of transmission periods of the interrogation portions of the transponder detection cycle; and

monitors at least two antennas for any responses to the interrogation signals during a number of detection periods of the interrogation portions of the transponder detection cycle, the detection periods following respective ones of the transmission periods sufficiently closely in time that the transponder is still emitting a response to the interrogation signals by all of the antennas in the array except one that emitted the most recent signal.

41. The system of claim 40 wherein the controller monitors at least two antennas for any responses to the interrogation signals during a number of detection periods of the interrogation portions of the transponder detection cycle by monitoring all antennas of the antenna array.

42. The system of claim 40 wherein the controller monitors at least two antennas for any responses to the interrogation signals during a number of detection periods of the interrogation portions of the transponder detection cycle by monitoring all antennas of the antenna array except the antenna that emitted a most recent one of the interrogation signals.

43. The system of claim 40 wherein the controller is further configured to determine a respective noise estimation for each antenna and to compensate any responses received via the antenna using the respective noise estimation.

44. The system of claim 40 wherein the controller is further configured to determine a respective noise estimation for each antenna based on noise monitored on a number of the antennas of the antenna array other than the antenna for which the noise estimation is being determined and to compensate any responses received via one of the antennas using the respective noise estimation for the antenna.

45. The system of claim 40 wherein the antennas of the antenna array are physically coupled to a light fixture positioned above a patient support structure.

46. The system of claim 40 wherein the antennas of the antenna array are physically coupled to the patient support structure.

47. The system of claim 40 wherein the antennas of the antenna array are physically coupled to a curtain adjacent to the patient support structure.

48. The system of claim 40, further comprising:

a hand held wand antenna communicatively coupled to the controller to emit an number of interrogation signals and to monitor for a number of responses to interrogation signals.

49. An apparatus, comprising:

at least one electrically insulative substrate; and

a first plurality of antennas distributed along at least a portion of the at least one insulative substrate, each antenna comprising at least one coil with a plurality of windings and composed of a plurality of segments electrically coupled in series to one another, the segments of each antenna carried on at least two different layers and electrically connected through at least one via, the segments on a first layer laterally spaced apart from one another with respect to a longitudinal axis of the coils to form gaps between successively adjacent ones the segments on the first layer, and the segments on at least a second layer laterally spaced apart from one another to form gaps between successively adjacent ones of the segments on the second layer, the segments on the second layer located directly below the gaps formed between the successively adjacent ones of the segments on the first layer.

50. The apparatus of claim 49 wherein the segments have a width and the gaps have a width approximately equal to the width of the segments such that any attenuation of electromagnetic radiation by the segments is approximately constant in an area enclosed between an outer perimeter and an inner perimeter of each of the antennas.

51. The apparatus of claim 49 wherein each antenna comprises two coils, a first coil composed of segments on the first layer and the second coil composed of segments on the second layer, and a single electrical connection that electrically connects a distal end of the first coil to a distal end of the second coil through the at least one via.

52. The apparatus of claim 49, further comprising:

a controller communicatively coupled to the antennas and configured to drive the antennas to emit a number of electromagnetic interrogation signals to provide energy to a transponder, the controller being further configured to monitor at least some of the antennas for any electromagnetic responses from the transponder to the interrogation signals.

53. The apparatus of claim 52, further comprising:

a hand held wand antenna communicatively coupled to the controller to emit a number of interrogation signals and to monitor for a number of responses to interrogation signals.

54. The apparatus of claim 49 wherein there are from six to eight antennas in the first plurality of antennas.

55. The apparatus of claim 49 wherein the first plurality of antennas are arranged in a substantially non-overlapping configuration.

56. The apparatus of claim 55, further comprising:

a second plurality of antennas spaced longitudinally from the first plurality of antennas and which overlap at least some of the antennas of the first plurality of antennas.

57. The apparatus of claim 56 wherein there are from six to eight antennas in the first plurality of antennas and from two to four antennas in the second plurality of antennas.

58. The apparatus of claim 49 wherein the at least one electrically insulative substrate is part of a patient support structure.