Patent Publication Number: US-2018039753-A1

Title: Method and apparatus to detect transponder tagged objects and to communicate with medical telemetry devices, for example  during medical procedures

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional patent application of U.S. patent application Ser. No. 12/606,963, now U.S. Pat. No. 9,792,408, and claims benefit under 35 U.S.C. 119(e) to U.S. provisional patent application Ser. No. 61/222,847 filed Jul. 2, 2009; and U.S. provisional patent application Ser. No. 61/242,699 filed Sep. 15, 2009, both of which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure generally relates to a wireless medical procedure environment, and more particularly detection of transponder tagged objects and communications with various pieces of medical equipment in an environment in which medical procedures are performed. 
     Description of the Related Art 
     It is often useful or important to be able to determine the presence or absence of an object. 
     For example, it is important to determine whether objects associated with a medical procedure, for instance surgery or child birth delivery, are present in a patient&#39;s body before completion of the medical procedure. Such objects may take a variety of forms used in medical procedures. For example, the objects may take the form of instruments, for instance scalpels, scissors, forceps, hemostats, and/or clamps. Also for example, the objects may take the form of related accessories and/or disposable objects, for instance surgical sponges, gauzes, and/or absorbent pads. When used in surgery, failure to locate an object before closing the patient may require additional surgery, and in some instances may have serious adverse medical consequences. In other medical procedures, such as vaginal child birth deliveries, failure to remove objects, for instance gauze or absorbent pads can lead to infections. 
     Some hospitals have instituted procedures which include checklists or requiring multiple counts to be performed to track the use and return of objects during surgery. Such a manual approach is inefficient, requiring the time of highly trained personnel, and is prone to error. 
     Another approach employs transponders and a wireless interrogation and detection system. Such an approach employs wireless transponders which are attached to various objects used during surgery. The interrogation and detection system includes a transmitter that emits pulsed wideband wireless signals (e.g., radio or microwave frequency) and a detector for detecting wireless signals returned by the transponders in response to the emitted pulsed wideband signals. Such an automated system may advantageously increase accuracy while reducing the amount of time required of highly trained and highly compensated personnel. Examples of such an approach are discussed in U.S. Pat. No. 6,026,818, issued Feb. 22, 2000, and U.S. Patent Publication No. US 2004/0250819, published Dec. 16, 2004. 
     Commercial implementation of such an automated system requires that the overall system be cost competitive and highly accurate. In particular, false negatives must be avoided to ensure that objects are not mistakenly left in the patient. Some facilities may wish to install a single interrogation and detection system in each surgery theater or room in which medical procedures are conducted, while other facilities may move an interrogation and detection system between multiple surgical theaters or other rooms. In either case, the overall system will require a large number of transponders, since at least one transponder is carried, attached or otherwise coupled to each object which may or will be introduced into a patient or subject during the medical procedure. Consequently, the transponders must be inexpensive. However, inexpensive transponders typically have a relatively large variation in the frequency of signals they emit, making it difficult to accurately detect the signals returned by the transponders. This may be particularly difficult in some environments which are noisy with respect to the particular resonant frequencies of the transponders. Rooms in hospitals in which medical procedures are performed tend to have increasingly larger amounts of electronic equipment, and hence are becoming notoriously noisy environments. Consequently, a new approach to detection of the presence and absence of transponder that facilitates the use of inexpensive transponders is highly desirable. 
     BRIEF SUMMARY 
     A system for use in a medical facility may be summarized as including a number of antennas and a controller communicatively coupled to the antennas and configured to selectively cause at least one of the antennas to emit an interrogation signal and to detect a response signal, if any, from a number of transponders physically coupled to a number of objects used in medical procedures, wherein the controller is further configured to provide wireless communications of at least one of data or instructions with at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via the at least one of the antennas used to emit the interrogation signal or receive the response signal. 
     At least a plurality of the number of antennas may be carried by a patient support structure that carries a patient during a medical procedure. At least one of the number of antennas may be a handheld antenna that inductively cooperates with the plurality of antennas carried by the patient support structure. At least one of the number of antennas may be a handheld antenna, and one of the handheld antenna or the plurality of antennas carried by the patient support structure may transmit an interrogation signal and the other one of the handheld antenna or the plurality of antennas carried by the patient support surface may receive response signals, if any, to the interrogation signal. The number of antennas may include at least three loop antennas spaced along a longitudinal axis of the patient support structure, and the patient support surface may be one of an operating table, a bed, a mattress, or a sheet. At least a plurality of the number of antennas may be carried by a drape that at least partially surrounds a patient support structure that carries a patient during a medical procedure. At least a plurality of the number of antennas may be carried by a shade that extends from a light fixture positioned relatively above a patient support structure that carries a patient during a medical procedure. The controller may be configured to receive data signals from the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via at least one of the number of antennas, the data signals representing physiological characteristics of the patient measured by the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. The controller may be configured to receive data signals from the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via at least one of the number of antennas, the data signals representing operational characteristics of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. The controller may be configured to transmit control signals to the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via at least one of the number of antennas, the control signals representing operational instructions to control operation of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. The controller may be communicatively coupled to a display and may be operable to display information related to at least one of the patient or the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. The controller may be communicatively coupled to a user input device and may be operable to receive user input entered via the user input device and to transmit control signals based on the received user input to the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via at least one of the number of antennas, the control signals representing operational instructions to control operation of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. The controller may be configured to receive data signals from a first one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment and to transmit the data signals to a second one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. A first one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment may be a transducer coupled to the patient and a second one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment may be a dedicated control system for the transducer. The first one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment may be one of an electrocardiogram electrode, a pulse oximetry transducer and the second one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment may be a dedicated electrocardiogram processing system or a pulse oximetry processing system. At least one of the antennas may be responsive to a force exerted thereon and the controller may be configured to receive a signal indicative of the force exerted on the antenna and to produce a notification if the force exceeds at least one of an amplitude threshold or a time duration. 
     A method of operating a system in a medical facility, the system including a plurality of antennas and a controller communicatively coupled to the antennas may be summarized as including from time-to-time, transmitting a number of wideband interrogation signals from at least one of the antennas; determining whether a response to the interrogation signals was received via at least one of the antennas from a transponder that marks an object used in a medical procedure; from time-to-time, providing communications with at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via the at least one of the antennas used to emit the interrogation signal or receive the response signal. 
     Transmitting a number of wideband interrogation signals from at least one of the antennas may include transmitting the wideband interrogation signals from a number of antennas carried by a patient support structure that carries a patient during a medical procedure. Transmitting a number of wideband interrogation signals from at least one of the antennas may include transmitting the wideband interrogation signals from a handheld antenna that inductively cooperates with the plurality of antennas carried by the patient support structure. At least one of the number of antennas may be a handheld antenna, and transmitting the wideband interrogation signals may include transmitting the wideband interrogation signal by one of the handheld antenna or the plurality of antennas carried by the patient support structure, and further may include receiving any response signals to the wideband interrogation signals by the other one of the handheld antenna or the plurality of antennas carried by the patient support structure. Transmitting a number of wideband interrogation signals from at least one of the antennas may include transmitting the wideband interrogation signals from at least three loop antennas spaced along a longitudinal axis of one of an operating table, a bed, a mattress or a sheet. Transmitting a number of wideband interrogation signals from at least one of the antennas may include transmitting the wideband interrogation signals from a plurality of antennas carried by a drape that at least partially surrounds a patient support surface that carries a patient during a medical procedure. Transmitting a number of wideband interrogation signals from at least one of the antennas may include transmitting the wideband interrogation signals from a plurality of antennas carried by a shade that extends from a light fixture positioned relatively above a patient support surface that carries a patient during a medical procedure. Providing communications with at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via at least one of the antennas may include receiving data signals from the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via at least one of the number of antennas, the data signals representing physiological characteristics of the patient measured by the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. Providing communications with at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via at least one of the antennas may include receiving data signals from the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via at least one of the number of antennas, the data signals representing operational characteristics of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. Providing communications with at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via at least one of the antennas may include transmitting control signals to the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via at least one of the number of antennas, the control signals representing operational instructions to control operation of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. The method may further include transmitting information by the controller to a display to display information related to at least one of the patient or the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. The method may further include receiving by the controller user input entered by a user via a user input device; and transmitting control signals by the controller based on the received user input to the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment via at least one of the number of antennas, the control signals representing operational instructions to control operation of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. The method may further include receiving data signals by the controller via at least one of the antennas from a first one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment; and transmitting the received data signals to a second one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment. Receiving data signals by the controller via at least one of the antennas from a first one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment may include receiving data signals from a transducer coupled to the patient and transmitting the received data signals to a second one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment may include transmitting the data signals to a dedicated control system for the transducer. Receiving data signals by the controller via at least one of the antennas from a first one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment may include receiving data signals from one of an electrocardiogram electrode, a pulse oximetry transducer and transmitting the received data signals to a second one of the at least one piece of dedicated medical diagnostic, therapeutic or monitoring equipment may include transmitting the data signals to one of a dedicated electrocardiogram processing system or a pulse oximetry processing system. At least one of the antennas may be responsive to a force exerted thereon and may further include receiving signals by the controller indicative of the force exerted on the antenna; and may produce a notification if the force exceeds at least one of an amplitude threshold or a time duration. 
     A physiological condition monitor may be summarized as including a transducer coupleable to a patient to sense a physiological condition of the patient; an antenna physically coupled to the transducer; and a transmitter communicatively coupled to the transducer and to the antenna and configured to transmit signals indicative of the sensed physiological condition of the patient via the antenna to a plurality of antennas remote from the device. The antennas may be positioned proximate a patient support surface. 
     The physiological condition monitor may further include an energy storage device electrically coupled to provide power to the transmitter. The physiological condition monitor may further include a circuit configured to transform electromagnetic energy into electrical power, and coupled to supply the electrical power to the transmitter. The physiological condition monitor may further include a circuit that encodes an identifier that uniquely identifiers the physiological condition monitor from other physiological condition monitors. The physiological condition monitor may have a portion that bears an optical marking. The optical marking may encode an identifier which may uniquely identify the physiological condition monitor. 
     A system for use in a medical facility may be summarized as including a number of antennas, at least some of the antennas responsive to a force asserted thereon; and a controller communicatively coupled to the antennas and configured to selectively cause at least one of the antennas to emit an interrogation signal and to detect a response signal, if any, from a number of transponders physically coupled to a number of objects used in medical procedures, wherein the controller is further configured to receive signals from at least some of the antennas indicative of the force asserted on the antenna. 
     The controller may be configured to produce a notification if the force exerted on at least one of the antennas exceeds at least one of an amplitude threshold or a time duration threshold. The controller may be configured to produce a notification if the force exerted on at least one of the antennas exceeds an amplitude threshold over a period of time that exceeds a time duration threshold. The controller may be configured to produce a notification indicative of a position or location on the patient support structure or patient where an excessive force is being exerted. The controller may be configured to transmit a notification via at least one of the antennas in response to the force asserted on at least one of the antennas exceeding a defined threshold. 
     A method of operating a system in a medical facility, the system including a plurality of antennas and a controller communicatively coupled to the antennas, at least some of the antennas responsive to a force asserted thereon, may be summarized as including from time-to-time, transmitting a wideband interrogation signals from at least one of the antennas; determining whether a response to the interrogation signal was received via at least one of the antennas from a transponder that marks an object used in medical procedures; from time-to-time, receiving signals from at least some of the antennas indicative of the force asserted on the antenna. 
     The method may further include producing a notification by the controller which may be configured to produce a notification if the force exerted on at least one of the antenna exceeds at least one of an amplitude threshold or a time duration threshold. The method may further include producing a notification by the controller if the force exerted on at least one of the antenna exceeds an amplitude threshold over a period of time that exceeds a time duration threshold. The method may further include producing a notification by the controller indicative of a position or location on the patient support structure or patient where an excessive force is being exerted. The method may include transmitting a notification via at least one of the antennas in response to the force asserted on at least one of the antennas exceeding a defined threshold. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn, are not intended to convey any information regarding the actual shape of the particular elements, and have been solely selected for ease of recognition in the drawings. 
         FIG. 1  is a schematic diagram showing an environment in which a medical procedure is performed, for example a surgical environment including a table, bed or other structure to carry or support at least a portion of a patient, that includes a plurality of antennas, and a controller communicatively coupled to the antennas an interrogation and detection system to detect an object tagged with a transponder in a patient, according to one illustrated embodiment. 
         FIG. 2  a top plan view of the table, bed or other structure of  FIG. 1  showing the plurality of antennas, according to one illustrated embodiment. 
         FIG. 3  is a top plan view of the table, bed or other structure of  FIG. 1  showing approximate ranges of each of the antennas of  FIG. 2 . 
         FIG. 4  is a top plan view of a patient support structure showing a number of antennas on a patient support surface and a number of antennas on an opposed surface, according to another illustrated embodiment. 
         FIG. 5A  is a side elevational view of the patient support structure of  FIG. 4 . 
         FIG. 5B  is a cross-sectional view of the patient support structure of  FIG. 4  taken along section line  6  of  FIG. 4 . 
         FIG. 6A  is a top plan view of a support structure showing a number of antennas on a patient support surface and a number of antennas on an opposed surface, according to yet another illustrated embodiment. 
         FIG. 6B  is a cross-sectional view of the patient support structure of  FIG. 6A  taken along section line  7  of  FIG. 6A . 
         FIG. 6C  is a partial isometric view of the patient support structure of  FIGS. 6A and 6B , enlarged to illustrated electrically conductive paths or traces of the antennas. 
         FIG. 7  is a cross-sectional view of a patient support structure having recesses in which the antennas are received, according to another illustrated embodiment. 
         FIG. 8A  is a top plan view of a patient support structure in the form of a bed or an operating table showing a number of antennas arranged in a non-overlapping relationship, according to another illustrated embodiment. 
         FIG. 8B  is a top plan view of a patient support structure in the form of a mattress or pad showing a number of antennas arranged in a non-overlapping relationship, according to another illustrated embodiment. 
         FIG. 8C  is a top plan view of a patient support structure in the form of a sheet showing a number of antennas arranged in a non-overlapping relationship, according to another illustrated embodiment. 
         FIG. 9  is an enlarged top plan view of an antenna according to one illustrated embodiment, where the antenna is formed from multiple coils of a conductive material that is radiolucent. 
         FIG. 10A  is an enlarged top plan view of an antenna according to one illustrated embodiment, wherein the antenna is formed of a top coil of conductive material and a bottom coil of conductive material. 
         FIG. 10B  is an enlarged top plan view of the top coil of the antenna  FIG. 10A . 
         FIG. 10C  is an enlarged top plan view of the bottom coil of the antenna  FIG. 10A . 
         FIG. 10D  is a cross-sectional view of a portion of a patient support structure carrying the top and bottom coils of the antenna of  FIG. 10A  according to one illustrated embodiment. 
         FIG. 10E  is a cross-sectional view of a patient support structure with a plurality of antennas according to another illustrated embodiment. 
         FIG. 10F  is a top plan view of a patient support structure comprising a plurality of antennas according to still another illustrated embodiment. 
         FIG. 11  is a cross-sectional view of a portion of a patient support structure with an antenna carried in opposed surfaces thereof, according to yet still another illustrated embodiment. 
         FIG. 12  is a cross-sectional view of a portion of a patient support structure an antenna of  FIG. 10A  carried on opposed surfaced thereof, according to even another illustrated embodiment. 
         FIG. 13A  is a schematic diagram showing a surgical table with a plurality of antennas and a controller positioned in a pedestal of the surgical table, according to another illustrated embodiment. 
         FIG. 13B  is a schematic diagram showing a bed such as a patient bed used in an environment where medical procedures are preformed, the bed including a plurality of antennas and a controller positioned on a frame of the bed, according to another illustrated embodiment. 
         FIG. 14A  is a side elevational view of an overhead light fixture for use in a medical procedure and a light shade with several antennas supported by the light fixture, according to one embodiment in which the light shade is shown in a retracted position or configuration of  FIG. 10A . 
         FIG. 14B  is a side elevational view of the light fixture and a light shade in which the light shade is shown in an extended position or configuration. 
         FIG. 14C  is a side elevational view of a light fixture for use in a medical procedure and a light shade with several antennas according to another illustrated embodiment. 
         FIG. 15A  is an isometric view of a track and a curtain or drape containing several antennas, according to one illustrated embodiment. 
         FIG. 15B  is a side elevational view of a sheet containing several antennas and configured to be hung from a support according to one embodiment. 
         FIG. 16  is a schematic diagram of a controller, according to one illustrated embodiment, including a motherboard and a plurality of plug-in boards, one for each of the antennas. 
         FIG. 17  is a schematic diagram of a portion of a control system of the interrogation and detection system, according to one illustrated embodiment. 
         FIG. 18  is a schematic diagram of a software configuration of the interrogation and detection system, according to one illustrated embodiment. 
         FIGS. 19A-19I  are an electrical schematic diagram of the interrogation and detection system including a control circuit and antenna, according to one illustrated embodiment. 
         FIG. 20  is a timing diagram illustrating a method of frequency hopping, according to one illustrated embodiment. 
         FIG. 21A  is a timing diagram illustrating pulsed timing, according to one illustrated embodiment. 
         FIG. 21B  is a timing diagram illustrating pulsed timing, according to another illustrated embodiment. 
         FIG. 22  is a timing diagram showing activation of a pair of transistors of the control circuit in a push-pull configuration to drive the antenna, according to one illustrated embodiment. 
         FIG. 23A  is a flow diagram of a method of operating an interrogation and detection system, according to one illustrated embodiment. 
         FIG. 23B  is a flow diagram of a method of monitoring all antennas for a response to an interrogation signal, according to one illustrated embodiment. 
         FIG. 23C  is a flow diagram of a method of monitoring all antennas except a transmitting antenna for a response to an interrogation signal, according to one illustrated embodiment. 
         FIG. 24A  is a high level flow diagram of a method of operating an interrogation and detection system to detect transponders, according to one illustrated embodiment. 
         FIG. 24B  is a low level flow diagram of a method of operating an interrogation and detection system to sample noise and responses and to adjust sampling times and perform noise correction, according to one illustrated embodiment, the method useful with the method of  FIG. 24A . 
         FIG. 24C  is a flow diagram of a method of operating an interrogation and detection system to determine whether a transponder has been detected, according to one illustrated embodiment, the method useful with the method of  FIG. 24A . 
         FIGS. 25A-25F  are flow diagrams of methods of operating an interrogation and detection system by measuring and/or compensating for noise, according to various illustrated embodiments, the methods useful with the method of  FIG. 24A . 
         FIG. 26A  is a graph showing a measured or sampled response versus time without noise cancellation where a noise source is present but no transponder is present, according to one illustrated embodiment. 
         FIG. 26B  is a graph showing a measured or sampled response versus time with noise cancellation where a noise source is present but not transponder is present, according to one illustrated embodiment. 
         FIG. 26C  is a graph showing a measured or sampled response versus frequency without noise cancellation where a noise source is present but no transponder is present, according to one illustrated embodiment. 
         FIG. 26D  is a graph showing a measured or sampled response versus frequency with noise cancellation where a noise source is present but not transponder is present, according to one illustrated embodiment. 
         FIG. 27A  is a graph showing a measured or sampled response versus time without noise cancellation where a noise source and a transponder are present, according to one illustrated embodiment. 
         FIG. 27B  is a graph showing a measured or sampled response versus time with noise cancellation where a noise source and a transponder are present, according to one illustrated embodiment. 
         FIG. 27C  is a graph showing a measured or sampled response versus frequency without noise cancellation where a noise source and a transponder are present, according to one illustrated embodiment. 
         FIG. 27D  is a graph showing a measured or sampled response versus frequency with noise cancellation where a noise source and a transponder are present, according to one illustrated embodiment. 
         FIG. 28  is an isometric view of a surgical environment including an operating table that carries a plurality of antennas, a hand held wand antenna, and a controller according to one illustrated embodiment. 
         FIG. 29  is an isometric view of a surgical environment including a patient support structure in the form of a surgical table that includes a plurality of antennas, and a controller communicatively coupled to the antennas and to a display screen and user input. 
         FIG. 30A  is a top plan view of a wireless electrode, according to one illustrated embodiment. 
         FIG. 30B  is top plan view of a plurality of wireless electrode attached to a patient on a patient support structure. 
         FIG. 30C  is a top plan view of two wireless electrodes connected by one wire. 
         FIG. 31  is a top plan view of a plurality of leads attached to a patient, each lead extending to an intermediary relay which wirelessly communicates with at least one antenna of an interrogation and detection system. 
         FIG. 32  is a side elevational view of a wireless pulse oximeter attached to the finger of a patient, 
         FIG. 33  is a side elevational view of a wireless intra-cranial pressure monitor attached to a patient&#39;s head. 
         FIG. 34  is a side elevational view of an infusion pump with a radio attached thereto. 
         FIG. 35  is a side elevation view of an intra-aortal balloon pump with a radio attached thereto. 
         FIG. 36  is a schematic diagram of a controller, according to one illustrated embodiment, including a motherboard and a plurality of plug-in boards, one for each of the antennas, as well as additional plug-in boards to enable communication with medical telemetry devices. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with transmitters, receivers, or transceivers and/or medical equipment and medical facilities have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments. 
     Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, that is as “including, but not limited to.” 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Further more, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
     As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
     The headings and Abstract of the Disclosure provided herein are for convenience only and do not interpret the scope or meaning of the embodiments. 
     Many of the embodiments described herein, perform interrogation and detection of transponder tagged objects using multiple antennas (e.g., six antennas). Successive ones of the antennas may be used to transmit an interrogation signal, while two or more antennas are monitored for a response to the interrogation signal. Such may provide significant advantages over more conventional methods, for example motion based methods that employ motion (e.g., sweeping) of an antenna (e.g., wand) over a patient. For instance, this allows the transmit and receive paths to the transponder to be different from one another (e.g., transmit path is from a first antenna to a transponder, while the receive path is from the transponder to a second antenna). Hence, the path length to the transponder may be shortened in many configurations, thus improving the signal. For instance, when using a single antenna to both transmit an interrogation signal and to receive a response to the interrogation signal, the power of the received signal is equal to about the 6 th  root of the input power. However, when using multiple antennas to transmit and receive over the same area, interrogation path length in one direction may be shorter. Another advantage is that all scan time is averaged, allowing a longer noise time averaging (e.g., 10 seconds) as opposed to motion based scanning, where integration time may be limited (e.g., about 0.25 seconds per sample). Even further, a representative value of noise samples measured over a plurality of antennas may be employed to determine noise to be removed from noise plus signals received at one of the antennas, thereby advantageously lowering a noise floor and/or increasing range or performance. Thus, the various disclosed embodiments may provide significantly better performance. 
       FIGS. 1 and 2  show a medical procedure environment  10  in which medical procedures are performed, for example a surgical environment in which surgeries are performed, a patient room in which child birth deliveries or other medical procedures are performed or a physician&#39;s office, etc. The medical procedure environment  10  includes a table (e.g., surgical table), bed, or other structure  12  which can carry a patient or portion thereof and an interrogation and detection system  14 . The interrogation and detection system  14  includes a plurality of antennas  16   a - 16   f  (collectively  16 , shown in broken line in  FIG. 1  to indicate that such are hidden in that view) which are carried by the patient support surface  12 . The interrogation and detection system  14  also includes a controller  18  communicatively coupleable to the antennas  16  by one or more wired or wireless communication paths, for example coaxial cable  20 . As discussed in detail below, the interrogation and detection system  14  is operable to ascertain the presence or absence of objects  22   a,    22   b  (collectively  22 ) tagged with transponders  24   a,    24   b  (collectively  24 ), which may be in or on a patient (not shown). 
     The table, bed or other structure  12  may include a patient support structure  26  and a pedestal or base  28  which supports the patient support structure  26 . The patient support structure  26  should have dimensions sufficient to support at least a portion of a patient during a medical procedure, for instance during surgery, child birth, etc. Hence, the patient support structure  26  may have a length of six feet or more and a width of two feet or more. The patient support structure  26  may have two or more articulated sections  26   a - 26   c,  as illustrated in  FIG. 1 or 2 , or may be an unarticulated or unitary structure as illustrated in  FIGS. 4, 7 and 9 . Hinges  30   a,    30   b  (collectively  30 ) or other coupling structures may couple the articulated sections  26   a - 26   c.  The hinges  30  may, for example, be located along a longitudinal axis  32  of the patient support structure  26  at locations that would approximate the anticipated position of a between a patient&#39;s legs and torso and between the patient&#39;s torso and head. 
     The patient support structure  26  is preferably made of a rigid material and is preferably radiolucent. Various radiolucent materials may be employed, for instance carbon fiber or radiolucent plastics. Such advantageously allows radiological technologies to be employed, for example X-ray imaging. For example, the patient support structure  26  may be molded from plastics such as an acrylic or a phenolic resin (e.g., commercially available under the trademark SPAULDITE®). In some embodiments, the patient support structure  26  may include a frame. The frame may be made of a metal which may not be radiolucent. In such embodiments, the frame preferably makes up a small percentage of the total area of the patient support structure  26 . The patient support structure  26  may be capable of withstanding multiple cycles of sterilization (e.g., chemical, heat, radiation, etc.). A large variety of surgical tables, patient beds and other structures capable of carrying a patient or a portion of a patient are commercially available. Many of these commercially available structures include electric motors and electronics. Typically, there is no or minimum regulation of non-ionizing electromagnetic radiation generated by such electric motors and electronics. Hence, many environments  10  in which medical procedures are performed tend to be electromagnetically noisy environments. 
     The table, bed or other structure  12  may include one or more mattresses or pads  34   a - 34   c  (collectively  34 ), and/or may include one or more sheets (not shown in  FIG. 1  for sake of clarity of illustration). The mattresses or pads  34  and/or sheets may overlie the antennas  16 . The mattresses or pads  34  may take a variety of forms, and may be disposable, or may be capable of withstanding multiple cycles of sterilization (e.g., chemical, heat, radiation, etc.). The mattresses or pads  34  are preferably radiolucent. The mattresses or pads  34  may take a conventional form, for example cotton, open cell or a closed cell foam rubber, with or without an appropriate cover. Alternatively, the mattresses or pads  34  may include one or more bladders (e.g., dual layer urethane envelope) to receive a fluid (e.g., air, water, etc.) to selectively inflate one or more portions of the mattresses or pads  34 , and/or to control a temperature of one or more portions of the mattresses or pads  34 . In such embodiments, the fluid should be radiolucent. The mattresses or pads  34  may be detachably secured to the patient support structure  26  via various fasteners, for instance ties, or hook and loop fastener commonly available under the trademark VELCRO®. 
     The pedestal or base  28  may be fixed, or may be moveable. The pedestal or base  28  may include one or more actuators (e.g., motors, pumps, hydraulics, etc.) and/or drive mechanisms (e.g., gears, mechanical couplings) or linkages (not shown) that allow a position and/or orientation of the patient support structure  26  to be adjusted. For example, the pedestal or base  28  may telescope to allow the patient support structure  26  to be mechanically raised and lowered. Also for example, the pedestal or base  28  may allow the patient support structure  26  to be mechanically tilted or rotated about an axis that is perpendicular to a patient support surface  37  of the patient support structure  26 . 
     As illustrated, portions of one or more of the antennas  16  may overlap. For example, where the antennas are coil antennas, each formed of one or more coils, a portion of an area enclosed by an outermost coil of each antenna  16  may overlap a portion of an area enclosed by an outermost coil of a neighboring antenna  16 . The area enclosed or enclosed area may be an area enclosed by a normal or perpendicular projection of a perimeter defined the outermost coil of the respective antenna  16 . In such embodiments, neighboring antennas  16  may be electrically insulated from one another by one or more electrically insulating layers or substrates. For example, successively adjacent antennas  16  may be carried one opposite surfaces (e.g., opposed outer surfaces, or multiple inner surfaces, or one or more outer and inner surfaces) of a single substrate. As discussed in more detail below, the antennas may advantageously be radiolucent, for example being formed of a radiolucent material (e.g., substantially transparent to X-ray or Gamma ray radiation) or a material that at a thickness employed is substantially radiolucent. For example, an electrically conductive trace of aluminum having a thickness of 200 microns or less sufficiently passes X-rays to be considered radiolucent. More preferably, an aluminum trace having a thickness of 30 microns sufficiently passes X-rays such that even a stack or overlapping portions of three coils (combined thickness under 100 microns) to be radiolucent. An antenna may be considered radiolucent if it is not detectable by a radiologist in an X-ray produced via 10 kV to 120 kV X-ray machine, or preferably a 40 KV X-ray machine in conjunction with a standard 12 inch X-ray image intensifier. An antenna may be considered radiolucent if a coil includes thirty turns or windings and is not detectable by a radiologist in an X-ray. 
     The patient support structure  26  may include one or more film receiving receptacles  29  (only one called out in  FIG. 1 ). The film receiving receptacles  29  may be spaced relatively below a patient support surface  37  of the patient support structure  26 . The film receiving receptacles  29  are sized, dimensioned and/or positioned to receive film, for example X-ray film. The film receiving receptacles  29  my be sized and/or dimensioned to receive a film tray or other film holder (not illustrated) which holds the film. Along with the use of radiolucent materials, such advantageously allows a patient X-ray images or other radiological images of the patient to be produced, generated or made, while the patient is supported by the patient support structure  26 . As used herein an in the claims, the term radiolucent means substantially transmissive to energy in the X-ray portion of the electromagnetic spectrum, that is passing sufficient X-ray energy to produce an X-ray image at standard power levels and standard conditions employed in conventional medical imaging. 
     The table (e.g., surgical table), bed or other structure  12  may include an interrogation and detection system interface  36 . The interrogation and detection system interface  36  may include one or more communications ports  38  that allow communicative coupling to be selectively or detachably made between the antennas  16  and the controller  18 . Such communications ports  38  may, for example, take the form of coaxial connectors, or other communications connectors. Interrogation and detection system interface  36  may include one or more output devices to provide indications to a user. For instance, the interrogation and detection system interface  36  may include one or more visual indicators  40  (only one called out in  FIGS. 1 and 2 ) to provide indications of a presence and/or an absence of an object. Such may also provide a visual indication that is indicative of a status of a scanning operation by the interrogation and detection system  14 , for instance scanning started, scanning completed, and/or occurrence of an error condition. The visual indicators  40  may take a variety of forms, for example light sources of one or more colors. Light sources may include incandescent lights, light emitting diodes (LEDs), organic light emitting diodes (OLEDs), and/or liquid crystal displays (LCDs). Also for instance, the interrogation and detection system interface  36  may include one or more aural indicators  42  to provide aural indications of a presence and/or an absence of an object and/or a status of a scan operation or occurrence of an error condition. The aural indicator  42  may, for example, take the form of one or more speakers. The interrogation and detection system interface  36  may include one or more switches  44  that allow input to be provided to the controller  18 . Switches  44  may, for example, allow a user to turn ON the interrogation and detection system  14 , start a scan operation, stop a scan operation, adjust a sensitivity of the scanning, adjust one or more frequencies, select or adjust an output type (e.g., type of visual alert, type of aural alert) or level (e.g., brightness, sound level or volume, etc.). 
     The objects  22  may take a variety of forms, for example instruments, accessories and/or disposable objects useful in performing medical procedures, for example surgical procedures, child birth delivery procedures, and/or other medically related procedures. For instance, some objects  16   a  may take the form of scalpels, scissors, forceps, hemostats, and/or clamps. Also for example, some objects  22   b  may take the form of sponges (e.g., surgical sponges), gauze and/or padding. The objects  22  are tagged, carrying, attached or otherwise coupled to a respective transponder  24 . Some embodiments of the interrogation and detection system  14  disclosed herein are particularly suited to operate with transponders  26  which are not accurately tuned to a chosen or selected resonant frequency. Consequently, the transponders  24  do not require high manufacturing tolerances or expensive materials, and thus may be inexpensive to manufacture. 
     Transponders  24  may include a miniature ferrite rod with a conductive coil wrapped about an exterior surface thereof to form an inductor (L), and a capacitor (C) coupled to the conductive coil to form a series LC circuit. The conductive coil may, for example, take the form of a spiral wound conductive wire with an electrically insulative sheath or sleeve. The transponder  24  may include an encapsulation that encapsulates the ferrite rod, conductive coil, and capacitor. The encapsulant may be a bio-inert plastic, that protects the ferrite rod, conductive coil and/or capacitor from pressure and/or from fluids, for example bodily fluids. In some embodiments, the ferrite rod may include a passage sized to receive a physical coupler, for example a bonding tie or string. The bonding tie or string may take the form of an elastomeric x-ray opaque flexible elongated member, that may be used to attach the transponder  24  to various types of objects  22 , for example surgical sponges. The transponder  24  may have a length of about 8 millimeters and a diameter of about 2 millimeters. Employing such small dimensions ensures that the transponder  24  does not impede deformation of objects  16  such as sponges. The transponder  24  may include an optional diode (not shown), to protect against over-voltage occurrences caused by other electronic instruments. The transponders  24  may be attached to hemostats, scissors, certain forms of forceps, and the like. In some embodiments, the transponders  24  may be coupled to the object  22  by way of a clamp or holder. In some embodiments, the transponders  24  may be retained within a cavity of the holder. In some embodiments, the holder may be fashioned of a durable deformable material, such as surgical grade polymer, which may be deformed to clamp securely onto the finger or thumbhole of an instrument. In other embodiments, the transponders  24  may be attached to objects  22  by way of pouches fashioned of sheet material (e.g., surgical fabric) surrounding the transponder  24 . The transponder  24  is retained within the pouch, and in some embodiments the pouch may be sewn or otherwise sealed. Sealing may be done with adhesive, hot glue, clamping, grommeting, or the like. Various embodiments of suitable transponders and retention devices are discussed in U.S. Provisional Patent Application No. 60/811,376 filed Jun. 6, 2006, U.S. Provisional Patent Application No. 61/091,667 filed Aug. 25, 2008, U.S. patent application Ser. No. 11/759141 filed Jun. 6, 2007, U.S. patent application Ser. No. 12/046,396 filed Mar. 11, 2008, U.S. Pat. No. 6,026,818 issued Feb. 22, 2000, U.S. Design patent application Ser. No. 29/322,539 filed Aug. 6, 2008 and U.S. Design Pat. No. D568,186 issued May 6, 2008, all of which are incorporated herein by reference in their entireties. 
     In use, the medical provider  12  may use the switches  44  to cause a scan of the patient  18 , for instance jut before closing during surgery, in order to detect the presence or absence of the transponder  26 , and hence an object  16 . 
       FIG. 3  shows approximate ranges R 1 -R 6  for the six antennas  16  of the embodiment of  FIGS. 1 and 2 . 
       FIG. 3  is illustrative and does not necessarily represent actual ranges. The illustrated ranges R 1 -R 6  (collectively R) show that the ranges R 1 -R 6  are typically larger than the area of the antennas  16 . Ranges R 1 -R 6  may be affected by a variety of factors, including the power of the interrogation signal, distance between the transponders  24  and the antennas  16 , and/or the sensitivity and/or impedance matching between the transponders  24  and interrogation and detection system  14 . Many of the ranges R 1 -R 5  overlap neighboring ranges R 1 -R 5 , although in this illustrated embodiment one range R 6  does not overlap any other range R 1 -R 5 . In other embodiments, all ranges overlap. Alternatively, none of the ranges may overlap. Other arrangements of antennas  16  and/or ranges R, are of course possible. 
       FIGS. 4, 5A and 5B  show a patient support structure  626 , according to another illustrated embodiment. 
     The patient support structure  626  may, for example, be part of a table, for instance a surgical table, part of a bed or another structure designed to carry a patient or portion of a patient. The patient support structure  626  is a non-articulated, single piece or unitary structure. While illustrated as a single, unitary construction, the patient support structure  626  may be formed of two or more sections, which may or may not be articulated. The patient support structure  626  is formed as a substrate  650  having a patient support surface  637  and an opposed surface  652  that is opposed from the patient support surface  637 . The substrate  650  may be formed of one or more layers. For example, the substrate  650  may be a composite material. The substrate  650  may, for example, be formed as a resin impregnated carbon fiber structure, which may advantageously omit any metal or ferrous metal structural elements. Alternatively, the substrate  650  may minimize the use of any metal or ferrous metal structural elements and locate any metal or ferrous metal structural elements at the peripheries of the substrate  650 . 
     A first set of antennas  616   a,    616   c,    616   e,    616   g  are positioned on the patient support surface  637 , while a second set of antennas  616   b,    616   d,    616   f  are positioned on the opposed surface  652 . Such allows neighboring ones of the antennas (collectively  616 ), or portions thereof, to overlap, while electrically insulating each antenna  616  from one another. While illustrated as being carried on outer surfaces of the patient support structure  650  one or more of the antennas  616  could be carried on one or more inner layers of the patient support structure  650  where the patient support structure  650  is formed of two or more layers, for instance as a laminate structure. 
       FIGS. 6A-6C  show a patient support structure  626  and antennas  616   a - 616   h  (collectively  616 ), according to another illustrated embodiment, wherein individual ones of the electrically conductive paths or traces of the antennas  616  are visible. 
     The patient support structure  626  may, for example, be part of a table, for instance a surgical table, part of a bed (e.g., patient or hospital bed) or another structure designed to carry a patient or portion of a patient on which a medical procedure may be performed. The patient support structure  626  is a non-articulated, single piece or unitary structure. While illustrated as a single, unitary construction, the patient support structure  626  may be formed of two or more sections, which may or may not be articulated. The patient support structure  626  is formed as a substrate  650  having a patient support surface  637  and an opposed surface  652  that is opposed from the patient support surface  637 . The substrate  650  may be formed of one or more layers. For example, the substrate  650  may be a composite material. The substrate  650  may, for example, be formed as a resin impregnated carbon fiber structure, which may advantageously omit any metal or ferrous metal structural elements. Alternatively, the substrate  650  may minimize the use of any metal or ferrous metal structural elements and locate any metal or ferrous metal structural elements at the peripheries of the substrate  650 . 
     The patient support structure  626  carries antennas  616  thereon and/or therein. As best illustrated in  FIGS. 6A and 6B , the antennas can be treated as two sets. A first set of antennas  616   a - 616   f  arranged generally adjacent one another in an array of two rows on either side of a longitudinal axis  630  and three columns spaced along the longitudinal axis  630 . These antennas  616   a - 616   f  do not overlap with one another. These antennas  616   a - 616   f  substantially extend the full length and width of the patient support structure  628 . Alternatively, these antennas  616   a - 616   f  may be spaced inwardly from a perimeter of the patient support structure, for example where the range of the antennas  616   a - 616   f  sufficiently covers the area of the patient support structure  626 . A second set of antennas  616   g,    616   h  are arranged generally adjacent one another in an array of one row and two columns. These antennas  616   g,    616   h  do not overlap with one another, however these antennas  616   g,    616   h  overlap the antennas  616   a - 616   f  of the first set when viewed from above the patient support structure  626 . These antennas  616   g,    616   h  enhance the overall coverage of the entire area of the patient support structure  626  and volume spaced generally there above. 
     While illustrated as being carried an upper outer surface  637  of the patient support structure  626 , one or more of the antennas  616  could be carried on a lower outer surface  652  and/or on one or more inner layers of the patient support structure  626 , for instance where the patient support structure  626  is a laminate structure. 
       FIG. 6C  shows one embodiment of the antennas  616 , which may allow relatively simple and low cost manufacturing, and which prevents the antennas  616  from electrically shorting one another. 
     In particular, each antenna may be formed as electrically conductive paths or traces on one or more layers of an electrically non-conductive or insulative substrate, for instance a flexible substrate of circuit board material (e.g. FR4, Kapton). The electrically conductive path or trace may form a coil pattern, hence a coil antenna with multiple windings, as illustrated in  FIG. 6C . Portions of the electrically conductive path on one end or half of the substrate may be electrically coupled to respective portions of the electrically conductive path on the other end or half of the substrate via electrically conductive material received in a via that extends through a portion or all of the substrate. Thus, while the electrically conductive paths appear to terminate at a centerline  647  of each antenna, the electrically conductive paths are in fact electrically coupled to adjacent portions across the centerline  647  by way of respective vias. Alternatively, the electrically conductive path may have change in direction (e.g., 45 degree turn), such that the electrically conductive path spirals inwardly (or outwardly) with each half turn or half winding. Alternatively, or additionally, an electrically non-conductive or electrically insulative material may overlie the electrically conductive path on a lower surface or side and/or an upper surface or side of the substrate, to provide electrical insulation between overlying substrates. 
       FIG. 7  shows a patient support structure  726 , according to another illustrated embodiment. 
     The patient support structure  726  is formed as a substrate  750  having a patient support surface  737  and an opposed surface  752  that is opposed from the patient support surface  737 . The substrate  750  may be formed of one or more layers. For example, the substrate  750  may be a composite material. The substrate  750  may, for example, be formed as a resin impregnated carbon fiber structure, which may advantageously omit any metal or ferrous metal structural elements. Alternatively, the substrate  750  may minimize the use of any metal or ferrous metal structural elements and locate any metal or ferrous metal structural elements at the peripheries of the substrate  750 . While illustrated as a single, unitary construction, the patient support structure  726  may be formed of two or more sections, which may or may not be articulated. 
     A first set of antennas  716   a,    716   c,    716   e,    716   g  are positioned in respective recesses formed in the patient support surface  737 , while a second set of antennas  716   b,    716   d,    716   f  are positioned in respective recesses formed in the opposed surface  752 . Such allows neighboring ones of the antennas (collectively  716 ) to overlap, while electrically insulating each antenna  716  from one another. Such also advantageously spaced the antennas  716  of the first and second sets closer together with respect to one another, which may produce more consistent results or performance between the various antennas  716 . While illustrated as being carried on outer surfaces of the patient support structure  750  one or more of the antennas  716  could be carried on one or more inner layers of the patient support structure  750  where the patient support structure  750  is formed of two or more layers, for instance as a laminate structure. 
       FIG. 8A  shows a patient support structure  826 A, according to another illustrated embodiment. 
     The patient support structure  826 A is a non-articulated, single piece or unitary structure. While illustrated as a single, unitary construction, the patient support structure  826 A may be formed of two or more sections, which may or may not be articulated. The patient support structure  826 A may be formed of a variety of materials, for example, the materials of the above described embodiments. 
     Notably, the patient support structure  826 A carries a set of antennas  816 Aa- 816 Af (collectively  816 A), which are positioned along a longitudinal axis  830  of the patient support structure  826 A. While illustrated as positioned in non-overlapping fashioned, in some embodiments the antennas  816 A may be positioned in overlapping fashion. While five antennas  816 B are illustrated, the patient support structure  826 A may include a greater or lesser number of antennas  816 A. Consequently, the antennas  816 A may all be carried on the same outer surface (e.g., patient support surface) or inner surface or layer. Thus, may advantageously provide more consistent results or performance between the respective antennas  816 , and/or may simply manufacturing and/or maintenance. 
       FIG. 8B  shows a patient support structure, according to another illustrated embodiment. 
     The patient support structure takes the form of a mattress or pad  826 B which may, for example, be used on a table or bed when performing a medical procedure. While illustrated as an articulated structure with two joints or hinges  830 Ba,  830 Bb (collectively  830 B), the mattress or pad  826 B may be formed of a unitary, single piece non-articulated structure. The mattress or pad  826 B may be reusable, and hence should be capable of withstanding repeated sterilization procedures (e.g., heat, chemical, radiation, etc.). Alternatively, the mattress or pad  826 B may be disposable after a single use. The mattress or pad  826 B may be formed of a variety of materials, for example, the materials of the above described embodiments of mattresses or pads. As previously discussed in reference to mattresses or pads, the mattress or pad  826 B may include an outer layer or cover  892 B and an interior  890 B (visible through broken portion of outer layer  892 B). The outer layer or cover  892 B provides environmental protection to the interior  890 B. The interior  890 B may, for example, take the form of a conformable interior, which may be made of any variety of materials. Suitable material may, for example, include cotton or a foam material such as a closed or an open cell foam rubber or LATEX®. Alternatively, the conformable interior may take the form of a fluid (e.g., a liquid or a gas). The outer layer or cover  892 B may be made of cotton, nylon, rayon or other natural or synthetic materials. The outer layer or cover  892 B may, for example, be impervious to liquids. For example, the outer layer or cover  892 B may include one or more layers of a rubber, LATEX®, polyvinyl chloride, plastic or other material that is impervious to fluids, for example bodily fluids. 
     Notably, the mattress or pad  826 B carries a set of antennas  816 Ba- 816 Be (collectively  816 B), which are positioned along a longitudinal axis  832 B of the mattress or pad  826 B. While illustrated as positioned in overlapping fashioned, in some embodiments the antennas  816 B may be positioned in non-overlapping fashion. While five antennas  816 B are illustrated, the mattress or pad  826 B may include a greater or lesser number of antennas  816 B. For example, the mattress or pad  826 B may have antennas  816  arranged in a similar fashion to that illustrated in  FIGS. 6A-6C . The antennas  816 B may on opposite sides of a layer on or in the mattress or pad  826 B, or on two or more different layers on or in the mattress or pad  826 B. The layer or layers may be an outer surface (e.g., patient support surface) or an inner surface or layer. The mattress or pad  826 B includes an interface, such as a connector  894 B, to allow the antennas  816 B to be communicatively coupled to the controller  18  ( FIG. 1 ). 
       FIG. 8C  shows a patient support structure, according to another illustrated embodiment. 
     The patient support structure takes the form of a sheet  826 C. The sheet  826 C may, for example, be used on, over, or in conjunction with a table, bed, frame or other structure during a medical procedure. The sheet  826 C may be formed of a unitary, single piece of material or a cloth, for example a fabric. The cloth may, for example, be woven, knitted, felted, pressed, etc. The sheet  826 C may be reusable, and hence should be capable of withstanding repeated sterilization procedures (e.g., heat, chemical, radiation, etc.). Alternatively, the sheet  826 C may be disposable after a single use. The sheet  826 C may be absorbent or may be impermeable to fluids, for example bodily fluids. The sheet  826 C may be formed of a variety of materials, for example, cotton, nylon, rayon, or other natural or synthetic fibers. For example, the sheet  826 C may include one or more layers of a rubber, LATEX®, polyvinyl chloride, plastic or other material that is impervious to fluids, for example bodily fluids. 
     Notably, the sheet  826 C carries a set of antennas  816 Ca- 816 Ce (collectively  816 C), which are positioned along a longitudinal axis  832 C of the sheet  826 C. While illustrated as positioned in overlapping fashioned, in some embodiments the antennas  816 C may be positioned in non-overlapping fashion. While six antennas  816 C are illustrated, the sheet  826 C may include a greater or lesser number of antennas  816 C. For example, the antennas  816  may be arranged on the sheet  826  in an identical or similar fashion as illustrated in  FIGS. 6A-6C . The antennas  816 C may be on opposite sides of the sheet  826 C, or on two or more different layers of the sheet  826 C. The layer or layers may be an outer surface (e.g., patient support surface) or an inner surface or layer. The sheet  826 C includes an interface, such as a connector  894 C, to allow the antennas  816 C to be communicatively coupled to the controller  18  ( FIG. 1 ). 
       FIG. 9  shows an antenna  916 , according to one illustrated embodiment. The antenna  916  may, for example, be suitable for use in any of the previously described embodiments. 
     The antenna  916  may, for example, take the form of an annulus or air-coil formed of coils of conductive material. The conductive material may, for example, take the form of wire or may take the form of a conductive trace printed or otherwise deposited on an inner layer or an outer surface  952  of a substrate  950 . In one embodiment, the antenna  916  includes ten turns evenly spaced between an inner diameter of about 11 inches and an outer diameter of about 14 inches. The antenna  916  acts as an inductor. While being formed of a conductive material, the antenna  916  is preferably formed of a radiolucent material. For example, the antenna  916  may be formed as a thin (e.g., thickness, width) strip line aluminum antenna. 
     The antenna  816  includes a pair of terminals  854   a,    854   b  that provide electrical coupling to the controller  18  ( FIG. 1 ), for example via the ports  38  of interrogation and detection system interface  36  ( FIGS. 1 and 2 ) and the coaxial cable  20 . 
       FIGS. 10A-10C  illustrate a coil antenna  1016  according to one embodiment. 
     The coil antenna  1016  comprises a top coil  1017  (illustrated in isolation in  FIG. 10B ) and a bottom coil  1019  (illustrated in isolation in  FIG. 10C ). The top and bottom coils  1017 ,  1019  are carried by the patient support surface  26 , the top coil  1017  carried on one layer  1021   a  and positioned relatively above the bottom coil  1019  carried on another layer  1021   b.  The top coil  1017  is electrically coupled to the bottom coil  1019 , for example, by a plug of electrically conductive material  1015  in a via. In practice the via connecting the top coil  1017  to the bottom coil  1019  may comprise a vertical connector of the same material as the coils  1017 ,  1019 . Any suitable conductor may be used to connect the top coil to the bottom coil at the via point. In addition to being offset from each other vertically along a longitudinal axis  1018  of the coils (see  FIG. 10D ), the individual windings of the two coils are also offset from each other laterally along two perpendicular axes in a horizontal plane (i.e., the plane of the drawing sheet  FIG. 10A ) that is perpendicular to the longitudinal axis. The layers  1021   a,    1021   b  may be opposed outer surfaces of an electrically insulative substrate, one or more inner surfaces of the electrically insulative substrate, or a combination thereof. The electrically insulative substrate may be a unitary part of the patient support surface, integral part of the patient support surface or attach or carried by the patient support surface. 
       FIG. 10D  shows the coil antenna  1016  carried by a patient support structure  26 , according to one illustrated embodiment. 
     Top coil  1017  is positioned relatively above the bottom coil  1019  in an interior of the patient support structure  26 . As noted above, the bottom coil  1019  is offset from the top coil  1017  vertically along a longitudinal axis  1018  as well as laterally in a horizontal plane which is perpendicular to the longitudinal axis  1018 . The individual windings  1021  of the top coil  1017  are spaced apart leaving gaps between each winding  1021 . The individual windings  1023  of the bottom coil  1019  are spaced directly below the gaps between the windings  1021  of the top coil  1017 . The windings  1021 ,  1023  are thus spread in such a way to provide a more even distribution of radiolucence. This distribution of the windings  1021 ,  1023  may smooth the contrast that could appear in a radiological image (e.g., X-ray image).  FIG. 10D  illustrates an embodiment in which the windings  1023  are spaced directly below the gaps between windings  1021  without overlapping the windings  1021  in a lateral direction in the horizontal plane. In other embodiments the windings  1023  may instead slightly overlap the windings  1021 . In some embodiments the windings  1021 ,  1023  may cross over each other although such crossings may have an adverse effect on radio transparency. Many other configurations of the coils  1017 ,  1019  and the windings  1021 ,  1023  will be apparent to those of skill in the art and fall within the scope of this disclosure. The configuration of windings illustrated in  FIG. 10D  are given only by way of example and do not limit the scope of the disclosure. The patient support structure  26  and antenna  1016  are not drawn to scale. Relative heights, widths, and separations of the patient support structure  26  and antenna coils  1017 ,  1019  may be different in practice than what is shown in  FIG. 10D . 
     This design may minimize interference with radiological imagery sources (e.g., X-rays, CAT scans, MRIs) which may be employed while a patient is on the patient support structure  26 . Radiological imaging is commonly employed while patients are on the patient support structure  26 , for example during surgery. This may, for example, be performed by positioning an X-ray machine above the patient support structure  26  and positioning an X-ray sensitive film below the patient support structure  26 . An X-ray image is formed by exposing the film to the X-rays through the patient and patient support structure  26 . Any object or material that absorbs or reflects X-rays more than its surroundings will cause an area of contrast in the developed X-ray image. Thus, portions of the patient support  26  structure that absorb more or less than other portions of the patient support structure  26  will appear as a high level of contrast in the developed X-ray image. This can make it difficult to interpret the X-ray image. For this reason it may be beneficial to spread the coils of an antenna, even where nominally radio transparent to reduce the contrast which the antenna may otherwise cause in an X-ray image. A coil antenna with many windings which are stacked or layered are above others may produce a relatively high contrast and appear in an X-ray image even if a single layer of coil is nominally radio transparent. A coil whose windings are spread apart, spread laterally from one another, may also produce relatively large changes in contrast, even where nominally radio transparent. As disclosed herein, the windings of the coils are positioned to be in adjacent non-overlapping relationship to one another when viewed along the longitudinal axis  1018 . Such creates an area having a very uniform distribution of antenna material, and hence a very uniform radiological attenuation distribution across that area. Such advantageously may cause any attenuation to be uniform, reducing the antenna&#39;s effect on the radiological image. 
       FIGS. 10E and 10F  show a patient support structure  26  according to one embodiment. 
     The patient support structure carries six antennas  1016   a - 1016   f.  Each of the antennas  1016   a - 1016   f  may be similar or identical in form to the antenna  1016  illustrated in  FIG. 10A-10D . The antennas  1016   a - 1016   f  are positioned to provide little or no gap between antennas in the lateral directions of the horizontal plane of the patient support surface  26 , while not overlapping. As described above, this configuration may help to reduce areas of sharp contrast in radiological images.  FIG. 10E  shows the antennas  1016   a - 1016   f  embedded within the patient support structure  26 . Of course the antennas  1016   a - 1016   f  may not actually be visible from a top view of the support structure  26 . However, FIG.  10 F shows the antennas  1016   a - 1016   f  from the top view to illustrate the relative positions of the antennas  1016   a - 1016   f.  The number and configuration of coils, as well as the number and configuration of the winding forming those coils, shown in  FIG. 10F  is not meant to be limiting. In practice there may be a greater or lesser number of coils and/or a greater or lesser number of windings. In practice, the windings are typically not independent loops, but are illustrated as such in  FIG. 10F  for ease of illustration. 
       FIG. 11  shows a patient support structure carrying an antenna  1116 , according to another illustrated embodiment. 
     The antenna  1116  comprises a top coil  1117  and a bottom coil  1119  as previously described. The top coil  1117  comprises windings  1121 , while the bottom coil comprises windings  1123 . The windings  1121 ,  1123  are laterally offset from each other in two perpendicular directions in a horizontal plane that is perpendicular to a longitudinal axis of the antenna  1116 . The top coil  1117  is formed adjacent to and below a top surface  1137  of the support structure  26 , for example in a channel or recess formed in the top section  1137 . The bottom coil  1119  is formed above and adjacent to a bottom surface  1152  of the support structure  26 , for example, in a channel or recess formed in the bottom section  1152 . 
       FIG. 12  illustrates a patient support structure that carries an antenna  1126 , according to yet another illustrated embodiment. The antenna  1216  comprises a top coil  1217  and a bottom coil  1219 . The top coil  1217  comprises windings  1221 , while the bottom coil comprises windings  1223 . The windings  1221 ,  1223  are laterally offset from each other in a horizontal plane that is perpendicular to a longitudinal axis of the antenna  1216 . The top coil  1217  is carried directly on a top surface  1237  of the support structure  26 . The bottom coil  1219  is carried directly on a bottom surface  1252  of the support structure  26 . The top and/or bottom coils  1217 ,  1219  may be adhered or otherwise physically coupled to the respective surfaces  1237 ,  1252 . The relative dimensions of the features shown in  FIG. 12  may not be accurate. For instance, the antenna windings  1221 ,  1223  may not, in practice, protrude from the surfaces  1237 ,  1252  to the same extent as illustrated. Many other configurations for the antennas are possible and the preceding embodiments are given only by way of non-limiting example. 
       FIG. 13A  shows a surgical environment  1310  that includes a surgical table  1312  and an interrogation and detection system  1314 , according to another illustrated embodiment. The embodiment of  FIG. 13A  is similar in some respects to one or more of the previously described embodiments, hence only significant differences in structure and operation will be discussed. 
     The surgical table  1310  may include a patient support structure  1326  and a pedestal or base  1328 . The patient support structure  1326  may be a laminate structure having multiple layers. Alternatively, the patient support structure  1326  may be a shell type structure or housing having an open interior. Alternatively, the patient support structure  1326  may be a solid structure, for example a roto-molded structure. 
     The plurality of antennas  1316   a - 1316   f  (collectively  1316 ) of the interrogation and detection system  1314  are carried by the surgical table  1312 , for example carried by inner layers of the patient support structure  1326  or positioned in an interior of a shell or housing forming the patient support structure  1326 . While illustrated as being in overlapping relationship, in some embodiments the antennas  1316  may not overlap. The controller  1318  of the interrogation and detection system  1314  may be positioned in the pedestal or base  1328 , for example in an interior  1330  of the pedestal or base  1328 . One or more wired or wireless communication paths may communicatively couple the controller  1318  to the antennas  1316  and/or to an interrogation and detection system interface  1336 , for example coaxial cable  1320 . 
     The interrogation and detection system  1314  may receive power for a variety of sources, for example from a wall outlet or receptacle via a conventional power cord and plug  1332 . 
     The antennas of the interrogation and detection system  14  are not limited to being implemented in a patient support structure  26 . Previous embodiments have, by way of example, described various ways of implementing antennas within a patient support structure. These embodiments have been given purely by way of example and are not intended to be limiting. Those of skill in the art will recognize that the antennas may be implemented in many configurations throughout the environment in which medical procedures are performed. 
       FIG. 13B  shows an environment in which medical procedures are performed  1340  that includes a bed (e.g., patient bed)  1342  and an interrogation and detection system  1344 , according to another illustrated embodiment. The embodiment of  FIG. 13B  is similar in some respects to one or more of the previously described embodiments, hence only significant differences in structure and operation will be discussed. 
     The environment  1310 , may for example, take the form of a hospital room, clinic room, or examination room of a medical practitioner&#39;s office. 
     The bed  1342  may include a patient support structure  1346  and a frame or base  1348 . The patient support structure  1346  may support one or more mattresses, for example a segmented mattress  1347 . The frame  1348  may be made of plastic, metal, composite, reinforced composited, and/or roto-molded materials. Various commercially available designs of frames for patient beds are suitable. The frame  1348  may include a set of wheels  1350  (only one called out in  FIG. 13B ) allowing the bed  1342  to be easily moved. The frame  1348  may include one or more rails  1352 , which may, or may not, be removable or which may, or may not, fold down. 
     The bed  1342  may include one or more electric motors  1354  (only one called out in  FIG. 13B ) and linkages  1356  (only one called out in  FIG. 13B ) which are selectively actuated to move or articulate portions of the bed  1342  or mattress  1346 . Other mechanisms may be used to move portions of the mattress  1346 . Commercially available patient or hospital beds  1342  typically include one or more pieces of electrical or electronic equipment (e.g., electric motors  1354 ) which are sources of radio noise which may interfere with the interrogation and detection system  1344 . Such equipment typically produce very consistent or periodic (i.e., non-random) noise. Some embodiments of the interrogation and detection system  1344  discussed herein employ various techniques to address such non-random noise. 
     The interrogation and detection system  1344  includes a plurality of antennas  1366   a - 1366   f  (collectively  1366 ) of the interrogation and detection system  1344  are carried by the patient support structure  1346 , mattress  1347  or frame  1348 . For example, the antennas  1366  may be carried by inner layers of the mattress  1347  or positioned in an interior of a shell or housing forming the patient support structure  1346 . While illustrated as being in non-overlapping relationship, in some embodiments the antennas  1366  may overlap. A controller  1368  of the interrogation and detection system  1344  may be carried by the frame or base  1348 . One or more wired or wireless communication paths may communicatively couple the controller  1368  to the antennas  1366  and/or to an interrogation and detection system interface, for example coaxial cable  1370 . 
     The interrogation and detection system  1314  may receive power for a variety of sources, for example from a wall outlet or receptacle via a conventional power cord and plug (not shown in  FIG. 13B ). 
     In some embodiments, antennas, for instance antennas  1316 ,  1366  ( FIGS. 13A, 13B , respectively) may form strain sensors as part of a strain gauge. For example, the antennas may be carried by flexible substrate, for instance a flexible printed circuit board such as a polyimide (Kapton®) or polyester (Mylar®) printed circuit board. The resistance of the antenna varies as the substrate flexes in response to an asserted force. The change in resistance may be measured to determine strain, and hence force applied. The antennas may be configured and coupled in groups of fours to form full Wheatstone bridges. The antennas may additionally, or alternatively, be oriented along various axes or dimensions to detect strain in different directions. Multiple layers of antennas may be employed to detect flex in two opposite directions, normal to the plane of the substrate. Alternatively, dedicated strain sensors or gauges may be employed, which function only to sense force (e.g., strain or pressure) and which do not function as antennas. Sensing strain may be useful in detecting excessive and/or prolonged pressure asserted between a patient and the patient support surface. Excess and/or prolonged pressure may cause the patient to develop “bed sores” or ulcers. Tracking or monitoring pressure may allow the medical care provider to intervene before the “bed sores” or ulcers occur. Thus, the control system may be configured to provide a warning or alert (e.g., visual, aural and/or tactile) when pressure or strain exceeds some threshold in amplitude and/or time. For instance, the controller may produce a notification if the force exerted on at least one of the antenna exceeds an amplitude threshold over a period of time that exceeds a time duration threshold. The control system may additionally, or alternatively, provide an indication of a position or location on the patient support surface or patient where the excessive pressure is occurring or being asserted. For instance, the controller may display a map of the patient support structure and/or patient, with icons or alphanumeric indications indicative of various locations where excessive force is being asserted and/or an amplitude of force being asserted at respective locations on the map. 
       FIG. 14A  shows a number of antennas  1416  carried by a lightshade  1432  of a light fixture  1434  used in medical procedures, according to one illustrated embodiment, in which the lightshade is shown in a retracted or undeployed position or configuration. The light fixture  1434  may house one or more lights to be used during surgery, birth delivery or other medical procedure, including dental procedures. During a medical procedure such as surgery, the patient laying on a patient support structure is typically illuminated brightly by an overhead light fixture  1434 . The light fixture  1434  may be situated directly above the operating table or slightly offset as desired. The light fixture  1434  is also generally positioned as close to the patient as possible without impeding the medical services providers (e.g., surgeons and staff) during the medical procedure (e.g., surgery, birth delivery). The proximal overhead position allows the light fixture  1434  to brightly illuminate the patient. The light fixture  1434  is positioned so as to reduce or eliminate any shadows on the patient&#39;s body during the surgery. 
     The proximal overhead position of the light fixture  1434  provides an excellent location for the antennas  1416  of an interrogation and detection system. There are five loop antennas  1416  visible in the lightshade  1432  illustrated in  FIG. 14A . However, there may be more antennas  1416  on a far side of the lightshade  1432 , not visible in  FIG. 14A . The number of antennas  1416  located on the lightshade  1432  may be any number suitable for the interrogation process. 
     The lightshade  1432  may be attached to the light fixture  1434  by extendable and retractable support arms  1436 . As noted,  FIG. 14A  illustrates the lightshade  1432  in a retracted or undeployed position or configuration, raised relative to the light fixture  1434 . The support arms  1436  may include hinges  1438  or other linkages. The hinges  1436  or other linkages enable the lightshade  1432  to be moved to an extended or deployed position or configuration, lowered relative to the light fixture  1434  and the patient support surface, for example, as illustrated in  FIG. 14B . In one embodiment the antennas  1416  of the lightshade  1432  may be operable in the raised position. In one embodiment the antennas  1416  may be attached to the light fixture  1434  in a form other than that of a lightshade  1432 . 
       FIG. 14C  shows a lightshade  1432  is coupled to the light fixture  1434  without the use of supporting arms  1436 , according to yet another illustrated embodiment. 
     The lightshade  1432  may be a flexible sheet carrying a number of antennas  1416 . The flexible sheet is coupleable to the light fixture  1434  by wrapping the flexible sheet around the light fixture  1434  and securing the flexible sheet thereto. The lightshade  1432  may be attached to the light fixture  1434  by hooks, hook-and-loop fasteners (e.g., VELCRO®), clips, or any other suitable fasteners or adhesives. Two ends of the lightshade  1432  may be attached to each other to create an opening sized to securely receive a portion of the light fixture  1434  therein. In this configuration the lightshade  1432  remains on the light fixture by virtue of having a smaller diameter opening than a diameter of the portion of the light fixture. The lightshade  1432  may alternatively be an integral part of the light. 
     In one embodiment, the antennas  1416  of the lightshade  1432  are communicatively coupled to an interrogation and detection system interface  36 . The interrogation and detection system interface  36  may be located at any suitable position in the room or in another room. The antennas  1416  may be connected to the system interface  36  by a wired connection (e.g., wire bundle  1450 ) or a wireless connection. The wire bundle  1450  may run along a ceiling, wall and/or floor of the operating room to communicatively couple with a controller  18 . In one embodiment the light fixture  1434  is attached to a mobile support which can be moved about the room or even from one room to another. In one embodiment the system interface  36  is also attached to the light fixture  1434 . In one embodiment the controller  18  may be attached to the mobile support of the light fixture  1434  with the antennas  16  directly connected to the controller by  1450 . 
     The function and operation of the interrogation and detection system  14  in embodiments in which the antennas  1416  are coupled to a light fixture  1434  may be substantially the same as those embodiments in which the antennas  1416  are coupled to the patient support structure  26 . 
     While  FIGS. 14A, 14B , illustrate the antennas  1416  in a particular non-overlapping configuration, the antennas  1416  may be carried by the lampshade  1432  in any suitable configuration. In contrast to the previously described embodiments in which the patient support structure carried the structures, the lightshade  1432  are unlikely to interfere with radiological imaging. Hence, the antennas  1416  may overlap each other, or may be in a non-overlapping configuration. The antennas  1416  may be attached to one or both exterior surfaces of the lightshade  1432 . Alternatively the antennas  1416  may be formed within the lightshade  1432 , for example, via lamination or weaving. The lightshade  1432  may be made of any material suitable to not interfere with the function of the antennas  1416 . 
       FIG. 15A  shows a drape or curtain  1542  that carries a number of antennas  1516  according to one illustrated embodiment. 
     The terms drape and curtain are used interchangeably herein and in the claims. The drape or curtain  1542  may, for example, be used on, over, or in conjunction with a table, bed, frame or other structure during a medical procedure. The drape or curtain  1542  may be coupled to a track  1540  which surrounds a patient support structure  26 . The track  1540  is typically in close proximity to the patient support structure and affords a suitable location for the antennas  1516  of the interrogation and detection system  14 . In one embodiment, the track may be fastened to a ceiling of a room, for example an operating room, patient room or physician&#39;s office or examination room. In such an embodiment, a wire bundle  1550  may also be attached to the ceiling as the wire bundle runs to the system interface  36  or controller  18  situated elsewhere in the surgical environment. The system interface  36  and controller  18  may be attached to a wall of the environment or may be in any other suitable location within the environment in which medical procedures are performed. In another embodiment, the track  1540  may be supported by a freestanding structure or structure fixed or coupled to a floor of the room such as a frame. 
     The antennas  1516  may be carried on either exterior surface of the drape or curtain  1542  or be situated (e.g., laminated) within the drape or curtain  1542 . While  FIG. 15A  shows the antennas  1516  on two opposing sides of the patient support structure  26 , the antennas  1516  may be positioned on a few or greater number sides of the patient support structure  26  while in use. The drape or curtain  1542  may be selectively deployed and retracted along the track  1540  during use. For example, the drape or curtain  1542  may be retained in a retracted, undeployed position or configuration during times or periods when scanning or interrogation is not being performed. The drape or curtain  1542  may be moved to an extended, deployed position or configuration in preparation for scanning or interrogation, for example, just prior to completing the medical procedures (e.g., surgery) and, for example closing the patient. In other embodiments, the drape or curtain  1542  may be retained in the extended or deployed position or configuration throughout the surgical procedure. The antennas  1516  may be connected to system interface  36  by means of the wire bundle  1550  extending from the curtain  1540 . 
       FIG. 15B  shows a sheet  1544  carrying a number of antennas  1516  which sheet  1544  may be quickly hung on a rack or frame  1540 . The term sheet is used interchangeably herein and in the claims the terms drape or curtain. The term rack is used herein and in the claims interchangeably with the term frame. The sheet  1544  can be hung from the rack  1540  by connectors  1546 . More than one sheet  1544  may be hung from the rack  1540  on one or more sides of the patient support structure  26 . The antennas  1516  may be attached on either exterior surface of the sheet  1544  or be situated (e.g., laminated or woven) within the sheet  1544 . While the sheet  1544  is illustrated as having four antennas  1516 , there may be as few or as many antennas  1516  on the sheet as desired. Connectors  1546  may include hooks, clamps, or any other fastener suitable to attach the sheet  1544  to the rack  1540 . The antennas  1516  may be connected to the system interface  36  by means of a wire bundle  1550  extending from the sheet  1544 . 
       FIG. 16  shows a controller  1618 , according to one illustrated embodiment. 
     The controller  1618  may include a housing  1670 . The housing  1670  may contain a motherboard  1672  with a number of ports or connectors  1674   a - 1674   f  (collectively  1674 ) to communicatively couple the motherboard  1672  to respective ones of the antennas (e.g., antennas  16 ). The motherboard  1672  may also include a number of slot connectors  1676   a - 1676   f  (collectively  1676 ) to physically receive respective plug-in boards  1678   a - 1678   f  (collectively  1678 ) and communicatively couple the plug-in boards  1678  to the motherboard  1672 . There may, for example be one plug-in board  1678  for each antenna, each of the antennas  16  and plug-in boards  1678  constituting a separate channel. The motherboard  1672  may include additional slot connectors, allowing expansion or use with different antenna configurations or different patient support structures (e.g., surgical tables, patient beds). The plug-in boards  1678  may each carry one or more circuits (e.g., analog and/or digital circuit components) configured to transmit interrogation signals from the respective antenna and to monitor the antenna for responses to the interrogation signals. For example, the plug-in boards  1678  may implement or carry the circuits disclosed in U.S. patent application Ser. No. 11/759,141 filed Jun. 6, 2007, U.S. Provisional Patent Application Ser. No. 61/056,787 filed May 28, 2008, and U.S. Provisional Patent Application Ser. No. 61/091,667 filed Aug. 25, 2008, with or without change, which Patent Applications are incorporated herein by reference in its entirety. 
     The motherboard  1672  may also include one or more ports  1679  to receive control signals, for example from the interrogation and detection system interface  36 ,  1336  ( FIG. 1 ,  FIG. 13A ). The motherboard  1672  may also include one or more synchronization circuits  1680  configured to control and synchronize the operation of the various plug-in boards  1678 . The synchronization circuit  1680  may be configured to cause one of the plug-in boards  1678  to transmit an interrogation signal from a first antenna, and cause one or more of the other plug-in boards to monitor for a response by a transponder to the interrogation signal. For instance, the synchronization circuit  1680  may cause the plug-in boards  1678  to have all of the antennas monitor for a response to the interrogation signal. Alternatively, the synchronization circuit  1680  may cause the plug-in boards  1678  to have all of the antennas other than the antenna that transmitted a most recent interrogation signal monitor for a response. Such may advantageously allow monitoring sooner than would otherwise be possible since such can avoid the need to allow the transmitting antenna to return to a quiescent state after transmitting before monitoring for a response. The synchronization circuit  1680  may synchronize the plug-in boards  1678  to successively cause the various antennas to transmit, for example starting with an antenna at one end, and successively transmitting from each of the antennas in order along the longitudinal axis  30  ( FIGS. 1 and 2 ). Alternatively, the synchronization circuit may synchronize the plug-in boards  1678  to cause the various antennas to transmit, but not in order along the longitudinal axis  30 . As a further alternative, the synchronization circuit  1680  may synchronize the plug-in boards  1678  to cause the transmission of interrogations signals from a subset of the total set of antennas. 
     While illustrated as a motherboard  1672  and plug-in boards  1678 , other embodiments are possible. For example, the various antennas may be controlled by respective circuits integrated into a signal circuit board. Alternatively, the various antennas may be controlled by a single circuit. 
       FIG. 17  shows a control system  1700  of a controller of an interrogation and detection system, according to one illustrated embodiment. 
     The control system  1700  includes a field programmable gate array (FPGA) board  1702 , one or more analog boards  1704 , and a display board  1706 , communicatively coupled to one another. The analog board(s)  1704  may take the form of one or more plug-in boards  1678 , as discussed in reference to  FIG. 16 . Hence, there may be a respective analog board  1704  for each of the antennas  16  ( FIGS. 1 and 2 ). 
     The FPGA board includes an FPGA  1708 , configuration jumpers  1710 , RS-232 drivers  1712 , oscillator  1714 , random access memory (RAM)  1716 , flash memory  1718 , and voltage monitoring (VMON) analog-to-digital converter (ADC)  1720 . 
     The FPGA  108  may take the form of a Xilinx Spartan 3 FPGA, which runs FPGA and application software. As explained below, on power up, the FPGA reads the configuration information and application software program from the flash memory  1718 . 
     The configuration jumpers  1710  are used to select the application software configuration. 
     The RS-232 drivers  1712  are used to allow the application software to communicate using serial RS-232 data for factory test and diagnostics. 
     The oscillator  1714  sets the clock frequency for the operation of the FPGA  1708 . The oscillator  1714  may, for example, take the form of 40 MHz oscillator, although other frequencies are possible. 
     The RAM  1716  is connected to the FPGA  1708  and is available for use by the application software. The application software uses this memory space for storage of both the executable program and program data. The RAM  1716  may, for example, have a capacity of 1 MB. 
     The flash memory  1718  contains both the FPGA configuration data and the binary application program. On power up the FPGA  1708  reads the flash memory to configure the FPGA  1708  and to copy the application program binary data from the flash memory  1718  to the RAM  1702 . 
     The voltage monitor ADC  1720  is connected to the FPGA  1708  and controlled by the application software to monitor a power supply and regulated voltage forms in controller electronics. 
     The analog board  1704  includes transmit control circuits  1722 , capacitor selection circuits  1724 , an antenna detection circuit  1726 , signal ADC  1728 , audible beeper  1730  and self-test signal  1732 . 
     The transmit control circuits  1722  on the analog board  1704  are controlled by signals from the FPGA  1708  to generate a transmit waveform. These signals are denominated as LO_FET_ON and HI_FET_ON, which control the transmit or drive transistors Q 1 , Q 2  ( FIG. 18A ) along with a signal denominated as DUMP_ON which controls a dump TRIAC ( FIG. 18A ). 
     Optional capacitor selection circuits  1724  on the analog board  1704  are controlled by the signals from the FPGA  1708  to tune the drive circuit to match an inductance of the antenna  16  ( FIGS. 1 and 2 ). 
     The antenna detection circuit  1726  detects when an antenna  16  ( FIGS. 1 and 2 ) is connected to the controller  20 . The output of the antenna detection circuit  1726  drives a signal denominated as the LOOP_LEVEL_OUT signal, which is an input to the FPGA  1708 . 
     The signal ADC  1728  is used to sample the signals received at the antenna  16  from the transponders  24  ( FIG. 1 ). The signal ADC  1728  may, for example, operate at a 1 MHz sample rate and may have 12-bits of resolution. The FPGA board  1702  generates the timing and control signals for the signal ADC  1728 , which signal are denominated as ADC_CTRL, CS1, SCLK, SDO. 
     The aural indicator (e.g., speaker or beeper)  42  ( FIGS. 1 and 2 ) can be controlled by the FPGA  1708  to emit sounds to indicate various states, modes or operating conditions to the medical provider. 
     The FPGA  1708  can cause the generation of the self test signal  1732  on the analog board  1704  at the signal ADC  1728 . Self-testing may be performed at start up, and/or at other times, for example periodically or in response to the occurrence of certain conditions or exceptions. 
     The display board  1706  includes user interface elements, for example a number of visual indicators (e.g., LEDs, LCDs, etc.)  40  ( FIGS. 1 and 2 ). The FPGA board  1702  can control the visual indicators  40  on the display board  1706 . The display board  1706  also includes a user selectable activation switch  44 , denominated as front panel button  1736 . The front panel button  1736  is connected to the display board  1706  which allow the FPGA  1708  to monitor when the front panel button  1736  is activated (e.g., pressed). 
       FIG. 18  shows a software configuration  1800  of the interrogation and detection system  14 , according to one illustrated embodiment. 
     The software may include application software  1802  that is responsible for operating the controller  18  ( FIGS. 1 and 2 ). The application software  1802  controls the timing for generating transmit pulses, processes sampled data to detect transponders  24  ( FIGS. 1 and 2 ), and indicates status to the user with the visual indicators  40  ( FIGS. 1 and 2 ) on the display board  1706  ( FIG. 17 ) and/or via the aural indicator  42  on the analog board  1704  ( FIG. 17 ). The application software  1802  is stored in the flash memory  1718  ( FIG. 17 ) and transferred into the RAM  1716  by a boot loader  1804 . 
     The boot loader  1904  is automatically loaded when the FPGA  1708  is configured, and starts execution after a processor core  1806  is reset. The boot loader  1804  is responsible for transferring the application software  1802  from the flash memory  1718  to the external RAM  1716 . 
     The processor platform  1808  is configured into the FPGA  1708  ( FIG. 17 ) on power up from the configuration information stored in the flash memory  1718 . The processor platform  1808  implements a custom microprocessor with a processor core  1806 , peripherals  1810   a - 1810   n,  and custom logic  1812 . 
     The processor core  1806  may take the form of a soft processor core supplied by XILINX under the name MICROBLAZE™, that implements a 32-bit processor including memory caches and a floating point unit. A soft core processor is one that is implemented by interconnected FPGA logic cells instead of by a traditional processor logic. The processor core  1806  is connected to the internal FPGA peripherals  1810   a - 1810   n  using a 32-bit processor bus  1811  called the On-Chip Peripheral Bus. The XILINX supplied peripherals for the MICROBLAZE™ processor core  1806  include external memory interfaces, timers, and general purpose I/O. 
     The custom logic  1812  to create the transmit signals, sample the ADC, and accumulate the transponder return signals is designed as a peripheral to the processor core  1806 . The custom logic  1812  is the part of the design of the FPGA  1708 . 
     Some embodiments may substitute a full microprocessor for the soft processor core. Thus, for example, a microprocessor such as the ATOM™ processor, commercially available from Intel Corporation, may be employed in place of the MICROBLAZE™ processor core. The full microprocessor may be communicatively coupled to multiple analog antenna channels via one or more FPGAs and one or more suitable buses. The FPGA may, for example, act as a co-processor and/or cache. Additionally, or alternatively, a higher bandwidth bus architecture may be employed. For example, a PCI express™ or PCIe™ bus architecture may be employed, rather than an ISA bus architecture. Suitable FPGAs may include those from ATMEL Corporation. Such FPGAs may advantageously have built in PCIe bus architecture, allowing easy integration. This approach may enable more I/O ports, such as USB ports, may provide more or better video options, and may provide faster data rates from the analog antenna channels that otherwise possible using the ISA bus architecture and soft processor core approach. 
       FIGS. 19A-19I  show a control circuit  1900  according to one illustrated embodiment. The control circuit  1900  is used to drive the antenna  16  ( FIGS. 1 and 2 ) to excite or interrogate transponders  24  ( FIGS. 1 and 2 ), and to detect and process signals received by the antenna  16  from the transponders  24 . As previously noted, there may be a respective control circuit  1900  for each of the antennas  16 , or a single control circuit may be configured to control multiple antennas. 
     The control circuit  1900  includes a transmitter circuit  1902  formed by a pair of drive transistors (e.g., field effect transistors) Q 1 , Q 2  operated in a push-pull configuration between a high voltage rail (e.g., 24 V) and a low voltage rail (e.g., GND). The drive transistors Q 1 , Q 2  are responsive to respective drive signals DRIVE_HI, DRIVE_LO, which are applied to the gates of the respective drive transistors Q 1 , Q 2 . The drive transistors Q 1 , Q 2  are coupled to the antenna  16  by a non-switched capacitor C 8  and the coaxial cable  20 . The antenna  16  and capacitor C 8 , as well as capacitance provided by the coaxial cable  20 , form an LC circuit. 
     Optionally, the control circuit  1900  may also include a dynamic tuning circuit  1904 . The dynamic tuning circuit  1904  selectively adjusts the capacitance of the LC circuit. In the illustrated embodiment, the dynamic tuning circuit  1904  includes a number of switched capacitors C 33 -C 36  and relays U 9 , U 10 . The relays U 9 , U 10  are operated to selectively couple the switched capacitors C 33 -C 36  in series with the non-switched capacitor C 8 , thereby adjusting the LC characteristics of the LC circuit, and allowing fine tuning of the LC circuit around center frequencies or center channels of a number of wide band frequency bands, as described in more detail below. 
       FIG. 20  illustrates a detection cycle  2000  that employs an approach that optimizes signal to noise ratio (SNR), according to one illustrated embodiment. Such may, for example, advantageously increase range or increase sensitivity at a given range. 
     One embodiment is optimized based on having an overall detection cycle that performs well for transponders with resonant frequencies from approximately 136 KHz to approximately 154 KHz, and which has a pulse timing that is consistent with hardware limitations. An optimal SNR may be achieved by, for example, transmitting a single wideband frequency pulse. 
     The application software  1802  ( FIG. 18 ) implements the detection cycle  2000  using transmission or interrogation in a frequency band centered around a center channel or frequency. In the illustrated embodiment, the application software  1802  sequences through a non-measurement portion (i.e., gap)  2000   a,  and two distinct measurement portions, denominated as a noise detection portion  2000   b  and an interrogation or signal detection portion  2000   c,  each detection cycle  2000 . In at least one embodiment, the detection cycle  2000  may, for example, be approximately 275 milliseconds, the gap portion may be approximately 10 milliseconds, the noise portion approximately 37 milliseconds and the interrogation or signal portion approximately 228 milliseconds. 
     During the noise detection portion  2000   b,  which may, for example be a first measurement portion of each detection cycle  2000 , ambient or background noise is measured or sampled, providing a value indicative of a level of ambient or background noise for the particular environment. The noise measurements or samples are taken or captured at a time sufficiently after excitement of the transponders  24  ( FIG. 1 ) by the interrogation signal emitted by the transmitter such that the transponders  24  are substantially not resonating or responding to any previous excitation by interrogation signals. In particular, a number N of measurements or samples are taken during the noise detection or first measurement portion  2000   b.    
     During the interrogation portion  2000   c,  which may, for example take the form of the second measurement portion of each detection cycle  2000 , responses by transponders  24  are measured or sampled. The response measurements or samples are taken with the transmitter transmitting or at a time sufficiently close to excitement of the transponders  24  by the interrogation signal emitted by the transmitter such that the transponders  24  are still substantially resonating or responding to the interrogation signal. In particular, a number M of measurements or samples are taken during the interrogation or second measurement portion  2000   c.    
     While the interrogation portion  2000   c  is illustrated as one contiguous or continuous portion  2000   c,  in some embodiments the interrogation portion  2000   c  may take the form of two or more separate portions or intervals. Each of the portions  2000   c  may employ the same transmit frequency band, for example centered around 145 KHz. Other center channels or frequencies may for example be 136 KHz, 139 KHz, 142 KHz, 145 KHz, 148 KHz, 151 KHZ and/or 154 KHz, or any other frequency suitable for exciting the transponder to resonate. Some embodiments may employ frequency hopping, for example transmitting a different center channel or frequency for each of a plurality of interrogation portions  2000   c  of each detection cycle  2000 . Such is discussed further in U.S. provisional patent application Ser. No. 60/892,208, filed Feb. 28, 2007 and U.S. non-provisional application Ser. No. 11/743,104, filed May 1, 2007. 
     The gap portion  2000   a  may provide time for the response of the transponders  24  to the interrogation signal to decay sufficiently to allow measurement of noise. 
     Some embodiments may arrange the gap  2000   a,  the noise detection portion  2000   b  and/or the interrogation portion  2000   c,  or parts thereof, in a different order. 
     In one embodiment, the time to accumulate the noise sample or value indicative of a noise level may, for example, be approximately 37 milliseconds, and the time to accumulate the transponder signal measurement approximately 228 milliseconds. Along with a gap  2000   a  of approximately 10 milliseconds between the signal and noise portions, the time for a single detection cycle  2000  would be approximately 275 milliseconds. As noted above, the transmitter is OFF during the noise measurement portion  2010   b  of each detection cycle to measure ambient noise, and the signal measurement portion  2010   c  is taken with the transmitter transmitting a wideband interrogation signal about the particular center channel or frequency. 
     The noise samples may be accumulated and a highest one or more of multiple samples or measurements over one or more detection cycles selected or used to prevent unwarranted fluctuations. The response signals from the transponder  26  may be accumulated and/or averaged or integrated over one detection cycle or over multiple detection cycles. 
     The number N of noise measurements or samples and/or the number M of response measurements or samples may be selected to achieve a desired ratio of N to M, in order to achieve or maintain a desired signal to noise ratio. For example, obtaining 200 noise measurements or samples and 800 response measurements or samples each detection cycle results in an SNR of approximately 2 (e.g., the square root of the 800 divided by 200). While an SNR as low as 1.1:1 may be sufficient in some embodiments, an SNR approaching 2:1 ensures sufficient differentiation to eliminate or reduce the possibility of false positives to an acceptable level for the particular applications envisioned herein. Any known hardware and software accumulators, summer, integrators and/or other hardware or software may be suitable. 
       FIG. 21A  illustrates pulse timing, according to one illustrated embodiment. 
     The custom logic in the FPGA  1708  ( FIG. 17 ) generates the timing and control signals for each pulse  2110 . During a transmit portion  2110   a  of the pulse  2110 , the logic of the FPGA  1708  drives the drive transistor control lines to generate the transmit signal. The FPGA logic controls the frequency of the transmit signal. During a dump portion  2110   b  of the pulse  2110 , the logic of the FPGA  1708  drives the gate of the dump TRIAC T1 to quickly drain the transmit energy from the antenna  21  in order to allow detection of the response signal form the transponder  24 , if any. A recovery portion  2110   c  of the pulse  2110  allows receiver filters and amplifiers to recover from the transmitted pulse before detecting the response signal from the transponder  24 , if any. During the receive response portion  2110   d  of the pulse  2110 , the FPGA  1708  controls the signal ADC  1728  to sample the response signal from the transponder  24 , if any. The signal ADC  1728  may, for example, sample at a 1 MHz sample rate with a 12-bit resolution. A dither portion  2110   e  of the pulse  2110  has a random variable length of time, and may, for example be generated by a pseudo-noise (PN) sequence generator. Adding a random length of time between pulses de-correlates the response signal received from the transponder  24  from constant frequency sources of interference, if any. 
     For example, within each of 228 millisecond signal measurement intervals  400   c  discussed above, the custom logic of the FPGA  1708  ( FIG. 17 ) accumulates the received signals from, for example 800 pulses. 
       FIG. 21B  illustrates pulse timing, according to one illustrated embodiment. The pulse timing is similar in some respects to that illustrated in  FIG. 21A , hence similar or identical structures, acts or features are identified using the same reference numbers. Only significant differences between the two are discussed below. 
     In contrast to the embodiment of  FIG. 21A , the embodiment of  FIG. 21B  may advantageously eliminate the dump portion  2110   b  of the pulse  2110 . Such may be omitted, for example, where the antenna  21  that transmitted the most recent interrogation signal is not being used to monitor for a response to the interrogation signal. Such may advantageously allow monitoring for the response to occur sooner than would otherwise be possible if the dump portion  2110   b  were needed. 
     Also in contrast to the embodiment of  FIG. 21A , the embodiment of  FIG. 21B  may advantageously eliminate the recovery portion  2110   c  of the pulse  2110 . Such may be omitted, for example, where the antenna  16  that transmitted the most recent interrogation signal is not being used to monitor for a response to the interrogation signal. Such may advantageously allow monitoring for the response to occur sooner than would otherwise be possible if the recovery portion  2110   c  were needed. 
     Removal of the dump portion  2110   b  and/or recovery portion  2110   c  may allow for a more favorable sampling rate or better resolution or may allow a longer noise detection portion, which may significantly enhance performance. 
       FIG. 22  shows signal timing for driving the drive transistors Q 1 , Q 2  ( FIG. 19A ), according to one illustrated embodiment. 
     The custom logic in the FPGA  1708  ( FIG. 17 ) generates the signals  2220   a,    2220   b  to drive the drive transistors Q 1 , Q 2  ( FIG. 19A ) during the transmit portion  2110   a  ( FIG. 21 ) of the pulse  2110 . A transmit (TX) period value is used by the logic of the FPGA  1708  to set the transmit frequency. The low transistor (e.g., Low FET) Q 2  turns ON at the beginning of the transmit period. The Low FET off value controls when the low transistor (e.g., Low FET) Q 2  is turned OFF. The low transistor Q 2  is turned OFF before the high transistor (e.g., High FET) Q 1  is turned ON to avoid a short circuit through the transistors Q 1 , Q 2 . The High FET on value controls when the high transistor (e.g., High FET) Q 1  is turned ON. The High FET Off value controls when the high transistor Q 1  is turned OFF. The high transistor is turned OFF before the low transistor Q 2  is turned ON to avoid a short circuit through the transistors Q 1 , Q 2 . For example, to achieve a transmit frequency of 144.9 KHz, the transmit period should be set to 6.9 μsec. Also for example, a suitable duration that both the low and high transistors Q 1 , Q 2  are OFF may be set to 400 nsec. 
     The ADC converts the signal received from the transponder  24 , if any, from analog to digital. Such conversion may, for example, be performed at a sampling rate of 1 MHz with a 12-bit data resolution. The sampled ADC data is then accumulated together or integrated, for example over 800 measurements or samples, to compute the total summed response signal received from the transponder  24 , if any. 
     The accumulated or integrated received signal may be match filtered with both in-phase and quadrature reference signals to determine the signal magnitude. The received receive signal is matched filtered with a plurality of reference signals, for example with the seven reference signals, for instance as shown in Table 1 below. Some embodiments, may employ match filtering before accumulating or integrating the received signal. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Match Frequency 
               
               
                   
               
             
            
               
                 136 KHz 
               
               
                 139 KHz 
               
               
                 142 KHz 
               
               
                 145 KHz 
               
               
                 148 KHz 
               
               
                 151 KHz 
               
               
                 154 KHz 
               
               
                   
               
            
           
         
       
     
     The maximum value for the matched filters (e.g., seven matched filters) with active transmit is compared with an adjusted detection threshold. If the maximum value is greater than the detection threshold, then a response signal from a transponder  26  is considered as having been detected, and appropriate action is taken. 
     Noise faults may be detected as well as antenna transmit voltage faults. Noise faults may be detected when the matched filter output during the noise detection portion is greater than a noise fault threshold (e.g., a threshold magnitude 2.7 mV over a threshold time, e.g., 7 seconds or threshold magnitude 7 mV over a time threshold of 7 seconds). Antenna transmit voltage faults may be detected when the antenna transmit voltage drops below an antenna voltage fault threshold (e.g., 270 V Peak-to-Peak ). Two environmental faults in a row such as the above, may trigger an Environmental Error Mode, while two normal measurements in a row may return to a normal Scan Mode. Faults in general are discussed in more detail below. Alternatively, the interrogation and detection system may employ a fast Fourier transform approach in lieu of match filtering. 
       FIG. 23A  shows a method  2300  of operating the interrogation and detection system  14 , according to one illustrated embodiment. 
     The method  2300  starts at  2302 . For example, the method  2300  may start on application of power to the interrogation and detection system  12  or in response to activation of a switch by a user such as a clinician, surgeon 
     In response to detecting an application of power, the interrogation and detection system  14  may enter a Power-Up mode. The Power UP mode  502  may, for example, in response to the application of power to the controller  18  and turning ON the switch on the controller  18 . In the Power-Up mode, a Power indicator (e.g., LED) may be turned ON or illuminated, and may remain ON or illuminated as long as the power is applied and the switch is in the ON state. In response to entering the Power UP mode, the software  1800  may perform software initialization, built in tests, and an audio/visual test. If a fault is detected, the software  1800  may progress to a System Fault Mode. If no faults are detected, the software  1800  may turn a System Ready indicator (e.g., LED green), and enter an antenna Detection Mode. In the System Fault mode, the software  1800  may cause an indication of the detection of a system fault by blinking a System Ready indicator (e.g., LED) yellow, and/or issuing a sequence of rapid beeps or other sounds. The corrective action for the System Fault Mode may be to cycle power to reinitiate the Power Up mode. Continued failure indicates a failed controller  18 . 
     In the Antenna Detection Mode, the software  1800  checks for antennas  16  connected to the controller  18 . The Antenna Detection Mode may be indicated by turning the System Ready indicator (e.g., LED) green and turning the Antenna Ready indicator (e.g., LED) OFF. If no antenna  16  is detected, the software  1800  remains in the Antenna Detection Mode. If one or more antennas  16  are detected, the software  1800  makes note of the total number of antennas and progresses to the Antenna Initialization Mode. 
     At the start of the Antenna Initialization Mode, after the detection of the antennas  16 , the software  1800  may turn the Antenna Ready indicator (e.g., LED) yellow and optionally check for the presence of a respective fuse coupled to antennas  16 . If a fuse is found, the software  1800  may attempt to blow the fuse and verify that the fuse was correctly blown. After the fuse is blown the software  1800  may verify that respective antenna  16  is operating within tolerances. The software  1800  may indicate that the antenna  16  is ready by turning the Antenna Ready indicator green. The software  1800  may also start a timer which will allow the antenna  16  to be disconnected and reconnected to the controller for a period to time (e.g., 5 hours) after the fuse is blown. The controller  18  may determine the adjustments or fine tuning to be made about the center frequencies or channels during Antenna Initialization Mode. In particular, the controller  18  may determine the particular frequency in each of the frequency bands that elicits the response with the highest voltage. The controller  18  may determine such be varying the capacitance of the LC circuit using the switched capacitors C 33 -C 36  during the Antenna Initialization Mode. The particular combination of switched capacitors C 33 -C 36  which achieved the response with the highest voltage may then be automatically employed during the Scan Mode (discussed below) to adjust or fine tune about the center frequency or channel in each broad band of transmission. Other approaches to determining the fine tuning may be employed. 
     If the software  1800  does not successfully complete the Antenna Initialization Mode, the software  1800  enters an Invalid Antenna Mode. If the software  1800  successfully completes the Antenna Initialization Mode, the software  1800  progresses to the Scan Mode to automatically start scanning. In the Invalid Antenna Mode, the software  1800  may blink the Antenna Ready indicator yellow and issues a slow beep pattern. The Invalid Antenna Mode may be entered in response to any of the following conditions: 1) the antenna  16  connected to the controller  18  is out of tolerance; 2) the controller  18  is unable to blow the fuse of the antenna  16 ; 3) the antenna  16  does not have a fuse and more than the set time period has past (e.g., 5 hours) since a fuse was blown; 4) the antenna  16  does not have a fuse and the controller  18  has been restarted; 5) the antenna  16  has been connected to the controller  18  for more than the set time period (e.g., 5 hours); 6) the antenna  16  is detuned due to close proximity to metal. The corrective action for the Invalid Antenna Mode is to remove the invalid antenna  16  and attach a new antenna  16  to the controller  18  that contains a fuse or to reconnect the antenna  16  while holding it in the air at least 2 feet away from large metallic objects. The software  1800  enters the Scan Mode when the antennas  16  are ready and the operator presses a Start/Stop button. The software  1800  may issue a short three beep pattern via the speaker or beeper when entering the Scan Mode to identify the entry to the user. 
     In the Scan Mode, the software  1800  may continuously or periodically perform the following functions: 1) look for response signals from transponders  24 ; 2) monitor the noise level; 3) insure the antennas  16  are connected and operating correctly; and 4) blink the appropriate indicator in a circular pattern. The interrogation and monitoring for response may be performed using a detection cycle, such as that set out in  FIGS. 21A, 21B  and the description related to those Figures. While, not specifically set out in  FIG. 18 , such may also include optimization of signal to noise ratio, such as set out in  FIG. 20  and the description related thereto. 
     At  2304 , a timer starts. The timer allows a limit to be set on the amount of time spent scanning for a transponder  24  (i.e., scan maximum time interval). Alternatively, a counter could be employed to set a limit of the number of iterations that the antennas  16  are successively employed to transmit interrogation signals. 
     At  2306 , an antenna counter i is set, for example set to 1. The antenna counter allows the method  2300  to successively iterate through each of a number N of antennas  16  to transmit the interrogation signal. The number N of antennas  16  may have been determined during the Antenna Detection Mode. 
     At  2308 , an interrogation signal is transmitted from an i th  antenna  16 . In particular, the FPGA  1708  ( FIG. 17 ) may cause one of the plug-in boards to cause the antenna  16  coupled thereto to transmit an interrogation signal. The interrogation signal may advantageously take the form of an unmodulated interrogation signal, for example in the radio or microwave portions of the electromagnetic spectrum. 
     At  2310 , one or more antennas  16  are monitored for a response to the interrogation signal. In particular, a number of the plug-in boards may monitor the respective antenna coupled thereto for the response to the interrogation signal. For example, all of the antennas  16  may be monitored to a response to the interrogation signal. Alternatively, all except the antenna  16  that transmitted the most recent interrogation signal (i.e., i  th  antenna) may be monitored for a response to the interrogation signal. As another alternative, some subset of all of the antennas  16  may be monitored for a response to the interrogation signal. The response may advantageously take the form of an unmodulated response signal, for example in the radio or microwave portions of the electromagnetic spectrum. 
     At  2312 , it is determined if a response to the interrogation signal was received. For example, the FPGA  1708  ( FIG. 17 ) may poll or otherwise monitor each of a number of plug-in or analog boards to determine if a response signal was detected via any of the antennas coupled to those plug-in or analog boards. If a response to the interrogation signal was received, a suitable indication is provided at  2314 , and the method  2300  terminates at  2316 . For example, when an appropriate response signal from a transponder  24  is detected while in Scan Mode, the software  1800  may turn ON an amber DETECT indicator (e.g., LEDs) and/or provide an audible alarm. The alarm may, for example, beep a continuous solid tone as long as the transponder is detected, with a minimum of beep duration of, for instance 0.5 second. If a response to the interrogation signal was not received, it is determined whether there are additional antennas to transmit the interrogation signal from at  2318 . 
     If there are additional antennas to transmit from, the counter is incremented at  2320  and control returns to  2308  to transmit via the next i+1 th  antenna  16 . This can allow iteration through a number of antennas  16  as the antenna that transmits the interrogation signal. As previously explained, antennas  16  may be operated to transmit an interrogation signal in an order of appearance along a longitudinal axis of the patient support surface or may be operated in any other order. Also as previously noted, all or some lesser number of antennas may be employed to transmit the interrogation signal in any single pass or iteration through the set or subset of antennas  16 . 
     If there are not further antennas to transmit the interrogation signal from, it is determined if a time limit (i.e., scan maximum time interval) has been exceeded at  2322 . If the time limit has been exceeded the method  2300  terminates at  2316 . If the time limit has not been exceeded, the counter is reset at  2306 . This allows multiple passes through the use of each antenna in a set or subset of antennas  16  as the interrogating antenna  16 . When the operator or user pushes the Start/Stop button or the a scan maximum time interval (e.g., 4 minute) has been reached, the software  1800  may issue a short three beep pattern and return to the Antenna Ready Mode. 
     If the software  1800  detects that one of the antennas  16  is disconnected while in the Scan Mode, the software  1800  enters the Scan Fault Mode. In the Scan Fault Mode, the software  1800  may issue a sequence of rapid beeps and blink ON and OFF the amber DETECT indicator. The Scan Fault Mode can be cleared by pushing the Start/Stop button. The software  1800  will automatically clear the scan fault mode after 10 beeps. 
     While in the Scan Mode, if excess noise or loss of transmit signal is detected, the software  1800  may progress to the Environment Error Mode. In the Environment Error Mode, the software  1800  may issue or produce an appropriate indication. For example, the software  1800  may cause the production of a sequence of slow beeps and the blinking ON and OFF the green circle indicator. The corrective action for the Environment Error Mode is to reposition the antenna with respect to any large metal objects or sources of electrical interference. The software  1800  may automatically stop the scan if the environment error condition lasts for more than a set time or number of beeps (e.g., 5 beeps). 
       FIG. 23B  shows a method  2310   b  of monitoring all antennas for a response to an interrogation signal, according to one illustrated embodiment. 
     At  2318 , an interrogation and detection system monitors all antennas  16  for a response to the interrogation signal. 
       FIG. 23C  shows a method  2310   c  of monitoring all antennas except a transmitting antenna for a response to an interrogation signal, according to one illustrated embodiment. 
     At  2320 , an interrogation and detection system monitors all antennas  16  for a response to the interrogation signal, except the antenna  16  the transmitted the most recent interrogation signal. 
       FIG. 24A  shows a method of operating an interrogation and detection system to detect transponders  2400   a,  according to one illustrated embodiment. 
     The method  2400   a  starts at  2401 . For example, the method  2400   a  may start when the interrogation of detection system is turned ON, or when power is supplied, or in response to a call from a procedure or function. 
     At  2402 , an antenna counter I is set, allowing the method  2400   a  to iterate through one or more antennas (n) of the interrogation and detection system. The interrogation and detection system iterates through the antennas by transmitting interrogations signals successively from each of a number of the antennas, typically one antenna at a time, and monitoring or listening for response signals on one or more of the antennas. 
     At  2403 , the interrogation and detection system measures averaged noise and averaged signals. At  2404 , the interrogation and detection system processes the averaged noise and averaged signal, and at  2405  determines whether a transponder (i.e., return or response signal from transponder) has been detected. 
     In the embodiment illustrated in  FIG. 24A , the interrogation and detection system requires more than one (e.g., two) successive detections of the transponder to conclude that the signal detected indicates the presence of a transponder. Such prevents against false positive determinations. Hence, at  2406 , the interrogation and detection system again measures averaged noise and averaged signals. At  2407 , the interrogation and detection system again processes the averaged noise and averaged signal and at  2408  determines whether a transponder (i.e., return or response signal from transponder) has been detected. 
     If a transponder has been detected an adequate number of times (e.g., twice), the interrogation and detection system provides notification at  2409 . Notification may, for example, include sending an electrical or optical signal and/or producing a visual, aural or tactile alert to a user (e.g., medical service provider). If the interrogation and detection system determines that a transponder has not been detected at either  2405 ,  2407 , control passes to  2410 . 
     At  2410 , the interrogation and detection system determines whether there are further antennas to iterate through. If so, the antenna counter is iterated, and control returns to  2403 . If not, the method  2400   a,  may terminate at  2412 . Alternatively, the method  2400   a  may return to  2402  and continuously repeat as long as power is supplied to the interrogation and detection system. 
       FIG. 24B  shows a method of operating an interrogation and detection system to sample noise and responses and to adjust sampling times and perform noise correction  2400   b,  according to one illustrated embodiment, the method useful with the method of  FIG. 24A . 
     The method  2400   b  starts at  2420 . For example, the method  2400   b  may start in response to a call from a procedure that implements the method  2400   a.  The method  2400   b  may, for example, be employed in measuring averaged noise and averaged signal  2403  ( FIG. 24A ). 
     At  2421  a transmitter of the interrogation and detection system is OFF (i.e., not transmitting interrogation signals) or is turned OFF if not already OFF. This starts a noise detection portion of a transponder detection cycle. At  2422  ambient noise received by the antennas is sampled. For example, ambient noise detected by all of the antennas may be sampled by the interrogation and detection system. 
     At  2423 , the interrogation and detection system determines noise cancellation factors for each antenna. The interrogation and detection system may employ a variety of approaches for determining the noise cancellation factors, for example computing a noise cancellation factor for each antenna based on ambient noise detected on all of the other antennas except the antenna for which the respective noise cancellation factor is being computed. 
     At  2424 , the interrogation and detection system determines a sample averaging time for sampling nose based on the measured ambient noise level. At  2425 , the interrogation and detection system determines a sample response averaging time based on the measured ambient noise level. The sample averaging times determine how long samples of noise or response will be averaged in determining noise or response measurements or levels. Such dynamic determination of sample averaging times allows the interrogation and detection system to accommodate a changing noise environment. For example when a piece of equipment is introduced or removed from the environment or a piece of equipment turns ON or OFF, or otherwise changes amount or frequency distribution of noise it generates in the environment. Thus, the interrogation and detection system may obtain adjust the noise floor to increase range in real time or almost real time in response to the actual noise in the environment. 
     At  2426 , the interrogation and detection system averages noise corrected noise samples for the noise sample averaging time. As noted above, the noise sample averaging time may be determined dynamically. The noise samples may be corrected, for example, using the determined nose cancellation factors. 
     At  2427 , the interrogation and detection system transmits interrogation signal(s) from one of the antennas. As previously noted, the interrogation and detection system may iterate through the antennas one at a time, for example using an antenna counter I. At  2428 , the interrogation and detection system averages noise corrected responses for the response averaging time. As noted above, the response sample averaging time may be determined dynamically. The response samples may be corrected, for example, using the determined nose cancellation factors. It is noted that as received, the response signals typically contain a mix of signal and noise, hence is generally referred to herein as responses. After noise correction, the result is theoretically pure signal. In practice there may be some still be some amount of noise remaining, however the signal will typically dominate the noise after noise correction. 
     The method  2400   b  may terminate at  2429 , for example until called again by the procedure that implements  2400   a  ( FIG. 24A ) to transmit interrogation signals from a next antenna. 
       FIG. 24C  shows a method of operating an interrogation and detection system to determine whether a transponder has been detected  2400   c,  according to one illustrated embodiment, the method useful with the method of  FIG. 24A . 
     The method  2400   c  starts at  2440 . For example the method  2400   c  may start in response to a call from a procedure that implement the method  2400   a  ( FIG. 24A ). The method  2400   c  may, for example, be employed in processing transponder detection  2404  ( FIG. 24A ). 
       FIGS. 25A-25E  are flow diagrams of methods of operating an interrogation and detection system by measuring and/or compensating for noise, according to various illustrated embodiments, the methods useful with the method of  FIG. 24A . 
     At  2441 , the interrogation and detection system transforms the averaged noise and response samples from a time domain to a frequency domain. The interrogation and detection system may, for example, perform fast Fourier transforms on the averaged samples. At  2442 , the interrogation and detection system may find a peak of response fast Fourier transformed spectrum data. 
     At  2443 , the interrogation and detection system determines an amplitude threshold based on the averaged noise level. At  2444 , the interrogation and detection system determines whether the response amplitude is equal or exceeds the determined amplitude threshold. If so, control passes to  2445 . If not, control passes to  2448  where a signal may optionally be produced indicative of no tag being detected. 
     At  2445 , the interrogation and detection system determines whether the signal is in appropriate frequency range. While the frequency range is illustrated as being between 137 KHz and 165 KHz, inclusive, other frequency ranges may be employed depending on the specific structure and frequency of the transponders. The disclosed embodiments are particular suited for use with low Q transponders in which the response frequencies of various transponders are not closely controlled, advantageously allowing large manufacturing tolerances to reduce cost. If the signal is in the appropriate frequency range, control passes to  2446 , otherwise control goes to  2448 . 
     At  2446 , the interrogation and detection system determines the Q value of the response. For example, the interrogation and detection system may compute the slope of the received signal decay at a number of windows (e.g., 5 windows). At  2450 , the interrogation and detection system determines if the determined Q value is greater than or equal to a threshold Q value (e.g., 35). While the threshold Q value is illustrated as being 35, other Q values may be employed depending on the Q value(s) of the specific transponders. If the tag response Q value below the Q value threshold, the interrogation and detection system determines that a transponder has been detected at  2450 . If the tag response Q value is equal or above the Q value threshold, the interrogation and detection system determines that a tag has not been detected  2448 . 
     The method  2400   c  may terminate at  2449 , for example until called again by the procedure that implements the method  2400   a  ( FIG. 24A ). 
       FIG. 25A  shows a method  2500   a  of measuring or sampling responses, according to one illustrated embodiment. 
     In particular, at  2510 , the interrogation and detection system measures or samples response on all antennas or antenna channels. 
       FIG. 25B  shows a method  2500   b  of determining noise estimates, according to one illustrated embodiment. 
     In particular, at  2520 , the interrogation and detection system determines noise estimates based on measures or samples from all antennas or antenna channels other than the respective antenna or antenna channel for which the noise estimate will provide the compensation factors. 
       FIG. 25C  shows a method  2500   c  of determining noise estimates, according to one illustrated embodiment. 
     In particular, at  2530 , the interrogation and detection system determines an average noise estimate based on averaging of measures or samples from all antennas or antenna channels other than the respective antenna or antenna channel for which the noise estimate will provide the compensation factors. 
       FIG. 25D  shows a method  2500   d  of determining noise estimates, according to one illustrated embodiment. 
     In particular, at  2540 , the interrogation and detection system determines an average noise estimate based on averaging of measures or samples from all antennas or antenna channels other than the respective antenna or antenna channel for which the noise estimate will provide the compensation factors. The averaging includes averaging of noise detection portions which occur both before and after an interrogation portion of a transponder detection cycle. Such allows the interrogation and detection system to essentially determine whether the noise is consistent, periodic, or non-random. 
       FIG. 25E  shows a method  2500   e  of determining noise estimates, according to one illustrated embodiment. 
     In particular, at  2550 , the interrogation and detection system determines an average noise estimate by determining a decomposed least squares average of noise measurements or samples. While a decomposed least squares approach is illustrated, a wide variety of other approaches may be employed (e.g., Bayesian averaging). 
       FIG. 25F  shows a method  2500   f  of determining noise estimates, according to one illustrated embodiment. 
     In particular, at  2560 , the interrogation and detection system compares noise measured from before an interrogation portion of the transponder detection to noise measured after the interrogation portion of the transponder detection cycle. A difference between the noise measurements may represent variation in noise. At  2562 , the interrogation and detection system may increase the sample averaging time for sampling responses to interrogation signals if a determined difference (i.e., variation in noise) is greater than a variation threshold. Such may allow the interrogation and detection system to accommodate different noise sources, such as those that produce periodic or non-random versus those that produce random noise. 
       FIG. 26A  shows a measured or sampled response  2600   a,  according to one illustrated embodiment. 
     The response  2600   a  in the time domain was measured in an environment which contained a noise source (e.g., fluoroscope) but no transponder. The response  2600   a  has not been subjected to noise cancellation or adjustment. The amplitude (Y-axis) is in mV, while the time (X-axis) is in ps. 
       FIG. 26B  shows a measured or sampled response  2600   b,  according to one illustrated embodiment. 
     The response  2600   b  is the response  2600   a  having been subjected to noise cancellation or adjustment. Most of the peaks have noticeably been diminished. 
       FIG. 26C  shows a measured or sampled response  2600   c,  according to one illustrated embodiment. 
     The response  2600   c  is the response  2600   a  after a fast Fourier transformation to the frequency domain. The amplitude (Y-axis) is in mV, while the time (X-axis) is in frequency. There are three distinctive peaks of noise. 
       FIG. 26D  shows a measured or sampled response  2600   d,  according to one illustrated embodiment. 
     The response  2600   d  is the noise cancelled response  2600   b  after a fast Fourier transformation to the frequency domain. The peaks have been noticeable diminished, indicating that almost all noise has been removed by the noise cancelation. 
       FIG. 27A  shows a sampled or measured response  2700   a,  according to one illustrated embodiment. 
     The response  2700   a  in the time domain was measured in an environment which contained a noise source (e.g., fluoroscope) and a transponder. The response  2700   a  has not been subjected to noise cancellation or adjustment. The amplitude (Y-axis) is in mV, while the time (X-axis) is in ps. 
       FIG. 27B  shows a measured or sampled response  2700   b,  according to one illustrated embodiment. 
     The response  2700   b  is the response  2700   a  after being subjected to noise cancellation. While many the peaks (associated with noise) have noticeably been diminished, other distinctive peaks remain. 
       FIG. 27C  shows a measured or sampled response  2700   c,  according to one illustrated embodiment. 
     The response  2700   c  is the response  2700   a  after a fast Fourier transformation to the frequency domain. The amplitude (Y-axis) is in mV, while the time (X-axis) is in frequency. There are three distinctive peaks. 
       FIG. 27D  shows a measured or sampled response  2700   d,  according to one illustrated embodiment. 
     The response  2700   d  is the noise cancelled response  2700   b  after a fast Fourier transformation to the frequency domain. Two of the three peaks have been noticeable diminished, indicating that almost all noise has been removed by the noise cancelation, and leaving a single distinctive peak at the resonant frequency of the transponder. 
     The above described embodiments may improve a detection range versus noise performance over other more conventional approaches. The embodiment of the present disclosure may be capable of achieving far superior performance, having greater detection range in even mildly noisy environments. Such is particularly advantageous in environments such as operating theaters, and substantially helps reduce false readings (e.g., false positives, false negatives). Thus, such may provide the level of performance demanded by hospitals and doctors. 
     Thus, during each of a plurality of detection cycles, the interrogation and detection system performs a number of acts or operations. The interrogation and detection system receives unmodulated electromagnetic signals during a noise detection portion of the detection cycle. 
     The interrogation and detection system determines a noise value indicative of a noise level that corresponds to a highest one of a number N of samples or measurements of the unmodulated electromagnetic signals received during the noise detection portion of the detection cycle, where the number N is greater than one. The interrogation and detection system may determine a noise value indicative of a noise level based at least in part on the unmodulated electromagnetic signals received during the noise detection portion of the detection cycle by setting the noise value based on the highest one of six samples or measurements of the unmodulated electromagnetic signal received during the noise detection portion of the detection cycle. The interrogation and detection system adjusts a signal detection threshold based at least in part on the determined noise value of at least one of the detection cycles. The interrogation and detection system may adjust the signal detection threshold by adjusting the signal detection threshold based at least in part on a first number of determined noise values indicative of a noise level during at least one noise detection portion that occurred before the receive response portion of a first one of the detection cycles and a second number of determined noise values indicative of a noise level during at least one noise detection portion that occurred after the receive response portion of the first one of the detection cycles. The interrogation and detection system may adjust the signal detection threshold based at least in part on the determined noise value of at least one of the detection cycles by adjusting the signal detection threshold to be approximately twice an average of at least one of the first and the second number of determined noise values. The interrogation and detection system may, for example, adjust the signal detection threshold based at least in part on the determined noise value of at least one of the detection cycles by adjusting the signal detection threshold to be approximately twice a greatest one of at least one of the first and the second number of determined noise values. 
     The interrogation and detection system emits at least one electromagnetic interrogation signal during a transmit portion of the detection cycle. The interrogation and detection system receives unmodulated electromagnetic signals during a receive response portion of the detection cycle that follows the transmit portion of the detection cycle. 
     The interrogation and detection system determines the presence or absence of a transponder based at least in part on a number M of samples or measurements of the unmodulated electromagnetic signals received during the detection cycle and the adjusted signal detection threshold, where the number M is greater than one. A ratio of N:M may be at least equal to 4. N may be equal to about 200 and M may be equal to about 800. For example, the interrogation and detection system may determine the presence or absence of a transponder by comparing a maximum value of a plurality of matched filter outputs with the adjusted signal threshold. 
     In some embodiments, the interrogation and detection system determines if an output of at least one matched filter during the noise detection portion of the detection cycle exceeds a noise fault threshold indicative of a noise fault. Such may be employed to prevent extraneous objects (e.g., metal table, EKG leads, etc.) from producing a positive result. For example, the interrogation and detection system may determine if the output of the at least one matched filter during the noise detection portion of the detection cycle exceeds the noise fault threshold for a defined period of time. The interrogation and detection system may then terminate the detection cycle in response to the output of the at least one matched filter exceeding the noise fault threshold for the defined period of time. 
     The interrogation and detection system may convert the received signal(s) from the time domain to the frequency domain spectrum. Such may be employed, for example in lieu of the match filtering. The interrogation and detection system may, for example, perform a Fourier transform, for instance a fast Fourier transform such as a 256 point fast Fourier transform. Suitable algorithms and/or sets of software code for performing such are available or can be written. The interrogation and detection system may search the frequency domain spectrum to determine the object with the strongest resonance in a defined frequency band. For example, the interrogation and detection system may search the frequency domain spectrum from about 120 KHz to about 175 KHz. An amplitude of the resonant object may be computed as the sum of the resonant power plus and minus 2 fast Fourier transform bins from the peak resonance frequency. This approach may provide a more accurate measurement of power than simply using the peak value. The frequency of the resonant object may be computed using an interpolation approach. This approach may provide a more accurate determination of resonant frequency than simply using the fast Fourier bin number. The interrogation and detection system may determine the presence or absence of a transponder based at least in part on a frequency of the unmodulated electromagnetic signals received during the detection cycle being within a defined frequency range. The defined frequency range may extend from about 137 KHz to about 160 KHz. 
     The interrogation and detection system may ignore any unmodulated electromagnetic signals received during a recovery portion (if any) of the detection cycle that precedes the receive response portion of the detection cycle. Such may be useful in preventing false positives (i.e., tag detections) from being triggered by the transmission of the interrogation or excitement signals. 
     The interrogation and detection system may determine a Q value (i.e., Quality factor) of the resonant object from a signal decay slope for the received unmodulated electromagnetic signal(s) returned by the resonant object. For example, the interrogation and detection system may determine a Q value of the unmodulated electromagnetic signals received during the detection cycle being at least equal to a threshold Q value. The threshold Q value may, for example, be 35. The interrogation and detection system may, for example, use multiple windows, for instance five (5) window positions may provide suitable results. The interrogation and detection system may determine the presence or absence of a transponder based at least in part on a Q value of the unmodulated electromagnetic signal(s) received during the detection cycle. The interrogation and detection system may preferably employ the Q value determination in conjunction with determination based on the frequency and on the determination based on the adjusted signal detection threshold. 
     Consequently, in some embodiments the tag detection may advantageously be based on the received unmodulated electromagnetic signal(s) satisfying all three conditions: 1) measured amplitude is above a threshold, which may be an adjustable threshold, 2) measured frequency is between a lower limit and an upper limit, and 3) measured Q value is above a minimum Q threshold. Interference, for example from RFID tags or EKG cables, are rejected when any of the following three conditions are satisfied: a) measured frequency is below the lower frequency limit, b) measured frequency is above the upper frequency limit, or c) measured Q value is below the threshold Q value. Such may provided significantly superior results over previous approaches, preventing false positives which could otherwise cause a patient to remain open for longer period of time during surgery and tie up hospital personnel and resources. 
     The above description of illustrated embodiments, particularly the use of multiple antennas, the pulsed wide band frequency hopping with dynamic adjustment of the transmission frequency in the various frequency bands and the use of switched capacitors to achieve such, advantageously permit the use of inexpensive transponders which are not accurately tuned to a chosen or selected resonant frequency. This is in marked contrast to the approach typically taken with other types of resonant transponders (i.e., transponders without memory). Such approaches typically interrogate or excite the resonant transponder using narrow frequency bands centered closely on specific frequencies, to achieve a selected resonant response from a highly accurate transponder in order to differentiate signal from noise. This is also in marked contrast to the approach typically taken with radio frequency identification (RFID) tags whether active or passive, which also typically employ are narrow band to achieve a selected response from a highly accurate RFID tag. 
     The interrogation and detection system herein described may further implement a handheld wand  2802  as illustrated in  FIG. 28 . Wand  2802  comprises a loop antenna  2806 , a handle  2808 , and a cord  2810 . The wand  2802  may be configured to interface with the interrogation and detection system. The wand  2802  may be connected to the controller  18  by means of the chord  2810 . The wand  2802  may be waved over the patient on the patient support structure  26  while emitting an interrogation signal to excite any transponder  24  which may be in or near the patient. The antennas  16   a - 16   f  may then all be used to detect a signal from the transponder as previously described. In one embodiment the controller  18  controls the wand  2802 . In one embodiment the wand  2802  emits an interrogation signal and monitors for a response from a transponder  24 . In one embodiment the wand  2802  operates independent of the antennas  16  and the controller  18 . In one embodiment the wand  2802  is wirelessly operated. In one embodiment the wand  2802  only detects a transponder and does not emit an interrogation signal. Many other implementations of the wand  2802  will be apparent to those of skill in the art in light of the illustrated embodiments. For example, the wand  2802  may be implemented in a form other than a loop antenna. The illustrated embodiments are given only by way of non-limiting example. 
     In some embodiments, the wand  2802  may interact (e.g., inductively) with the other antennas  16  and/or the transponders to, for example, advantageously increase sensitivity and/or range. For example, the antennas  16  may emit interrogation signals and the wand  2802  may be used to detect return or response signals from the transponders. Alternatively, the wand  2802  may emit interrogation signals and the antennas  16  may be used to detect return or response signals from the transponders. Also for example, an electromagnetic field may be set up between the wand  2602  and one or more of the antennas  16 , and disturbances of the electromagnetic field caused by the presence of a transponder therein detected. Other approaches that combined the wand  2802  and one or more of the antennas  16  may be advantageously employed. 
     The above-described interrogation and detection system  14  may additionally be utilized to reduce the total number of wired devices used in a medical procedure environment such as a surgical environment and attendant clutter associated with such wired devices. In an operating room or even in most modern patient rooms or clinician&#39;s offices there is typically a large number of electronic instruments and equipment used to aid in surgery. This may include various medical instruments which monitor the vital signs or other characteristics or aspects of the patient and hence which may provide telemetry (telemetry medical instruments). A non-exhaustive list of these medical telemetry instruments includes EKG machines, other types of electrogram devices, pulse oximeters, intracranial pressure monitors, blood pressure monitors, thermometers or other temperature sensitive devices, pH sensors, electrical conductivity sensors, etc. There may also be life support equipment, for example, cardiopulmonary bypass machines, ventilators, intra-aortic balloon pumps, an infusion pumps, etc. All of these instruments may comprise one or more wires including power cords and wires that extend between the patient and the instrument and/or monitors or displays. These wires may be an obstacle to medical personnel performing or assisting in the surgery. This may put the patient at risk, as well as increase the risk of damaging the equipment. Additionally, many of these cords and wires must be sterilized after each use. Sterilizing a wire can be extremely expensive since inventory control must be maintained, wires are typically difficult to sterilize, and repeated sterilization may shorten the useful life of the wire. 
     The interrogation and detection system  14  described herein may advantageously enable the wireless operation of many systems and instruments in a surgical environment. As described above in relation to  FIGS. 1-28  the interrogation and detection system  14  may comprise antennas  16  embedded in a patient support structure  26 , or situated in other configurations throughout the operating room. The interrogation and detection system  14  may further comprise a controller  18  configured to control the operation of the antennas  16 . The antennas  16  and controller  18  comprise a useful infrastructure which reduces a total number of wires used in the vicinity of a patient. The reduction of wires can reduce complications and costs of surgery. 
       FIG. 29  shows an environment in which medical procedures (e.g., therapeutic and/or diagnostic medical procedures) are performed, according to one illustrated embodiment. As previously noted, the medical procedure environment may take a variety of forms such as an operating room or theater, a patient room, examination room, a clinician&#39;s office, etc. 
     The medical procedure environment includes a plurality of antennas  2916   a - 2916   f  (collectively  2916 ). As illustrated, some or all of the antennas  2916  may be carried by a patient support structure  2926  (e.g., operating table, bed, pads, mattress). Alternatively, one or more of the antennas  2916  may be located elsewhere in the medical procedure environment, for example carried by a light fixture or associated shade, a curtain or drape, etc. 
     The medical procedure environment may include a controller  2918  communicatively coupled to one or more of the antennas  2916 . The controller  2918  is preferably communicatively coupled to the antenna(s)  2916  via one or more wired communications channels, for example via one or more cables, for instance shielded coaxial cables (not shown in  FIG. 29 ). The controller  2918  may, for example, be positioned on or within a pedestal  2928  which supports the patient support structure  2926 . 
     As previously described, one or more of the antennas  2916  may emit interrogation signals and receive responses to interrogation signals in order to detect a presence or absence of transponders which mark various types of objects used in medical procedures, for instance instruments, implements, and various other supplies such as sponges, pads, gauze. Thus, the controller  2918  may provide a notification (e.g., visual, aural, tactile) in response to a detection of a presence or absence of a transponder in the range of one or more of the antennas  2916 . Advantageously, one or more of the antennas  2916  may also be used to provide wireless communications with one or more pieces of dedicated medical diagnostic, therapeutic or monitoring equipment  2959   a,    2059   b  (collectively  2959 ). The dedicated medical diagnostic, therapeutic or monitoring equipment  2959  may include one or more antennas  2961   a,    2961   b,  receivers, transmitters and/or transceivers (not shown in  FIG. 29 ) to provide wireless communications to and/or from the dedicated medical diagnostic, therapeutic or monitoring equipment  2959 . As explained in more detail with respect to other Figures below, the antennas  2916  may serve as a relay between pieces of dedicated medical diagnostic, therapeutic or monitoring equipment  2959 , for example as a relay between sensors (not illustrated in  FIG. 29 ) and a dedicated controller or control system of a piece of dedicated medical diagnostic, therapeutic or monitoring equipment  2959 , remotely located from the sensors. Additionally, or alternatively, the controller  2918  of the interrogation and detection system  2914  may serve as a user interface to display information from and/or to interact with the pieces of dedicated medical diagnostic, therapeutic or monitoring equipment  2959 , for instance as described directly below. 
     A display  2950  and a user input device  2952  may be communicatively coupled to the controller  2918 . The display  2950  may be any screen or monitor (e.g., LCD panel, CRT) suitable to display information and/or a user interface (e.g., graphical user interface). The display  2950  may be a touch-sensitive display device, capable of functioning as a user input device of a user interface. The display  2950  may be a stand alone, separate piece of equipment. Alternatively, the display  2950  may be integrated into the controller  2918  or the patient support structure  2926 . 
     The display  2950  and/or user input device  2952  may be a dedicated medical telemetry terminal or part of a piece of dedicated medical diagnostic, therapeutic or monitoring equipment  2959 . Alternatively, the display  2950  and/or user input device  2952  may be general purpose equipment capable of providing display of information from, and/or control over, a variety of pieces of dedicated medical diagnostic, therapeutic or monitoring equipment  2959 . 
     The display  2950  may be configured to display medical telemetry or data received via antennas  2916 . The medical telemetry or data may be received by one or more of the antennas  2916  from one or more of a variety of medical telemetry devices such as dedicated medical diagnostic, therapeutic or monitoring equipment  2959  (e.g., EKG sensors or electrodes, intra-cranial pressure sensors, pulse oximetry sensors or pulse oximeters, or any other of numerous medical measurement or sensor devices). The medical telemetry or data may be related to a characteristic or physiological condition of a patient. Alternatively, or additionally, the telemetry or data may be related to one or more operational characteristics of the dedicated medical diagnostic, therapeutic, or monitoring equipment themselves, whether equipment dedicated to medically related measurement or sensing, or equipment that performs a therapeutic function on the patient. The telemetry or data may be conveniently displayed by the display  2928 , either in processed and/or raw form. Processing may be preformed by the dedicated medical diagnostic, therapeutic or monitoring equipment  2959  or by the controller  2918  of the interrogation and detection system  2914 . Telemetry or data from multiple pieces of dedicated medical diagnostic, therapeutic or monitoring equipment  2959  may be displayed sequentially or concurrently (e.g., substantially simultaneously) on the display  2950 . 
     One or more of the antennas  2916  of the interrogation and detection system  2914  may communicate with the dedicated medical diagnostic, therapeutic or monitoring equipment, for example receiving data from, and/or providing data, instructions and/or new programs to the dedicated medical diagnostic, therapeutic or monitoring equipment. For example, one or more of the antennas  2916  may relay commands to the dedicated medical diagnostic, therapeutic or monitoring equipment such as a cardiopulmonary bypass machine, ventilator, intra-aortic balloon pump, infusion pump, etc. Also for example, one or more of the antennas  2916  may relay data or telemetry from the dedicated medical diagnostic, therapeutic or monitoring equipment, such as an EKG electrodes, pulse oximetry sensors, blood pressure sensors, intracranial pressure monitor sensors, etc. The user input device (e.g., keyboard, keypad, pointer device, and/or graphical user interface)  2952  can be used to instruct the controller  2918  to control one or more of the dedicated medical diagnostic, therapeutic or monitoring equipment in wireless communication with the interrogation and detection system  2914 . These pieces of dedicated medical diagnostic, therapeutic or monitoring equipment or instruments (e.g., life support equipment) are not shown in  FIG. 29 , but one or more may be present in the environment in which medically related diagnostic, therapeutic and/or monitoring procedures are performed. Exemplary embodiments of dedicated medical diagnostic, therapeutic or monitoring equipment which can communicate via one or more of the antennas  2916  are described below. 
     The medical procedure environment may include one or more automatic data collection readers  2990   a,    2990   b  (collectively  2990 , only two illustrated). The automatic data collection readers  2990  are dedicated to reading and/or writing data to one or more data carriers  2924   a - 2924   d  (collectively  2924 , only three illustrated), hence may be denominated as dedicated automatic data collection readers herein and in the claims. Such denomination means that the dedicated automatic data collection readers  2990  perform only reading and/or writing to data carriers  2924 , and are not otherwise used to measure or sense physiological conditions of a patient or therapeutically interact with a patient. 
     The dedicated automatic data collection readers  2990  may, for example, take the form of, or include, a machine-readable symbol reader  2990   a,  for instance a scanner or imager capability of optically reading machine-readable symbols  2924   c  (e.g., barcode, area or matrix code or stacked code symbols). Also for example, the dedicated automatic data collection readers  2990  may take the form of, or include, a radio frequency identification (RFID) reader  2990   b,  for instance an RFID interrogator capability of wirelessly reading information from an RFID data carrier such as an RFID tag  2924   b.  The dedicated automatic data collection readers  2990  may combine machine-readable symbol and RFID reading capabilities. Suitable dedicated automatic data collection readers  2990  may be commercially available from Intermec Technologies or Symbol Technologies. Additionally, or alternatively, the dedicated automatic data collection readers  2990  may be capable of reading or writing to other data carriers such as optical memories, touch memories (e.g., available from Dallas Semiconductor), magnetic stripes, etc. 
     The data carriers  2924  may take a large variety of forms, including but not limited to labels or tags that carry machine-readable symbols or that otherwise encode machine-readable information (e.g., RFID, optical memories, touch memories, magnetic stripes). The data carrier  2924  may advantageously encode information in two or more forms, for example an RFID transponder that carries or bears a machine-readable symbol. Also for example, the data carrier  2924  may include a transponder and an RFID transponder. Details of such are discussed in U.S. patent application Ser. No. 12/472,199 filed May 26, 2009, as well as in U.S. provisional patent applications Ser. Nos. 61/056,299 and 61/102,749, filed May 27, 2008 and Oct. 3, 2008, respectively, and which are incorporated by reference herein in their entireties. 
     The dedicated automatic data collection readers  2990  may include one or more processors and/or memory. The dedicated automatic data collection readers  2990  may be configured to process or pre-process information read from the data carrier. For example, the dedicated automatic data collection readers  2990  may be configured to automatically recognize symbols from various symbologies and decode the same. The dedicated automatic data collection readers  2990  may be configured to write data to a data carrier  2924 . For example, the dedicated automatic data collection reader  2990   b  may be configured to automatically write information to an RFID data carrier  2924 . 
     The dedicated automatic data collection readers  2990  may be communicatively coupled to the controller  2918 , either via a physical or wired channel (e.g., electrical or optical) as illustrated for the reader  2990   a  or wirelessly as illustrated for the reader  2990   b.  Wireless communications may occur via one or more of the antennas  2916  of the interrogation and detection system. While  FIG. 29  illustrates all antennas  2916  of the interrogation and detection system as being carried by the patient support structure, one, more or all of the antennas of the interrogation and detection system may be carried by other structures, for example a shade associated with a light fixture or a drape. The dedicated automatic data collection readers  2990  may form part of a network, along with the communications channel(s) and controller  2918 . 
     The dedicated automatic data collection readers  2990  may be employed to read information from data carriers  2924  physically associated with various objects (e.g., implements  2922   a,  tools, machines  2922   d,  devices, sponges  2922   b,  pads, gauze, articles and/or other supplies), and/or a patient and/or one or more medical care providers (e.g., doctors, nurses, anesthesiologist, radiology technician), for instance from a data carrier of a wrist band  2922   c,  anklet or badge worn by the patient or medical care provider. Such can be integrated with other automatically collected information, such as information indicative of a physiological condition of the patient or subject, or information indicative of an operational parameter of a piece of dedicated medical diagnostic, therapeutic or monitoring equipment. 
     In addition to the dedicated automatic data collection readers  2990 , or alternatively, one or more of the antennas  2916  of the interrogation and detection system may be used to reader from, and/or write to, data carriers  2924 . For example, the controller  2918  may be configured to cause one or more of the antennas  2916  to emit interrogation signals in a frequency band employed by RFID transponders or tags, and to receive response signals encoding information from the RFID transponder&#39;s memory. 
     Information received from the RFID transponder may, for example, include an identifier, such as a unique identifier that uniquely identifies the RFID transponder or tag. A database stored on a computer-readable medium may associate the identifier with information that identifies the object to which the RFID transponder or tag is attached, as well as information about the object. The information may include identity of the object such as manufacturer, model, type, classification, lot number and/or date of manufacture. The information may include a history of the object, for instance number of uses, number and/or type of sterilization cycles, number and/or date of refurbishment, dates and/or times of use, dates of inspection and/or identity of inspector. The information may be accessible (e.g., read, write) by the controller  2918  of the interrogation and detection system, and/or by one or more pieces of dedicated medical diagnostic, therapeutic or monitoring equipment. 
     An EKG machine may be used to monitor the heart activity of a patient during surgery. Conventionally, a plurality of electrodes or sensors are attached to a patient at various locations on the patient. Each electrode or sensor is electrically coupled to the EKG machine by a respective electrically conductive wire. Each EKG electrode and wire is commonly referred to as a lead. As many as twelve or more electrodes may be attached to the patient simultaneously, each electrode having its own wire coupled to an EKG machine. EKG lead wires can be particularly obtrusive during surgery. The EKG lead wires frequently become tangled. Medical personnel moving about the patient are impeded by the wires. Medical personnel may bump into the wires and either break a wire or detach one or more of the EKG electrodes. Once detached, the electrodes may be difficult to reattach as there may be bodily fluid covering the area where the detached electrode was previously attached. If more than one electrode becomes detached, the electrodes are particularly susceptible to being replaced in the wrong location. Also, fluid on the electrodes may cover a distinguishing mark meant to indicate the proper location of the electrodes. Reattaching the electrodes wastes valuable time and can lead to improper placement of the electrodes and faulty EKG data. Reducing the amount of wires leading from the EKG electrodes to an EKG machine is desirable. 
       FIG. 30A  shows a piece of dedicated medical diagnostic, therapeutic or monitoring equipment in the form of wireless sensor or transducer  3054 , according to one embodiment. The wireless sensor or transducer may take the form of an electrode  3054   a,  for instance an electrode suitable for measuring EKGs. While such may be referred to as a “wireless lead,” applicants understand that such term is somewhat a misnomer since the “lead” or electrical wire is eliminated and all that remains of the original “lead” is the electrode (i.e., electrically sensitive sensor or transducer). 
     The wireless sensor or transducer  3054  carries a battery  3056  and a radio  3058 . The radio  3058  comprises at least a transmitter and may include a receiver as well, and may be formed as a transceiver. The wireless sensor or transducer  3054  may also include an inscription or marker indicating a proper position of the wireless sensor or transducer  3054  on the body of the patient. The individual wireless electrodes  3054   a  may sense activity of the heart or other physiological activity (e.g., electrical) in any suitable manner. While illustrated as an active component having a discrete exhaustible power source (e.g., chemical battery, fuel cell), the wireless sensor or transducer  3054  may take a passive form, deriving power from a wireless interrogation signal, similar to radio frequency identification (RFID) transponders. While discussed in terms of an electrode  3054   a  to sense electrical physiological characteristics (e.g., conductivity, impedance, resistivity, capacitance), a wireless sensor or transducer  3054  can be employed which is responsive to other physiological characteristics (e.g., temperature, moisture, pH, salt, pressure, stress, strain or force). 
       FIG. 30B  shows a plurality of “wireless leads” or electrodes  3054   a  attached to a patient  3060  according to one embodiment. 
     As described above, a patient may have twelve or more EKG electrodes positioned on the torso, back, limbs, or any suitable location. The configuration of the wireless electrodes  3054   a  in  FIG. 30B  is given only by way of broad example of the number and positioning of the wireless electrodes  3054   a.  In practice, the number and positioning of wireless electrodes  3054   a  may be different from that shown in  FIG. 30B . 
     Each wireless electrode  3054   a  comprises a radio  3058  configured to transmit EKG data to an antenna  16  coupled to the interrogation and detection system  14 . In one embodiment the controller  18  processes the data received from the wireless electrodes  3054   a  and displays the resulting EKG waveform on the display  2950  ( FIG. 29 ). 
     Each wireless electrode  3054   a  may transmit a unique identifier to the controller  18  so that the controller  18  may know which data came from which wireless electrode  3054   a.  The identifier may also indicate the position of an individual wireless electrode on the patient&#39;s body. The electrodes  3054   a  may bear a marking which identifies the wireless electrode  3054   a  and/or a location on the body at which the wireless electrode  3054   a  should be placed or is placed. 
     Two or more electrodes  3054   a  may be wirelessly communicatively coupled to each other. Two wireless electrodes  3054   a  are wirelessly coupled when at least one of the wireless electrodes  3054   a  is configured to transmit data to the other wireless electrode  3054   a.  One wireless electrode  3054   a  can send a signal to a second wireless electrode  3054   a  and the second wireless electrode  3054   a  can then transmit data to the antenna  16  representing the data gathered by one or both wirelessly coupled wireless electrodes  3054   a.  The controller  18  may receive wireless transmissions from only one or from both wireless electrodes  3054   a.    
     The configuration shown in  FIG. 30B  greatly reduces the number of wires in the vicinity of the patient. Medical personnel moving about the patient support structure  2726  will face a much lower risk of bumping a wire and either detaching an electrode  2854  or stumbling themselves. There are fewer wires on the body of the patient to impede surgeons performing delicate and precise operations on the body of the patient. In addition to this, the EKG machine no longer needs to be present in the surgical environment. The controller  18  may process the data sent from the electrodes  3054   a  and displays the data (e.g., EKG waveform) on the display  2950  ( FIG. 29 ). 
     While it has been noted that the dedicated piece of medical diagnostic, therapeutic or monitoring equipment (e.g., EKG machine) may not be present in the medical procedure environment, typically the dedicated piece of medical diagnostic, therapeutic or monitoring equipment will be co-located in the same room as the patient. The wireless electrodes  3054  may wirelessly transmit telemetry or data to a piece of dedicated medical diagnostic, therapeutic or monitoring equipment (e.g., an EKG machine). The piece of dedicated medical diagnostic, therapeutic or monitoring equipment may in turn transmit data to the controller  18  of the interrogation and detection system, for example via the antennas  16  or via one or more wired connections (e.g., electrically conductive cables or optical fiber cables). The controller  18  may also transmit instructions to the piece of piece of dedicated medical diagnostic, therapeutic or monitoring equipment. For example, the controller  18  may transmit operating instructions which cause the piece of piece of dedicated medical diagnostic, therapeutic or monitoring equipment to operate in a certain fashion, or may transmit new software or firmware instructions or upgrades of existing software or firmware instructions, to reconfigure the piece of piece of dedicated medical diagnostic, therapeutic or monitoring equipment. Alternatively, one or more of the antennas  2916  ( FIG. 29 ) may provide wireless communications between the display  2950 , user input device  2952  and the piece of piece of dedicated medical diagnostic, therapeutic or monitoring equipment, which may employ conventional wired electrodes (not shown). 
       FIG. 30C  shows sensor or transducer  3054  according to an alternative embodiment. One electrode  3054   a  may be connected by a wire  3062  to another wireless lead or electrode  3054   a.  One or both of the electrodes  3054  a comprises a radio  3058  (i.e., transmitter and/or receiver or transceiver that communicates via portions of the electromagnetic spectrum typically associated with radio communications such as the radio and microwave portions of the electromagnetic spectrum) and optionally a discrete consumable power source such as battery  3056  or fuel cell. At least one of the pair of wireless electrodes  3054   a  transmits telemetry or data (e.g., EKG signals) to one or more of the antennas  16  of the interrogation and detection system  14 . There may be one or more pairs of wireless electrodes  3054   a  attached to the patient in which one wireless electrode  3054   a  of each pair is wired to the other wireless electrode  3054   a  of the pair. 
       FIG. 31  shows a plurality of sensors or transducers  3154  in the form of leads or electrodes  3154   a  and an intermediary relay  3164 , according to one illustrated embodiment. 
     The leads  3154   a  may, for example, include an electrode, sensor or other transducer, and a physical communications conduit, for example an electrically conductive or optical wire or cable. Each of the leads  3154   a  is attached to a patient  3160  at various locations on the patient to sense a physiological characteristic of the patient. Each lead  3154   a  is also communicatively attached or coupled to the intermediate relay  3164 . The intermediate relay  3164  is a commonly shared communications device  2964  (i.e., common communications device shared by two or more of the leads  3154   a ), and is interchangeably referred to as such herein. 
     The intermediate relay or common communications device  3164  may take the form of, or include, a multiplexer and/or demultiplexer. The common communications device  2964  includes a radio  3158  operable to transmit telemetry or data (e.g., signals) detected by the leads  3154   a  to one or more of the antennas  16  of the interrogation and detection system  14 . The radio  3158  includes one or more antennas, a transmitter and may also include a receiver, and may be formed as transceiver. The common communications device  3164  may be powered by a battery  3156  or other power source. The leads  3154   a  may be powered by respective batteries located at the electrode portions of the leads  3154   a.  Alternatively, the leads  3154   a  may receive power from the intermediate relay or common communications device  3164  via the respective wires. As a further alternative, the leads  3154   a  may wirelessly receive power via an interrogation signal. 
     The intermediate relay or common communications device  3164  wireless transmits telemetry or data (e.g., EKG signals) to the controller  18  of the interrogation and detection system via one or more antennas  16 . The controller  18  may displays the telemetry or data on the display  2950  ( FIG. 29 ), either in processed or raw form. Alternatively, the controller  18  may communicate the telemetry or data to a piece of dedicated medical diagnostic, therapeutic or monitoring equipment. For instance, the controller  18  may relay the telemetry or data to an EKG machine for processing and display or printing. Such may take place over a physical media, such as electrical wires or optical fibers. This advantageously eliminates many of the wires around the patient  3160  which would have connected the leads  3154   a  directly to an EKG machine. The EKG machine likewise may not be needed as the common communications device  3164  and the controller  18  may process the EKG data. 
     Another piece of dedicated medical diagnostic, therapeutic or monitoring equipment that provides dedicated medical telemetry or data is a pulse oximeter. A typical pulse oximeter sensor is attached to a finger of a patient to measure the blood-oxygen level of a patient. The pulse oximeter sensor is normally connected by one or more wires to a pulse oximeter processing system to process raw data from pulse oximeter sensor. The pulse oximeter processing system includes or is coupled to a display to display processed data. 
       FIG. 32  shows a wireless pulse oximeter sensor  3266 , according to one embodiment. The pulse oximeter sensor  3266  may be used to monitor the oxygen content of a patient&#39;s blood. 
     The wireless pulse oximeter sensor  3266  is physically attached to a portion of the patient, for example a finger  3268  of the patient. The wireless pulse oximeter sensor  3266  comprises a transducer  3257  and a radio  3258  transmitter and/or receiver or transceiver). The radio  3258  includes an antenna (now shown) and is configured to wirelessly transmit data sensed by the transducer  3257  to at least one antenna  16  coupled to the interrogation and detection system  14 . The controller  18  may process the data received via the at least one antenna. The controller  18  may display the patient&#39;s blood-oxygen data on the display  2950  ( FIG. 29 ) in processed or raw form. The data may advantageously be displayed simultaneously with EKG data on a single display  2950  ( FIG. 29 ). Of course, more than one display  2950  may be utilized. Alternatively, the controller  18  may relay the sensed measurements to a dedicated pulse oximeter processing system or controller, either via wireless or wired communications. Thus, the interrogation and detection system  14  may advantageously be utilized to eliminate extraneous wire, and/or an extra display or processor. 
     Hence, some embodiments may take advantage of the proximity of antennas  16  to the patient to wirelessly collect data from various sensors or transducers, and to relay that data directly to associated processing equipment dedicated to a particular function or task. Alternatively, the controller  18  of the interrogation and detection system  14  may itself implement some or all of the processing usually performed by the associated dedicated processing system. 
       FIG. 33  illustrates an intracranial pressure monitor  3370  according to one embodiment. 
     The intracranial pressure monitor  3370  is a dedicated piece of medical diagnostic, therapeutic or monitoring equipment which is attached to a head of the patient to monitor pressure in the head. The intracranial pressure monitor  3370  may include one or more pressure sensors or transducers (e.g., piezo-electric or resistance based strain gauge)  3371  and a radio  3372  (i.e., transmitter and/or receiver or transceiver) that includes an antenna (not shown). The pressure sensors or transducers  3371  may be implemented in a MEMS device or other suitable mechanism. The radio  3172  is communicatively coupled to the pressure sensor  3371 . The radio  333172  transmits data from the pressure sensor or transducer  3371  to an antenna  16  of the interrogation and detection system  14 . 
     The controller  18  may process the data and display the processed data on the display  2950  ( FIG. 29 ). Alternatively, the controller  18  may simply display raw, unprocessed data via the display  2950 . Additionally, or alternatively, the controller  18  may relay the raw or partially processed data to a controller of a dedicated intracranial pressure monitor processing system or controller. In one embodiment, the display  2950  ( FIG. 29 ) advantageously displays intracranial pressure monitor sensor data along with pulse oximetry and/or EKG data collected from one or both of the pulse oximeter  3266  ( FIG. 32 ) and/or electrodes  3054  ( FIG. 30A ). When processing occurs in dedicated medical diagnostic, therapeutic or monitoring equipment, that dedicated medical diagnostic, therapeutic or monitoring equipment may relay processed data back to the interrogation and detection system  14 , via antennas  16 , for display on display  2950 , possibly with other processed data. Alternatively, the dedicated medical diagnostic, therapeutic or monitoring equipment may be communicatively coupled directly to the display  2950 , for example via one or more wired or wireless connections. 
     The interrogation and detection system  14  can further be utilized to communicate with and issue commands to other dedicated medical diagnostic, therapeutic or monitoring equipment, for example dedicated medical therapeutic equipment used to perform a therapeutic function on the patient or dedicated medical diagnostic equipment used to collect diagnostic information from the patient. 
       FIG. 34  illustrates an infusion pump  3474  according to one illustrated embodiment. 
     The infusion pump  3474  is a piece of dedicated medical diagnostic, therapeutic or monitoring equipment that may be used to inject fluid (e.g., intravenously) into a patient. The fluid may be one or more drugs, anesthetic, blood, plasma, saline, food or sucrose, etc. The infusion pump  3474  may be programmed to introduce fluid into the patient at a desired rate. The infusion pump  3474  may include a radio (e.g., transmitter and/or receiver, or transceiver)  3458  configured to communicate wirelessly with an antenna  16  of the interrogation and detection system  14 . The radio  3458  may receive wireless control signals from a remotely located controller, for instance the controller  18 . The control signals may indicate, for example, an infusion rate at which to pump the fluid into the patient, a start time, a stop time, a duration, a delivery profile indicating various rates over time. The radio  3458  may additionally or alternatively, transmit monitoring signals to a remotely located controller, for instance the controller  18 . The monitoring signals may indicate various operational characteristics of the infusion pump  3474 , for instance, amount and/or rate of actual fluid delivery, an amount of fluid remaining, and whether a battery of the infusion pump  3474  is nearing depletion. The data from the infusion pump  3474  may be displayed on the display  2950  ( FIG. 29 ) along with other medical telemetry or data described in relation to  FIGS. 30-33 . Additionally, or alternatively, the medical telemetry or data may be relayed by the controller  18  of the interrogation and detection system  14  to a dedicated controller of an infusion pump system. Such may be done over one or more wired or wireless communications channels. 
     In one embodiment, a user may use the input device  2952  and/or touch screen of the display  2950  ( FIG. 29 ) to enter a new fluid infusion rate for the infusion pump  3474 . The controller  18  then sends a control signal to the infusion pump  3474  via an antenna  16  of the interrogation and detection system  14 . Alternatively, the user may enter a new rate via a user input device of a dedicated infusion pump system, which relays control instructions to the interrogation and detection system  14 . The signal is received at the radio  3458  of the infusion pump  3474  and the infusion pump  3474  adjusts the fluid infusion rate accordingly. 
     The controller  18  may be configured to communicate with remotely located equipment, such as a display at a nurse&#39;s station outside of the room in which the medical procedure is preformed. Any of the data received by the controller  18  can be displayed at the nurse&#39;s station. In this way medical personnel remote to the patient&#39;s room may monitor any of the equipment communicating with the interrogation and detection system  14 . 
     The controller  18  may be configured to receive commands from the nurse&#39;s station to adjust the fluid infusion rate of the infusion pump  3474 . The controller  18  may be configured to receive commands from the nurse&#39;s station to adjust a function of any of the equipment coupled to the interrogation and detection system. 
       FIG. 35  illustrates an intra-aortic balloon pump system  3576 , according to one illustrated embodiment. Typically, a balloon pump system is a dedicated piece of medical diagnostic, therapeutic or monitoring equipment used to inflate or deflate catheter balloons. The balloon pump system is typically controlled by a computer coupled to an EKG machine. The computer controls the pulsation of the balloon pump according to data from the EKG. 
     The intra-aortic balloon pump system  3576  comprises a pump  3577  operable to selectively inflate and deflate an intra-aortic balloon. The intra-aortic balloon pump system  3576  may include a user interface  3578  including a display  3578   a  and one or more user input devices (e.g., keys, switches, knobs, pointer devices)  3578   b.  The display  3578   a  and user input devices  3578   b  are dedicated to the display of information related to operation of the aortic balloon pump system  3576  and control thereof, respectively. 
     The intra-aortic balloon pump system  3576  may include a radio (e.g., transmitter and/or receiver or transceiver)  3558  configured to communicate with an antenna  16  of the interrogation and detection system  14 . The controller  18  may be configured to control the balloon pump  3576  from a remote location, for example in response to EKG data. The controller  18  may transmit data, for instance EKG data, to the balloon pump system  3576  and allow the balloon pump system  3576  to process the data and control the pump  3577  accordingly. In either case, the balloon pump system  3576  does not need to be connected by wire to another piece of dedicated medical diagnostic, therapeutic or monitoring equipment (e.g., EKG machine), thus enhancing the environment in which the medical procedure is preformed. Alternatively, or additionally, the interrogation and detection system  14  may function as a relay between sensors or transducers (e.g., electrodes), pumps (e.g., pump of inter-aortic balloon system) and other dedicated medical diagnostic, therapeutic or monitoring equipment or dedicated medical diagnostic, therapeutic or monitoring control systems of such dedicated medical diagnostic, therapeutic or monitoring equipment. The interrogation and detection system  14  may be further utilized to interact with a balloon pump during or after surgery. 
       FIG. 36  illustrates a controller  3618 , according to one illustrated embodiment. 
     The controller  3618  is similar to that of  FIG. 16  but has been adapted to enable operation of the antennas  16  to communicate with pieces of dedicated medical diagnostic, therapeutic or monitoring equipment as described in relation to  FIGS. 29-34 . The controller  3618  comprises a motherboard  3672 . The motherboard  3672  includes or is communicatively coupled to a plurality of ports or connectors  3674  to communicatively couple the motherboard  3672  to respective antennas  16  as previously described in relation to  FIG. 16 . The motherboard  3672  may also include slot connectors  3676  to receive plug-in boards  3678  as previously described in relation to  FIG. 16 . The controller  3618  has been expanded to include one or more additional slot connectors  3676  for receiving one or more additional plug-in boards  3678  for enabling communication through the antennas  16  or additional antenna(s) with one or more medical telemetry or data and support or control pieces of dedicated medical diagnostic, therapeutic or monitoring equipment, for example equipment such as EKG electrodes  3054 , pulse oximeter sensor  3266 , intracranial pressure monitor  3370 , fusion pump  3474 , and balloon pump system  3576 . There are of course many other dedicated medical diagnostic, therapeutic or monitoring equipment which may be used during and after a medical procedures (e.g., operation), any or all of which may be fitted with radios (e.g., transmitter and/or receiver, or transceiver) and configured to interface with the interrogation and detection system. The one or more additional plug-in boards  3676  enable the controller  3618  to operate the interrogation and detection antennas  16  in a mode for interacting with pieces of dedicated medical diagnostic, therapeutic or monitoring equipment. 
     A single antenna  16  of the interrogation and detection antennas may be dedicated to communicate with the pieces of dedicated medical diagnostic, therapeutic or monitoring equipment. Alternatively more than one antenna  16  of the interrogation and detection system  14  may be configured to communicate with the pieces of dedicated medical diagnostic, therapeutic or monitoring equipment. In some embodiments, all of the antennas  16  of the interrogation and detection system  14  are configured to communicate with the pieces of dedicated medical diagnostic, therapeutic or monitoring equipment. In some embodiments, one or more of the antennas  16  of the interrogation and detection system  14  are dedicated to communications with the pieces of dedicated medical diagnostic, therapeutic or monitoring equipment, the plug-in boards being different from the plug-in board used with antennas  16  that perform interrogations to locate transponders  24 . In some embodiments, one or more antennas  16  are used to perform all of interrogation, detection of transponders and to communicate with sensors, pumps, and/or other instruments or equipment, and/or with dedicated control systems of the same. In some embodiments, one or more additional antennas  16  may be connected to ports  3674  of the motherboard  3672  dedicated solely to interface with the pieces of dedicated medical diagnostic, therapeutic or monitoring equipment. 
     The controller  18  of the interrogation and detection system may be operable to communicate with radios  3058 ,  3258 ,  3372 ,  3458 ,  3558  of the various pieces of dedicated medical diagnostic, therapeutic or monitoring equipment  3054 ,  3266 ,  3370 ,  3474 ,  3576 . Radios  3058 ,  3258 ,  3372 ,  3458 ,  3558  may operate in more precise frequency bands than the transponders  24 . 
     Antennas of the interrogation and detection system  14  may be configured to operate in a first mode to detect transponders  24  and in a second mode to communicate with the pieces of dedicated medical equipment. The first mode may include operating in a first broad frequency range as previously described with regards to the interrogation and detection process. The second mode may include operating in a second frequency range, more narrow than the first frequency range. In one embodiment, the first and second frequency ranges may overlap. In other embodiments, the first and second frequency ranges do not overlap. 
     In an alternative embodiment, the radios may be passive, employing passive RFID type technology. Such radios may employ a first antenna dedicated solely to receiving a first signal to charge a charge pump of the radio to power the radio. The second antenna operates at a different frequency than the first antenna and is configured to communicate with an antenna  16  of the interrogation and detection system  14 . A dedicated power antenna may be installed in the interrogation and detection system  14  to supply a constant signal to power EKG wireless leads or electrodes  3054 . Alternatively the power antenna could be installed in the operating room independent of the interrogation and detection system  14 . In either case, the power antenna should be near the patient support structure  26  in order to supply an adequately strong signal to the radios. In one embodiment the power generated by the charge pump supplements the battery  3056  to extend the life thereof in the case of a long medical procedure which may last several hours. Otherwise, the battery  3056  of the wireless leads or electrodes  3054  may run out of power. Thus, the power generated by the charge pump from the power antenna signal may advantageously prolong the life of the battery  3056 . The radios may also comprise two antennas to supplement the batteries of the pieces of dedicated medical diagnostic, therapeutic or monitoring equipment. 
     The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Although specific embodiments of and examples are described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the disclosure, as will be recognized by those skilled in the relevant art. The teachings provided herein of the various embodiments can be applied to other transponders and interrogation and detection systems, not necessarily the exemplary surgical object transponders and interrogation and detection systems generally described above. 
     For instance, the teachings herein may employ any variety of other electrodes, sensors or transducers and diagnostic, therapeutic or monitoring equipment. For example, photo-electric pulse plethysmograph transducers, respiratory effort transducers, GSR finger electrode transducers, physiological sounds microphone, active electrodes, air flow transducers, blood pressure transducers, blood pressure cuff transducers, hand dynamometers, variable range force transducer, twin axis goniometer, torsion meter, laser Doppler surface flow probe, skin surface temperature, fast response temperature probe, surface temperature banjo probe, liquid immersion probe, digit surface temperature probe, accelerometer, pulse oximeters transducer. 
     Also for instance, the foregoing detailed description has set forth various embodiments of the devices and/or processes via the use of block diagrams, schematics, and examples. Insofar as such block diagrams, schematics, and examples contain one or more functions and/or operations, it will be understood by those skilled in the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one embodiment, the present subject matter may be implemented via Application Specific Integrated Circuits (ASICs). However, those skilled in the art will recognize that the embodiments disclosed herein, in whole or in part, can be equivalently implemented in standard integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more controllers (e.g., microcontrollers) as one or more programs running on one or more processors (e.g., microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of ordinary skill in the art in light of this disclosure. 
     In addition, those skilled in the art will appreciate that the mechanisms of taught herein are capable of being distributed as a program product in a variety of forms, and that an illustrative embodiment applies equally regardless of the particular type of physical signal bearing media used to actually carry out the distribution. Examples of signal bearing media include, but are not limited to, the following: recordable type media such as floppy disks, hard disk drives, CD ROMs, digital tape, and computer memory. 
     The various embodiments described above can be combined to provide further embodiments. To the extent not inconsistent with the teachings herein, all U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications commonly owned with this patent application and referred to in this specification and/or listed in the Application Data Sheet including: U.S. Patent Publication No. US 2004/0250819, published Dec. 16, 2004; U.S. Provisional Patent Application No. 60/811,376 filed Jun. 6, 2006; U.S. Provisional Patent Application No. 61/109,104 filed Oct. 28, 2008; U.S. Provisional Patent Application No. 61/222,443 filed Jul. 1, 2009; U.S. Provisional Patent Application No. 61/222,847 filed Jul. 2, 2009; U.S. Provisional Patent Application No. 61/242,704, filed Sep. 15, 2009 and entitled “METHOD AND APPARATUS TO DETECT TRANSPONDER TAGGED OBJECTS, FOR EXAMPLE DURING MEDICAL PROCEDURES”; U.S. provisional patent application Ser. No. 61/242,699 filed Sep. 15, 2009; U.S. Non-Provisional patent application Ser. No. 11/743,104 filed May 1, 2007; U.S. Non-Provisional patent application Ser. No. 12/472,199 filed May 26, 2009; U.S. Non-Provisional patent application Ser. No. 12/473,059 filed May 27, 2009; and U.S. Pat. No. 6,026,818, issued Feb. 22, 2000, are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary, to employ systems, circuits and concepts of the various patents, applications and publications to provide yet further embodiments. 
     These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.