Tagging Systems, Methods and Apparatus

Technical Field

The present invention relates to tagging systems, methods and apparatus. It relates particularly to the RFID tagging of items that have to undergo sterilization, including for example healthcare products and equipment. Background

The monitoring and tracking of healthcare items through a medical or surgical procedure and/or through their lifecycles can be labour-intensive and expensive, and is a significant undertaking for hospitals and other healthcare goods and services providers.

The logistical complexity is exemplified in the provision and use of loan kits. Rather than stock suites of surgical instruments for prosthetic surgeries, e.g. orthopaedic implants, a hospital will generally be provided with loan kits of instruments and implants by the implant manufacturer. The hospital pays for the parts of the kit that are used and returns the instruments and unused implants to the manufacturer. The kit needs to include various sizes and types of implant, as well as dedicated instruments for each, e.g. specifically sized jigs, saws, boring tools, reamers, fasteners and the like, as a surgeon will often not know a patient's exact needs until surgery has begun and the implant site has been explored. Such kits therefore often include a large number of parts.

The kit provider and hospital must keep a meticulous inventory of these kit parts at various stages in the loan process including at dispatch, receipt and sterilization of the kits, as mistakes may not only result in unnecessary expense and part replacement, but also the inability to conduct or complete a procedure. A kit inventory may for example take up to four hours to perform, and four or more separate inventories may be needed during the course of a loan.

Other examples of the need to track medical and surgical equipment include the need to monitor the number of times that equipment has been used or sterilized, and to provide tracking for infection control, recall and alert facilities and life cycle management.

A possible way to increase the efficiency and accuracy of such inventory and tracking processes would be to tag instruments and implants

with RFID (Radio Frequency IDentification) tags. Unlike other tagging methods, such as engraving serial numbers or attaching barcodes or data matrices (2D barcodes), RFID tags have the advantage that they do not require line-of-sight reading. They may also store more information, and may be written to as well as read.

Although RFID tagging of surgical instruments has been suggested, this is problematic in practice, and a major stumbling block is the need for the tags to survive sterilization processes, such as autoclaving and gamma ray irradiation. For example, whilst it might be attempted to provide an RFID tag with sufficient insulation to survive the temperatures of an autoclave for a required period of time, this may be expensive, difficult to achieve and result in a large and cumbersome tag that may be unsuitable for a number of applications. Also, it would be difficult to shield a tag from gamma irradiation, yet allow it to respond to an RF interrogation signal. A method of RFID tagging items that are to be sterilized has been described in USSN 60/860,795 filed on 24 November 2006 (to the present inventor), the contents of which are incorporated herein in their entirety by reference. This method utilises tags made from micromechanical resonant members that vibrate in response to an excitation signal, and that are able to withstand the rigours of sterilization. Such tags are for example described in US2006151613 and US2006152313, (also to the present inventor), the contents of which are also incorporated herein in their entirety by reference.

The present invention aims to provide further systems, methods and apparatus that facilitate the tagging of items that are to be sterilized, which in their various embodiments may provide a number of advantages. Disclosure of the Invention

Viewed from one aspect, the present invention provides a system for the identification of items that undergo sterilization, the system including: a container for holding items that have been tagged with RFID tags able to survive a sterilization process , the container including one or more internal antennas, and a container interrogator for interrogating the item tags via the internal antennas, the interrogator being removably coupled to the container;

wherein the container includes a coupling element in a wall portion thereof for providing a contactless coupling between the internal antennas and the container interrogator.

The items may for example be surgical instruments and the container may be a surgical instrument tray, and the invention may enable the interrogation of RFID tags on surgical instruments inside a tray through the removable interrogator coupled to the tray.

The one or more internal antennas via which the interrogator interrogates the item tags may strengthen the RF signal coupling between the container interrogator and the tagged items.

The coupling element may be formed in any wall portion of the container, e.g. in a side, bottom or top wall of the container, to provide a coupling between the internal antenna and the container interrogator. This may be especially useful with containers made of metal or other material that prevents or interferes with the passage of RF signals.

The contactless coupling between the antenna and interrogator may for example be inductive or capacitive. In an inductive coupling arrangement, the antenna and interrogator may include coil elements that couple together in the manner of a transformer. In a capacitive coupling arrangement, the container antenna may include capacitive plates that couple with corresponding capacitive plates of the interrogator.

The contactless coupling enables the interrogation of RFID tags on instruments in a container that is covered in a drape. Often, surgical trays will be covered by a drape or other cover during sterilization which allows steam to permeate through but acts as a barrier to infectious agents. The cover may then be opened up in the theatre so that its inner surface provides a sterile area on which instruments from the tray may be placed.

The contactless coupling arrangement allows infection control protocols to be met, by allowing the item RFID tags to be interrogated without breaking the sterile seal of the drape.

The system allows for effective item tracking through a combination of individual item tags that are sterilization-hard (i.e. are able to survive the sterilization process with their functionality intact), but that may be lacking in read range and/or intelligence, and a container interrogator that may be

removed from the container during sterilization so that it may implement functionality, such as intelligence and/or appropriate read ranges, through componentry that need not be sterilization-hard.

The interrogator may itself respond to external interrogation signals with data from the item tags. In this regard, the system may allow an external interrogator, e.g. an RFID reader of a surgical instrument tracking system, to obtain information regarding for example the instruments and implants in a surgical tray by applying an interrogation signal to the tray interrogator, whilst allowing for sterilization of the tagged instruments together in the tray without the tray interrogator.

The item tags may take a form such as discussed in USSN 60/860,795 and US2006151613 and US2006152313, e.g. micromechanical resonant members that respond to an interrogation signal through vibration, and need not include sensitive microelectronic components or power sources, whilst the container interrogator may include sterilization sensitive components, such as a controller, e.g. a microprocessor, memory and/or an internal power source. It is to be understood that the invention extends to any type of RFID tag, whether formed by MEMS or CMOS or any other suitable manufacturing procedure. The system can therefore provide a tagging system that does not rely on expensive heat-insulated interrogators and also provides a tagging system that may be used in radiation sterilization processes, e.g. in gamma ray sterilization processes.

The system may also allow an external reader to obtain information on tagged items through interrogation of a single container interrogator, rather than having to interrogate multiple item tags. In this regard, the container interrogator may include memory for storing data from the instruments ready for transmission to an external reader. Alternatively, the container interrogator may obtain and relay information from item tags to an external reader without storage of the information. The container interrogator may be programmed to respond to specific commands, e.g. to obtain specific information from the tagged items, and/or to initiate communication, e.g. if it determines that there is an error in the items stored, e.g. incorrect items are in a tray or items are missing.

In one implementation, the container interrogator may be written to by an external device, e.g. to log an event or the like during a handling stage of the container. The container interrogator may therefore hold data relating to a container's history, and so the history of the items contained within it. This may be especially useful for example where the item tags are read-only tags.

In one example, a surgical loan kit provider may utilize an instrument tracking system that has readers for reading the tagged items after a tray is loaded and before dispatch, and on return of a kit from a hospital. In this case, the tray interrogator may be removed from the tray during any sterilization processes, such as when a used kit is returned. Further, the trays may be placed in totes for transport between a kit provider and a hospital, and interrogation of the tray interrogators may allow the tagged items to be read whilst the trays are in the tote, thereby enabling the location of the trays to be monitored throughout the distribution and return processes. If an interrogator is inadvertently left off of a tray, e.g. when being placed in a tote or the like, the system will not be able to address the tray, and will note missing equipment. This can then alert an operator to the missing interrogator.

In a hospital, the kit may be received by a hospital sterilization unit (for example a Central Supply and Sterilization Department - CSSD), and have the contents, e.g. instruments and implants, read by a reader connected to an instrument tracking system of the hospital. An operator may remove the tray interrogators from the kit trays, sterilize the trays and their contents and reattach the tray interrogators. The kit contents could alternatively be re-packed into in-house hospital trays, sterilized, and then tray interrogators applied to the hospital trays. The tray contents may be re-read and checked before the kit is sent to an operating theatre. A reader in the theatre may be used to read the tagged items through the tray interrogator prior to start of the surgical procedure. After surgery, the instruments may be returned to the hospital sterilization unit, e.g. in their trays, where they will be resterilized prior to dispatch back to the kit provider. Again, at this stage, the interrogator may be used as appropriate to conduct an audit of parts in the trays, whilst also being removable for the autoclave procedures.

By having sterilization-hard tags on the items, the system can also overcome problems in tag-item relationship integrity. For example, if individual

item tags were easily removable, there would be a risk that item tags could be reattached to the wrong items. This could cause serious problems. In the present system, however, the container interrogators need not be dedicated to a particular container, and a container may be identified by its contents, i.e. the tagged items within it, rather than by the container interrogator. Thus, for example, if a number of trays are to be sterilized, the tray interrogators may be removed and reattached randomly after sterilization without needing to keep track of which interrogators are attached to which trays.

In one implementation, a hospital or the like may have a pool of in- house tray interrogators that are attached to received trays, and that remain with the trays. The tray interrogators may then be used throughout the hospital process, before being removed and stored when the tray is returned to the kit provider. This may be useful when the kit provider uses a different tracking system, e.g. a non-RFID system or one that uses different tagging methods.

The container interrogator may have an identity, so that it may be tracked and monitored directly, and the container interrogator may take the form of an RFID tag that may communicate with item tags and external readers. Identification of the container interrogators may be useful where for example there is an infection, in which case possibly compromised tray interrogators may be tracked. Also, interrogator identification may allow for a one-to-one correspondence between containers and interrogators during a process and/or a lifecycle, as a tracking system may monitor a container's interrogator identification and the container's contents and ensure that the same interrogator is applied to the same container at each step.

The container itself may be tagged by an RFID tag that is sterilization- hard, e.g. through the use of tags discussed for the item tags. Thus, the container may have two tags: a sterilization-hard tag, which will generally be a permanent tag and which will ensure the integrity of the container's identify, and a removable sterilization-sensitive tag, which may provide appropriate read ranges and/or intelligence. The sterilization-hard tag may include information regarding the container's contents, which may for example be written to the tag prior to or after its application to the tray, and may be read

only or rewriteable. This may facilitate checking of the actual container contents with the expected contents listed in the container tag.

The sterilization processes may include autoclaving and irradiation processes. Autoclaving practice may involve applying pressurised steam to an instrument at a suitable high temperature for an appropriate period of time. For example, a WHO recommended autoclave procedure includes autoclaving at 121 °C for 30 minutes with the instruments resting in a bath of 1 N sodium hydroxide (NaOH) within the autoclave (WHO/CDS/CSR/APH/2000.3). Also, Australian autoclave practice includes autoclaving for a holding time of 3 minutes at 134 °C or 15 minutes at 121 °C (AS NZS 4187-2003) together with a penetration time (time to bring the complete instrument up to temperature), which is dependent upon instrument material and size and may typically be 15 minutes. Irradiation processes may include gamma ray irradiation, e.g. at a dosage in excess of about 25 kGy, or beta (electron) irradiation. Other sterilization processes may include exposing the instruments to dry heat (convection air above 160°C) or sterilizing the instruments at low temperatures using ethylene oxide, hydrogen peroxide plasma or peracetic acid.

The container may include a plurality of antennas, each antenna associated with a specific location of the container. In this system, each antenna may be polled separately to determine which items are in which locations in the container. A particular location may be associated with one or more items, and for example a location may relate to a shadowboard location of an item, e.g. of a surgical instrument on an instrument tray. Thus, antennas may be embedded in a shadowboard of the container. They may also for example be formed on a printed circuit board mat that may for example sit in the bottom of a container.

The multiple antenna system may be used to check whether the correct items are in their correct locations. This may be important where for example similar instruments are provided in the same loan kit, and it may be difficult to discern by eye the difference in the instruments, e.g. screw size, and so it may be difficult to tell by eye whether or not instruments are in the correct locations.

The use of a plurality of antennas may also facilitate better coupling of the interrogation signal with the item tags, and may be positioned adjacent to the expected location of an item's antenna when the item is correctly located in

the container. This may be especially useful where items are made of metal and so may block a more general interrogation signal. If only good coupling is a concern, rather than position determination, then the antennas may be interrogated at the same time, using appropriate anti-collision protocols. If a determination of item location is required, then the antennas are preferably interrogated one at a time, so that the antenna location can be identified with the item response.

Where the container has a plurality of antennas, the antenna coupling element may include a plurality of connectors, e.g. coils, capacitive plates, or plugs and sockets, each associated with an antenna and mounted in an array on a panel of the container. The interrogator may then have a corresponding coupling element with a corresponding array of components.

The container may have a removable inner holder for holding a set of tagged items. For example, a surgical tray may include a cassette on which a set of surgical instruments are mounted, which may be removed from the tray in an operating theatre so that instruments are readily accessible.

The inner holder may be provided with a sterilization-hard tag, and may include an antenna or antennas thereon as discussed above for the container itself. They may take the place of or complement a container tag or antennas. The inner holder may be provided with a coupling element for coupling the antenna or antennas with the container interrogator. This may be through a further coupling element in a wall portion of the container. The coupling element may again be inductive or capacitive. An interrogator may be provided that may attach directly to an inner holder. The interrogator may attach to the inner holder so that it engages with the inner holder coupling element directly, rather than through the container wall.

Viewed from another aspect, the present invention provides a system for the identification of items that undergo sterilization, the system including: a container having an inner holder for holding items that have been tagged with RFID tags able to survive a sterilization process , the inner holder including one or more internal antennas, and an interrogator for interrogating the item tags via the internal antennas, the interrogator being removably coupled to the inner holder;

wherein the inner holder includes a coupling element for providing a contactless coupling between the internal antennas and the interrogator.

The container and/or inner item holder may include registration elements for ensuring that the inner holder is positioned correctly in the container so that the items may be interrogated, e.g. so that coupling elements may register with one another. The registration elements may take any suitable form, e.g. guiding formations, such as ribs and grooves, fasteners and the like. The container and container interrogator, and inner holder and inner holder interrogator, may be removably coupled together in any suitable manner. They may for example be mechanically fastened together, e.g. by a clamping, clipping, hook, friction-fit, push-fit or snap-fit action, or by fastening elements such as screws, bolts or pins. The interrogator could be mounted in a pocket or recess in or on a container wall or lid. It could also be removably adhered to the container or fastened magnetically.

The interrogator may take any suitable size and shape, and may be configured to include a grip portion to easily allow a user to handle the interrogator. Sterilization-hard circuitry or components that may be required by the interrogator may be mounted permanently on the container and may not be removable with the interrogator itself. For example, an antenna may be mounted on the container, e.g. on an outer surface thereof, that the interrogator connects with, when coupled with the container, in order to communicate with an external reading device. Thus, the removable interrogator may only include a controller, memory and the like, and may have connectors for connecting with an antenna circuit on the container.

In one form, the container interrogator may be provided as a portable cradle that is configured to hold the container. The use of a portable cradle has particular advantages, as for example surgical trays may be simply mounted on the cradles, and handled by the cradles. As previously discussed, surgical trays will often be covered by a drape or other cover during sterilization which allows steam to permeate through but acts as a barrier to infectious agents. The cover may then be opened up in the theatre so that its

inner surface provides a sterile area on which instruments from the tray may be placed. The cradle can be simply configured for accommodating the covered tray, and the cover may lie over the cradle in the theatre, so that the cradle is not within the sterile area defined by the cover. A cradle may for example include a base portion on which the container is mounted, and for example may include a recess within which a surgical tray is mounted. The cradle may including a coupling element, e.g. within a base or side wall portion, that couples with an antenna coupling element of the tray. This is a contactless coupling, e.g. inductive or capacitive, so as to allow coupling through a tray drape or the like.

The cradle may include fasteners for holding the container in place, and may include a locking device. The cradle may include registration means to ensure that the container is positioned so that the tagged items can be interrogated by the interrogator, e.g. to locate coupling elements of the container and interrogator adjacent one another.

A cradle may be provided for the inner holder, where this is provided. This may be the same or a different cradle from a container cradle, and the container and inner holder may have dedicated cradles that will not fit one another. An inner holder, e.g. cassette, will generally not be covered by its own sterile cover, e.g. drape, when in the container, e.g. tray. Therefore, in order to maintain infection control protocols, a cradle for an inner holder may be covered by the sterile cover of the container or a separate further sterile cover before the inner holder is placed into it. Separate cradles may also be used by a kit provider and a hospital, e.g. to accommodate different trays or the like.

The cradle may be configured so that the cradle and mounted container will not fit inside an autoclave or other sterilization machine. This can help prevent the interrogator from being accidentally exposed to the rigours of a sterilization process. Other forms of removable interrogator may also be similarly configured, and where an inner holder is provided, the arrangement of the inner holder and interrogator may be such that the inner holder cannot be placed within the container with the interrogator attached. It may also, however be advantageous to provide systems that allow this so that items can be read through the inner holder interrogators whilst in the container.

The container may include a closure element, such as a lid, and the container and interrogator may couple together such that the container may only be closed when the interrogator is detached from the tray e.g. by using a suitable mechanical interlock. For example, the lid may have a pin attached to it which prevents the lid from closing properly unless the interrogator is detached. This may help to prevent interrogators from being left on containers during their sterilization, as the container will generally be opened to check the contents prior to sterilization. The closing mechanism may be designed so that the lid can be removed whilst the interrogator is attached, but can then not be refitted. The mechanism may also be designed so that the interrogator may be attachable to the container when the lid is closed.

The system may include sterilization apparatus, such as an autoclave or gamma irradiation equipment, and may include an interrogator associated with the apparatus, which monitors for the presence of a container interrogator prior to commencing a sterilization process. This again can prevent accidental exposure of the container interrogator to a sterilization process. For example, the commencement of a surgical instrument autoclaving process could be dependent on receiving no response from a tray interrogator. If a response is received, an alarm or other indicator may be activated to alert the operator that an interrogator is inside the autoclave, and the sterilization process may be halted. The interrogator may be programmed with a type identifier, indicating that it is a removable/sterilization-sensitive interrogator, and/or with an individual identifier, which the sterilization apparatus may read on interrogation. The present invention extends to methods of tagging items to be sterilized, and, viewed from another aspect, the present invention provides a method for the identification of RFID tagged items through a process including a sterilization stage, the method including the steps of: placing items that have been tagged with RFID tags able to survive a sterilization process in an item container that includes one or more internal antennas and a coupling element in a wall portion thereof for providing a contactless coupling with an interrogator; coupling an interrogator for interrogating the item tags to the container coupling element, the interrogator being removable from the container;

reading the item tags via the internal antennas; and sterilizing the container and tagged items with the interrogator detached from the container.

The method may include any of the steps discussed above in relation to the systems.

The present invention also extends to apparatus for carrying out the above systems and methods. It provides for example a container for holding items that have been tagged with RFID tags able to survive a sterilization process, the container including one or more internal antennas and a coupling element in a wall portion of the container for providing a contactless coupling between the internal antennas and a container interrogator.

It will be understood that although the system is discussed above mainly in relation to surgical instrument trays, the present invention has broader application and may be used in relation to other items that have to undergo sterilization, e.g. to healthcare equipment in general, such as medical dressings, swabs, implants, drips and drugs, and that when discussing surgical and medical equipment, this will also include dental and veterinarian equipment. The system may for example also be applied to food sterilization and e.g. cold chain applications.

As well as being useful in sterilization processes, various of the above- discussed features are also useful in more general applications. For example, a container having a plurality of internal antennas, each associated with a specific item location, is in itself a useful feature that allows for the determination of the identity and presence of items at particular locations in the container and/or provides for good coupling, and, viewed from another aspect, the present invention provides a container for containing RFID tagged items, the container including a plurality of internal antennas, each antenna associated with a specific location in the container in which an item is to be placed.

The multiple antennas may be interrogated at the same time when it is not desired to determine the location of items in a container, or may be interrogated separately when it is. The container may include one or more inner holders for the items on which such antennas are provided.

Viewed from another aspect, the present invention provides a method for the identification of items, the method including the steps of: mounting RFID tagged items in a container, the container having a plurality of antennas, each antenna associated with a specific location in the container; interrogating for item RFID tags through the antennas by interrogating each antenna separately; and determining the presence and location of an item in the container based on a determination of which antenna detects the item. When the container includes a coupling element to couple an antenna or antennas with a removable interrogator, the same coupling element may also be used with other interrogators. For example, if a coupling element is provided in the base of the container, a corresponding coupling element may be provided in a container support, such as a table, bench, trolley or the like, so that the items may be read through the coupling elements when the container is mounted on the support.

In this regard, the provision of a coupling element in the surface of a container support to couple with a coupling element in a container, so as to enable the interrogation of RFID tagged items within the container is also useful in itself.

The container support may be a table, bench, trolley or any other support, and includes a portable cradle with the features discussed above.

The container support may include registration elements for locating the container antenna coupling element adjacent the container support coupling element when the container is mounted on the support. The coupling element of the container support may be linked by cable or wirelessly to a logistics system for identifying and tracking the RFID tagged items within the container.

The container support may be configured to allow interrogation of instruments in a draped tray. A draped tray could then be placed on the container support and the drape unfolded to cover the container support. The container support could then provide a draped sterile surface on which instruments may be placed as well as allowing interrogation of RFID tagged instruments within the tray.

It should be noted that any one of the aspects mentioned above may include any of the features of any of the other aspects mentioned above and may include any of the features of any of the embodiments described below.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings. It is to be understood that the particularity of the drawings does not supersede the generality of the preceding description of the invention. Brief Description of the Drawings

Figure 1 is a schematic diagram showing a loan kit process; Figure 2 is a schematic diagram of an RFID tracking system;

Figure 3 is a flowchart of a surgical instrument tracking and sterilization process that may be implemented by a hospital;

Figure 4 is a flowchart of a surgical instrument tracking and sterilization process that may be implemented by a loan kit provider; Figure 5 is a schematic plan view of a tray with an internal antenna according to an embodiment of the invention;

Figure 6 is a schematic plan view of a tray with a plurality of internal antennas according to an embodiment of the invention;

Figure 7 is a flowchart of a process for determining the location and identification of instruments in a tray according to an embodiment of the invention;

Figures 8 and 9 are schematic diagrams of an inductive coupling between a tray and tray interrogator according to an embodiment of the invention; Figure 10 is a schematic diagram of a capacitive coupling between a tray and tray interrogator according to an embodiment of the invention;

Figure 11 is a schematic diagram of a galvanic coupling between a tray and tray interrogator;

Figure 12 is a schematic plan view of a tray with a cassette according to an embodiment of the invention;

Figure 13 is a cross-sectional view of a tray mounted in a cradle;

Figure 14 is a cross-sectional view of a tray mounted in a cradle that includes an antenna coupling element according to an embodiment of the invention;

Figure 15 is a schematic view of a tray with a closing mechanism according to an embodiment of the invention;

Figure 16 is a schematic view of an RFID monitoring system for a sterilization apparatus according to an embodiment of the invention; and Figure 17 is schematic cross-sectional view of a tray mounted on a tray support the tray support providing an interrogation function according to an embodiment of the invention. Detailed Description

It is common for hospitals to order equipment for a surgical operation from a loan kit provider. For example, a prosthetics, e.g. orthopaedic implant, loan kit may include a number of implants of varying sizes and types together with sets of instrument of appropriate size and shape for use with the implants.

During surgery, a surgeon will determine which implants to use, and after surgery, the hospital will return unused implants and the instruments to the kit provider.

Fig. 1 shows schematically a kit loan process 10 where instruments 12 and implants 14 are loaned by a kit provider 16, e.g. from a distribution centre, to a healthcare provider 18, e.g. a hospital.

At the kit provider 16, the instruments 12 are mounted in trays 20, checked for compliance with the hospital's order and loaded into a tote 22 for shipping to the hospital 18. Several sizes of implants 14 are placed on trays 21 which are loaded into a tote 23. The implants 14 are provided in sterilized packaging. At the hospital 18, totes 22 and 23 are received by a central sterilization department 24 (sometimes known as a CSSD - Central Supply and Sterilization Department) where the trays 20 and 21 are removed from totes 22 and 23, and the instruments 12 are washed, scrubbed and sterilized and the instruments 12 and implants 14 are inventoried. The instruments 12 and implants 14 are then sent to an operating theatre 26 in either the same or new trays 20 and 21 , and the instruments 12 and implants 14 are set out and re- checked in a sterile area. Once surgery is over, the trays 20 and 21 , instruments 12 and unused implants 14 are returned to the central sterilization department 24, where the instruments 12 are re-sterilized and the instruments 12 and implants 14 are repacked and returned to the kit provider 16 in totes 22 and 23. The kit provider 16 receives the used kit, sterilizes the trays 20 and

instruments 12, disassembles the kit and conducts an inventory check of instruments 12 and implants 14. The instruments 12 and unused implants 14 are stored for future use in new kits, and the hospital is billed accordingly.

The sterilization processes that the trays 20, instruments 12 and implants 14 undergo may include autoclaving and gamma ray irradiation. For example, implants 14 may be gamma irradiated at manufacture and held in sterile packaging until use, whilst instruments are generally autoclaved at manufacture and during use. At the kit provider and hospital, the instruments are autoclaved, but could also be subject to other processes. A gamma ray irradiation process may for example include a dosage in excess of about 25 kGy, whilst an autoclaving sterilization process might for example include the application of pressurised steam at an appropriately high temperature for an appropriate period of time. Example Australian autoclave protocols include a holding time of 15 minutes at 121 °C or 3 minutes at 134°C, plus a penetration time of for example 15 minutes, whilst an example WHO protocol includes autoclaving at 121 °C for 30 minutes with the instruments resting in a bath of 1 N sodium hydroxide (NaOH) within the autoclave.

The inventorying and tracking of the instruments, implants and trays through these procedures and through their lifetime can be an onerous and expensive undertaking, and would be assisted by the use of RFID tags, as these facilitate automation of identification and tracking processes. A problem, however, is the need to sterilize instruments and implants, which would destroy standard types of RFID tags.

A RFID tagging system that can cope with the sterilization of instruments and implants and that can be used in the process of Fig. 1 is shown in Fig. 2.

In Fig. 2, the surgical instruments 12 are tagged with RFID tags 24 that are sterilization-hard (can withstand the sterilization of the instruments and retain functionality). A tray interrogator 26 that can read the RFID tags 24, respond to an external interrogation signal 28 and provide additional functionality, but that is also sensitive to the sterilization process, is removably coupled to the tray 20 by a releasable coupling 30. Similarly the implants 14 may be tagged with RFID tags that are sterilization-hard, and may for example

be attached directly to the implants or their packaging, whilst a sterilization sensitive interrogator may be coupled to the implant tray.

The sterilization-hard tags 24 may for example take a form as discussed in USSN 60/860,795, and may include tags as in US2006151613 and US2006152313. These tags include micromechanical resonant members that respond to interrogation signals through vibration. The members may for example be vibrated by a Lorentz force, or a magnetic, electrostatic or piezoelectric force, and the detection of the presence and/or absence of a vibrating member of a particular frequency may be equated with a binary "1 " or "0" or other encoding. Such tags are robust and may be configured to survive sterilization processes, such as gamma irradiation, beta irradiation and/or autoclaving, and will have sterilization hard circuitry for initiating vibrations in the members and for providing a resonant response to an interrogation signal. They may be in the form of passive tags without an internal power source. The RFID tags, however, may take any other form and could be made through MEMS, CMOS or any other suitable process.

The tray interrogator 26 may include sterilization sensitive components, such as a microprocessor and associated circuitry. The tray interrogator 26 may for example include a controller 32 for controlling interrogation of instruments 12 or implants 14 and for communicating with external devices, an antenna 34, and a memory 36 for storing information, such as identity, usage and life history data. The data may relate to the interrogator itself, the tray 20 or 21 and/or the instruments 12 and implants 14 in tray 20 or 21. The tray interrogator 26 may also include a power source 38 for supplying power to the various components, and may take the form of an active RFID tag. It would also be possible for the antenna 34 and other sterilization-hard circuitry and components to be mounted permanently on tray 20 or 21 , e.g. on an outer wall surface thereof, with the interrogator 26 connecting to them, when it is mounted to tray 20 or 21 , e.g. through a contactless or direct electrical coupling.

Thus, the instruments 12 and implants 14 may be accurately identified by their sterilization-hard RFID tags 24, which will generally be permanently applied to them for integrity of identification, whilst the tray interrogators 26 are able to provide additional functionality, such as for example extended read

ranges, interrogation control, intelligence and a write-to ability, through the use of sterilization sensitive components, as the tray interrogators 26 may be removed from tray 20 or 21 during a sterilization process.

A hospital or kit provider logistics/information management system 40 is able to identify and track the instruments 12 and implants 14 by reading the permanent tags 24 on the instruments 12 and implants 14 through the tray interrogators 26, through for example the use of a system interrogator 42. The management system 40 may include a central control 44, a database 46 for storing information regarding the instruments, implants, trays, tray interrogators and their histories and relationships, and input and output devices 48 for interacting with users and providing alerts, information and the like.

As the system 40 may monitor the instruments 12 and implants 14 directly, it is not necessary for the tray interrogator 26 to have an identification, and the fact that the tray interrogator 26 is removable need not affect the integrity of an item's identity. If a tray interrogator 26 is removed from one tray 20 or 21 and mounted on another, this is not necessarily a problem, as the management system 40 need not rely on a tray and tray interrogator match for consistency of tracking, but can for example monitor a batch of instruments across a number of trays and/or tray interrogators. The identification of the tray interrogators 26 may however be useful, and the tray interrogators 26 may therefore include identity information, e.g. in its memory 36, so that they too may be tracked and monitored.

In addition, the tray 20 or 21 itself may include identification. The identification may for example be a marker or tag 50, and may take any suitable form that is sterilization-hard and for example allows it to be read by the tray interrogator 26. The tag 50 could for example be a sterilization-hard RFID tag, as discussed above, or could take a contact form, such as a coded array of pins or contacts that are directly readable by the tray interrogator 26. As these tags 50 are generally not removed, the system 40 can construct and monitor tray and instrument relationships through the loan process.

The coupling 30 for removably mounting the tray interrogator 26 to the tray 20 or 21 may take any suitable form. For example, tray 20 or 21 and interrogator 26 may be fastened together by a mechanical fastening, e.g. by a clamping, clipping, hook, friction-fit, push-fit, snap-fit or cam-lock action, or by

fastening elements such as screws, bolts, pins and ties. The tray interrogator

26 could be mounted in a pocket or recess in or on a wall or lid of tray 20 or 21. It could also be removably adhered to tray 20 or 21 or fastened magnetically. The tray interrogator 26 may be sized and shaped to allow for ease of handling, and may include a grip portion that an operator may hold when attaching or removing the interrogator 26 from the tray 20 or 21. In a preferred form discussed later, the tray interrogator may take the form of a cradle in which the tray fits. The tray interrogator 26 may communicate with the system interrogator

42 in any suitable manner. It may act merely as a relay by passing information from an instrument or implant tag 24 to the system interrogator 42, when it receives a read request from the system interrogator 42. It may also store data from the instrument and implant tag 24 ready for passing to the system interrogator 42, and may analyse information received from the instrument and implant tags 24. It may determine if a problem exists and, if so, may issue an alert or the like to a management system 40. It may communicate based on a polled and/or exception basis.

As well as storing information regarding the instruments 12, implants 14, trays 20 and 21 and tray interrogators 26 in the management system 40, e.g. in database 46, any of the tags 24, 50 and the tray interrogator 26 may be designed to be written to and to hold data. They may be write-once or rewritable tags. For example, information could be written to the tray tag 50 prior to or after its application to tray 20 or 21 and may include data as to the instruments or implants to be provided in the tray, and/or this information may be provided in the tray interrogator 26. In one form, the tray interrogator 26 may read data from the tray tag 50 and compare this to data read from the instrument or implant tags 24. Also, during use, surgical instruments may be written to with lifecycle data. While the instrument and implant tags 24 and tray tags 50 may be permanent, they may also be removable. In this case, care needs to be taken to ensure item-tag integrity. The tray tag 50 may for example be designed to remain on a tray throughout a loan kit process, but may be reapplied to a tray

afresh at the initiation of any particular loan process or replaced, so that the tray may include new information on the items placed in the tray.

In a management system, an RFID system interrogator 42 may be provided in a hospital central supply and sterilization department 24, in an operating theatre 26, and in reception and dispatch areas of a kit provider 16.

A flowchart of a hospital surgical instrument tracking and sterilization process that may use the system of Fig. 2 is shown in Fig. 3. A tray having surgical instruments is received at a hospital cental sterilization department at step S100, the contents of the tray are checked using a system interrogator at step S102, the tray interrogator is detached at step S104, the instruments are unpacked, cleaned, washed, inspected and re-packed, and the tray is covered with a drape (permeable to steam but not to infectious agents) and sterilized, for example by autoclaving, at step S106. The draped tray is then sent to the operating theatre at S108. If it is desired to track instruments between the sterilization department and the theatre, the tray interrogator may be reattached, although it should not break the seal of the drape. In this regard, an advantageous form of tray interrogator is a portable cradle in which the tray may sit, as discussed below. Other possibilities also exist e.g. clamping or strapping the interrogator to the tray and drape. A tray interrogator may already be mounted on a tray when it is received from a kit provider, or a hospital may have a pool of tray interrogators which may be attached to the trays on receipt and retained by the hospital on return of the kit to the provider. The same tray interrogator may remain with a tray throughout the hospital process, or a tray interrogator may be provided at and mounted to a tray at each stage at which the tray items need to be read. If a number of trays are to be sterilized, the tray interrogators may be removed and reattached randomly after sterilization without needing to keep track of which interrogators are attached to which tags.

A hospital may have a pool of tray interrogators that may be used at any stage in the process, and may for example include a pool of tray interrogators that are attached to incoming trays and that may follow the trays through the hospital until they are removed when the trays are returned to the kit provider or the like. This may occur for example when there are no tray interrogators

on the incoming tray, or where such interrogators are incompatible with a hospital tracking system.

The hospital may also have separate trays in which instruments are mounted on receipt from the kit provider. As kit provider trays may be quite heavy and difficult to lift, the hospital may use lighter in-house trays to hold the instruments during movement between the central sterilization department and the operating theatre. The trays and tray interrogators could be configured so that the tray interrogators are attachable to both the kit provider and in-house hospital trays or may use separate interrogators. A kit provider tracking and sterilization process is shown in Fig. 4. The kit provider receives a used tray from a hospital at step S110, the tray interrogator is interrogated at step S1 12, the interrogator is detached and the tray is sterilized at step S1 14 and the tray is stored at step S116. The tray may be stored with or without the tray interrogator attached. If missing instruments are noted at step S1 12, the kit provider may bill the hospital for their replacement.

In another kit provider tracking and sterilization process, the kit provider may receive a used tray from a hospital, remove the tray interrogator, sterilize the tray and instruments, re-assemble the instruments on the tray, attach a tray interrogator, read the instrument RFID tags through the interrogator to verify that the correct instruments are in the tray and then store the tray with or without the tray interrogator attached.

On receiving a loan request from a hospital, the tray may be taken from storage and an interrogator attached if not already on the tray. The tray contents may then be verified through an interrogator, and the tray shipped to the hospital in a tote. The tray interrogator may be dispatched with a tray, or may be retained. Dispatch of a tray interrogator with a tray facilitates monitoring of the tray and its contents during transport of the kit. Again, the kit provider may have a pool of tray interrogators to use at any stage in the procedure. If an operator forgets to attach an interrogator to a tray, then the instruments in the tray will not be registered, and an error will occur in the audit procedures. This may then prompt the operator to correctly attach an interrogator.

Fig 5 shows one implementation of a surgical tray 20 and tray interrogator 26. In this implementation, the tray 20 has an internal antenna 60 through which the interrogator 26 interrogates the instrument RFID tags 24 and optionally a tray tag 50. The antenna 60 may for example be formed on a printed circuit board mat that could sit in the bottom of the tray 20. A coupling element 62 is provided in a wall portion (e.g. base, side or lid wall portion) of the tray 20 for coupling the antenna 60 with the interrogator 26. This arrangement is particularly useful where the tray 20 is made of metal or other materials that prevent or interfere with the passage of RF signals. The coupling element 62 may take many different forms, as discussed below.

Fig. 6 shows a further implementation of a surgical tray 20 with multiple antennas 64, each of which is associated with a specific location in the tray 20. In this implementation, each antenna 64 may be polled separately to determine which instruments 12 are in which locations on the tray. A particular location may be associated with one or more instruments, and for example an instrument location may relate to a location on a shadowboard image 66 in the tray. The antennas 64 may connect with a coupling plate 62 formed in a wall portion of the tray 20, and may form an array of couplings with which the tray interrogator 26 can couple. The use of multiple antennas may be particularly useful in situations when two or more of the instruments 12 are difficult to tell apart by eye, e.g. instruments or fasteners that only vary in size to a small degree. By using this system, a user can ensure that the correct instruments are in their correct locations, and so can accurately choose an instrument of a desired size. A process for determining the location of instruments 12 in a tray 20 is shown in Fig. 7, and includes interrogating for an instrument RFID tag 12 through a specific antenna 64 at step S130, determining the presence and identity of an instrument 12 at that antenna's location at step S132, and repeating this process for each antenna 64 at step S134. Another advantage of the use of multiple antennas 64 is that they can provide enhanced coupling, and can reduce problems with the blocking or interference of signals from a single common antenna when the instruments are metal or the like. The antennas 64 can be located, at instrument locations

in the tray 20, adjacent the position where the RFID tags of the instruments are expected to lie, when the instruments are correctly oriented in the tray location.

If correct location of the instruments is not needed, the antennas 64 may all be addressed together, e.g. using a suitable anti-collision protocol for distinguishing the different tag replies, as all that is then required is to know that a tag has replied and not at which antenna the reply occurred.

The coupling elements 62 of Figs. 5 and 6 may take a number of forms. They may for example provide inductive, capacitive or galvanic coupling between the antenna 60 or antennas 64 and the tray interrogator 26. Where a drape or other covering is provided over a tray, then the coupling is preferably contactless, so as to preserve the drape seal and sterility of the inside of the drape.

An inductive coupling arrangement for a multi-antenna tray is shown in

Figs. 8 and 9. A coupling plate 80, as the coupling element 62, includes a coil 82 for each antenna 64 inside the tray 20. The interrogator 26 includes corresponding coils 84 that couple with the coils 82 in the manner of a transformer.

A capacitive coupling arrangement is shown in Fig. 10, in which the tray 20 includes a coupling plate 100 that includes an array of capacitive plates 102, and the tray interrogator 26 includes a corresponding array of capacitive plates 104 that couple with the capacitive plates 102 on attachment of the tray interrogator 26 to the tray 20. A pair of plates 102,104 may be required for each antenna 64.

A galvanic coupling arrangement is shown in Fig. 11 , in which the tray 20 includes a coupling plate 1 10 with an array of sockets 1 12, and the tray interrogator 26 includes a corresponding array of plugs 1 14 that couple with the sockets 1 12 on attachment of the tray interrogator 26 to the tray 20. A pair of plugs 1 14 and sockets 1 12 may be required for each antenna 64.

In each of Figs. 8 to 1 1 , the tray interrogator 26 will apply a signal to each antenna 64 through the array of connectors 82,84, 102,104 and 112,1 14, and will monitor for a response from each.

Fig. 12 shows a further implementation of a tray and interrogator combination, in which the tray 20 includes one or more cassettes 120 for holding RFID tagged surgical instruments 12. When internal cassettes 120 are

used, they may include all or some of the functionality and features associated with the tray 20 in the above discussions.

Where the cassette has antennas 64, it may include a coupling element 122 that couples the antennas 64 with the tray interrogator 26. The cassette coupling element 122 may couple directly with the tray interrogator 26, but in the shown implementation, the tray 20 itself also includes a coupling element 124 in a wall portion thereof, through which the cassette coupling element 122 and the tray interrogator 26 couple. This coupling may take any of the above- discussed forms, and is shown as an inductive coupling in Fig. 12, where the cassette coupling element 122, the tray coupling element 124 and the tray interrogator 26 include coils 122a and 26a respectively for each antenna 64, and the tray coupling element 124 includes a pair of coils 124a, 124b at the inner and outer faces of the wall portion of the tray 20 that are connected together to couple the coils 122a and 26a. The tray 20 may include registration elements 126, e.g. guiding ribs, that ensure that the cassette coupling element 122 is located appropriately for coupling with the tray interrogator 26.

The tray cassette 120 may include an identifier 128, which is sterilization-hard. This may be an identifier such as used for the tray tag 50, and may be an RFID tag.

Fig. 13 shows another implementation of a tray and tray interrogator system in which the tray interrogator takes the form of a portable cradle 130 in which the tray 20 is mounted, e.g. in a recess 132. The cradle 130 includes a interrogator 134 that wirelessly interrogates the RFID tags 24 on the instruments 12 and the RFID tag 50 on the tray 20, and that can respond to an interrogation signal 28 from a system interrogator 42.

The use of a portable cradle 130 within which the tray 20 may be mounted is a particularly advantageous arrangement. It allows a user to simply place a tray 20 in a cradle 130 to enable reading of the tray 20 and instruments 12, and allows a user to handle the cradle 130 rather than the tray 20. The cradle 130 can be configured to accommodate a tray 20 wrapped in a drape 135 or other covering. Such drapes 135 are used to retain sterility of the tray from the sterilization unit to the theatre, and allow steam to permeate through, but provide a barrier to infectious agents. They are applied to the

trays prior to sterilization, and are opened In the theatre. The inside of the drape 135 can then define a sterile area on which instruments can be placed. The drape 135 can extend over the cradle 130, so that it remains on the other side of the drape from the sterile area. The wireless interrogation of the instruments allows them to be tracked without breaking the sterile seal.

A number of different cradles 130 may be provided. For example, a kit provider may have their own cradles that they send their trays out on, and a hospital may have their own cradles which they use for the trays after having removed the kit provider's trays. There may also be a cradle, e.g. for use in theatres, which is designed to fit the inner cassettes 120 of the trays 20 rather than, or as well as, the trays 20 themselves. As a cassette will generally not have its own drape, the cassette cradle may be covered with the sterile drape of the tray or with a further separately provided sterile drape before an inner cassette is placed into it. Fig. 14 shows another implementation of a tray and cradle system, in which a cradle 130, tray 20 and cassette 120 include coupling elements 140, 142 and 144, e.g. as discussed above. In this implementation, the cradle coupling element 140 is provided in a tray supporting surface 146 of the cradle 130 and the tray coupling element 144 is provided in a bottom wall 148 of the tray 20. Where a drape 135 is to be accommodated, the coupling is a contactless coupling, e.g. an inductive or capacitive coupling, as discussed above.

An interrogator component 150 of the cradle 130 is connected to the coupling element 140, and is able to respond to an interrogation signal 28 of an external system interrogator 42.

A retention element 152, which may for example be a spring-mounted locking element, may hold the tray 20 firmly in place on the cradle 130. The cradle 130 may also include a registration element 154, e.g. guiding ribs, for holding the tray 20 in the correct location on the cradle 130 for reading. The cradle 130 may be configured so that the cradle and mounted tray will not fit inside a sterilization apparatus, e.g. an autoclave. This can help prevent the cradle from being accidentally exposed to the rigours of a sterilization process. This may be applied to any of the removable interrogators 26.

Fig. 15 shows a tray implementation that can help to prevent a tray interrogator 26 from being accidentally sterilized. In Fig. 15, the tray 20 has a closure element, e.g. a lid 160, and a closing mechanism 162, which ensures that the lid 160 may not be closed whilst the tray interrogator 26 is attached to the tray 20. For example, the lid 160 may have a pin attached to it which prevents the lid from closing properly unless the interrogator is detached and/or the interrogator could be mounted in a pocket on the side of the tray and a portion of the lid may need to enter the pocket for the lid to close, with the interrogator interfering with the lid closure unless it is first removed. Again, this may prevent a tray interrogator 26 from being accidentally left on a tray 20 during sterilization as the tray 20 will generally be opened to check its contents prior to sterilization, and the lid 160 must be closed prior to sterilization.

The closing mechanism 162 may be designed so that the lid 160 may be removable whilst the tray interrogator 26 is attached to the tray 20, but can then not be refitted. The mechanism 162 may also be designed so that the interrogator 26 may be attachable to the container 20 when the lid 160 is closed.

Fig. 16 shows a sterilization apparatus 170, e.g. an autoclave, with a controller 172 for running the sterilization process and a display 174 and operator controls 176. The apparatus also includes an interrogator 178 that connects with an internal antenna 180. The controller 172 monitors for the presence of a tray interrogator 26 through the interrogator 178 and antenna 180 before commencing a sterilization process. If a tray interrogator 26 is detected, the sterilization process is halted, and an appropriate alert is issued to warn an operator of the potential for damage to the tray interrogator 26, e.g. through the display 174. The tray interrogator 26 could for example be programmed with a type identifier, indicating it is a removable/sterilization- sensitive interrogator, and/or it could be provided with an individual identifier, so that its details may be checked with a central information management system.

Fig. 17 shows further interrogation apparatus, in which a coupling element 190 for reading tagged instruments 12 may be mounted in the surface 192 of a trolley 194 or other support. The support coupling element 190 may

therefore couple with the coupling element 62 of a tray, e.g. the coupling elements 142 and 144 of the tray of Fig. 14, that are used with the cradle 130. This tray support 194 may therefore be used as an adjunct to the portable cradles. The tray support 194 may include registration elements, for example corner ribs 196, for locating the tray 20 in position on the support 194, such that the coupling elements are mounted adjacent one another. The tray support coupling element 190 may be linked to a suitable interrogator. The link could be wired or wireless, and could be a direct link to a system interrogator or a link to an intermediate interrogator on the support 194.

The tray support 194 may allow interrogation of instruments within a draped tray 20. In the operating theatre, the draped tray 20 would be placed on the tray support 194 and the drape 135 unfolded to cover the tray support 194 and provide a sterile surface defined by the inside of the drape 135 on which instruments and the like may be placed.

As well as a trolley, the tray support 194 may be a table, bench or any other support capable of holding the tray 20 at a convenient height.

The tray support may be used by itself in a suitable system, irrespective of the use of a cradle 130 or the like. Although the above discussion have been directed to the identification and tracking of surgical instruments and implants. The systems have broader application. For example, a system may be provided for identifying and tracking items in general that are to be sterilized by tagging the items with sterilization-hard tags, by mounting the items in a container, e.g. on an inner holder that is removable from the container, and by reading the tagged items through a sterilization-sensitive interrogator that is removably coupled to the container This system could be used, for example, with healthcare equipment such as medical dressings, swabs, implants, drips and drugs and in food sterilization and cold chain applications. Also, various of the features above may be used independently of a sterilization process. For example, the use of multiple internal antennas associated with locations in a tray or other container is generally advantageous. The cradle may also be used in non-sterilization applications, as may the tray support and imbedded reader.

It is to be understood that various alternations, additions and/or modifications may be made to the parts previously described without departing from the ambit of the present invention, and that, in the light of the above teachings, the present invention may be implemented in a variety of manners as would be understood by the skilled person.