Abstract: The invention relates to an apparatus for location of an instrument or appliance having at least one magnet which produces a magnetic moment at right angles to the appliance shaft and can be rotated independently of the instrument or appliance. This results in a location system which allows precise location at an accurate time, determination of the axis direction and control of an appliance which is being operated in a channel or medium.

Abstract: The invention relate to an interventional device (I2) conceived to be positioned in a body and comprising an electrically operable unit (E1, E2) conceived to carry out an interaction with the body upon a receipt of electric power, wherein the device further comprises a sensor (2) arranged for wirelessly receiving electromagnetic energy from a remote source, the said sensor being arranged as a resonant circuit (2a, 2b) and being conceived to convert the received electromagnetic energy into the said electric power. The electrically operable device may comprise a diagnostic and/or therapeutic module.

Abstract: A system is operable to detect the orientation of an implant component. The system comprises an implantable component, an external component, and a logic component. The implantable component comprises a first coil operable to transmit a first signal having a phase. The external component comprises a second coil operable to transmit a second signal having a phase. The logic component is operable to compare the phase of the first signal with the phase of the second signal. The logic component is further configured to determine an orientation of the first coil relative to the second coil based on a comparison of the phase of the first signal with the phase of the second signal. The system may be used to determine the orientation of an injection port in an implanted gastric band system. The system may alternatively be used in a variety of other types of systems.

Abstract: A system and method for accurately locating and tracking the position of a target, such as a tumor or the like, within a body. In one embodiment, the system is a target locating and monitoring system usable with a radiation delivery source that delivers selected doses of radiation to a target in a body. The system includes one or more excitable markers positionable in or near the target, an external excitation source that remotely excites the markers to produce an identifiable signal, and a plurality of sensors spaced apart in a known geometry relative to each other. A computer is coupled to the sensors and configured to use the marker measurements to identify a target isocenter within the target. The computer compares the position of the target isocenter with the location of the machine isocenter. The computer also controls movement of the patient and a patient support device so the target isocenter is coincident with the machine isocenter before and during radiation therapy.

Abstract: A system and method for accurately locating and tracking the position of a target, such as a tumor or the like, within a body. In one embodiment, the system is a target locating and monitoring system usable with a radiation delivery source that delivers selected doses of radiation to a target in a body. The system includes one or more excitable markers positionable in or near the target, an external excitation source that remotely excites the markers to produce an identifiable signal, and a plurality of sensors spaced apart in a known geometry relative to each other. A computer is coupled to the sensors and configured to use the marker measurements to identify a target isocenter within the target. The computer compares the position of the target isocenter with the location of the machine isocenter. The computer also controls movement of the patient and a patient support device so the target isocenter is coincident with the machine isocenter before and during radiation therapy.

Abstract: A system and method for accurately locating and tracking the position of a target, such as a tumor or the like, within a body. In one embodiment, the system is a target locating and monitoring system usable with a radiation delivery source that delivers selected doses of radiation to a target in a body. The system includes one or more excitable markers positionable in or near the target, an external excitation source that remotely excites the markers to produce an identifiable signal, and a plurality of sensors spaced apart in a known geometry relative to each other. A computer is coupled to the sensors and configured to use the marker measurements to identify a target isocenter within the target. The computer compares the position of the target isocenter with the location of the machine isocenter. The computer also controls movement of the patient and a patient support device so the target isocenter is co-incident with the machine isocenter before and during radiation therapy.

Abstract: The invention relates to a method and a system for identification of a medical implant that is inserted into a patient. Identification data of the medical implant is stored in an RFID chip. The RFID chip is inserted into the body of the patient. The RFID chip can be inserted into a different location than the medical implant into the body of the patient or can be arranged on the medical implant. A signal from the RFID chip comprising the identification data of the medical implant is called up by a reading unit.

Abstract: A method of operating a navigation system that can orient the distal end of a medical device in a selected direction to navigate the medical device through a network of body lumens in an operating region in a subject that includes identifying a path through the network of body lumens in the operating region; displaying a two-dimensional image of the operating region including the path through the body lumens; determining at least one location on the path; and operating the navigation system to orient the distal end of the medical device in a direction substantially aligned with the path at the at least one location and advancing the distal end of the medical device.

Abstract: An implantable soft tissue prosthesis comprising a hollow shell formed of a flexible elastomeric envelope, the shell having an inner volume and an exterior surface, when the inner volume is filled with an elastomeric silicone tubing that is preshaped conforming to the inner volume of the shell, the prosthesis being adapted to be surgically implanted in a human breast.

Abstract: A mobile pill transmitter system that moves through or adjacent to one or more organs in an animal's body and that provides signals from which the pill's present location and/or present angular orientation can be determined. The system also provides signals from which the present roll angle of the pill, about a selected axis, can be determined. When the location coordinates and the roll angle of the pill are within selected ranges, an aperture on the pill container releases a selected chemical into or onto the body. Optionally, the pill as it moves also provides a sequence of visually perceptible images; the times for image formation may correspond to times at which the pill transmitter system location or image satisfies one or at least four different criteria.

Abstract: A system for imaging and magnetically navigating a medical device within an operating region in a subject's body includes a first C-arm and a second C-arm. The system includes an imaging beam source and an imaging beam receiver mounted on the first C-arm disposed on opposite sides of the operating region to image the operating region. The system includes a pair of magnetic pods, which are movably mounted on either the first or second C-arm. The magnetic pods are movable between an imaging position and a navigating position in which the pods are disposed on opposite sides of the operating region in the same plane as at least one imaging beam source. The second C-arm is movable between an imaging position in which the imaging beam source and imaging beam receiver on the second C-arm is positioned so that the imaging beam sources and receivers are in the same plane.

Abstract: A temporary bioabsorbable-radiopaque marker for use on an implantable endoprosthesis. The bioabsorbable-radiopaque marker is adapted to be disposed on or adjacent an implantable endoprosthesis in a body lumen for a predetermined amount of time until the bioabsorbable and radiopaque materials are absorbed or dispersed in the body.

Abstract: An intra-subject position display system for displaying a position of an intra-subject device, which is introduced into a subject and moves therein, wherein a relative position of the intra-subject device to an outer surface of the subject is detected and displayed. The position of the intra-subject device is displayed in a relation with the outer surface of the subject. Thereby, it is possible to easily determine in which site of the subject the intra-subject device exists. The present invention is effective to recognize a position of, for example, a capsule type endoscope or a test capsule therefor in the subject (e.g., a human body). To recognize the outer surface of the subject, for example, a plurality of radio devices are arranged on the outer surface of the subject and their radio signals are analyzed.

Abstract: As described herein vascular anchoring systems are used to position an implant in a vascular area such as a bifurcated vasculature with relatively high fluid flow, for instance, in an area of a pulmonary artery with associated left and right pulmonary arteries. Implementations include an anchoring trunk member having a first anchoring trunk section and a second anchoring trunk section. Further implementations include a first anchoring branch member extending from the anchoring trunk member. Still further implementations include a second anchoring branch member extending from the anchoring trunk member.

Abstract: Methods and devices are provided for marking tissue to be subsequently located for removal from a body or for other examination. In general, a marker is provided that can be delivered adjacent to tissue desirable for marking. The marker can coil adjacent to the desired tissue. The marker can remain disposed in the body in its coiled position and be subsequently palpably identified and/or visually identified to locate the desired tissue.

Abstract: Methods and devices are provided for marking tissue to be subsequently located for removal from a body or for other examination. In general, a marker is provided that can be delivered through a tissue wall proximate to tissue desirable for marking. The marker can be movable between a non-deployed or unexpanded position, in which the marker is configured to be delivered through a relatively small diameter passageway, to an expanded, balloon-like position in which the marker is configured to engage opposed sides of a tissue wall proximate to the desired tissue. The marker can remain disposed in the body in its expanded position and be subsequently palpably identified and/or visually identified to locate the desired tissue.

Abstract: Methods and devices are provided for marking tissue to be subsequently located for removal from a body or for other examination. In general, a marker is provided that can be delivered to a target tissue. In one embodiment, the marker can include a solution having a visual marking component and a palpably identifiable tactile marking component. The marker can remain in the body and be subsequently visually and/or palpably identified to locate the target tissue.

Abstract: The invention relates to devices and methods for reforming tissue surrounding the airway of a subject suffering from obstructive sleep apnea so as to open the airway and alleviate the occurrence of apneic events. Devices comprise a combination of resiliently deformable material and bioerodible material. The deformable portion of the device has a preferred shape that corresponds to the desired final shape of the device once placed in an airway. In making a transplant-ready device, however, the deformable portion is placed into a deformed shape and constrained in that shape by the bioerodible material. After implantation, the device gradually assumes the preferred shape as the constraining bioerodible material erodes. As the device gradually reforms toward the preferred shape, it reforms the tissue into the therapeutically desirable configuration. The gradual nature of the shape change generally stabilizes the device in the tissue, and supports tissue reforming into a stable configuration.

Abstract: A method for detecting at least partial medical device disengagement from a patient includes inserting the device in the patient so a Hall effect sensor connected to the device is positioned at an initial location substantially proximate to one of a plurality of magnetically charged components. Each of the components is removably attached to the patient, and is positioned a predetermined distance from another component. A magnetic field indicative of the one of the plurality of magnetically charged components is detected with the sensor. The sensor monitors for a failure to detect the magnetic field. In response to the failure detection, the sensor monitors for a subsequent detection of another magnetic field indicative of another of the plurality of magnetically charged components. The subsequent detection is associated with movement of the medical device substantially equal to the predetermined distance between the one and the other of the components.

Abstract: An interface for remotely controlling a medical device in a patient's body provides a two dimensional display of a three dimensional rendering of the operating region, and allows the user to select the orientation or location of the distal end of the medical device on the display and then operate a navigation system to cause the distal end of the medical device to approximately assume the selected orientation or location.

Abstract: A patient equipped with a device in a first mode is scheduled for a procedure in a procedure room at a facility with pre-procedure rules (e.g., requiring procedure site marking). Only a surgeon or other authorized individual is permitted to change the first mode to a second mode after complying with the rules (e.g., marking a site on the patient's body). A detector is located at or near the entrance of the procedure room for detecting devices having the first mode. If the first mode is detected, an alarm is provided indicating that the rule may not have been followed.

Abstract: A medical, surgical, or operating kit for occluding or controlling blood flow or fluid flow is disclosed. The kit is comprised of (a) a dispersion of magnetic microparticles which can be administered into a blood vessel or fluid vessel, and (b) an external magnetic field source which is adapted to be placed at the desired site above the path of the bloodstream or fluid flow to form a plug or blockade within the blood vessel or fluid vessel that occludes or controls blood flow or fluid flow.

Abstract: A system is for detecting a position of a device. The device is swallowed, passes through a subject, and includes a magnetic field generator generating a constant magnetic field. The system also includes a position transducer. The position transducer includes a magnetic detector detecting an intensity of a magnetic field component parallel to a constant magnetic field output from the magnetic field generator, and a position processor calculating a position of the device in the subject based on the intensity detected by the magnetic detector.

Abstract: A system for monitoring and/or affecting parameters of a patient's body and more particularly to such a system comprised of a system control unit (SCU) and one or more other devices, preferably battery-powered, implanted in the patient's body, i.e., within the envelope defined by the patient's skin. Each such implanted device is configured to be monitored and/or controlled by the SCU via a wireless communication channel. In accordance with the invention, the SCU comprises a programmable unit capable of (1) transmitting commands to at least some of a plurality of implanted devices and (2) receiving data signal from at least some of those implanted devices. In accordance with a preferred embodiment, the system operates in closed loop fashion whereby the commands transmitted by the SCU are dependent, in part, on the content of the data signals received by the SCU.

Abstract: A capsule endoscope is disclosed that includes a capsule and a transparent cover having a central axis and that is located in front of an objective optical system within the capsule. The objective optical system has a depth of field, a field of view, and an image surface that has curvature of field, and is arranged on the central axis of the transparent cover and the capsule. The field of view of the objective optical system includes a spherical surface that is tangent to the transparent cover at a periphery of the field of view, and the near point of the depth of field on the optical axis of the objective optical system is positioned farther from the objective optical system than is the transparent cover. Various conditions are satisfied so as to provide high quality imaging.

Abstract: An elastically deformable marker (1) which can be completely implanted by means of a cannula for marking a tissue site, wherein the marker assumes a relaxed condition without an external force acting thereon and has at least one flexurally elastic wire, an elongate central marker portion and a proximal and a distal end portion, wherein a respective one of the two end portions is disposed at one of the two ends of the central marker portion, wherein in the elongate central marker portion at least two portions of the same flexurally elastic wire or a plurality of flexurally elastic wires are twisted together.

Abstract: Following are six improvements on the prior art entitled “Instant Face-Lifter”. “Intra-scalp TV/Radio/Stereo-Music-Reproducing Device Face-Lifter”: uses an intra-scalp silicone Face-Lifter as stand for an implanted TV set and/or AM-FM Radio and/or an Open Platform Stereo Music device (MP3, MP4 Ipod®, Walkman®, WMA®). “Intra-scalp GPS-Face-Lifter”: a Face-Lifter as a stand for a GPS device. “Intra-scalp Heart Pace-Maker-Face-Lifter”: a Face-Lifter as a stand for a heart pace-maker device. “Intra-scalp Artificial Hair Anchoring Base Face-Lifter”: a Face-Lifter as an anchoring base for permanently implanting small bundles of artificial hair on balding people. “Intra-scalp Bullet-Proof Head-Armor Face-Lifter”: a Face-Lifter as bullet-proof head armor. “Intra-scalp Orgasm-inducer Face-Lifter”: a Face-Lifter as a stand for an orgasm-inducing electric device.

Abstract: In one embodiment, an external programming device is operable to determine and graphically display power consumption of an implantable medical device (“IMD”). In accordance with this particular embodiment, the external programming device includes a graphical user interface display and a communication interface operable to receive information from an IMD. In this embodiment, the external programming device is operable to receive IMD parameter settings and/or battery parameter values from the IMD, calculate an power consumption rate for the IMD, and then display the power consumption on the graphical user interface display using a graphical visual indicator.

Abstract: Externally detectable electronic article surveillance markers are attached to surgical implements, such as sponges and surgical instruments, appointed for use in a surgical wound. The attachment mechanism facilitates detection by an external interrogating field before the wound has been closed and the patient has left the operating table. The markers are responsive to the imposition of an interrogating field produced by an electronic article surveillance system. Markers contain one or more magnetomechanically responsive elements that are urged into mechanical resonance by the interrogating field. The ring-down of the resonance and the associated dipolar electromagnetic field provide a signal-identifying characteristic detected by a detection system. Upon detection, an audible or visible signal is triggered to alert relevant medical personnel to the need for follow-up care and removal of the offending item. The resonance occurs at a frequency ranging from about 70 to 300 kHz.

Abstract: A surgical sponge comprises a plurality of radiopaque markers having a high radiographic density and a distinctive, visually recognizable shape. The markers have an x-ray density equivalent to at least about 0.1 g/cm2 of BaSO4. The markers produce an x-ray image with high contrast and a shape that is readily recognizable and differentiated from the images produced by other items and structures commonly seen in x-rays of post-operative patients. Owing to the distinctive, high contrast image produced by the markers, the sponge is reliably and unambiguously detected. This is so even in situations where the sponge is inadvertently left in the surgical wound. Discomfort, trauma, and possibly fatal consequences that might otherwise occur are virtually eliminated. The surgical procedure is carried out with decreased likelihood of a sponge being retained inadvertently.

Abstract: A vaginal probe includes a metal detection sensor for detecting the presence of ferrous-laden endometriotic tissues. The probe is electrically connected to external electronic circuitry for interpreting the readings taken by the sensor and for providing a qualitative or quantitative measurement of the amount of endometriotic tissues present. The probe is inserted in either the vagina or peritoneal cavity of a patient to detect the location and the relative amounts of iron or ferrous-laden tissues in the pelvic area of the patient. Using the probe and monitoring the readings over time as part of pelvic exams assists in determining the early onset or progression of endometriosis and/or the response to one or more therapies being provided to the patient to treat the disease.

Abstract: An electrode system includes an implantable electrode having at least one electrode contact, an insertion tool, and a technique or method that allows the electrode contact to be positioned within soft tissue at a selected target stimulation site.

Abstract: A system and method that facilitates stimulating neural pathways, e.g., muscles and/or associated nerves, of a patient's body for the purpose of therapeutic medical treatment by rehabilitating weakened muscles and using neuroplasticity to retrain sequential muscle movements and/or to provide the ability to directly deliver functional motor movements. Use of the present invention is of particular value for treating a patient following a stroke. More particularly, such systems are characterized by a plurality of discrete devices, preferably battery powered but may alternatively include RF-powered devices as well or in combination, configured for implanting within a patient's body via injection, each device being configured to affect a parameter, e.g., via nerve and/or muscle stimulation and/or to sense a body parameter, e.g., temperature, O2 content, physical position, electrical potential, etc.

Abstract: A delivery system for an implantable medical device including a tether retaining feature having a bore. The system includes a connector having a top surface, a bottom surface, a rail extending in a proximal direction from the connector, and an aperture sized to receive the tether retaining feature and reduce movement of the connector with respect to the implantable medical device in a plane parallel to the aperture. A tether is sized to fit within the bore of the tether retaining feature. The tether acts against the top surface of the connector to retain the bottom surface of the connector proximal to the implantable medical device when the tether is located within the bore of the tether retaining feature. A method for delivering an implantable medical device including a tether retaining feature.

Abstract: Leads and introduction tools are proposed for deep brain stimulation and other applications. Some embodiments of the present invention provide lead designs with which may be placed with a stylet, while others do not require a stylet. Some lead embodiments use standard wire conductors, while others use cable conductors. Several embodiments incorporate microelectrodes and/or microelectrode assemblies. Certain embodiments of the present invention provide introduction tools, such as cannula and/or cannula systems, which ensure proper placement of, e.g., leads.

Abstract: Methods and systems for measuring volume and size of features such as lesions, tumors, sores, and wounds external to animal, human and plant skin, using 3D structured light scanners are provided. These methods and systems obtain a point cloud of the scanned feature, and employ algorithms to adjust the suggested feature geometry parameters to minimize deviations of the point cloud from suggested feature geometry. Obtained geometry parameters permit the calculation of the features' sizes and volumes.

Abstract: Embodiments of the invention include channel selection and mapping for medical device communication. The communication system can implement a two-stage listen before talk protocol to choose a channel for communication. The first stage samples the interference of each channel for a relatively short time and chooses the best signal. The second stage samples the channel selected by the first stage and samples it for a relatively longer time to confirm the channel selected by the first stage is the best channel for communication.

Abstract: An implantable microstimulator configured to be implanted beneath a patient's skin for tissue stimulation to prevent and/or treat various disorders, e.g., neurological disorders, uses a self-contained power source such as a primary battery, a rechargeable battery, or other energy sources. For the rechargeable battery, and other energy sources that may require a periodic or occasional replenishment, such recharging or replenishment is accomplished, for example, by inductive coupling with an external device. A suitable bidirectional telemetry link allows the microstimulator system to inform the patient or clinician regarding the status of the system, including the charge level of the power source, and stimulation parameter states. Processing circuitry within the microstimulator automatically controls the applied stimulation pulses to match a set of programmed stimulation parameters established for a particular patient.

Abstract: Methods and systems have been developed allowing for increased strain storage in shape memory polymer devices. Larger stored strains allow for smaller and different implantable shapes of shape memory polymer devices. For example, by storing a larger strain, a shape memory polymer device may be implanted at a smaller fraction of its final implanted shape. Benefits include shorter patient recovery times, smaller implantation sites, and flexibility of implantation techniques.

Abstract: A power control circuit for an implantable medical device is presented. The power control circuit includes a first high rate cell, a second high rate cell, at least one resistive load, and at least one control circuit. The at least one resistive load is connected between the first and the second high rate cells. The at least one control circuit is coupled to the first and the second high rate cells.

Abstract: A medical technology device has an x-ray CT imaging system and a magnet system for generation of a radio-frequency alternating magnetic field for treatment of a tumor injected with ferrite nanoparticles, the x-ray CT system and the magnet system being combined to form a unitary structure. Imaging and tumor therapy can be conducted with one apparatus, and the monitoring of the course of the tumor therapy is simplified.

Abstract: A device and method for deploying a mechanical closure device for closing a passageway in a body, for example a patent foramen ovale (PFO) in a heart. The single disc mechanical closure device is comprise of a distal and proximal anchor constrained by a closure line to facilitate mechanical closure by bringing the distal and proximal anchors into close proximity along the closure line.

Abstract: Disclosed herein are biointerface membranes including a macro-architecture and a micro-architecture co-continuous with and bonded to and/or located within at least a portion of the macro-architecture. The macro- and micro-architectures work together to manage and manipulate the high-level tissue organization and the low-level cellular organization of the foreign body response in vivo, thereby increasing neovascularization close to a device-tissue interface, interfering with barrier cell layer formation, and providing good tissue anchoring, while reducing the effects of motion artifact, and disrupting the organization and/or contracture of the FBC. The biointerface membranes of the preferred embodiments can be utilized with implantable devices such as devices for the detection of analyte concentrations in a biological sample (for example, from a body), cell transplantation devices, drug delivery devices, electrical signal delivering or measuring devices, and/or combinations thereof.

Abstract: Methods and devices to prevent and/or treat breathing disorders (e.g., upper airways disorders) in mammals related to impaired airflow are described. Methods and devices apply force to soft tissue that avoids obstruction of airflow in the mammel's airway. Breathing disorders that are avoided by the methods and/or devices include apnea.

Abstract: A system and method that facilitates multiple systems of communicating devices, i.e., a master device and one or more implantable slave devices, to coexist on a common, e.g., RF, communication channel having a limited temporal bandwidth while maintaining the required update rate between each master device and its associated slave devices. In embodiments of the present invention, master devices periodically transmit one or more beacon messages that are suitable for identification by other such master devices at a communication range greater than the communication range that may cause interference between systems and thus enabling one or more systems to cause the position of its frame periods to be interleaved with the frame periods of other such systems in anticipation of systems moving in closer proximity and actually interfering with each other.

Abstract: A capsule medication administration system includes: a first capsule for internal body marking; a second capsule for medication; a marking device which makes a marking within a living body; a drug retention section which retains a drug; a release device which releases the drug; a detection device which detects the marking; a decision device which decides whether or not a marking which has been detected by the detection device is a specified marking; and a release control device which operates the release devices if it has been decided by the decision device that it is the specified marking; wherein the first capsule comprises the marking device. The second capsule comprises the drug retention section and the release device.

Abstract: A method of navigating a medical device in an operating region in a subject. The method includes applying a magnetic field to the operating region and changing the magnetic moment of the medical device by selectively changing a physical condition of at least one magnet element in the medical device to change the orientation of the device with respect to the applied magnetic field.

Abstract: A device useful for oral drug delivery device consisting of: (a) a capsule, tablet or pill designed to disperse in the gastrointestinal system; (b) an RFID tag positioned in the capsule, tablet or pill, the RFID tag comprising an antenna; (c) an object selected from the group consisting of a magnet, a ferromagnetic object, a ferrite object and an electromagnetic shielding object positioned within, over or adjacent the antenna of the RFID tag to alter the antenna characteristics of the RFID tag so that if the RFID tag is interrogated before the capsule, tablet or pill disperses in the gastrointestinal system, the response of the RFID tag is sufficiently altered or attenuated to determine that the capsule, tablet or pill has not dispersed in the gastrointestinal system and so that if the RFID tag is interrogated after the capsule, tablet or pill has dispersed in the gastrointestinal system, the object separates from the RFID tag so that the response of the RFID tag is sufficiently detectable to determine that t

Abstract: A system for navigating a catheter probe through a body cavity includes a sensing coil affixed to a distal end of the probe. Magnetic fields are projected into the body cavity to induce voltage signals in the sensing coil that are sufficient to describe the orientation and position of the probe. A set of magnetic coils each generates a substantially uniform field in a single respective dimension. The orientation angles of the sensing coil may be determined from known values of the unidirectional fields and the measured induced voltage signals. Gradient magnetic fields with components in two dimensions are projected into the body cavity to induce another group of voltage signals. The geometrical intersection of constant voltage surfaces developed by certain gradient fields that produce the measured induced voltage signals is a set of lines on which the catheter is located. The point of intersection of such lines yields the positional coordinates.

Abstract: A system for navigating a catheter probe through a body cavity includes a sensing coil affixed to a distal end of the probe. Magnetic fields are projected into the body cavity to induce voltage signals in the sensing coil that are sufficient to describe the orientation and position of the probe. A set of magnetic coils each generates a substantially uniform field in a single respective dimension. The orientation angles of the sensing coil may be determined from known values of the unidirectional fields and the measured induced voltage signals. Gradient magnetic fields with components in two dimensions are projected into the body cavity to induce another group of voltage signals. The geometrical intersection of constant voltage surfaces developed by certain gradient fields that produce the measured induced voltage signals is a set of lines on which the catheter is located. The point of intersection of such lines yields the positional coordinates.