Instrument having radio frequency identification systems and methods for use

One RFID equipped instrument includes an elongate body with a plurality of uniquely identified radio frequency identification chips spaced along the length of the elongate body. One system used for determining the position of an instrument includes an instrument; a plurality of radio frequency identification chips attached to the instrument; a reader connected to an antenna and adapted to communicate with each radio frequency identification chip using the antenna. One method for determining the position of an instrument using radio frequency identification chips includes providing a radio frequency identification chip reader and antenna; providing an instrument having a longitudinal axis and comprising a plurality of radio frequency identification chips placed along the longitudinal axis; moving the instrument relative to the antenna; and using information about a radio frequency identification chip detected by the antenna to determine the position of the instrument.

FIELD OF THE INVENTION

The present invention relates generally to endoscopes and endoscopic medical procedures. More particularly, it relates to methods and apparatus for tracking the insertion and/or withdrawal of a flexible endoscope along a tortuous path, such as for colonoscopic examination and treatment.

BACKGROUND OF THE INVENTION

An endoscope is a medical instrument for visualizing the interior of a patient's body. Endoscopes can be used for a variety of different diagnostic and interventional procedures, including colonoscopy, bronchoscopy, thoracoscopy, laparoscopy and video endoscopy.

Colonoscopy is a medical procedure in which a flexible endoscope, or colonoscope, is inserted into a patient's colon for diagnostic examination and/or surgical treatment of the colon. A standard colonoscope is typically 135-185 cm in length and 12-19 mm in diameter, and includes a fiberoptic imaging bundle or a miniature camera located at the instrument's tip, illumination fibers, one or two instrument channels that may also be used for insufflation or irrigation, air and water channels, and vacuum channels. The colonoscope is usually inserted via the patient's anus and advanced through the colon, allowing direct visual examination of the colon, the ileocecal valve and portions of the terminal ileum. Insertion of the colonoscope is complicated by the fact that the colon represents a tortuous and convoluted path. Considerable manipulation of the colonoscope is often necessary to advance the colonoscope through the colon, making the procedure more difficult and time consuming and adding to the potential for complications, such as intestinal perforation. Steerable colonoscopes have been devised to facilitate selection of the correct path though the curves of the colon. However, as the colonoscope is inserted farther and farther into the colon, it becomes more difficult to advance the colonoscope along the selected path. At each turn, the wall of the colon must maintain the curve in the colonoscope. The colonoscope rubs against the mucosal surface of the colon along the outside of each turn. Friction and slack in the colonoscope build up at each turn, making it more and more difficult to advance and withdraw the colonoscope. In addition, the force against the wall of the colon increases with the buildup of friction. In cases of extreme tortuosity, it may become impossible to advance the colonoscope all of the way through the colon.

Another problem which arises, for example, in colonoscope procedures, is the formation of loops in the long and narrow tube of the colonoscope. Such loops may arise when the scope encounters an obstacle, or gets stuck in a narrow passage. Instead of progressing, the scope forms loops within the patient. In an attempt to proceed in insertion of the colonoscope, excess force may be exerted, damaging delicate tissue in the patient's body. The physician may proceed with the attempted insertion of the endoscope without realizing there is a problem.

Through a visual imaging device the user can observe images transmitted from the distal end of the endoscope. From these images and from knowledge of the path the endoscope has followed, the user can ordinarily determine the position of the endoscope. However, it is difficult to determine the endoscope position within a patient's body with any great degree of accuracy. This becomes even more difficult when attempting to determine endoscopic positioning using, e.g., automatically controlled endoscopic devices, as described in U.S. Pat. No. 6,468,203; U.S. patent application Ser. No. 09/969,927 filed Oct. 2, 2001; U.S. patent application Ser. No. 10/229,577 filed Aug. 27, 2002; U.S. patent application Ser. No. 10/087,100 filed Mar. 1, 2002; and U.S. patent application Ser. No. 10/139,289 filed May 2, 2002, each of which is incorporated herein by reference in its entirety.

Another method used to determine the configuration of the endoscope is x-ray imaging. Yet another method used is magnetic field positioning, which avoids the x-ray exposure to the patient and the operator. Such a method typically uses magnetic position determination via low frequency magnetic fields to determine the position of a miniature sensor embedded within the endoscope tube. Based on the position of the sensor at sequential time periods, an image of the configuration of the endoscope tube is produced.

Another method involves the placement of a series of markings on the endoscope that can aid the physician in proper placement of the device in the patient's body during a procedure. These markings can include bands, dots, lettering, numbering, colors, or other types of indicia to indicate position or movement of the device within the body. Visually distinguishable marks are often located at regular predetermined intervals. Such a system of indicia can be made to be visible under fluoroscopy by the use of certain radiopaque metals, or compounds incorporated into or printed on the device.

However, each of these methods are limited in their flexibility and applicability when the position of the endoscope within a patient's body is desired with any accuracy. Furthermore, such conventional position determination methods in many cases may also fail to account for the real-time position of the endoscope during advancement and/or withdrawal into the patient.

SUMMARY OF THE INVENTION

The information on the length of an endoscope or colonoscope inserted into a body organ within a patient may be used to aid in mapping the body organ, anatomical landmarks, anomalies, etc., and/or to maintain real-time knowledge along the entire length of the endoscope position within the body. This is particularly useful when used in conjunction with various endoscopes and/or colonoscopes having a distal steerable portion and an automatically controlled proximal portion which may be automatically controlled by, e.g., a controller. Examples of such devices are described in detail in the following granted patents and co-pending applications: U.S. Pat. No. 6,468,203; U.S. patent application Ser. No. 09/969,927 filed Oct. 2, 2001; U.S. patent application Ser. No. 10/229,577 filed Aug. 27, 2002; U.S. patent application Ser. No. 10/087,100 filed Mar. 1, 2002; and U.S. patent application Ser. No. 10/139,289 filed May 2, 2002, each of which has been incorporated by reference above.

One method for determining endoscopic insertion depth and/or position is to utilize a fully instrumented endoscopic device which incorporates features or elements configured to determine the endoscope's depth of insertion without the need for a separate or external sensing device and to relay this information to the operator, surgeon, nurse, or technician involved in carrying out a procedure. Another method is to utilize a sensing device separate from and external to the endoscope that may or may not be connected to the endoscope and which interacts with the endoscope to determine which portion of the endoscope has passed through or by a reference boundary. The external sensing device may also be referred to herein interchangeably as a datum or datum device as it may function, in part, as a point of reference relative to a position of the endoscope and/or patient. This datum may be located externally of the endoscope and either internally or externally to the body of the patient; thus, the interaction between the endoscope and the datum may be through direct contact or through non-contact interactions.

An instrumented endoscope may accomplish measurement by polling the status of the entire scope (or at least a portion of the scope length), and then determining the endoscope position in relation to an anatomical boundary or landmark such as, e.g., the anus in the case of a colonoscope. The polled information may be obtained by a number of sensors located along the length of the device. Because the sensed information may be obtained from the entire endoscope length (or at least a portion of its length), the direction of endoscope insertion or withdrawal from the body may be omitted because the instantaneous status of the endoscope may be provided by the sensors.

Aside from endoscopes being instrumented to measure insertion depth, other endoscope variations may be used in conjunction with a separate and external device that may or may not be attached to the body and which is configured to measure and/or record endoscope insertion depth. This device may be referred to as an external sensing device or as a datum or datum device. These terms are used interchangeably herein as the external sensing device may function, in part, as a point of reference relative to a position of the endoscope and/or patient. This datum may be located externally of the endoscope and either internally or externally of the body of the patient; thus, the interaction between the endoscope and the datum may be through direct contact or through non-contact interactions. Moreover, the datum may be configured to sense or read positional information by polling the status of sensors, which may be located along the body of the endoscope, as the endoscope passes into the body through, e.g., the anus. The datum may be positioned external to the patient and located, e.g., on the bed or platform that the patient is positioned upon, attached to a separate cart, or removably attached to the patient body, etc.

If the patient is positioned so that they are unable to move with any significant movement during a procedure, the datum may function as a fixed point of reference by securing it to another fixed point in the room. Alternatively, the datum may be attached directly to the patient in a fixed location relative to the point of entry of the endoscope into the patient's body. For instance, for colonoscopic procedures the datum may be positioned on the patient's body near the anus. The location where the datum is positioned is ideally a place that moves minimally relative to the anus because during such a procedure, the patient may shift position, twitch, flex, etc., and disturb the measurement of the endoscope. Therefore, the datum may be positioned in one of several places on the body.

One location may be along the natal cleft, i.e., the crease defined between the gluteal muscles typically extending from the anus towards the lower back. The natal cleft generally has little or no fat layers or musculature and does not move appreciably relative to the anus. Another location may be directly on the gluteal muscle adjacent to the anus.

In one alternative embodiment, there is provided an instrument having an elongate body; and a plurality of uniquely identified radio frequency identification chips spaced along the length of the elongate body. Additionally, the instrument may include a covering over the elongate body that contains the plurality of radio frequency identification chips. Additionally, the instrument may include a plurality of hinged segments along the length of the elongate body wherein each hinged segment of the plurality of hinged segments contains at least one uniquely identified radio frequency identification chip of the plurality of uniquely identified radio frequency identification chips. Alternatively, an antenna of at least one radio frequency identification chip of the plurality of radio frequency identification chips wraps at least partially around at least one hinged segment of the plurality of hinged segments. In another embodiment, the plurality of uniquely identified radio frequency identification chips are evenly spaced along the length of the elongate body. In another alternative, the plurality of uniquely identified radio frequency identification chips are spaced at different intervals along the length of the elongate body. Additionally, the plurality of uniquely identified radio frequency identification chips operate at a frequency of about 13.56 MHz or a frequency of about 2.45 GHz. In one embodiment, the one or more one radio frequency identification chips are contained within a 2 mm spacing along the length of the elongate body. In another embodiment, the one or more radio frequency identification chips are contained within a 1 cm spacing along the length of the elongate body. In yet another alternative, each radio frequency identification chip of the plurality of uniquely identified radio frequency identification chips is encoded with position information about the location of the radio frequency identification chip on the elongate body.

In another alternative embodiment, there is provided a system for determining the position of an instrument including an instrument; a plurality of uniquely identified radio frequency identification chips attached to the instrument; a reader connected to an antenna and adapted to communicate with each radio frequency identification chip in the plurality of uniquely identified radio frequency identification chips using the antenna. In another embodiment, the system includes a uniquely identified radio frequency identification chip separate from the radio frequency identification chips attached to the instrument and positioned within the detectable field of the antenna to always be detected by the reader without regard to the position of the instrument. In another alternative, least one radio frequency identification chip in the plurality of uniquely identified radio frequency identification chips attached to the instrument is configured to transmit an authentication code. In another alternative, the antenna and the radio frequency identification chips are configured to operate at a frequency of about 13.56 MHz or 2.45 GHz. In one embodiment, the instrument is an endoscope or a colonoscope. In another embodiment, the instrument is a segmented instrument having a controllable distal tip and a plurality of controllable proximal segments. In one embodiment, the antenna in the system is straight. In another alternative, the antenna has a circular shape sized to allow the instrument to pass through the circular shape. In one aspect, the circular shape is a circle. In another alternative, there is provided a flexible substrate wherein the uniquely identified radio frequency identification chip separate from the radio frequency identification chips attached to the instrument and the antenna are mounted. In one aspect, the flexible substrate includes an aperture sized to allow the passage of the instrument.

In yet another aspect, there is provided a method for determining the position of an instrument using radio frequency identification chips by providing a radio frequency identification chip reader and antenna; providing an instrument having a longitudinal axis and comprising a plurality of radio frequency identification chips placed along the longitudinal axis; moving the instrument relative to the antenna; and using information about a radio frequency identification chip detected by the antenna to determine the position of the instrument. In one aspect, the moving step includes passing the instrument through a hoop formed by the antenna. Another aspect includes providing information about the position of the instrument relative to the antenna to a system used to control the instrument. In one aspect, the step of providing a radio frequency identification chip reader and antenna comprises placing the antenna adjacent an opening in the body of a mammal. Additionally, the opening may be a natural opening or a surgically created opening. In another aspect, the using step comprises using information about a radio frequency identification chip detected by the antenna to determine the position of the instrument relative to the antenna. In another aspect, the information about a radio frequency identification chip includes an indication that the radio frequency identification chip has entered the opening in the body of the mammal. In one embodiment, the indication is that the reader no longer detects the radio frequency identification chip.

DETAILED DESCRIPTION OF THE INVENTION

A determination of the length of an endoscope or colonoscope inserted into a body organ within a patient, or generally into any enclosed space, is useful information which may be used to aid in mapping the body organ, anatomical landmarks, anomalies, etc., and/or to maintain real-time knowledge of the endoscope position within the body. The term endoscope and colonoscope may be used herein interchangeably but shall refer to the same type of device. This is particularly useful when used in conjunction with various endoscopes and/or colonoscopes having a distal steerable portion and an automatically controlled proximal portion which may be automatically controlled by, e.g., a controller. Examples of such devices are described in detail in the following granted patents and co-pending applications: U.S. Pat. No. 6,468,203; U.S. patent application Ser. No. 09/969,927 filed Oct. 2, 2001; U.S. patent application Ser. No. 10/229,577 filed Aug. 27, 2002; U.S. patent application Ser. No. 10/087,100 filed Mar. 1, 2002; and U.S. patent application Ser. No. 10/139,289 filed May 2, 2002, each of which has been incorporated by reference above.

There are at least two different approaches which may be utilized in determining endoscopic insertion depth and/or position when an endoscope has been inserted within the body. One method is to utilize a fully instrumented endoscopic device which incorporates features or elements which are configured to determine the endoscope's depth of insertion and to relay this information to the operator, surgeon, nurse, or technician involved in carrying out a procedure.

Another method is to utilize a sensing device separate from and external to the endoscope and which interacts with the endoscope to determine which portion of the endoscope has passed through or by a reference boundary. The external sensing device may also be referred to herein interchangeably as a datum or datum device as it may function, in part, as a point of reference relative to a position of the endoscope and/or patient. This datum may be located externally of the endoscope and either internally or externally to the body of the patient; thus, the interaction between the endoscope and the datum may be through direct contact or through non-contact interactions.

One method of determination for endoscopic insertion depth and/or position is through an endoscopic device which may be configured to determine its depth of insertion. That is, an endoscopic device may be configured to indicate the portion of the endoscope that has been inserted into a body organ without the need for a separate or external sensing device. This type of determination may reflect an endoscope configured such that its depth measurement is independent of its progress during insertion or withdrawal into the body organ and instead reflects its depth instantaneously without regards to its insertion history.

Such an endoscopic device may accomplish this, in part, by polling the status of the entire scope (or at least a portion of the scope length), and then determining the endoscope position in relation to an anatomical boundary or landmark such as, e.g., the anus in the case of a colonoscope. The polled information may be obtained by a number of sensors located along the length of the device, as described in further detail below. Because the sensed information may be obtained from the entire endoscope length (or at least a portion of its length), the direction of endoscope insertion or withdrawal from the body may be omitted because the instantaneous status of the endoscope may be provided by the sensors. Directional information or history of the endoscope position during an exploratory or diagnostic procedure may optionally be recorded and/or stored by reviewing the endoscope time history of insertion depth.

One variation is seen inFIG. 1Awhich shows endoscope assembly10. Endoscope12may be configured to have at least a single circuit14wired through the length of the shaft of endoscope12. Circuit14may also be wired through only a portion of the shaft length or through a majority of the shaft length depending upon the desired proportion of the shaft that the operator, surgeon, or technician desires to act as a sensor. The single circuit14may thus configure the endoscope12to function as a single continuous sensor. Depending upon the type of sensors implemented, as described in further detail below, changes in an output variable received by the sensors may be measured and recorded. The degree of change in the output variable may then be correlated to the length of the endoscope12inserted into the body. The change in the output variable may also be based upon varying environmental factors experienced by the endoscope12. For instance, one example of an environmental factor which may instigate changes in the output variable sensed by the circuit14may include pressure sensed from the surrounding tissue, e.g., from the anus, where endoscope12is initially inserted into the body. Another factor may include changes in electrical conductivity, e.g., from the tissue, when the endoscope12is inserted into the body.

Endoscope12may alternatively be configured to detect and correlate the length of the endoscope12remaining outside the body rather than inside the body to indirectly calculate the insertion depth. Moreover, the endoscope12may additionally detect and correlate both the length of the endoscope12remaining outside the body as well as the length of endoscope12inserted within the body. Alternatively, endoscope12may sense the location of the orifice or anus20along the length of the device and then calculate either the length remaining outside the body or the insertion length relative to the position of anus20.

Another example of changing environmental factors leading to a change in an output variable is shown inFIGS. 1B and 1C, which show an example of endoscope assembly10configured as a capacitive sensing endoscopic device. As seen inFIG. 1B, patient18may be positioned upon table and/or grounding pad16which may be connected to electrical ground22.FIG. 1Cshows endoscope12inserted within anus20of patient18. Prior to or while endoscope12is inserted in patient18, a constant input current may be provided to endoscope12and the voltage may be measured in accordance. Endoscope12may thus act as a plate within a capacitor while grounding pad16placed under patient18may function as a second opposing plate to endoscope12, as represented in the schematic24. The resulting capacitance between endoscope12and grounding pad16may be calculated based upon the value of the current, i, over a time period, t, and/or upon the measured difference in phase shift between the input frequency and the resulting frequency. As endoscope12is inserted or withdrawn from anus20, the calculated capacitance will vary according to differences in the dielectric constants between the tissue of patient18and that of air. This capacitance change may be constantly monitored and mapped against the length of endoscope12to indicate the length of insertion within patient18.

Another variation on endoscopic sensing may utilize resistivity rather than capacitance. For instance, continuous circuit14may be configured into a single printed circuit with an overlay of conductive printed carbon.FIG. 1Dshows one variation on a cross-section of endoscope12which may be configured as such. As seen, conductive printed carbon layer25may be positioned circumferentially within printed flex circuit26while surrounding endoscope interior28. The endoscope12may be optionally covered by an outer jacket or sheath27to cover the endoscope and its electronics. In use, when the endoscope12is inserted into the patient18through, e.g., the anus20, pressure from the surrounding tissue at the point of insertion into the body may force contact between carbon layer25and flex circuit26within endoscope12and thereby close the circuit14at the point of insertion. As endoscope12is inserted and withdrawn from anus20, the contact point between carbon layer25and flex circuit26will vary according to where the pressure is applied at the point of insertion and the resistance of the circuit14at any one time may be measured and mapped against the length of endoscope12to indicate the length of insertion within anus20.

Another variation is shown inFIGS. 2A and 2B, which show an endoscopic device having a series of individual sensors or switches for sensing its insertion depth or position. Endoscope30is shown as having a continuous circuit with a plurality of open, individual switches or conductive sections32positioned along the length of the device30. Switches, S1to SN, may be positioned at regular intervals along endoscope12. The spacing between the switches may vary and may depend upon the desired degree of accuracy in endoscope position determination. Switches may be positioned closely to one another to provide for a more accurate reading, while switches spaced farther apart from one another may provide for a less accurate determination. Moreover, the switches may be positioned at uniform distances from one another, or alternatively they may be spaced apart at irregular intervals, depending upon the desired results. The switches may also take a variety of electrically conductive forms, e.g., membrane switches, force sensitive resistors (FSR), etc.

Another variation on the type of switch which may be used is light-detecting transducers. The switches S1to SN, may be configured as one of a variety of different types of photo-sensitive switches, e.g., photoemissive detectors, photoconductive cells, photovoltaic cells, photodiodes, phototransistors, etc. The switches S1to SN, may be located at predetermined positions along the length of the endoscope30. As the endoscope30is inserted into the patient18, the change in ambient light from outside the patient18to inside the patient18may result in a voltage change in the switches inserted within the body18. This transition may thereby indicate the insertion depth of the endoscope30within the body18or the length of the endoscope30still located outside the body18. The types of photo-sensitive switches aforementioned may have a current running through them during a procedure, with the exception of photovoltaic switches, which may be powered entirely by the ambient light outside the body18.

FIG. 2Bshows a schematic representation34of the device ofFIG. 2A. As shown, switches, S1to SN, may be configured such that they are in parallel to one another. Insertion or withdrawal of the endoscope12within patient18may activate or close a switch through, e.g., interaction with electrically conductive tissue, pressure from the anus closing the switch, changes in moisture or pH, temperature changes, light intensity changes, etc. The closing of a particular switch will vary according to how deep the endoscope12is inserted within the anus20. When a particular switch is electrically activated, a corresponding resistance value, ranging from R1to RN, may be measured and then mapped against the endoscope12to indicate the length of insertion.

Another variation is shown inFIGS. 3A and 3Bwhich show an endoscope40having a number of sensors positioned along the length of the endoscope40at discrete locations. In this variation, a number of sensor wires may be placed along the length of the endoscope12such that each wire terminates at subsequent locations along the endoscope12, as shown inFIG. 3B. Although only three wires are shown, this is merely intended to be illustrative and any number of fewer or additional wires may be utilized depending upon the desired length of the endoscope12to be instrumented. The placement of the distal ends of sensor wires46′,48′,50′ may coincide with the number of vertebrae or links of the endoscope12structure. The sensor wires46′,48′,50′ may be simply routed through-within the endoscope12length or they may be placed along the exterior of the device. The distal ends of the wires may be exposed to allow for communication with the tissue or they may alternatively be each connected to corresponding conductors42which divide the endoscope12up into a number of segments44. These optional conductors42may be formed in the shape of rings to allow for circumferential contact with the tissue. Each sensor wire46′,48′,50′ may thus be in electrical communication with a corresponding conductor46,48,50, respectively, and so on, depending upon the number of wires and corresponding conductors utilized. The individual sensors may also be networked together on a single bus and more complex networking and placement of sensors may also be implemented to yield additional information, e.g., rotational position of the endoscope12. The proximal ends of the sensor wires46′,48′,50′ may each be connected to a corresponding processor52,54,56, respectively, such that the length of the endoscope12inserted within the anus20may be determined by polling the status of each individual sensor wire46′,48′,50′.

FIG. 4shows another endoscopic assembly variation60in which corresponding pairs of wire sensors may be positioned along an endoscope62body. A first pair64of wire sensors may extend along the endoscope62and terminate at a first distal location; a second pair66of wire sensors may also extend along the endoscope62and terminate at a second distal location which is proximal of the first distal location; and a third pair68of wire sensors may also extend along the endoscope62and terminate at a third distal location which is proximal of the second distal location, and so on. Any number of wire pairs may be used and the distances between each of the first, second, third, etc., distal locations may be uniform or irregular, depending upon the desired measurement results. This variation60may operate in the same manner as above by measuring which pair of wire sensors is disrupted when inserted or withdrawn from a patient.

Yet another example is shown inFIGS. 5A to 5Dwhich shows endoscope assembly70which may comprise an endoscope72having at least one or more, preferably at least two or more, conductive sensors74positioned along the length of endoscope72. Sensors74may be in the shape of rings and may be further configured to measure resistance between each adjacent ring.FIG. 5Bis a detailed view of a portion of endoscope72which shows first sensor76and adjacent second sensor78. Each sensor76,78may be connected to a separate sensor wire76′,78′ such that the electrical resistance, e.g., R1, between adjacent sensors, e.g., sensors76,78, may be measured when contacting a region of tissue.FIG. 5Cshows sensors76,78contacting tissue79. As the endoscope72is advanced or withdrawn from the tissue, resistance values between adjacent sensors may be measured to determine the position of the endoscope72within the patient18. As seen inFIG. 5D, resistance values may be subsequently measured between each adjacent sensor, shown as sensors1,2,3, etc., as the device is advanced into patient18. This may be accomplished, in part, by correlating measured resistance values between sensors where R≈∞. when sensors are measured outside of the body, and R<<when sensors are measured inside the body when surrounded by tissue.

As mentioned above, other output variables aside from pressure or force, capacitance, and resistance measurements may also be employed to determine endoscopic insertion depth. For instance, moisture or pH sensors may be utilized since moisture or pH values change dramatically with insertion into the body. Temperature or heat flux sensing may also be utilized by placing temperature sensors, e.g., thermistors, thermocouples, etc., at varying locations along the endoscope body. Temperature sensing may take advantage of the temperature differences between air and the body. Another alternative may include heating or cooling the interior of the endoscope at ranges above or below body temperature. Thus, the resultant heat flux into or out of the endoscope, depending upon the interior endoscope temperature, may be monitored to determine which portion of the endoscope are in contact with the body tissue. Another alternative may include light sensing by positioning light sensors at locations along the endoscope body. Thus, light intensity differences may be determined between outside and inside the body to map endoscope insertion depth. Alternatively, sound waves or other pressure waves, ultrasound, inductive proximity sensors, etc., may also be utilized.

In utilizing sensors positioned upon the endoscope body, an algorithm may be utilized for determining and recording the insertion depth of the endoscope within a patient, as shown inFIG. 6. This variation on an algorithm operates on the general principle that each of the sensors are triggered sequentially as the endoscope is inserted or withdrawn from the patient. A register may be used to record and keep track of the latest insertion depth, i.e., the most recent and valid triggered sensor. The endoscope and algorithm may be configured such that sensor readings that are considered valid are those readings which are triggered by the same sensor or adjacent sensors such that insertion, withdrawal, or no motion may be indicated. Other sensor triggers can be ignored or rejected while valid sensor triggers may cause the register to update.

Such an algorithm may be implemented with any of the devices described above to eliminate false measurements and to maintain accurate insertion depth measurements. Step80indicates the start of the algorithm as the endoscope waits for a sensor to be triggered82. If a sensor has not been triggered84, the algorithm would indicate a “No” and the device would continue to wait for a trigger signal. Upon an indication that a sensor has been triggered84, a comparison of the triggered signal takes place to compare whether the sensed signal is from an adjacent sensor85by comparing the triggered sensor information to stored register information in sensor register88. If the triggered signal is not from an adjacent sensor, the signal is rejected as a false signal87and the endoscope goes back to waiting for a sensor to be triggered82. However, if the triggered signal is from an adjacent sensor when compared to the value stored in register88, register88is updated86with the new sensor information and the endoscope then continues to wait for another sensor to be triggered82.

Endoscopes Using External Sensing Devices

Aside from endoscopes being instrumented to measure insertion depth, other endoscopes may be used in conjunction with a separate device configured to measure and/or record endoscope insertion depth. This separate device may be referred to as an external sensing device or as a datum or datum device. These terms are used interchangeably herein as the external sensing device may function, in part, as a point of reference relative to a position of the endoscope and/or patient. This datum may be located externally of the endoscope and either internally or externally to the body of the patient; thus, the interaction between the endoscope and the datum may be through direct contact or through non-contact interactions. Moreover, the datum may be configured to sense or read positional information by polling the status of sensors or transponders, which may be located along the body of the endoscope, as the endoscope passes into the body through, e.g., the anus. Alternatively, the datum may be configured to detect sensors or transponders only within a limited region or area. The datum may be positioned external to the patient and located, e.g., on the bed or platform that the patient is positioned upon, attached to a separate cart, or removably attached either internally or externally to the patient body, etc.

FIGS. 7A and 7Bshow one variation in using an endoscope assembly90in conjunction with external sensing device or datum96. Datum96may be positioned externally of patient18adjacent to an opening into a body cavity, e.g., anus20for colonoscopic procedures. Datum96may accordingly have a sensor or reader98located next to opening100, which may be used as a guide for passage of endoscope92therethrough into anus20. Endoscope92may be configured to have a number of tags94, e.g., sensors, transponders, etc., located along the body of endoscope92. These tags94may be positioned at regular intervals along endoscope92. The spacing between the tags94may vary and may also depend upon the desired degree of accuracy in endoscope position determination. Tags94may be positioned closely to one another to provide for a more accurate reading, while tags94spaced farther apart from one another may provide for a less accurate determination. Moreover, tags94may be positioned at uniform distances from one another, or alternatively they may be spaced apart are irregular intervals, depending upon the desired results. Moreover, tags94may be positioned along the entire length of endoscope92or only along a portion of it, depending upon the desired results. As shown inFIG. 7B, as endoscope92is passed through datum96via opening100and into anus20, reader98located within datum96may sense each of the tags94as they pass through opening100. Accordingly, the direction and insertion depth of endoscope92may be recorded and/or maintained for real-time positional information of the endoscope92.

Any number of technologies may be utilized with tags94. For instance, one variation may have tags94configured as RF identification tags or antennas. Reader98may accordingly be configured as a RF receiving device. Each tag94may be encoded with, e.g., position information such as the distance of a particular tag94from the distal end of endoscope92. The reader98may be configured to thus read in only certain regions or zones, e.g., reader98may read only those RF tags passing through opening100or only those tags adjacent to anus20. Alternatively, the RF tags may be configured to transmit the status of, e.g., pressure switches as described above, to datum96to determine the length of insertion.

Another variation on tags94may be to configure the tags for ultrasonic sensing. For example, each tag94may be configured as piezoelectric transducers or speakers positioned along the endoscope92. The reader98may thus be configured as an ultrasonic receiver for receiving positional information from tuned transducers or tags94each of which relay its positional information. Alternatively, optical sensors may be used as tags94. In this variation, each tag94may be configured as a passive encoded marker located on an outer surface of endoscope92. These markers may be in the form of a conventional bar code, custom bar code, color patterns, etc., and each may be further configured to indicate directional motion, i.e., insertion or withdrawal. Furthermore, each tag94may be configured as active encoded markers, e.g., LEDs which may be blinking in coded patterns. Reader98may thus be configured as an optical sensor.

Another alternative may be to configure tags94and reader98for infrared (IR) sensing in which case IR emitters may be positioned along the length of endoscope92such that each IR emitter or tag94is configured to emit light at a specific frequency according to its position along the endoscope92. Reader98may thus be configured as an IR receiver for receiving the different frequencies of light and mapping the specific frequency detected against the length of endoscope92. Yet another alternative may be to have tags94configured magnetically such that a magnetic reader in datum96can read the position of the device, as described in further detail below.

Yet another alternative may be to configure the datum and endoscope assembly as a linear cable transducer assembly. In this variation, reader98may be configured as a transducer having a cable, wire, or some other flexible member extending from reader98and attached to the distal end of endoscope92. While the datum96remains external to the patient and further remains in a fixed position relative to the patient, the endoscope92may be advanced within the patient while pulling the cable or wire from reader98. The proximal end of the cable or wire may be attached to a spool of cable or wire in electrical communication with a multi-turn potentiometer. To retract the cable or wire when the endoscope92is withdrawn, the spool may be biased to urge the retraction of the cable or wire back onto the spool. Thus, the change of wire length may be correlated to an output of the reader98or of the potentiometer to a length of the extended cable and thus the length of the endoscope92inserted within the patient.

Yet another alternative may be to mount rollers connected to, e.g., multi-turn potentiometers, encoders, etc., on datum96. These rollers may be configured to be in direct contact with the endoscope92such that the rollers rotate in a first direction when endoscope92is advanced and the rollers rotate in the opposite direction when endoscope92is withdrawn. The turning and number of revolutions turned by the rollers may be correlated into a length of the insertion depth of endoscope92.

Yet another alternative may be to use the endoscopes, or any of the endoscopes described herein, in conjunction with conventional imaging technologies which are able to produce images within the body of a patient. For instance, any one of the imaging technologies such as x-ray, fluoroscopy, computed tomography (CT), magnetic resonance imaging (MRI), magnetic field location systems, etc., may be used in conjunction with the endoscopes described herein for determining the insertion depth.

In yet another alternative, the datum may be used to sense the positional information from the endoscope through the use of one or several pressure sensors located on the datum, e.g., datum96. The pressure sensor may be positioned upon datum96such that it may press up against the endoscope92as it is advanced or withdrawn. This pressure sensor may be configured, e.g., as a switch, or it alternatively be configured to sense certain features on the endoscope92, e.g., patterned textures, depressions, detents, etc., which are located at predetermined lengths or length intervals to indicate to the pressure switch the insertion depth of endoscope92.

Yet another alternative is to sense changes in the diameter of the endoscope body inserted into the patient, as seen inFIG. 7C. The insertion length of the endoscope may have multiple sections each having a unique diameter, e.g., a distal most section102may have the smallest diameter and each successive proximal section104,106may have incrementally larger diameters. Alternatively, successive sections may have alternating diameter sizes where a first section may have a first diameter, a second section may have a second larger diameter, and the third section may have a diameter equal to the first diameter or larger than the second diameter, and so on. The differences in endoscopic diameter may be used to detect the endoscopic insertion depth by using a datum108which may be configured to maintain contact with the endoscope and move according to the diameter changes of the endoscope, as shown by the arrows. This diameter referencing device and method may be used independently or in conjunction with any of the other methods described herein as a check to ensure that the position of the endoscope concurs with the results using other methods of sensing.

FIG. 8shows another example in endoscope assembly110in which endoscope112may have a number of sensors or tags114located along the body of the endoscope112. As endoscope112is advanced or withdrawn from anus20, datum116, which may be mounted externally of the patient and at a distance from endoscope112, may have a receiver or reader118configured in any of the variations described above. For instance, receiver or reader118may be adapted to function as a RF receiver, ultrasonic receiver, optical sensor, or as any of the other variations described above, to read only those tags114adjacent to anus20and to map their position on the endoscope112and thus, the length of insertion.

If reader118were configured as an optical sensor, it may further utilize a light source, e.g., LED, laser, carbon, etc., within datum116. This light source may be utilized along with a CCD or CMOS imaging system connected to a digital signal processor (DSP) within reader118. The light may be used to illuminate markings located at predetermined intervals along endoscope112. Alternatively, the markings may be omitted entirely and the CCD or CMOS imaging system may be used to simply detect irregularities normally present along the surface of an endoscope. While the endoscope is moved past the light source- and reader118, the movement of the endoscope may be detected and correlated accordingly to indicate insertion depth.

FIG. 9shows another variation with endoscope assembly120in which endoscope122may have a number of sensors124located along the length of endoscope122. These sensors124may be configured as Hall-effect type sensors, as will be described in greater detail below. The datum126may be configured as a ring magnet defining an endoscope guide128F therethrough such that the magnetic field is perpendicularly defined relative to the sensors124. Thus, sensors124may interact with magnet126as they each pass through guide128. As a Hall sensor124passes through datum126, the sensor124may experience a voltage difference indicating the passage of a certain sensor through datum126. These types of sensors will be described in greater detail below.

In order to determine the direction of the endoscope when it is either advanced or withdrawn from the patient, directional information may be obtained using any of the examples described above. Another example is to utilize at least two or more sensors positioned at a predetermined distance from one another.FIG. 10shows one variation illustrating sensor detection assembly130with first sensor132and second sensor134. First and second sensors132,134may be positioned at a predetermined distance, d, from one another. As endoscope136is advanced or withdrawn past sensor assembly130, the direction of travel138of endoscope136may be determined by examining and comparing the signals received from each sensor132,134. By determining which sensor has a rising edge or input signal first received relative to the other sensor, the direction of travel138may be determined. As shown inFIG. 1A, plot140generally illustrates signals received from first sensor132. From position x=1 to position x=2, a rise in the signal is measured thus sensing a peak in advance of the signal measured from position x=1 to position x=2 in plot142, which is the signal received from second sensor134, as seen inFIG. 11B. Thus, a first direction of travel, e.g., insertion, may be indicated by the relative comparisons between signals in plots140and142. If endoscope136were traveling in the opposite direction, e.g., withdrawal, second sensor134would sense a peak in advance of first sensor132.

A more detailed description for determining the endoscope's direction of travel follows below.FIGS. 12A to 12Dillustrate various cases for determining endoscopic direction of travel using first sensor150and second sensor152. First and second sensors150,152are preferably at a predetermined distance from one another while an endoscope is passed adjacent to the sensors. For the purposes of this illustration, a direction to the right shall indicate a first direction of travel for an endoscope device, e.g., insertion into a body, while a direction to the left shall indicate a second direction of travel opposite to the first direction, e.g., withdrawal from the body.

FIG. 12Ashows a situation in which first sensor150measures a voltage less than the voltage measured by second sensor152, as indicated by plot154. If first and second sensors150,152both measure a decrease in voltage, this may indicate a motion of the endoscope to the right while an increase voltage in both first and second sensors150,152may indicate a motion of the endoscope to the left.FIG. 12Bshows another situation in which first sensor150measures a voltage greater than the voltage measured by second sensor152, as indicated by plot156. If first and second sensors150,152both measure an increase in voltage, this may indicate a motion of the endoscope to the right. However, if both first and second sensors150,152measure a decrease in voltage, this may indicate a motion of the endoscope to the left.

FIG. 12Cshows another situation where first sensor150measures a voltage equal to a voltage measured by second sensor152, as shown by plot158. In this case, if first sensor150measures an increase in voltage prior to second sensor152also measuring an increase in voltage, this may be an indication of the endoscope moving to the right. On the other hand, if second sensor152measures an increase prior to first sensor150measuring an increase in voltage, this may indicate movement of the endoscope to the left.FIG. 12Dshows a final situation in plot160where first sensor150again measures a voltage equal to a voltage measured by second sensor152. In this case, the opposite to that shown inFIG. 12Coccurs. For instance, if the voltage measured by first sensor150decreases prior to the voltage measured by second sensor152, this indicates a movement of the endoscope to the right. However, if second sensor152measures a voltage which decreases prior to a decrease in voltage measured by first sensor150, this may indicate a movement of the endoscope to the left.

FIG. 13shows one variation of an algorithm which may be implemented as one method for determining whether an endoscope is being advanced or withdrawn from the body.FIG. 13illustrates how the various determinations described above may be combined into one variation for an algorithm. As seen, the algorithm begins with step170. In step172an initial step of determining whether first sensor150measures a voltage greater than second sensor152is performed. If first sensor150does measure a voltage greater than second sensor152, then a second determination may be performed in step174where a determination may be made as to whether the voltages measured by both sensors150,152are increasing or not. If both voltages are increasing, step178may indicate that the endoscope is being inserted. At this point, the position of the endoscope and its fractional position, i.e., the distance traveled by the endoscope since its last measurement, may be determined and the algorithm may then return to step172to await the next measurement.

If, however, first sensor150does not measure a voltage greater than second sensor152in step172, another determination may be performed in step176to determine whether the voltages measured by sensors150,152are equal. If the voltages are not equivalent, the algorithm proceeds to step180where yet another determination may be performed in step180to determine if both voltages are increasing. If they are not, then step178is performed, as described above. If both voltages are increasing, then step184may indicate that the endoscope is being withdrawn. At this point, the position of the endoscope and its fractional position, i.e., the distance traveled by the endoscope since its last measurement, may again be determined and the algorithm may then return to step172to await the next measurement.

In step176, if the voltages measured by first sensor150and second sensor152are equivalent, then the algorithm may await to determine whether a peak voltage is detected in step182. If a peak voltage is detected, step186increments the insertion count. However, if a peak is not detected, then step188decrements the insertion count. Regardless of whether the insertion count is incremented or decremented, the algorithm may return to step172to await the next measurement.

Endoscopes Using Magnetic Sensing Devices

One particular variation on measuring endoscopic insertion depth may utilize magnetic sensing, in particular, taking advantage of the Hall effect. Generally, the Hall effect is the appearance of a transverse voltage difference in a sensor, e.g., a conductor, carrying a current perpendicular to a magnetic field. This voltage difference is directly proportional to the flux density through the sensing element. A permanent magnet, electromagnet, or other magnetic field source may be incorporated into a Hall effect sensor to provide the magnetic field. If a passing object, such as another permanent magnet, ferrous material, or other magnetic field-altering material, alters the magnetic field, the change in the Hall-effect voltage may be measured by the transducer.

FIG. 14illustrates generally Hall effect sensor assembly190which shows conductor or sensor192maintained at a distance, d, as it is passed over magnets194,196,198at distances x1, x2, x3, respectively. Each magnet may be positioned such that the polarity of adjacent magnets is opposite to one another or such that the polarity of adjacent magnets is the same. As sensor192is passed, voltage differences may be measured to indicate which magnet sensor192is adjacent to.

FIG. 15shows one variation illustrating the general application for implementing Hall effect sensors for endoscopic position measurement. As shown, sensor assembly200illustrates one variation having magnet202with first sensor204and second sensor206adjacent to magnet202. Magnet202may be a permanent magnet or it may also be an electromagnet. First and second sensors204,206are connected to a power supply (not shown) and are positioned from one another at a predetermined distance. Both sensors204,206may also be located at a predetermined distance from magnet202. A general representation of endoscope208is shown to reveal the individual links or vertebrae210that may comprise part of the structure of the endoscope, as described in further detail in any of the references incorporated above. Each vertebrae210is shown as being schematically connected to adjacent vertebrae via joints212which may allow for endoscope articulation through tortuous paths. Endoscope208may be passed by sensor assembly200at a predetermined distance as it is inserted or withdrawn from an opening in a patient. Each or a selected number of vertebrae210may be made of a ferrous material or other material that may alter or affect a magnetic field or have ferrous materials incorporated in the vertebrae210. Thus, as endoscope208passes first and second sensors204,206, the ferrous vertebrae210may pass through and disrupt a magnetic field generated by magnet202and cause a corresponding voltage measurement to be sensed by sensors204,206. Direction of travel for endoscope208, i.e., insertion or withdrawal, as well as depth of endoscope insertion may be determined by applying any of the methods described above.

Another variation is shown inFIG. 16which illustrates a schematic representation220of Hall effect sensing in which the sensors may be located on the endoscope226itself. Magnet222may be positioned adjacent to, e.g., the anus of a patient, such that endoscope226passes adjacent to magnet222when inserted or withdrawn from the patient. Endoscope226may have a number of discrete Hall switches228positioned along the body of endoscope226. As endoscope226passes magnet222, the magnetic field lines224may disrupt a switch228passing adjacently. Hall switches228may be bipolar, unipolar, latched, analog, etc. and may be used to determine the total resistance RI2in order to determine insertion length of the endoscope226.

FIGS. 17A and 17Bshow another variation for Hall sensor positioning.FIG. 17Ashows a sensor assembly230adjacent to an individual vertebrae232of an endoscope. A single vertebrae232is shown only for the sake of clarity. As seen, when vertebrae232is directly adjacent to magnet234, magnetic flux lines238are disrupted and are forced to pass through sensor236. Flux lines238passing through sensor236may cause a disruption in the current flowing therethrough and may thus indicate the passage of the endoscope.FIG. 17Bshows the assembly ofFIG. 17Awhen endoscope230has been advanced or withdrawn fractionally such that magnet234is positioned inbetween adjacent vertebrae232and232′. When a vertebra is not immediately adjacent to magnet234, flux lines238′ may return to their normal undisturbed state such that sensor236is also undisturbed by magnetic flux. The resumption of current within sensor236may indicate that endoscope230has been moved relative to sensor assembly230.

FIG. 18shows another variation in assembly240where a discrete magnet248may be positioned on individual vertebrae242to produce a more pronounced effect in sensor measurement. Magnets248may be positioned along the longitudinal axis of the endoscope for creating a uniform magnetic field radially about the endoscope. Discrete magnets248may be permanent magnets or they may alternatively be electromagnets. In either case, they may be placed on as many or as few vertebrae or at various selected positions along the endoscope body depending upon the desired measurement results. As shown, when vertebrae242having discrete magnet248mounted thereon is brought into the vicinity of magnet244, the interaction between the magnets produces an enhanced flux interaction250such that Hall sensor246is able to sense a more pronounced measurement. The polarity of each individual magnet248located along the endoscope body may be varied from location to location but the polarity of adjacent magnets on the endoscope body are preferably opposite to one another.

Alternatively, a number of magnets each having a unique magnetic signature may be placed at predetermined positions along the length of the endoscope. Each magnet248may be mapped to its location along the endoscope so when a magnet having a specific magnetic signature is detected, the insertion depth of the endoscope may be correlated. The magnets248may have unique magnetic signatures, e.g., measurable variations in magnetic field strength, alternating magnetic fields (if electromagnets are utilized), reversed polarity, etc.

FIGS. 19A and 19Bshow yet another variation in assembly260in which more than one magnet may be used in alternative configurations. A first magnet262may be positioned at an angle relative to a second magnet264such that the combined flux lines268interact in accordance with each magnet. Thus, the polarity of each magnet262,264may be opposite to one another as shown in the figures. Sensor266may be positioned such that the undisturbed field lines268pass through sensor266. As vertebrae270is passed adjacent to sensor266, the disturbed flux lines268′, as shown in assembly260′ inFIG. 19B, may be altered such that they no longer pass through sensor266due to the interaction with vertebrae270. Alternatively, the field lines268passing through sensor266may be altered in strength as vertebrae270passes.

FIG. 20shows yet another variation in which discrete magnets may be placed on each individual vertebrae of an endoscope assembly. As shown, sensor assembly280shows only the vertebrae282of an endoscope for clarity. Discrete magnets284having a first orientation may be placed on alternating vertebrae282while magnets286having a second orientation may be placed on alternating vertebrae282inbetween magnets284. Thus, when the endoscope is moved, e.g., along the direction of travel292, flux lines288having alternating directions on each vertebrae282can be sensed by sensor290. The measured alternating flux lines may be used as an indication of endoscope movement in a first or second direction. Each of the magnets may be positioned along the periphery of the vertebrae on a single side; however, they may also be positioned circumferentially, as described below in further detail.

FIGS. 21A and 21Bshow side and cross-sectional views, respectively, of another alternative in magnet positioning.FIG. 21Ashows a side view of endoscope assembly300in which a number of magnets304having a first orientation may be positioned circumferentially about endoscope302. A number of magnets306having a second orientation opposite to the first orientation may also be positioned circumferentially about endoscope302separated a distance, d, longitudinally away from magnets304. With discrete magnets positioned circumferentially about endoscope302, the rotational orientation of endoscope302becomes less important as it passes sensor308in determining the insertion depth of the device.FIG. 21Bshows a cross-sectional view of the device ofFIG. 21Aand shows one example of how magnets304may be positioned about the circumference. Although this variation illustrates magnets304having a “N” orientation radially outward and a “S” orientation radially inward of endoscope302, this orientation may be reversed so long as the adjacent set of circumferential magnets is preferably likewise reversed. Moreover, although seven magnets are shown in each circumferential set in the figure, any number of fewer or more magnets may be used as practicable.

FIG. 22Ashows yet another variation in which endoscope310may have discrete circumferentially positioned magnets312placed at each vertebrae312on an outer surface of the endoscope310. As endoscope310is passed into anus20, Hall sensor314may be positioned adjacent to anus20such that sensor314is able to read or measure the discrete magnets312as they pass into anus20.FIG. 22Bshows yet another variation in which endoscope assembly320may have endoscope322in which individual vertebrae326may have some ferromagnetic material328integrated or mounted onto or within the vertebrae326. The ferromagnetic material328may be in the form of a band, coating, or other non-obstructive shape for integration onto vertebrae326or for coating over portions of vertebrae326. A sheath or skin324may be placed over the vertebrae326to provide for a lubricious surface. Inbetween vertebrae326, non-magnetic regions330may be maintained to provide for the separation between vertebrae326and between ferromagnetic material328. Moreover, ferromagnetic material328may be applied retroactively not only to endoscopes having vertebrae, but also other conventional endoscopes for which a determination of insertion depth is desired. As endoscope322passes magnet332, sensor334may detect disturbances in flux lines336as the regions having the ferromagnetic material328passes. Additionally, endoscope322may be passed at a distance, h, from sensor334which is sufficiently close to enable an accurate measurement but far enough away so as not to interfere with endoscope322movement.

FIG. 23shows yet another variation in which conventional endoscopes may be used with any of the Hall sensor datum devices described herein. As shown, elongate support or tool337may have a number of magnets338, or ferrous material or other materials that may alter or affect a magnetic field, positioned along the tool at predetermined intervals. Magnets338may be positioned along the length of tool337such that the adjacent magnets are either alternating in polarity or uniform in polarity. Furthermore, magnets338may be made integrally within the tool337or they may be made as wireforms or members which may be crimped about tool337. Tool337may be positioned within the working lumen339of any conventional endoscope for use with a datum device as described herein. The inclusion of the tool337may then enable the determination of insertion depth of a conventional or instrumented endoscope. If a conventional endoscope is used, tool337may be securely held within the working lumen339during an exploratory procedure. Tool337may optionally be removed during a procedure to allow for the insertion of another tool and then reinserted within lumen339at a later time to proceed with the insertion and/or withdrawal of the endoscope.

FIGS. 24A to 24Cshow perspective views of alternative variations for attaching permanent magnets, ferrous materials, or other materials that may alter or affect a magnetic field, onto individual vertebrae.FIG. 24Ashows one variation in which vertebrae340may be manufactured with a notch or channel342circumferentially defined along its outer surface344. A ring made of a ferrous material or other material that may alter or affect a magnetic field, such as permanent magnets, may be placed within notch342.FIG. 24Bshows another variation in which a formed ring348made of a permanent magnet or other such materials may be separately formed and attached onto vertebrae346.FIG. 24Cshows yet another variation in which a wire form354made from a ferrous material or other material that may alter or affect a magnetic field, such as a permanent magnet, may be placed within notch352of vertebrae350. Alternatively, ferrous powder may be molded into a circumferential shape and placed within notch352. Another alternative may be to simply manufacture the entire vertebrae from a ferrous metal or simply cover a vertebrae or a portion of the vertebrae with a ferrous coating.

Another alternative for utilizing Hall sensors is seen inFIGS. 25A and 25B. The variation inFIG. 25Amay have a fixed platform360upon which a magnet364may be mounted. A pressure sensor or microforce sensor362may be placed in between magnet364and platform360. As an endoscope is passed adjacent to magnet364, the magnet364may be attracted to vertebrae366as it passes adjacently. Vertebrae366may optionally include ferrous materials or other materials that may alter or affect a magnetic field as described above to enhance the attraction and/or repulsion. As magnet364is pulled or repulsed by the magnetic force, pressure sensor362may record the corresponding positive or negative force values for correlating to endoscope insertion depth.FIG. 25Bshows another example in which magnets368may be attached to a pressure gauge370, e.g., a Chatillon® gauge made by Ametek, Inc. As the endoscope passes magnets368at some distance, h, the attraction and/or repulsion between magnets368and vertebrae366may be accordingly measured by gauge370and similarly correlated to endoscope insertion depth.

Yet another variation is shown inFIGS. 26A and 26Bin assembly380. Rather than utilizing the linear motion of an endoscope past a static datum, a rotatable datum382may be used to record insertion length. Datum wheel382may be configured to rotate about pivot384while sensing the movement of endoscope386, which shows only schematic representations of the vertebrae for clarity. The datum wheel382may have a number of magnets398incorporated around the circumference of wheel382. Each magnet may be arranged in alternating pole configurations or alternatively in the same pole arrangement. Each of the magnets398are also preferably spaced apart from one another at intervals equal to the linear distances between the magnets388,390or permanent magnet located along the body of endoscope386. Ferrous materials, or materials that may otherwise alter a magnetic field, may be used in place of the permanent magnets. As endoscope386is moved past datum wheel382, wheel382rotates in corresponding fashion with the linear movement of endoscope386past the datum382.

The rotation of datum wheel382that results when endoscope386is moved past can be sensed by a variety of methods. One example includes rotary optical encoders, another example includes sensing the movement of magnets398on datum wheel382as they rotate relative to a fixed point as measured by, e.g., Hall effect sensors or magnetoresistive sensors. As datum wheel382rotates with the linear movement of endoscope386, datum wheel382may directly touch endoscope386or a thin material may separate the wheel382from the body of endoscope386.FIG. 26Bshows one variation of an assembly view of datum wheel382which may be rotatably attached to housing392. Housing392may be connected to stem or support394, which may extend from housing392and provide a support member for affixing datum wheel382to the patient, an examination table, a stand, or any other platform. Support394may also be used to route any cables, wires, connectors, etc., to housing392and/or datum wheel382. The associated sensors and various support electronics, e.g., rotary encoders, magnetic field sensors, etc., may also be located within housing392. Support394may further include an optional flexible joint396to allow datum wheel382to track the movement of endoscope386as it passes into or out of a patient.

Examples of External Sensing Devices

The external sensing devices, or datum, may function in part as a point of reference relative to a position of the endoscope and/or patient, as described above. The datum may accordingly be located externally of the endoscope and either internally or externally to the body of the patient. If the patient is positioned so that they are unable to move with any significant movement during a procedure, the datum may function as a fixed point of reference by securing it to another fixed point in the room, e.g., examination table, procedure cart, etc. Alternatively, the datum may be attached directly to the patient in a fixed location relative to the point of entry of the endoscope into the patient's body. The datum variations described herein may utilize any of the sensing and measurement methods described above.

For instance, for colonoscopic procedures the datum may be positioned on the patient's body near the anus. The location where the datum is positioned is ideally a place that moves minimally relative to the anus because during such a procedure, the patient may shift position, twitch, flex, etc., and disturb the measurement of the endoscope. Therefore, the datum may be positioned in one of several places on the body.

One location may be along the natal cleft, i.e., the crease defined between the gluteal muscles typically extending from the anus towards the lower back. The natal cleft generally has little or no fat layers or musculature and does not move appreciably relative to the anus. Another location may be directly on the gluteal muscle adjacent to the anus.

One variation for the datum for positioning along the natal cleft408is shown inFIG. 27. Datum400may have sensor402positioned in the distal tip of the sensing device, which may be placed adjacent to anus20. The datum itself may be positioned within the natal cleft408and temporarily held in place on the patient with adhesive406. The datum may have a connector404extending via a wire or cable for connection to a processor (not shown).

Another variation is shown inFIG. 28in which the datum410may have a base comprising a substrate. The substrate may have an adhesive side that may be placed against the small of the patient's back. An elongate flexible member or arm412may extend from the substrate and lie within or against the natal cleft such that the distal end414of member412is adjacent to anus20. Distal end414may have a sensor mounted within for sensing the movement of an endoscope as it is passed through anus20. The flexible member412may be secured along the natal cleft using, e.g., adhesive tape, to prevent excessive movement of the device.

FIGS. 29A and 29Bshow a detailed view of a variation of the datum device410ofFIG. 28.FIG. 29Ashows another view for possible positioning of datum410on patient18. The substrate may be positioned proximal of anus20while member412extends along the natal cleft for positioning sensor tip414proximally adjacent to anus20.FIG. 29Bshows datum410laid out and having a substrate420upon which sensors and electronics may be positioned. Substrate420, as mentioned above, may have an adhesive backing for temporary placement against the patient18. Moreover, datum410, or any of the other datum examples described herein, may be optionally configured to be disposable for one-time use on a patient. Support electronics422may optionally be placed upon substrate420and sensor426may be positioned within the distal end414at or near the end of the flexible member or arm412. An optional magnet428may be positioned along member412proximally of sensor426. Connector424may extend via a wire or cable from datum410for connection to a processor.

Another variation is shown inFIGS. 30A and 30Bwhich shows datum substrate430having sensor436positioned within the distal end of elongate flexible assembly434for placement adjacent to anus20. Connector432may be provided for connection to a processor. Here, elongate assembly434may be secured against or within the natal cleft by use of, e.g., an adhesive strip438.FIG. 30Bshows a cross-sectional top-down view of elongate assembly434positioned against the natal cleft. A sponge, silicone wedge, or some other wedging device440may be positioned inbetween elongate assembly434and adhesive strip438to ensure secure positioning of the datum device relative to anus20.

FIG. 31shows another variation on the datum device which may utilize a disposable substrate. Datum assembly450may have substrate452for placement against the patient. A retaining pocket454may be defined within or upon substrate452and it may be configured to allow for a reusable electronic sensor assembly458to be placed within pocket454. Sensor assembly458may have a wire or cable462extending therefrom and it may further have a sensor460positioned or potted upon sensor assembly458. The sensor assembly458may be positioned within pocket454by slipping sensor assembly458through an opening456defined within substrate452and sensor assembly458is preferably positioned within pocket454such that sensor460is positioned at the distal end of substrate452to allow for positioning adjacent the anus.

Another variation for positioning a datum is directly on the gluteal muscle adjacent to the anus. Generally, the sensor and associated circuitry may be incorporated into a patch or small chassis that may then be attached to the muscle adjacent to the anus. The entire datum assembly may optionally be mounted onto a bandage-like package with an adhesive backing.FIGS. 32A and 32Bshow a variation in datum470which is formed into a small chassis having connector472extending therefrom. Datum470may be attached temporarily to patient18via adhesive474adjacent to anus20. A guide, ramp, or other similar structure476for situating, orienting, or guiding endoscope relative to datum470may be optionally incorporated into the device.

FIG. 33Ashows another variation of the device in datum480. In this example, datum480may be in the form of a patch with sensor482positioned thereon. The device may be placed upon one of the gluteal muscles such that sensor482is adjacent to anus20.FIG. 33Bshows a detailed view of how datum480may be positioned upon the gluteal muscle adjacent to anus20. Adhesive484may be placed over datum480to temporarily hold it onto the gluteal muscle as shown.FIG. 33Cshows an example of how datum480may interact with endoscope486as it is advanced or withdrawn from anus20. Because datum480may have a relatively small diameter, D, discomfort may be reduced for the patient and close proximity to anus20may be assured. As endoscope486moves past datum480, the sensors within datum480may measure the insertion depth. Zone488shows generally the zone of operation, i.e., the region within which the operator's or surgeon's hands generally operate during a colonoscopy procedure. Because of the small diameter of datum480and its position adjacent anus20, it is generally out of the way of the operator or surgeon during a procedure and thereby allows for unhindered operation of the endoscope486while maintaining accurate measurement or sensing with datum480.

FIG. 34shows yet another variation in datum490which may have a substrate with sensor494mounted at one end. Support electronics492may be optionally mounted on datum490and wire or cable496may be used to transmit the measured signals from sensor494. Datum490may be in a triangular shape for placement upon a single gluteal muscle, as shown, such that a vertex of the substrate is positioned adjacent to anus20to allow sensor494to sense or measure signals as endoscope498is advanced or withdrawn into anus20. Although shown in this variation in a triangular pattern, this is not intended to be limiting and is intended merely to illustrate one possible shape for the datum.

Another variation is shown inFIG. 35in which datum500may incorporate multiple sensors. Datum500may be placed on a single gluteal muscle and it may define an insertion region508at which the anus of the patient may be positioned. Each of the sensors502,504,506may thereby be configured to sense or read the endoscope as it passes through or past the insertion region508. Although three sensors are shown in this configuration, fewer or more sensors may be utilized depending upon the configuration of the datum500and the desired signal processing results.

FIG. 36shows yet another variation in which datum510may be encased in a rigid housing. Datum510may thus encapsulate support electronics512within with sensor514directed towards one end of the housing. The housing may incorporate a connector516attached via a wire or cable extending from the datum510. The rigid housing may be temporarily adhered to the patient on a gluteal muscle in the same fashion as described above.

FIG. 37shows yet another variation in which datum520may be configured to extend across the natal cleft to position an opening defined in the datum over the anus of the patient. As shown, an adhesive substrate522may be configured, e.g., into a “butterfly” configuration. Substrate522may have at least two wings or flaps524for adhering to each gluteal muscle across the natal cleft while sensor526and support electronics528may be contained adjacent an opening534defined at or near the center of substrate522. Sensor526and support electronics528may be potted or contained within a housing530on substrate522. Connector532may be attached via a wire or cable for connection to a processor.

A datum device may also be configured to encircle an endoscope as it passes into the body. Such a datum configuration may be useful when using sensing technology such as RF. In the case of RF, the datum may be in a looped configuration to facilitate the exchange of RF signals with components or sensors mounted along the endoscope, as described above. One variation of a looped datum configuration is shown inFIGS. 38A and 38B. As shown, datum540may have a loop542defined at a distal end to function as a signal receiver, e.g., RF signals, and/or as a guide loop. The datum540may be aligned along the natal cleft408and secured in place with adhesive tape544. A connector546may be attached to datum540via a wire or cable at a first end of datum540while sensor548may be positioned at the opposing end of datum540. Sensor548may be positioned adjacent to anus20, while loop542encircles the opening of anus20. The loop542may define an insertion region550through which an endoscope may be passed. The loop542may be made of a thin, flexible material such as mylar and it optionally have an adhesive backing for placement upon the tissue surrounding anus20. Although shown in a circle configuration, loop542may be in a variety of looped configuration and is not limited by its shape.

Yet another variation is shown inFIG. 39where a supporting garment560, e.g., a pair of underpants, may define an opening562in the region surrounding the anus20. A loop564may be incorporated into the fabric such that the loop surrounds the opening562. The fabric in the middle of loop564may either be removable at the time of the procedure or omitted altogether. Connection to the loop564may be made through connector566, which can be connected via a wire or cable extending from, e.g., the waistband, front, or side of garment560.

Aside from colonoscopy, other applications may include uses in minimally invasive surgery (MIS). MIS typically depends upon the use of long, thin tools for insertion into the body via small incisions, e.g., often through a cannula. Instruments typically employed during MIS may include rigid endoscopes, laparoscopes, thoracoscopes, needle drivers, clamps, etc. Because each of these tools must pass through an opening in the body, a datum device may be used adjacent to that body opening for tracking instrument insertion depth. In situations where cannulas are used, the cannula itself may be instrumented through one of the methods described above.

For other types of endoscopy procedures, various types of flexible endoscopes may be used, e.g., upper endoscopes, duodenoscopes, sigmoidscopes, bronchoscopes, neuroscopes, ENT scopes, etc. Any of the devices and methods described above may be utilized and configured to maintain insertion depth for any of these types of endoscopes. For instance, for flexible endoscopes that enter the body transorally, a mouthpiece configured as a datum may be utilized.

In another embodiment of the present invention, there is provided an instrument, system and method for the use of RFID technology to the sensing of position. A series of RFID tags are affixed to an object that passes in close proximity to an RFID reader & antenna. The passage of the series of RFID tags allows the position of the object to be determined by identifying the RFID tags that respond to queries by the reader.

Specifically, one application of this concept relates to sensing the depth of insertion of a flexible endoscope into a patient during an endoscopic procedure. This application describes an application specific to colonoscopy. The techniques, methods, components and systems described herein may be used with any flexible endoscope and any endoscopic procedure. Other related concepts are described in U.S. patent application Ser. No. 10/384,252 published as U.S. Patent Application No. 2004/0176683, which is incorporated herein by reference in its entirety.

There are 4 major families of RFID technologies, categorized by their operating frequencies:1. Low frequency (LF): 125 kHz-135 kHz2. High Frequency (HF): 13.56 MHz3. Ultra-High Frequency (UHF): 868 MHz-928 MHz4. Microwave: 2.45/5.8 GHzThe embodiments described herein may be implemented within any of the above listed RFID families. HF RFID has the following advantages:1. operates at frequencies that are not highly absorbed by water or living tissue2. mature technology with many readily available components3. compact components4. high read rates (<0.25 s)5. anti-collision (multiple RFID tags may be read simultaneously)

Other RFID families share some of these advantages; however HF is the only family that combines them all at the same time. The primary advantage of microwave RFID is the relatively small size of the RFID chip. The Hitachi μ-chip, for example, is about 0.4 mm×0.4 mm. This size allows the chip to be placed in nearly any location along, within or about an instrument.

RFID tags, readers and antennas are well known and widely commercially available. A typical RFID (Radio Frequency Identification) system is comprised of 4 basic elements: (1) RFID reader module; (2) RFID reader antenna, (3) RFID reader antenna cable and (4) RFID tag, chip or sensor.

RFID Reader Module

The RFID reader module is the source of the RF carrier wave used both to provide power to responding RFID tags, and to create the base carrier over which RF communications are achieved. The reader module can be off-the-shelf module such as the OBID® RFID Reader System provided by FEIG Electronic GmbH located in Weilburg, Germany or the Skyemodule M1 provided by SkyeTek, Inc. located in Westminster, Colo. The reader may include an anti-collision mechanism that allows for the orderly processing of responses from two or more RFID tags within the reader field range. Reader modules may be designed from conventional modular components or custom designed. Typically RFID readers are configured to operate with RFID tags that comply with ISO-15693, ISO-14443 and HF EPC, for example. Readers have a read range based on a number of factors such as antenna type (internal vs. external), surrounding structure that may interfere with operation and operating frequency. For example, an HF RFID reader may have a read range or reader field range of 9 cm with an internal antenna or 20 cm with an external antenna. In another example, a microwave RFID reader may have a reader field range of 1 m or more. Embodiments of the present invention utilize the entry and departure of individual RFID tags from a reader field range to determine the position of an instrument.

RFID Reader Antenna

The RFID reader antenna is the antenna used to broadcast the RF carrier wave created by the RFID reader module, and to receive the signal created by the RFID tag. The antenna is selected based on the operating frequency for the RFID system.

RFID Reader Antenna Cable

The RFID reader antenna cable is a conventional wired connection between the reader module and the reader antenna, typically impedance matched.

RFID Tags

An RFID tag is a conventional transponder that is excited and queried by an appropriate RFID reader assembly based on the operating frequency of the RFID system in use. RFID tags are passive ICs that receive power from the RF signal from the reader and generate electric power from the received RF signal. The RFID tag then transmits its ID or data to the reader. The response of a typical RFID tag may include but is not limited to: tag serial number, tag data field, placement within an item (i.e., distance from the distal end of an instrument or placement about the perimeter of an instrument) and/or sensor inputs. A typical RFID tag is comprised of an RFID integrated circuit (chip), an antenna, and discrete electronic components (e.g. inductors, capacitors, resistors, etc.). RFID tags are also referred to as short range contactless memory chips. Numerous various chips are commercially available and manufactured by STMicroelectronics of Geneva, Switzerland, among others. Another RFID IC is the μ-chip provided by Hitachi, Ltd., Japan. The RFID tag and reader may also be programmed to provide a number of other features such as: anti-clone, authentication, unique ID, and/or challenge/response. RFID tags may also include writable memory. One use of the writable memory would be to write the position orientation or other position information onto a specific tag as the instrument is assembled or as part of a tag initiation process. In this manner, the unique identification of a tag may be associated with a position on, in or about an instrument or component of an instrument. One exemplary write application would be to write onto tag memory the location of the tag relative to the distal end of the instrument. The write process may also include information related to the orientation of the tag on a portion of the instrument. Exemplary orientations may include 0, 90, 180 or 270 degree relative positions on a component of the instrument such as a vertebra or other structural member.

A plurality of RFID tags are provided on, in, about or along an instrument.FIGS. 45,46,47, and41provide non-limiting examples for various placement arrangements on, about or along an instrument. Additional specific but non-limiting examples of RFID tag placement include:a. RFID tags that are built into, or added onto, a articulating vertebra or other structural member of an instrument.b. RFID tags that are constructed into a stand alone structure that is then added-onto the structure of or a component of an instrument. One example is the RF bobbin illustrated inFIGS. 43A and 43B. As illustrated, the RFID IC and antenna is fabricated into a hoop that then slides over an exiting structural component of an instrument.FIGS. 42A and 42Billustrate the RF bobbin inFIGS. 43A and 43Bin place on two hinged segments of an instrument.c. RFID tags may be placed in a variety of positions relative to the segments or sections of an instrument.i. The RFID tag may be placed inside or formed within a segment or section ring.ii. The RFID tag may be placed outside of a ring such as within the instrument skin or outer barrier that covers the instrument. The RFID tag may be placed on, in or along a component between instrument structure and instrument skin such as the mesh or tube sleeve606illustrated inFIG. 42A. Strips of RFID tags (such as a plurality of μ-chips for example) may be located in various positions along or about the instrument as illustrated inFIGS. 44,41,40,45,46, and47.d. The number and placement of RFID tags on an individual vertebra, segment or structural element include, without limitation:i. One RFID tag per vertebraii. Multiple RFID tags per vertebra or other structural component of an instrumentiii. One tag per multiple vertebrae, segment or section.

In addition to providing a number of RFID tags on, in, along or about an instrument, it is to be appreciated that different function and types of RFID tags can be used, such as, for example:a. LF, HF, UHF, or microwave operating frequency.b. More than one tag per vertebra or per structural component of an instrument.c. RFID tags that respond only with their serial number (“bar code” style) in circumstances where no other storage or reporting of data is possible.d. RFID tags may provide bar code plus other parameter, e.g., rotational position or “torque”, switch open/closed, temperature, etc.e. RFID tags may be used to help determine scope shape and/or position or other descriptors. Other exemplary functions include triangulation of RFID tag position, based on signal strength for example, including RFID for triangulation to determine position and/or rotation of scopef. Advanced technology and compact design RFID chips such as the p-chip or the so called “grain of sand” RFID tags from Hitachi, Ltd.

In some embodiments, the reader antenna is designed in the form of a “patch,” or a flexible substrate or structure (see, for example,FIGS. 27-39,48,49, and50) that supports the reader antenna and provides an aperture sized to receive an instrument. The substrate may include an adhesive backing so that it may be affixed to a surface while in use. One exemplary use is that the flexible substrate is affixed to a patient near the point of entry into the body. At least one RFID tag may be used near the antenna (i.e., within the reader field range) for anti-cloning or anti-counterfeiting functions and to continuously verify function of the reader module. A plurality of RFID tags may be provided on or in the instrument to assist in determining, for example, the depth of insertion of the instrument, instrument function and/or performance.

An RFID reader antenna may also optionally be provided with an RFID tag built into or located near the antenna. Many details of various reader antenna alternatives are illustrated inFIGS. 48,49and50. One benefit of placing an RFID tag that remains within the reader field range is that the reader will always see one “known good” tag. The ability of the reader to be able to query a known tag may be used to verify system operation or to authenticate an antenna assembly (i.e., the antenna patch, seeFIGS. 27-34adapted for RFID applications andFIGS. 48,49and50). The “known good” tag may also be used to confirm the RFID positioning system is functioning properly.

The system described herein provides a programmable device that is manufactured as part of a single-use medical device for the purpose of determining calibration, manufacturer, operator and other information. These functions are accomplished without a conventional wired interface. Instead, these functions are accomplished using a radiofrequency interface provided by the reader antenna and the RFID tag for real time device operation or performance monitoring. Additionally, the use of a “known good” tag provides an operational check of RFID reader antenna circuitry to verify integrity of the cable and antenna.

Another feature is an anti-counterfeiting or anti-clone feature: An RFID tag may be assigned a code unique to the system. System software could be require identification of a “recognized” tag prior to operation of the system. An embedded RFID tag in the flexible antenna substrate may be used to prevent counterfeiting and ensure that the device remains a single-use medical device. Counterfeiting is prevented or discouraged because of the unique code that can be programmed into the memory of the RFID tag thereby making the single-use medical device difficult for others to copy.

In order to prevent counterfeiting, an RFID tag integrated circuit and antenna may be fabricated into a single-use device. The single use device has an integrated RFID antenna. When connected to an RFID reader, the RFID antenna can read tags in the vicinity as well as the integrated tag. Software inside the RFID reader will perform a check of the single-use device by reading the RFID tag to ensure the attached single-use devices in genuine. If a known RFID tag is not read, the software will prevent use of the single-use device. In addition, the RFID tag embedded the antenna serves as an indicator that the RFID reader antenna is connected to the RFID reader. When the RFID reader is unconnected, the RFID tag in the single-use device will not be seen by the RFID reader. RFID reader antenna mount, patch or substrate could be, preferably, disposable, but could also be made to be reusable.

FIG. 40illustrates an instrument having an elongate body640. The elongate body includes a distal end645. The instrument has working channel602, a camera608and fiber optic bundle609. In one embodiment, the instrument is an endoscope or a colonoscope. In another embodiment, the instrument is a segmented instrument having a controllable distal tip and a plurality of controllable proximal segments. A plurality of uniquely identified radio frequency identification chips614are spaced along the length of the elongate body640. The chips614may be evenly spaced or spaced at different intervals along the length of the elongate body. In one embodiment, more than one radio frequency identification chip is contained within a 2 mm spacing along the length of the elongate body. In another embodiment, one or more radio frequency identification chips are contained within a 1 cm spacing along the length of the elongate body. In one alternative embodiment, each radio frequency identification chip of the plurality of uniquely identified radio frequency identification chips is encoded with position information about the location of the radio frequency identification chip on the elongate body. For example, each chip could be encoded to contain the distance from the chip to the distal end645. In another example, the RFID chips attached to an instrument are configured to transmit an authentication code.

An antenna614A is provided for each chip614. The drawing is not to scale and the antenna614A may be longer and have a different shape or orientation relative to the elongate body than illustrated. The covering607is placed over the elongate body and contains the plurality of radio frequency identification chips614. An additional optional covering (not shown) may be placed over the covering607and chips614. The chips614may also be embedded within a covering607, between layers of a multilayered laminate structure. Alternatively, the chips614and antennas614A could be mounted on an adhesive backing and secured to the covering607. Optionally, the chips614and antennas614A on the adhesive backing could be encapsulated in a protective biocompatible covering.

FIG. 41illustrates an elongate body640including a plurality of hinged segments630along the length of the elongate body. The embodiment illustrated inFIG. 41also includes a plurality of uniquely identified radio frequency identification chips614spaced along the length of the elongate body. In this embodiment, the radio frequency identification chips are evenly spaced along the length of the elongate body640because they are placed on, in or about similarly sized segments630. Each hinged segment630includes segment hinges626. Adjacent segment hinges626join to form a hinged connection625between each hinged segment630. In the illustrated embodiment, each hinged segment630contains at least one uniquely identified radio frequency identification chip614. While illustrated in the same position on each segment630, the RFID chip614may be positioned in a different location on each segment or may be in the same location in similarly oriented segments. Here, similarly oriented segments may be determined by the location of the hinged connection625as being on the top/bottom (i.e., 12 o'clock and 6 o'clock positions) or the sides (3 o'clock and 9 o'clock positions). A cross section of an the RFID reader antenna710is also illustrated. It may be continuous ring that partially or completely encircles the elongate body640. As the instrument advances in the direction of the arrow, chips614to the left of the antenna710will eventually enter the reader field range and become detected while chips to the right of the antenna710will eventually leave the reader field range and no longer respond.

FIGS. 42A and 42Billustrate perspective and end views, respectively, of another alternative embodiment of an instrument having a plurality of RFID tags614. The instrument600includes an elongate body640and a plurality of uniquely identified radio frequency identification chips614spaced along the length of the elongate body. This embodiment also includes a plurality of hinged segments630along the length of the elongate body. Two segments630and segment hinges626are visible. One hinged connection625is visible and many more are present under skin or cover607but cannot be seen in this view. As inFIG. 41,FIG. 42Aillustrates an embodiment where each hinged segment of the plurality of hinged segments contains at least one uniquely identified radio frequency identification chip614.

FIG. 42Ais a perspective, partial section view of an RFID enabled segmented, controllable instrument600. The hinged segment links630form an articulating backbone that articulated along alternating hinged connections625. The interior of the segment links630are hollow and are used to house the other components of the instrument600. A working channel602, water channel603, air supply line604, camera assembly608, light fiber bundle609and steering tube coils605pass through the segment link interior. An organizing spacer601(best seen inFIG. 42B) fixes the relative position of the various components. An insertion tube skin606and skin607encapsulate the instrument600.

An RFID bobbin613A is best seen inFIGS. 43A and 43B. The bobbin613is a circular structure adapted to fit over the hinged segments without interfering with the segment movement. The bobbin613includes a recess613B to stow the antenna RFID tag antenna616. In this way the chip or a component of the chip wraps at least partially around at least one hinged segment. Depending on the RFID operating frequency, the dimensions of the hinged segments or other design criteria, the RFID antenna may wrap around the bobbin several times. The RFID chip614is attached to adhesive tape617and connected to antenna616with solder619. An appropriate label618may be applied to the bobbin for identification and inventory purposes. The entire bobbin assembly is enclosed using heatshrink615.

FIG. 44illustrates a system for determining the position of an instrument700. The system700includes an instrument640and a plurality of uniquely identified radio frequency identification chips (i.e., SA-SK) attached to the instrument. A reader705is connected to an antenna710. The reader705is adapted to communicate with each radio frequency identification chip using the antenna710. As illustrated, the antenna710has a circular shape sized to allow the instrument640to pass through the circular shape. In one embodiment, the circular shape is a circle. Other shapes, such as oval, oblong or other shapes suited to allow the passage of instruments are also possible.

When the reader705provides energy to the antenna710a field F (indicated by the arrows looping around antenna710). The field F is used by the reader705to power and communicate with the RFID chips SA-SK. The reader705has a reader field range715(indicated by the dashed lines) within which the reader can communicate with the RFID chips. If the antenna710is used to create a reference position R that approximately divides the reader field range into a +d direction and a −d direction. In this convention, +d indicates that the instrument640is moving to an increased depth with relation to the reference position R. Movement by the instrument in the opposition direction, −d, indicates decreasing depth or withdrawal of the instrument with regard to the reference position R. In this way, the position of an individual RFID chip may be determined relative a reference position R or with respect to the reader field range715. Knowing the position of individual RFID tags can then be used to determine the position of the instrument640.

FIGS. 45 and 46show one variation in using an endoscope assembly90in conjunction with external sensing device or datum96configured similar to the substrate740. Datum96may be positioned externally of patient18adjacent to an opening into a body cavity, e.g., anus20for colonoscopic procedures. Datum96may include the RFID reader98located next to opening100, which may be used as a guide for passage of endoscope92. With proper placement next to the body, the opening100in the datum96may be used to guide the endoscope92there through into anus20. Endoscope92may be configured to have a number of RFID tags94located along the body of endoscope92. These tags94may be positioned at regular intervals along endoscope92. The spacing between the RFID tags94may vary and may also depend upon the desired degree of accuracy in endoscope position determination. RFID tags94may be positioned closely to one another to provide for a higher resolution reading, while RFID tags94spaced farther apart from one another may provide for a lower resolution determination. Moreover, RFID tags94may be positioned at uniform distances from one another, or alternatively they may be spaced apart are irregular intervals, depending upon the desired results. Moreover, RFID tags94may be positioned along the entire length of endoscope92or only along a portion of it, depending upon the desired results. As shown inFIG. 46, as endoscope92is passed through datum96via opening100and into anus20, RFID reader98located within datum96may sense each of the RFID tags94as they pass through opening100. Accordingly, the direction and insertion depth of endoscope92may be recorded and/or maintained for real-time positional information of the endoscope92.

FIG. 47shows another example in endoscope assembly110in which endoscope112may have a number of RFID tags114located along the body of the endoscope112. As endoscope112is advanced or withdrawn from anus20, datum116(includes an RFID reader connected to an antenna118), which may be mounted externally of the patient and at a distance from endoscope112, may have a receiver or reader118configured in any of the variations described above. For instance, receiver or reader118may be adapted to function as a RFID reader as in any of the other variations described above. The reader may be placed a distance d from the opening20and at various orientations relative to the endoscope based upon several factors such as the operating frequency and interference caused by surrounding structures. The distance d and orientation are selected so that the endoscope92remains within the reader field range. As illustrated, the reader116is only reading those tags114adjacent to anus20and outside of the body. The RFID tags indicated in phantom are no longer read by the reader. The reader may be adapted to communicate with the control system703used to control the endoscope. In addition, the output from the reader116may be used to map RFID tag positions on the endoscope112and thus, the length of insertion of the endoscope112into a natural or surgically created body opening.

FIGS. 48,49and50illustrate alternative embodiments of a flexible substrate that is used to support the reader antenna710and the RFID chip614U that is separate from the RFID chips614attached to the instrument.FIG. 48illustrates a stingray shaped substrate740.1having an aperture773sized to allow passage of an instrument. The antenna710is positioned about the aperture773and is connected to the reader (not shown) via wires711and suitable connector712. The RFID chip614U is placed on the substrate740.1and within the reader field range so that it is always detected by antenna710.FIG. 740.2also contains an RFID chip614U (present but not shown inFIGS. 48-50), an antenna710and an aperture773. The substrate740.2differs from substrate740.1by slots793that are used to form flaps791. Reinforcement elements or battens788are also provided in the substrate740.2for added support. The substrate740.3differs from the other substrates by different sized slots793that are used to form various flaps791.

FIG. 51illustrates flow chart5100for an embodiment of a method for determining the position of an instrument using radio frequency identification chips. First, there is the step of providing a radio frequency identification chip reader and antenna (step5105). Next, there is the step of providing an instrument having a longitudinal axis and comprising a plurality of radio frequency identification chips placed along the longitudinal axis (step5110). Next, the instrument is moved relative to the antenna (step5115). Finally, the step of using information about a radio frequency identification chip detected by the antenna to determine the position of the instrument (step5120). An additional and optional step would be providing information about the position of the instrument relative to the antenna to a system used to control the instrument. One exemplary control system includes an electronic motion controller and actuators to facilitate the articulation of a steerable, articulating instrument having RFID features and functionalities as described herein. Additional details of the control system and controllable segmented instruments may be found in: U.S. Pat. No. 6,468,203; U.S. patent application Ser. No. 09/969,927 filed Oct. 2, 2001; U.S. patent application Ser. No. 10/229,577 filed Aug. 27, 2002; U.S. patent application Ser. No. 10/087,100 filed Mar. 1, 2002; and U.S. patent application Ser. No. 10/139,289 filed May 2, 2002, each of which is incorporated herein by reference in its entirety.

In one alternative embodiment, the moving step5115includes passing the instrument through a hoop formed by the antenna. The step of providing a radio frequency identification chip reader and antenna may also include placing the antenna adjacent an opening in the body of a mammal. The opening in the body of a mammal may be a natural opening or an opening that is created surgically.

In another alternative embodiment, the using step5120includes using information about a radio frequency identification chip detected by the antenna to determine the position of the instrument relative to the antenna. Additionally or alternatively, the information about a radio frequency identification chip may include an indication that the radio frequency identification chip has entered the opening in the body of the mammal. One indication may be that the reader no longer detects the radio frequency identification chip. The reader would not be able to detect a tag if the RF energy is being absorbed by the surrounding tissue as in the case of using RFID systems in some UHF and microwave frequencies.

The applications of the devices and methods discussed above are not limited to regions of the body but may include any number of further treatment applications. Other treatment sites may include other areas or regions of the body. Additionally, the present invention may be used in other environments such as exploratory procedures on piping systems, ducts, etc. Modification of the above-described assemblies and methods for carrying out the invention, and variations of aspects of the invention that are obvious to those of skill in the art are intended to be within the scope of the claims.