Improved catheter calibration

Related application

This application is related to the PCT patent application PCT / IL97 / 00006, which is incorporated herein by reference.

The present invention generally relates to systems for medical diagnosis and treatment, particularly medical catheters capable of detecting the position of the catheter.

As in Patent Document 1 and Patent Document 2, various methods and devices for locating a probe or catheter tip inside the body using an electromagnetic field are described. These disclosures are incorporated herein by reference. Although not necessarily for medical use, other electromagnetic tracking systems are described in Patent Document 3, Patent Document 4, Patent Document 5, Patent Document 6, and Patent Document 7. These disclosures are incorporated herein by reference.

Patent Document 8, whose disclosure is incorporated herein by reference, describes a system that includes a catheter and that includes a position measuring device that can determine the position of the catheter in three dimensions but not the orientation. ..

Patent Document 9, which has been assigned to the assignee of this patent application and whose disclosure is also incorporated herein by reference, is a catheter system comprising means for determining the six dimensions of the position and orientation of the distal tip of the catheter. Is described. The system uses a position sensor formed from multiple non-coaxial coils adjacent to a position on the catheter that can be located, eg, near the distal tip of the catheter. Preferably three orthogonal coils are used. These coils generate signals in response to an externally applied magnetic field that allows the calculation of six position and orientation coordinates, so that the position and orientation of the catheter is known without the need to image the catheter. ..

Patent Document 10 describes a surgical laser system for connecting to various peripheral surgical devices. The system identifies to which device it is connected according to the characteristics of the signature registers embedded within the device. The register uniquely identifies the device in which it is embedded.

Patent Document 11 describes a system for identifying and monitoring a catheter, including an identification means carried within the handle of the catheter body. In one aspect of the catheter of this patent, the handle has a solid microchip preprogrammed with the identification code of the catheter and digital values representing other behavioral and functional characteristics. The handle is cabled to a control console that receives data from the microchip. In one disclosed embodiment, the microchip can record the number of times the catheter has been used.

Patent Document 12 describes an imaging system that determines the location of a medical device. A read-only storage device is placed on or in a medical device to store the initialization information characteristics of the device. Thus, the system can determine the type of equipment connected to it and receive initialization information related to the type of equipment. The patent further suggests that the use of the device is blocked unless the initialization information is transmitted from the storage device to the imaging system. There is also a proof method that proves that the initialization information is correct. Two methods are suggested for storage location. One person The law suggests embedding the device directly in the device. The second method suggests that an accessory (attachment) into which certain devices can be fitted, essentially embedding the storage device within the device handle.

Thus, in some of the aspects described in the patent above, information about the catheter (or other medical device) is stored in the accessories to the catheter, not in the catheter itself. These aspects are not suitable for storing item-specific information such as calibration information.

In another aspect of the patent described above, the information is stored in the catheter. However, these embodiments suffer from undue complexity and require, for example, multiple digital signal wires extending along the catheter. This complexity cannot be implemented for mass use in disposable catheters.

<p><patcit num="1"><text>U.S. Pat. No. 5,042,486</text></patcit><patcit num="2"><text>PCT Patent Publication WO 94/04938</text></patcit><patcit num="3"><text>U.S. Pat. No. 3,644,825</text></patcit><patcit num="4"><text>U.S. Pat. No. 3,868,565</text></patcit><patcit num="5"><text>U.S. Pat. No. 4,017,858</text></patcit><patcit num="6"><text>U.S. Pat. No. 4,054,881</text></patcit><patcit num="7"><text>U.S. Pat. No. 4,849,692</text></patcit><patcit num="8"><text>U.S. Pat. No. 5,391,199</text></patcit><patcit num="9"><text>PCT patent application PCT / WO96 / 05768</text></patcit><patcit num="10"><text>U.S. Pat. No. 4,580,557</text></patcit><patcit num="11"><text>U.S. Pat. No. 5,383,874</text></patcit><patcit num="12"><text>U.S. Pat. No. 5,617,857</text></patcit></p>

An object of one aspect of the present invention is to provide a convenient electronic storage and recall of calibration information about a catheter.

Another object of one aspect of the present invention is to provide a convenient electronic storage and recall of calibration information about a catheter with minimal recall time.

Another object of one aspect of the invention is to provide a means for providing improved communication between the catheter and the control console.

A further object of one aspect of the invention is to provide a catheter of minimal cost and minimal complexity capable of storing and recalling calibration information.

In one aspect of the invention, the catheter assembly for connecting to the control console is between two components, the catheter with the least complexity inserted into the patient's body and the proximal end of the catheter to the console. Equipped with a connection cable. A catheter comprises a microcircuit that is not in common with other catheters of the same model and that has substantially only specific information about the catheter. Such information includes, for example, item-specific calibration data for the catheter and the date of first use of the catheter. The cable consists of an access circuit that receives information from the catheter and sends it to the console in the appropriate form.

Preferably, the cable works for all catheters of a particular model or type, so when the catheter is replaced, there is no need to replace the cable. In particular, catheters that are planned for single use do not require cable replacement that does not come into direct contact with the patient.

In a preferred embodiment of the invention, the access circuit demonstrates that the catheter is a cable compatible model. The connection between the catheter and the cable is preferably unique for each catheter model. As an alternative or additionally, model identifications are stored in microcircuits, and access circuits prove that model identifications are the same for cables and catheters.

In one preferred embodiment of the invention, each cable is associated with a small number of catheter models, and the model identification stored in the microcircuit is by an access circuit to identify which catheter model is being used. used.

In one preferred embodiment of the invention, the catheter microcircuit comprises digitally stored data. Preferably, the microcircuit leads are coupled directly to the socket of the receptacle at the distal end of the cable. Thus, the catheter does not include digital signal wires and yet allows fast access to information in microcircuits. And the digital electronic signal transmitted from the microcircuit to the console via the cable does not interfere with the low level analog signal transmitted by wire from the distal end of the catheter to the cable. Preferably, the access circuit includes a socket that is located in the receptacle at the distal end of the cable and receives the leads of the microcircuit.

In a preferred embodiment of the invention, the microcircuit stores minimal calibration and / or initialization information about the catheter. As an alternative or additionally, the microcircuit stores usage information about the catheter, such as the date of first use of the catheter.

In a preferred embodiment of the invention, the catheter is provided at its proximal end with a handle that includes a control device used to operate the catheter. For catheters where the handle is not at the proximal end of the catheter, the length beyond the handle does not increase the functionality of the catheter, but increases the cost of the catheter and its sterilization cost. Preferably, the catheter microcircuit is included in the handle. Alternatively, the handle is separated from the catheter, and rather fixed at the distal end of the cable, and the microcircuit is contained within the connector at the proximal end of the catheter that connects to the handle.

In one preferred embodiment of the invention, the catheter comprises a coil that produces an analog signal indicating the position of the catheter, eg, as described in PCT / WO96 / 05768 above. The cable preferably comprises an amplifier used to amplify the analog signal. As an alternative or additionally, the amplifier can be used to amplify other signals such as physiological measurements. The amplifier is preferably in the receptacle so that it is as close as possible to the coil and / or other signal source. It should be noted that placing the amplifier within the console is undesirable due to interference from the console circuit causing noise on the adjacent wires and due to noise pickup over a long distance between the distal end of the catheter and the console. The signal generated within the catheter must be relatively weak and protected from attenuation and noise. Placing the amplifier inside the catheter increases complexity and cost of the catheter, which is also undesirable. In one of these preferred embodiments, the access circuit comprises one or more analog-to-digital (A / D) converter circuits, which convert the analog signal from the catheter into a digital form. Is transmitted to the console. Thus, the attenuation and noise problems described above are substantially eliminated.

In another preferred embodiment of the invention, the catheter itself comprises one or more analog-to-digital (A / D) converter circuits. In these embodiments, the access circuit couples only the digital signal from the catheter to the console. In one such preferred embodiment, the A / D converter is adjacent to the distal tip of the catheter.

In one preferred embodiment of the invention, the cable comprises an additional microcircuit, in which the informational properties of one or more models of the catheter associated with the cable are stored. Such information can include, for example, catheter configuration and usage code. Preferably, the additional microcircuits also include calibration information for access circuits and amplifiers in the cable. The amplifier calibration information can include, for example, their zero gain, DC offset and linearity. Thus, unnecessary information in the catheter is stored in the cable and the catheter is less complex and less costly. Preferably, the console does not require any catheter-specific information other than the information provided by the catheter and preferably the microcircuit in the cable, so that newer models of catheters update the console software or hardware. Can be used with the console without any.

Preferably, the microcircuit comprises read / write memory components such as EEPROM, EPROM, PROM, flash ROM or non-volatile RAM, and the information is stored in digital form. Alternatively or additionally, any of the microcircuits may include read-only memory that is preprogrammed at the time of manufacture.

In a preferred embodiment of the invention, the calibration information includes data on the relative displacement of the distal tip of the catheter from the coil. In some other preferred embodiment of the invention, the calibration information also includes data on the deviation of the coil from orthogonality, or data on the respective gains of the coil, or a combination of these data. The above calibration information generally varies from catheter to catheter and is therefore preferably stored in microcircuits within the catheter. Preferably, the data are determined by a calibration method as described in PCT / IL97 / 00006. Other calibration information can include the general configuration of the catheter and the gain and offset of the access circuit, and is preferably stored in the cable microcircuit.

In one preferred embodiment of the invention, the catheter is electrically isolated from signal processing and computing devices in the console, and calibration information includes data about isolation circuits in the catheter. Preferably, the catheter is isolated by at least one guiding element, such as an insulated transformer adjacent to the proximal end of the catheter or at the catheter handle. Alternatively, the catheter can be isolated by one or more optoisolators or other types of isolation circuits known in the art. Such inductive elements and other isolation circuits typically introduce non-linearity into the signal transmitted thereby. Such non-linearity can cause significant deformation, especially in analog signals transmitted by wire from the distal end of the catheter to the signal processing circuit. Therefore, the calibration information preferably includes data on signal non-linearity introduced by inductive elements and / or other isolation circuits.

Calibration data can be recorded in microcircuits in catheters in the form of look-up tables, multinomial coefficients or other suitable forms known in the art.

In a preferred embodiment of the invention, the calibration data is generated and recorded at or near the time of manufacture, and the microcircuits are configured to prevent subsequent recording of the calibration data by the user. Suitable, for example, if the microcircuit consists of EPROM or PROM. A proper programming device connects to the catheter connector and programs the EPROM or PROM by inputting a digital signal to it from the computer used in the calibration through the connector. The EPROM or PROM can then be prevented from being reprogrammed.

In other such preferred embodiments where the microcircuit comprises an EEPROM or non-volatile RAM device, the EEPROM or non-volatile RAM device comprises a type of write-permitting input connection known in the art, which is a catheter. It is connected to the write permission pin on the proximal end connector. During calibration, write permission inputs are enabled and calibration data is stored in the microcircuit. After that, the write permission input may be disabled, for example by removing the write permission pin or by connecting the write permission pin to the electrical ground, so that no further calibration data can be recorded in the microcircuit. it can.

Alternatively, in a preferred embodiment of the invention in which the microcircuit comprises an EEPROM device, the write permission input can be disabled by sending a write protection command to the device. This directive can be reversible or irreversible.

In yet another preferred embodiment of the invention, the microcircuits in the catheter and / or the microcircuits in the cable are manufactured by, for example, Xicor, Inc. X76F041 Password Access Security Supervisor (PASS).^TM) Includes access control circuitry such as secure flash ROM devices. The microcircuit is preferably programmed with a password so that after the calibration data is generated and recorded at the time of manufacture, further calibration data can be unrecorded in the microcircuit, provided that the password is known. Data recording by a person with the permission of the factory is an exception.

In one preferred embodiment of the invention, the data recorded in the microcircuit comprises a calibration code, which according to methods known in the art to ensure that the calibration data is not altered or tampered with. Includes proofing code to be encrypted. When the user connects the catheter to a suitable console that includes a computer, the computer reads the calibration code and compares this code to the preprogrammed value. If the code does not match the desired preprogrammed value, the computer will display a message indicating that the catheter may not be properly calibrated. The computer can prevent further movement until a catheter with a code that matches the desired preprogrammed value is connected to it.

The proof code is encrypted using the RSA encryption scheme using methods that prevent unauthorized party decryption, such as public and private keys or other methods known in the art. Is preferable. When methods such as RSA encryption are used, the private key is an authorized manufacturer of catheters to prevent possible use of potentially inferior quality unauthorized alternatives. Known only to.

In a further preferred embodiment of the invention, the data recorded in the microcircuit includes an expiration date and time, after which the catheter can be disabled. When the user connects the catheter to a suitable console that includes a computer, the computer reads the expiration date and time and compares them to the actual date and time generated by, for example, a real-time clock. If the expiration date and time have passed, the computer will display a message indicating that the catheter is unsuitable for further use. The computer is connected to a catheter with a valid expiration date and time Until then, further operation can be prevented.

Preferably, the expiration date and time are recorded by a console computer by programming the microcircuits in the catheter when it is first used. Thus, when the catheter is first connected to the console, the computer detects that the expiration date and time have not yet been recorded in the microcircuit, and is appropriate at the preset interval after the actual date and time. Program the microcircuit using the expiration date and time. Preferably, the preset interval is stored in the cable and determined by the manufacturer based on the expected lifetime of the catheter.

In a preferred embodiment in which the microcircuit comprises an access control circuit, the microcircuit is programmed so that the memory location in it can be operated in "read access and program only" mode. This mode can only be changed by entering a suitable password that is generally not available to the catheter user. In "read access and program only" mode, the number stored in the memory location can be reduced by changing the bit from "1" to "0", but not increased. .. This is because the programmed microcircuit does not allow "0" to be changed to "1". Preferably, the memory location is set at the time of manufacture to include a maximum value, i.e., all bits are set to "1". Then, as mentioned above, upon initial use, the computer programs the microcircuit with an appropriate expiration date and time by changing one or more bits in the memory location from "1" to "0". After that, the expiration date cannot be changed on any subsequent day (unless the correct password is first entered).

As an alternative or additionally, the microcircuits including the access control circuits as described above are protected from possible tampering or error by the catheter user, the number of times the catheter has been used and / or its use. Can be used to track the period of. Preferably, a record corresponding to the number of times the catheter can be used and / or the length of time is stored in a memory location in the device or microcircuit within the catheter at the time of manufacture, and the microcircuit is in this memory location. Yong is programmed to operate in "read access and program only" mode as described above. Each time the catheter is used and / or at regular time intervals during use, the computer reads the record in the memory location and reads it, one or more bits in it from "1" to "0". Reduce by changing. When the record stored in the memory location reaches zero or some other predetermined minimum, the computer causes the user to display a message indicating that the catheter is unsuitable for further use, and preferably. Prevents further movement until a suitable catheter is connected to it.

Therefore, according to a preferred embodiment of the invention, a probe assembly for connecting a console that includes a probe for insertion into the body of a subject, the probe having a distal end and a proximal end. A probe assembly is provided that comprises a microcircuit for storing information about the probe and a cable for connecting the probe to the console, and the probe includes an access circuit for accessing the microcircuit in the probe.

Preferably, the cable is compatible and connectable to two or more different probes of a common type, and the microcircuit is uniquely information about that probe and is substantially common to other probes of that type. Memorize information that is not.

Preferably, the access circuit comprises a cable microcircuit that stores information commonly associated with different probes of a common type.

More preferably, the cable microcircuit stores information that identifies the type of probe.

Preferably, the information about the probe includes information about the use of the probe.

Preferably, the usage information includes a usage code that controls the availability of the probe to that user.

Preferably, the access circuit allows the code used to be changed so as to reduce the availability of the probe but not increase its availability.

Preferably, the microcircuit stores in its memory location the code of use controlled by the access circuit to operate in read access and program only mode.

Preferably, this mode can be changed by entering a password in the access circuit.

As an alternative or additionally, the usage code contains day information.

Preferably, the microcircuit is adjacent to the proximal end of the probe.

Preferably, the microcircuit includes a lead protruding from the proximal end of the probe, and the access circuit includes a socket that accepts the lead of the microcircuit.

Preferably, the probe comprises a functional portion that produces an analog signal, and the access circuit comprises one or more amplifiers that amplify the analog signal.

Preferably, the access circuit comprises one or more analog-to-digital converters.

Preferably, the access circuit comprises a cable microcircuit that stores information about the calibration of one or more amplifiers.

As an alternative or additionally, the access circuit includes a cable microcircuit that stores information about the probe assembly.

Preferably, the cable microcircuit stores information that describes the configuration of the probe.

Preferably, the cable microcircuit stores the allowed lifetime of the probe.

As an alternative or additionally, the cable includes an internal clock to measure the time since the first use of the catheter.

Preferably, at least a portion of the information in the microcircuit is encrypted.

Preferably, the information about the probe includes calibration information for the probe.

Preferably, the probe comprises a device that generates a signal that responds to the position or orientation of the probe, and the probe calibration information includes information about the calibration of the signal generator.

Preferably, the signal generator is adjacent to the distal end of the probe.

More preferably, the signal generator comprises one or more coils.

Preferably, the calibration information includes information about at least one gain of one or more coils.

Alternatively or additionally, the calibration information includes information about at least one angular orientation of one or more coils.

Alternatively or additionally, the calibration information includes information about the displacement of the signal generator with respect to the distal end of the probe.

Preferably, the probe comprises an isolation circuit, and the information about the probe includes information about the non-linearity of the isolation circuit.

Preferably, the microcircuit includes a programmable memory device, an EEPROM device, an EPROM or PROM device, a non-volatile RAM device or a flash ROM device.

Preferably, the cable includes means for disabling at least one of the connections for programming the programmable memory device.

A probe for insertion into the body of a subject and containing a microcircuit for storing calibration information of the probe, and a cable for connecting the probe to a console to access the microcircuit of the probe. To determine the position of the probe in the subject's body, including a cable containing the access circuit of the probe and a console containing a computer that receives the position or orientation response signal and the information about the calibration and then determines the position of the probe. The device is further provided according to a preferred embodiment of the present invention.

Preferably, the probe comprises a device that generates a signal in response to the position and orientation of the probe, and the probe calibration information includes information about the calibration of the signal generator.

Preferably, the microcircuit comprises a programmable memory device.

Preferably, the computer is designed to program a programmable memory device.

A method of initializing a console for use with a probe assembly that includes a probe and a connecting cable, where the cable is used to connect the probe to the console, and general model information from the microcircuits in the cable to the console. Further provided according to preferred embodiments of the invention are methods that include loading and loading the console with specific catheter information from a microcircuit within the catheter.

Preferably, the specific catheter information includes calibration information, code of use and / or date of first use.

Preferably, the general model information includes an acceptable period of use.

Preferably, the method comprises displaying a warning message when the period of use from the first date of use has expired.

Preferably, connecting the probe to the console involves connecting the probe through an access circuit in the cable.

Preferably, this method involves loading calibration information about the access circuit into the console.

The present invention, along with the drawings, will be more fully understood from the following detailed description of its preferred embodiments.

<figref num="1">FIG. 5 is a perspective view of a system having a catheter and connecting cable according to a preferred embodiment of the present invention.</figref><figref num="2">It is a detailed cross-sectional view of the distal end of the catheter of FIG.</figref><figref num="3">It is a detailed schematic diagram of the connection site between a catheter and a cable according to a preferred embodiment of the present invention.</figref>

FIG. 1 shows a probe system 18 according to a preferred embodiment of the present invention. System 18 comprises an elongated probe for insertion into the human body, preferably catheter 20. Although the following preferred embodiments have been described for catheters, it will be appreciated that the invention is equally applicable to other types of probes.

The distal end 22 of the catheter 20 includes a functional portion 24 adjacent to the distal tip 26 for performing diagnostic and / or therapeutic functions. The functional part 24 can include, for example, electrodes (not shown) for electrophysiological measurements or electrosurgical resection of the diseased area of the heart. As an alternative or additionally, the functional portion may include other types of sensors or optical image forming devices or ultrasonic image forming devices.

The distal end 22 of the catheter 20 further includes a signal generating device 28 used to determine the position and orientation of the catheter within the body. The device 28 is preferably adjacent to the functional portion 24. It is preferable that there is a certain positional and directional relationship between the device 28, the chip 26 and the portion 24.

The catheter 20 preferably comprises a handle 30, which includes a control device 32 used by the surgeon to guide the distal end of the catheter in a desired direction and / or position it as desired.

The system shown in FIG. 1 further comprises a console 34, which allows the user to observe and adjust the function of the catheter 20. The console 34 preferably includes a computer 36, a keyboard 38, typically a signal processing circuit 40 and a display 42 inside the computer. The signal processing circuit 40 typically receives, amplifies, filters, and digitizes the signals from the catheter 20, including the signals generated by the position signal generator 28, and then digitizes them. The signal received is received by the computer 36 and used to calculate the position and orientation of the catheter. Alternatively, as described below, a suitable circuit is associated with the catheter itself, thereby circuit 4 0 can be made to receive signals that have already been amplified, filtered, and / or digitized.

The catheter 20 is coupled to the computer 36 via an extension cable 21, which has a connector 44 at its proximal end, which fits into a mating receptacle 46 of the console 34. The distal end of the cable 21 comprises a receptacle 33 that connects to the handle 30. The receptacle 33 is preferably configured to accept a particular model of catheter, and preferably comprises a palpable identification of the user of the particular model. One of the advantages of using cable 21 is that different models and types of catheters, sometimes with different handle configurations, can be connected to the same console 34. Different cables 21 can be used to connect various catheters to the console 34. Another advantage of having a separate cable 21 is that the cable does not come into contact with the patient and therefore the cable can be reused without sterilization.

Preferably, the cable 21 further comprises one or more insulated transformers (not shown), which electrically isolates the catheter 20 from the console 34. The insulated transformer is preferably contained within the receptacle 33.

FIG. 2 which shows a detailed view of the distal end 22 of the catheter 20 according to the preferred embodiment of the present invention is referred to herein. The device 28 comprises three non-coaxial coils 60, 62 and 64 as described in PCT Patent Publication No. WO 96/05768. The disclosure of PCT Patent Publication No. WO 96/05768 is incorporated herein by reference. This device enables the continuous generation of 6-dimensional position and orientation information with respect to an externally applied magnetic field. The coils 60, 62 and 64 have axes 66, 68 and 70, respectively, which preferably define the orthogonal Cartesian axes Z, X and Y as shown in FIG. 2, respectively. In Figure 2, the Z axis is parallel to the length axis of the catheter, and the X and Y axes define a plane perpendicular to it. Each coil has a constant position and orientation with respect to each other.

Although preferred embodiments of the present invention are shown in FIG. 2 and described herein with respect to the position signal generator 28 described above, the inventive concept of the present invention is similarly applicable to probes including other position sensing devices. Will be understood. For example, in another preferred embodiment of the invention, the probe can include a single coil for generating position signals, or two or more such coils that can be coaxial or non-coaxial. Another preferred embodiment of the present invention may include Hall effect devices or other types of position sensing devices known in the art, such as ultrasonic or optical sensors.

As shown in FIG. 2, the device 28 is located in the catheter 20 at a distance L from the distal tip 26, where L is here along the Z axis from the central axis 68 of the coil 62 to the tip 26. It is defined as a distance for convenience. The axes 66 and 70 of the coils 60 and 64 are at their respective distances d._yAnd d_zOnly displaced from axis 68.

When a time-varying external magnetic field is applied to the distal end 22 of the catheter 20, the coils 60, 62 and 64 generate an analog signal, which is preferably transmitted through the catheter by the coil wire 72. The amplitude of these analog signals is typically smaller than the electrophysiological signals measured in and around the catheter 20 by other electrical signals such as the functional part 24 and transmitted through the catheter by the functional wire 76. .. Further, the external magnetic field may cause an unwanted current flowing through the coil wire 72 that is not generated by the coils 60, 62 and 64. These other electrical and unwanted currents cause noise or jamming signals to appear along with the signal generated by the coil. There is. Therefore, in a preferred embodiment of the invention, the wires 72 are configured as twisted pairs and shielded from electromagnetic interference by a shield 74 to maintain a high signal-to-noise ratio in the position and orientation signals received from the coil. Can also be done.

As described in the 05768 PCT patent publication above, the signal processing circuit 40 of the console 34 receives the signals carried by the coil wires 72 and sends them to the computer 36, which computer applies to a fixed external coordinate frame. , Calculate the three-dimensional translational position of device 28 and the rotational orientation of axes 66, 68 and 70. The actual position and orientation of the distal tip 26 is then calculated by taking into account the distance L of the tip 26 from the center of device 28 defined by axis 68 and the orientation of axes 66, 68 and 70.

It has been empirically found that due to variability in the method of manufacturing the catheter 20, the distance L typically varies from catheter to catheter, resulting in an error in calculating the position of the tip 26. Further, the axis 66 of the coil 60 typically deviates from absolute alignment with the axis of the length of the catheter 20 through the tip 26, and the axes 68 and 70 of the coils 62 and 64 typically typically deviate from each other. It is not exactly orthogonal to axis 66 or to each other, thereby inducing additional error in determining the position and orientation of the catheter. Finally, the gain variation and distance d of the coils 60, 62 and 64, respectively._yAnd d_zFluctuations in the catheter can cause additional errors in determining the position and orientation of the catheter.

Therefore, in a preferred embodiment of the invention, the device 28 used to determine the position and orientation of the catheter 20 is calibrated before the catheter is inserted into the patient's body. This calibration can be performed using any suitable method, including the method described in PCT / IL97 / 00006. The determined calibration correction function is then electronically stored in a memory device, which is preferably in the catheter 20. Once the catheter is coupled to the console 34, this memory device is accessible to the console computer 36.

FIG. 3 shows details of the receptacle 33 and the handle 30 according to a preferred embodiment of the present invention. The handle 30 includes a digital microcircuit 90 in which calibration data for the catheter 20 is electronically stored. The microcircuit 90 preferably includes EEPROM or flash ROM, but alternatives can include EPROM, PROM, non-volatile RAM or other types of programmable memory devices known in the art. Once the catheter 20 has been calibrated, its specific calibration data is stored in the microcircuit 90, thus the data is conveniently accessible to the computer 36 as described below.

Preferably, another microcircuit 88 is included in the receptacle 33 of the cable 21. The microcircuit 88 preferably includes a programmable memory similar to the memory of the microcircuit 90. Information about catheter 20 initialization, which is common to all catheters of a model, is preferably stored in microcircuit 88 rather than in microcircuit 90 embedded within the catheter itself. Most catheters have a limited number of uses due to cleaning, sterilization and wear issues. Normally, the catheter can be used only once. Therefore, it is desirable to minimize the cost of the catheter itself by incorporating only the required minimum circuit, including the smallest size microcircuit 90, into the catheter 20. All other information commonly characteristic of all catheters of a given model is stored within the receptacle 33, which is not inserted into the patient's body. Alternatively or additionally, the informational properties of a group of catheters are stored within the console 36, while the cable 21 holds only the minimum information that identifies which catheter model is being used.

The advantage of having model information in the receptacle 33 rather than in the console 36 is that it allows the use of a variety of catheters with the console 36 without having to load a large database into the console. Further, the microcircuit 88 preferably stores calibration information about the circuit in the receptacle as described below. These features allow the standard console to be used with different catheter types, rather than having a single console 36 associated with each type of catheter. In addition, newer model catheters can be used with the console 36 by simply connecting the newer model catheters to the console via their compatibility cable 21, thus requiring updates to the console software or. Reduce the need to get a new console.

In the preferred embodiment shown in FIG. 3, the handle 30 further comprises pins 92, 94, 96 and 98 that fit into the corresponding socket 93 of the receptacle 33. The functional pin 94 couples the analog electrophysiological signal transmitted through the functional wire 76 to the signal processing circuit 40. The coil pin 92 couples the analog position and orientation signals transmitted from the coils 60, 62 and 64 by the coil wire 72 to the signal processing circuit 40 and the computer 36, which calculates the position and orientation of the catheter 20. The computer also reads the digital calibration correction data stored in the microcircuit 90 via the memory pin 96 and uses these data to calculate the accurate catheter position and orientation.

The receptacle 33 preferably comprises one or more amplifiers 80 that amplify the position and orientation signals carried by the coil wire 72. These signals are generally very weak, so it is important to place the amplifier 80 as close as possible to the coils 60, 62 and 64 that generate the signal. However, it is advantageous not to place the amplifier 80 within the catheter 20. This is because the amplifier 80 significantly increases the cost and complexity of the catheter. Preferably, the receptacle 33 further comprises one or more analog-to-digital (A / D) converters 82 that convert the analog signal from the amplifier 80 into a digital form.

Preferably, the physiological signal transmitted through the functional wire 76 is also amplified by the amplifier 84 and then converted to digital form via the A / D converter 86. Preferably, calibration information for amplifiers 80 and 84, such as gain and offset, is stored in microcircuit 88.

One or more write permission pins 104 are preferably coupled to the microcircuit 90. These pins are used to allow programming of microcircuits with the desired calibration data. At the time of calibration, write permission input is enabled and the calibration data is stored in the microcircuit. After that, the write permission input is disabled, for example by removing the write permission pin or connecting it to the electrical ground 106 as shown in FIG. 3, so that further calibration data is sent to the microcircuit. Unrecordable, the microcircuit works in read-only mode. The microcircuit 88 can be programmed in a similar manner.

Alternatively, in a preferred embodiment of the invention in which the microcircuit 90 comprises an EEPROM device, the write permission input can be disabled by sending a write protection command to this device. This directive can be reversible or irreversible.

In another preferred embodiment of the invention, the microcircuit 90 comprises a device incorporating a password-guaranteed access control device, and write access to the microcircuit requires a suitable password to be entered first. For example, in one such preferred embodiment, the microcircuit 90 is a password access manufactured by Xicor, Inc. Security supervisor (PASS)^TM) X76F041 Secure Flash ROM Device (PASS)^TM) Consists of including X76F041. The microcircuit is programmed with factory calibration data and then operates in "read access only" mode with all write operations locked out, or some data as described below. Operates in "read access and program only" mode, which can write to the device but not proof data. Changing the operating mode of a microcircuit requires an appropriate password to be entered, which is not generally available to system users.

In another preferred embodiment of the invention, the microcircuit 90 comprises EPROM or PROM. Calibration data is recorded in EPROM or PROM at the time of manufacture using a suitable programming device (not shown) that receives data from the computer used for calibration. The programming device is connected to the handle 30 via a calibration socket (not shown), which, like the receptacle 33, accepts the handle 30. The programming device programs the EPROM or PROM by inputting a digital signal to the EPROM or PROM through a connector. After that, the EPROM or PROM can be made non-reprogrammable.

In one preferred embodiment of the invention, the data recorded in the microcircuit 90 and / or the microcircuit 88 is encrypted according to methods known in the art to ensure that the calibration data is not altered or tampered with. Includes proofreading code. Preferably, the calibration code includes the inspection total. When the user connects the catheter 20 to the console 34, the computer 36 reads the calibration code and compares it to the preprogrammed value. If the code does not match the desired preprogrammed value, the computer displays a message on the display 42 indicating that the catheter may not be properly calibrated. The computer can further suspend the operation of the system until a catheter with a code that matches the desired preprogrammed value is connected to it.

Preferably, the calibration code uses a method to prevent decryption by unauthorized parties, for example using a public or private key or other methods known in the art for RSA encryption schemes. Is encrypted using. When methods such as RSA encryption are used, the private key may be given to the authorized manufacturer of the catheter to prevent possible use of unlicensed alternatives of inferior quality. Only known.

In a further preferred embodiment of the invention, the data recorded in the microcircuit 90 includes the date and time of expiration, after which the catheter cannot be used. Microcircuit 88 also contains data on the maximum length of time the catheter can be used over that period. When the user connects the catheter 20 to the console 34, the computer 36 reads the expiration date and time and compares them with the actual date and time generated by, for example, a real-time clock circuit. If the expiration date and time have passed, the computer will display a message on display 42 indicating that the catheter is unsuitable for further use. Alternatively or additionally, the computer may block the use of the catheter 20 after the expiration date.

In a preferred embodiment of the invention, the cable 21 includes an internal clock that keeps track of time and day. As an alternative or additionally, the internal clock of cable 21 keeps track of the relative time from the first use of catheter 20. Thus, it is not possible to avoid blockages by changing the day on the console.

Preferably, the expiration date and time are recorded by the computer 36 by programming the microcircuit 90 when the catheter 20 is first used. When the catheter 20 is first connected to the console 34, the computer 36 detects that the expiration date and time have not yet been recorded in the microcircuit 90, and is appropriate for the preset interval after the current day and time. Program the microcircuit according to the expiration date and time. The preset interval is preferably determined by the manufacturer based on the expected lifetime of the catheter.

In a preferred embodiment of the invention in which the microcircuit 90 comprises a device comprising an access control circuit such as the X76F041 device described above, the microcircuit operates in a "read access and program only" mode in which its memory location is. Programmed to be possible. This mode can only be changed by entering a suitable password that is generally not available to the user of the system. In "read access and program only" mode, the number stored in the memory location can be reduced by changing the bit from "1" to "0", but not increased. This is because it does not allow the programmed microcircuit "0" to be changed to "1". Preferably, the memory location is set at the time of manufacture to include a maximum value, i.e. that all bits are set to "1". Then, as mentioned above, when the catheter 20 is first used, the computer 36 micros at a suitable expiration time and day by changing one or more bits in the memory location from "1" to "0". Program the circuit. After that, the expiration date cannot be changed to any subsequent day (unless the correct password is first entered).

As an alternative or additionally, the microcircuit 90, which includes the access control circuit as described above, tracks the number of times the catheter 20 has been used in such a way as to protect it from possible tampering or error by its user. Can be used to. Preferably, a record corresponding to the number of times the catheter 20 can be used is stored in the device's memory location at the time of manufacture, and the microcircuit is in "read access and program only" mode as described above. Programmed to work with. Each time the catheter is used, the computer 36 reads a record of the memory location and reduces it by changing one or more bits in it from "1" to "0". When all bits of the record are equal to zero or when the record reaches some other predetermined minimum, the computer causes the user to display a message indicating that the catheter is unsuitable for further use. And preferably, further movement is blocked until a suitable catheter is connected to it.

Similarly, as an alternative or additionally, the microcircuit 90 can be used to track the duration of use of the catheter 20. In this case, the record corresponding to the duration of use of the catheter is stored in the "read access and program only" memory location of the microcircuit. During the use of the catheter, at regular predetermined intervals, the computer 36 reads the record and reduces it by changing one or more bits in it from "1" to "0". When the entire record reaches zero or some other minimum, further operation is blocked as described above. As mentioned above, the low level analog signals transmitted from the coils 60, 62 and 64 through the coil wire 72 must generally be protected from interference by other analog signals on the functional wire 76 and digital signals transmitted from the microcircuit 90. It doesn't become. Therefore, in a preferred embodiment of the invention, as shown in FIG. 3, the handle 30 includes an electromagnetic shield 74, which is coupled to ground via a pin 98 on the connector.

In another preferred embodiment of the invention, the shield 74 is an active shield, which is driven by a noise canceling circuit (not shown).

Although the features and capabilities of the system 18, especially those relating to access control, have been described above for the microcircuit 90 of the catheter handle 30, many of these features and capabilities can also be implemented using the microcircuit 88 in cable 21. It will be obvious to those skilled in the art.

Further, while the preferred embodiment described above has been described for calibration of the position and orientation detector, in another preferred embodiment of the invention the calibration data stored in the catheter 20, especially the microcircuits 88 and 90, is the other surface of the catheter. May be related to. For example, in one preferred embodiment of the invention, calibration data for physiological sensors, actuators or therapeutic instruments is stored in the catheter. In another preferred embodiment of the invention, calibration data can be stored in the catheter with respect to the gain of the piezoelectric motion control device used to guide the distal end of the catheter.

It will be appreciated that the preferred embodiments of the invention described above are given by way of example, and that the entire scope of the invention is limited only by the claims.

An example of the embodiment of the present invention is shown below. 1. A probe for insertion into the subject's body that has a distal end and a proximal end and has a microcircuit that stores information about the probe. A cable that connects the probe to the console and has an access circuit to access the microcircuits in the probe. A probe assembly for connecting to a console, characterized in that the information about the probe has user-related information about the probe and a usage code that controls the availability of the probe to the user. .. 2. The cable can be compatiblely connected to two or more different probes of a common type, and the microcircuit is information that is unique to the probe and is substantially common to other probes of that type. The assembly described in 1 above that stores information that is not. 3. The assembly according to 2 above, wherein the access circuit has a cable microcircuit that stores information commonly related to different probes of a common type. 4. The assembly described in 3 above, where the cable microcircuit stores information that identifies the type of probe. 5. The assembly according to 1 above, wherein the access circuit modifies the code used so as to reduce the availability of the probe but not increase it. 6. The assembly according to 1 above, in which the microcircuit stores in its memory location the code of use controlled by the access circuit to operate in read access and program only mode. 7. The assembly according to 6 above, wherein the mode can be changed by entering a password in the access circuit. 8. The assembly described in 7 above, whose usage code contains date information. 9. The assembly according to 1 above, in which the microcircuit is adjacent to the proximal end of the probe. 10. The assembly according to 9 above, wherein the microcircuit has a lead protruding from the proximal end of the probe and the access circuit has a socket that accepts the lead of the microcircuit. 11. The assembly according to 1 above, wherein the probe has a functional part that produces an analog signal and the access circuit has one or more amplifiers that amplify the analog signal. 12. The access circuit has one or more analog-to-digital converters. Assembly. 13. The assembly according to 11 above, wherein the access circuit has a cable microcircuit that stores information about the calibration of one or more amplifiers. 14. The assembly according to 1 above, wherein the access circuit has a cable microcircuit that stores information about the probe assembly. 15. The assembly described in 14 above, where the cable microcircuit stores information that describes the configuration of the probe. 16. The assembly according to 14 above, in which the cable microcircuit remembers the allowed life of the probe. 17. The assembly according to 1 above, wherein the cable has an internal clock to measure the time since the first use of the catheter. 18. The assembly according to 1 above, in which at least part of the information in the microcircuit is encrypted. 19. The assembly according to 1 above, where the information about the probe has the calibration information for the probe. 20. The assembly according to 19 above, wherein the probe has a device that generates a signal in response to the position or orientation of the probe, and the calibration information of the probe has information about calibration of the signal generator. 21. The assembly according to 20 above, wherein the signal generator is adjacent to the distal end of the probe. 22. The assembly according to 20 above, wherein the signal generator has one or more coils. 23. The assembly according to 22 above, wherein the calibration information has information about at least one gain of one or more coils. 24. The assembly according to 22 above, wherein the calibration information has information about at least one angular orientation of one or more coils. 25. The assembly according to 20 above, wherein the calibration information has information about the positional displacement of the signal generator with respect to the distal end of the probe. 26. The assembly according to 1 above, wherein the probe has an isolation circuit and the information about the probe has information about the non-linearity of the isolation circuit. 27. The assembly according to 1 above, wherein the microcircuit has a programmable memory device. 28. The probe according to 27 above, wherein the programmable memory device has an EEPROM device. 29. The probe according to 27 above, wherein the programmable memory device has an EPROM or PROM device. 30. The probe according to 27 above, wherein the programmable memory device has a flash ROM device. 31. The device according to 27 above, wherein the cable has means for disabling at least one of the connections for programming a programmable memory device. 32. A probe for insertion into the subject's body, which has a microcircuit to store probe calibration information and generates a position or orientation response signal. A cable for connecting the probe to the console, which has an access circuit for accessing the microcircuits in the probe, A console with a computer that receives the position or orientation response signal and the information about the calibration and determines the position of the probe from the information. A device for determining the position of a probe in a subject's body, characterized in that it comprises. 33. The assembly according to 32 above, wherein the probe has a device that generates a signal that responds to the position and orientation of the probe, and the calibration information of the probe has information about the calibration of the signal generator. 34. The device according to 33 above, wherein the microcircuit has a programmable memory device. 35. The device according to 34 above, in which the computer is designed to program a programmable memory device. 36. A method of initializing the console for use with probe assemblies with probes and connecting cables. The process of connecting the probe to the console using a cable, The process of loading general model information from the microcircuits in the cable into the console, The process of loading specific probe information with calibration information from the microcircuits in the probe into the console, A method characterized by comprising. 37. The method according to 36 above, wherein the specific catheter information has a usage code. 38. The method according to 36 above, wherein the specific catheter information has a date of first use. 39. The method of 38 above, where the general model information has an acceptable period of use. 40. The method according to 39 above, which has a process of displaying a warning message when the period of use from the first use date has expired. 41. The method of 40 above, wherein the process of connecting the probe to the console comprises the process of connecting the probe via an access circuit in the cable. 42. The method according to 41 above, which has a process of loading calibration information about the access circuit into the console.