JP2003515104A - Optical fiber navigation system - Google Patents

Abstract

SUMMARY [57] The present invention is a system and method for determining the shape, positioning, and orientation of a passage, such as the lumen of a catheter inside a human or animal body. An array of optical fibers is disposed within the passage, and when the fiber is curved or bent within the passage, the nature of light traveling through the fiber is altered. Light travels through the fiber and changes in the physical properties of the light are measured to determine the curvature or bend of the fiber. Preferably, an array of three or more optical fibers is fixed together, and the amount of distortion inside these optical fibers and the shape of the fiber array are determined by a change in the wavelength of light passing through these fibers. Can be. By utilizing three or more optical fibers, the shape of the array in three dimensions can be determined. Additional methods are disclosed for determining the position and orientation of a fiber optic array within a selected passageway.

Description

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates generally to optical fibers and systems and methods for measuring properties and positions of objects on which the fibers are positioned. More specifically, the present invention provides a light for determining the shape, orientation, and position of an optical fiber to generate information about a particular path, passage, or tubular object within a human or animal body, such as a catheter. Intended for fiber systems and methods.

BACKGROUND OF THE INVENTION Catheter is employed in a variety of medical procedures, usually a long thin tube containing one or more lumens or passages. In some cases, catheters are used to deliver drugs or fluids from specific sites within the body to external devices. In some cases, the catheter includes a sensor to make a diagnostic measurement at a particular internal location. In other applications, catheters are used in surgical procedures to guide surgical instruments to internal sites.
The use of catheters minimizes cuts in the skin, muscles, and bones in these and other procedures.

As an example, a diagnostic procedure called Intravascular Ultrasound (IVUS) involves the use of skin detectors along with an array of ultrasound detectors inside a catheter to assess the health of arteries and veins, especially blood vessels near the heart. Use an ultrasonic transmitter positioned on the surface of the. In this application, it is extremely useful to have knowledge of the spatial position and orientation of the detector array, i.e. the shape of the catheter containing the detector and thus the shape of the blood vessel or other structure of the body. The three-dimensional shape, orientation, and position of the catheter cannot be determined using known methods and techniques. Therefore,
There is a need to effectively determine the shape, orientation, and location of tubular objects such as catheters that are placed inside the body of humans or other animals.

Alternatively, the optical fiber can be used in other environments to assess small or remote locations, where the optical fiber is used to generate information about the environment in which it is located. It is advantageous to know the shape, orientation and position of the.
Currently, there is no fiber optic measurement and positioning system or method available that can measure the properties and location of the optical fiber and the path along which the fiber travels. However, the applicant of the present invention is "PROBE POSITIONING S
ENSING SYSTEM AND METHOD OF EMPLOYIN
Co-pending US patent application Ser. No. 09/3 entitled “G THE SAME”
No. 73539, and “PROBE POSITI” filed on August 11, 2000.
ON SENSING SYSTEM AND METHOD OF EMPL
We have developed a system and method for determining the position of a probe located in a coordinate system, described in the US Partial Continuation / Patent Cooperation Treaty application entitled "OYMENT OF SAME".

The ability to measure the shape, orientation, and position of an optical fiber, especially when used in a medical environment, requires the physician to determine the exact position and orientation of the fiber, and also the anatomy to which the catheter is located. Make it possible to obtain the shape. It is also advantageous in other invasive medical applications such as catheter ablation procedures, catheterization methods for treating coronary artery disease, other vascular therapies, angioplasty, laparoscopy, and nerve block therapy, among others. .

SUMMARY OF THE INVENTION Optical fibers are commonly used in a variety of telecommunications, and also in other applications that use optical fibers as sensors that sense temperature, strain, acoustic fields and magnetic fields, and rotation. Can be used. The present invention relates to the three-dimensional shape, orientation, and
And position-measuring systems and methods, and thus can provide corresponding information regarding the environment in which the optical fiber is positioned, such as a passageway or tubular object including a catheter placed inside the body. This goal is achieved by measuring changes in the properties of light traveling in an optical fiber.

The system can include an array of optical fibers, each housed within an envelope. Light passes through the fiber and when the fiber is bent or bent, the nature of the light passing through the fiber changes. Changes in the nature of the light inside the fiber are used to determine changes in the shape, orientation, and / or position of the fiber, as well as the shape of the object or environment in which the fiber is placed. Changes in fiber shape, orientation, and / or position using changes in physical properties such as wavelength (frequency), intensity, phase, polarization state, or spectral properties of light traveling in a fiber depending on bend angle You can also ask.

Detailed Description of the Preferred Embodiments Various embodiments of the present invention will now be described in detail. Examples of embodiments are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to represent the same or like parts. These embodiments are directed to the use of the sensor system inside a catheter to perform various medical procedures, but the sensor system and method of the present invention determines the shape, orientation, or position of an object. Can be used in other applications or environments, or in some environments.

In one embodiment of the invention, the change in wavelength is measured to determine the curvature of the fiber optic array. Each optical fiber includes one or more fiber Bragg gratings ("FBGs"). The FBG constitutes an optical fiber consisting of a light guiding core region and an outer cladding region, one section of the core containing a periodic change in the optical index of refraction. The FBG can be prepared by side illumination of a small core area to high intensity ultraviolet (UV). The periodic spatial intensity pattern of UV light causes periodic physical and chemical changes inside the glass, which results in FBG
To form. When light that travels within the core of the fiber encounters the FBG, it either passes or is reflected by the FBG, depending on the wavelength of the light. The light is reflected when its wavelength λ satisfies the Bragg condition λ ₀ = 2dn, where d is the spacing of the periodic change in the refractive index and n is the average light of the glass core at the wavelength λ. Is the refractive index. In practice, the change in the index of refraction of the FBG is not perfectly periodic and the reflected light is contained within a wavelength range centered on the central wavelength 2d'n with d'as the average spacing.

When the fiber containing the FBG is subjected to stress that strains the fiber by the amount ε = Δd / d, the wavelength λ of the reflected light changes by the amount Δλ = λ (ε) −λ (ε = 0), Here, Δλ = 2dnε. Wavelength shifts can be detected using a variety of well-known optical techniques, including spectroscopy and interferometry.

By arranging the array of optical fibers in a predetermined geometry, fiber strain can be related to the shape of the fiber array. Here, the fiber acts as a sensor of the local curvature geometry, and the shape of the fiber configuration, the orientation, and the orientation of the fiber configuration, provided that the local curvature geometry is known at several sufficiently closely spaced locations.
And / or location can be determined. As an example, FIG. 1 illustrates an optical fiber 12 having three individual FBGs 14 formed along its length. The shape, and thus the orientation and / or position, can be determined over the region 16 of the fiber 12 that includes the FBGs that are coupled to form an array of at least three optical fibers. This area is called the active area or the active length of the sensor.

As shown in FIG. 2A, one embodiment of the sensor is an optical fiber having a predetermined geometry with an array 18 of three optical fibers 20, 21, and 22 arranged in a close-packed geometry. -Use an array. In FIG. 2B, three fibers 20, 21
, And 22 close-packed array configurations. In this configuration, the fiber is placed at the tip of an equilateral triangle. Other fiber configurations are possible as long as the information received from the fiber is sufficient to unambiguously determine the bend angle in three dimensions. Each optical fiber 20,
21 and 22 comprise glass strands.

As shown in FIG. 3, each optical fiber 20, 21, and 22 includes a series of FBGs 24, 26, 28, and 30 along its length. The FBGs 24, 26, 28, and 30 are positioned along each fiber 20, 21, and 22 when the fibers undergo bending. Upon bending, the FBG exhibits changes in reflected wavelength, providing signals for measuring and indexing changes in the shape, orientation, and position of array 18.

As shown in FIG. 5, three optical fibers 20, 21, and 22 are provided in this environment.
A fiber optic array comprising one or more fibers shown as is attached to a suitable adhesive, such as Norland Products Incorporated.
Arrays 18 can be bonded together in a fixed orientation using a UV (UV) curable adhesive NOA 68 manufactured by of New Brunswick, NJ, USA. After the adhesive has cured, the 3-cable array 18 can be surrounded by a jacket 19. Jacket 19
Can be composed of any polymeric or non-polymeric material suitable for the desired application. The composition and morphology of the jacket 19 is such that the fibers 20, 21,
And 22 are selected to protect and also provide the desired mechanical properties. The envelope can also be formed as a housing with a desired contour that can be adapted to the object in the environment in which the measurement is desired. Alternatively, no jacket or housing may be required for a given application or environment. In medical applications, examples of suitable envelope materials include silicone, polyetheretherketone (PEEK), polyimide, and polyurethane. The array 18 may be retained within the envelope 19 by a suitable adhesive. Adhesive may be applied to fill the voids between the outer surface of array 18 and the inner surface of jacket 19 along all or part of the length of the array. Further, in some applications, the protective jacket or housing 19 may be
It is contemplated to have markers to determine the placement of the array 18 within an object such as a catheter. An example of such a marker is a length delimiter.

Currently, it is necessary to utilize at least three optical fibers, as shown in FIG. 5, to ascertain a three-dimensional image of a passage or an object. At least three optical fibers can be used to make overall shape measurements when the various paths within which the sensor 18 and / or catheter of the present invention can be placed are bent simultaneously in multiple planes. it can. Sensors containing more than three fibers may also be utilized, depending on the particular application and the accuracy required for the application. When using a sensor with more than three fibers, as described above, the fibers are affixed in a fixed orientation with respect to each other, the strain within these fibers, as well as the shape, orientation of the sensor array, And positioning is calculated.

The curved geometry of the short section of the fiber array is characterized by two angle theta θ and phi φ, as shown in FIG. 2A. Under the assumption that the array bends in an arc, the strains ε _A , ε _B , and ε _{C of the} three fibers are ε _A = (2r / √3b) * θ * cos (φ) (1a) ε _B = (2r / √3b) * θ * cos (φ-2 * π / 3) (1b) ε _C = (2r / √3b) * θ * cos (φ-4 * π / 3) (1c) It is related to the angles θ and φ. Where b is the total length (fixed) of the section and r is the fiber radius. Knowing the three strains, the bending angle can be easily calculated.

Throughout the section of fiber identifiable by a given pair of angles (θ, φ), the proximal end of the section is at the origin of a well-selected coordinate system, with each point along the z-axis. (X, y, z) coordinates of the end points of the section are as follows: x = (b / θ) (1-cos θ) cos φ (2a) y = (b / θ) (1-cos θ) sin φ (2b ) Z = (b / θ) sin θ (2c). The vector r = [x, y, z] gives the position with respect to the origin r = 0 of the end points of the curved section.

The curve itself is expressed as follows: x (s) = (b ² / sθ) (1-cos [(s / b) θ]) cosφ (3a) y (s) = (b ² / sθ) (1-cos [(S / b) θ]) sinφ (3b) z (s) = (b ² / sθ) sin [(s / b) θ] (3c) can also be written in a parameterized form. Here, the parameter s is the length along the curve, and 0 ≦ s ≦ b.

An alternative parameterized description of the curve is for the partial angle αθ, where 0 ≦ α ≦ 1. x (α) = (b / αθ) (1-cosαθ) cosφ (4a) y (α) = (b / αθ) (1-cosαθ) sinφ (4b) z (α) = (b / αθ) sinαθ ( 4c)

As will be seen below, it is also useful to calculate the derivative with respect to the parameters of the parameterization curve. In the partial angle description, dx / dα = (b / θ) [sinαθ− (1 / αθ) (1-cosαθ)
] Cosφ (5a) dy / dα = (b / θ) [sinαθ- (1 / αθ) (1-cosαθ)
] Sin φ (5b) dz / dα = (b / θ) [cos αθ- (1 / αθ) sin αθ] (5c). The length L of the curve between α1 and α2 is L (α1, α2) = ∫ _ds = ∫ [(dx / dα) ² + (dy / dα) ² +
(Dz / dα) ² ] ^1/2 dα (6
) Given by. Here, the integration range is α1 ≦ α ≦ α2. The length component of the arc differentiated by the direct algebra is: ds (θ, φ) = [(dx / dα) ² + (dy / dα) ² + (dz / dα
) ² ] ^1/2 dα = (b / θ) [1+ (2 / (αθ) ² ) (1-cosαθ) −
(2 / αθ) sinαθ] ^1/2 dα (7
). By definition, L (0,1) = b.

At the endpoints of the section, the gradient of the curve corresponds to (x, y, z) in equations 2a-2c, with the vector g (θ, φ, α) = (dx / Note that dα, dy / dα, dz / dα) (8). Therefore, g (θ, φ, 1) = (b / θ) [(sin θ− (1 / θ) (1-cos θ
)) Cos φ, (sin θ- (1 / θ) (1-cos θ)) sin φ, (cos θ- (1 / θ) sin θ)] (9).

Embodiments for use in medical procedures can provide a combination of multiple sections of the fiber array described above. This allows the shape, orientation, and / or position of the section combination to be determined. Table 1 lists the symbols used to identify the characteristics of particular segments.

[Table 1]

A graphical rendering of the curved section can be obtained using the stepwise procedure in Table 2.

[Table 2]

It can be seen that with this method, a discontinuity of the angle φ may occur at the “joint” position that connects two adjacent segments. One approach to solving this problem is to smooth the change in φ over the length of the active portion of the catheter. Another approach is to use global cubic spline interpolation to estimate a three-dimensional curve whose shape is consistent with the least-squares method, where every strain is measured at every FBG in the sensor. It

Furthermore, the calculated shape is physically possible with respect to the actual mechanical object,
It may be desirable to employ additional constraints and corrections based on solid mechanics to ensure that they are globally consistent.

FIG. 3 illustrates one embodiment of the present invention for use in determining the shape, orientation, and / or position of sensor array 18 inside a patient's body. The sensor array 18 is
It is composed of three or more optical fibers 20, 21, and 22 and is positioned within the passageway to measure the shape, orientation, and / or positioning of the passageway, such as the lumen of a catheter. Each optical fiber 20, 21, and 22 includes an array of four 24, 26, 28, and 30 spaced 20 mm apart. The current manufacturer of suitable FBGs is ElectroPhotonics Corporation.
on, 3M Corporation, Thor Labs, or Innov
active Fibers, Inc .. Three fibers 20, 21,
And 22 are formed in array 18 and mechanically attached to each other over a length of about 100 mm. It should be appreciated that the spacing between the optical fibers FBGs, and likewise the overall length of the system of the present invention, can be scaled up or down as needed for various applications. Further, the FBG and its associated characteristics can be modified, if desired. Other optical properties may also serve to enable such measurements in an array of one or more optical fibers. The bend angle over the at least one array region can be determined from other changes in the physical properties of light within the array due to the rearrangement of the array.

In one preferred embodiment of the present invention, FBGs 24, 26, 28, and 30.
Are co-located along the length of the active area 16 of array 18, and each of these FBGs has compatible properties. Such an arrangement allows the strain inside the fibers 20, 21 and 22 and the shape of the array 18 to be more easily calculated, but has different properties and is different along the fibers 20, 21 and 22. Fibers with FBGs positioned in place can also be utilized.

Using the electro-optic system 32, three of the FBGs 24, 26, 28, and 30 are used.
Optically query one array. The electro-optical system 32 includes each optical fiber 2
It is directly connected to 0, 21, and 22. Electro-optic system 32 includes sources for both optical and electrical signals and communicates with computer 34 via a parallel port data link. Associated software and user interfaces are associated with the computer 34 to determine the shape, orientation, and / or position of the array 18, as well as the shape or configuration of the catheter or other object within which the array 18 is to be displayed and displayed. Display on the panel or monitor 36.

4A-4C illustrate components of an electro-optic system used to interrogate a fiber optic sensor according to the present invention. In one configuration of electronic components shown in FIG. 4A, electro-optic system 32 includes a light source 46 and a first property selection element 4.
2, a multiplexer / demultiplexer 40, a second property selection element 44,
And a photodetector 48. The light source 46 produces a light source to be introduced into the fibers 20, 21 and 22. The property selection element serves to select a particular property of the light such as wavelength (frequency), phase, intensity, polarization, or spectral property to be queried to determine the bend angle of the fiber. The properties required of the light source 46 will depend on the particular optical properties selected for the measurement. When using FBG, light source 4
6 preferably has the following properties: a) center wavelength around 1550 nm b) average spectral width greater than 40 nm c) average output greater than 100 nW

Light source 46 is also preferably configured to be simply optically connected to single mode optical fibers 20, 21, and 22. Excitation signal 52 is FBG2
4, 26, 28, and 30, after being reflected by the FBG within a narrow wavelength range centered at the FBG center wavelength and traveling to the photodetector 48 via optical fibers 20, 21, and 22, So that there is sufficient signal strength at the photodetector 48,
The average light output of the light source 46 should be high enough. In some situations, the photodetector 48
It may be necessary to use multiple light sources to maintain sufficient optical signal strength at.

In this configuration, the first property selection element 44 is used to select a particular light property and property range prior to introducing light into the optical fibers 20, 21, and 22. When measuring changes in the wavelength of light, a broadband filter can be used as the first property selection element 42 to filter light within the selected wavelength range and eliminate unwanted wavelength ranges. Alternatively, it may be a wavelength scanning device such as a scan filter.

The multiplexer / demultiplexer 40 connects the light source 46 to the optical fibers 20, 2
Route optical signal 52 to 1 and 22. Multiplexer / demultiplexer 40 also includes FBGs 24, 26, 28, within fibers 20, 21, and 22.
Coordinates the reception of reflected light signals from and 30 and directs these signals to the second property selection element 44.

A second property selection element is also utilized to select a particular property of the light after the light has passed through the optical fibers 20, 21, and 22 and before it travels to the photodetector 48. When monitoring changes in wavelength for measuring and indexing the amount of strain within the fibers 20, 21, and 22, the second property selection element can be a selection filter to select only a narrow wavelength range. . Alternatively, it may be a wavelength scanning device such as a scan filter. The first and second property selection elements can be used together to provide only the desired wavelength range to be measured by the photodetector 48. In some cases, one property selection element cannot select more than one property. The use of both the first property selection element 42 and the second property selection element 44 allows delegation of optical property filtering.

In this configuration, the second property selection element 44 can convert the measured change in the optical property of the original optical signal 52 into a change in the light intensity. A series of photodetectors 48 convert these changes in light intensity into electrical signals 54. The electrical signal 54 is then transmitted to the computer 34 shown in FIG. The change in intensity of the electrical signal 54 is related to the degree of strain or bending angle experienced by the optical fibers 20, 21, and 22. Using the difference in strain of the optical fibers 20, 21, and 22 of array 18, array 1
8 and the change in shape or environment of the object within which the array 18 is inserted.

FIG. 4B illustrates another configuration of the components of the electro-optic system used in accordance with the present invention. This configuration includes only one property selection element 42, which is located between the light source 46 and the multiplexer / demultiplexer 40. In this configuration, the light is demultiplexed by multiplexer / demultiplexer 40 and then directed to photodetector 48 for conversion into a voltage signal that is processed by computer system 32. In this configuration, FBGs 24, 26, 28, and 30
And the property selection element 42 have the effect of combining the fibers 20, 21, and 22.
Light intensity changes of the light passing therethrough and photodetector 48 converts these intensity changes into a voltage that can be measured by computer system 34. In a preferred embodiment of the present invention, this configuration is utilized and the Fiber Fabry Perot (F
A scan filter such as FP) is used as a property selection element to filter the wavelength range desired for the measurement.

In FIG. 4C, another configuration of components of an electro-optic system for use in accordance with the present invention is shown. This configuration utilizes only one property selection element, which is located between multiplexer / demultiplexer 40 and photodetector 48. When utilizing this configuration, a filter, such as a fixed edge filter, may be used to filter the light and provide a selected optical property or range of optical properties to the photodetector 48 for conversion into a voltage signal 54. it can. Alternatively, wavelength scanning devices such as scan filters can be used.

Although the configuration of the components illustrated by FIGS. 4A-C is shown as valid,
Other configurations, including various filters or other components, may also be utilized. In addition, wavelength was discussed as the optical property to measure to determine the strain within the fibers 20, 21, and 22, but other light sources may be used as long as the selected property varies with the bending or bending of the fiber optic array 18. Properties can also be used. These properties include intensity, amplitude, wavelength, phase, polarization state, or spectral properties.

For example, if the phase of the light is of a nature chosen to determine the strain within the fibers 20, 21, and 22, then the component arrangement illustrated in FIG. 4A may be used, An interferometer is formed using a fiber optic coupler as the property selection element 42 and an additional fiber optic coupler as the second property selection element 44. In this case, the intensity of the interferometer output is proportional to the phase difference of the light traveling to the two arms of the interferometer. In addition, the first property selection element 42 can optionally include a phase modulation component such as a piezoelectric element coupled to an optical fiber or an integrated optical phase shifter.

If it is desired to measure the state of polarization, the first property selection element 42 comprises a polarizer and the second property selection element 44 comprises a polarization analyzer. In another example where light intensity is selected as the property to be measured, both the first property selection element and the second property selection element are eliminated.

Various configurations and properties can be utilized depending on the application of the system and the required accuracy for its application.

A reference system 31 is also shown in FIGS. 4A-C to calibrate and stabilize the optical measurements of the optical fibers 20, 21, and 22. The exact nature and implementation of the reference system depends on the particular light properties chosen for the measurement. For example,
In a preferred embodiment of the invention, the reference system is an FBG inside an enclosure.
So as not to be strained or exposed to other environmental factors, a series of FBGs formed inside the optical fiber 23 located inside the enclosure. The wavelength of light that passes through or is reflected by the reference system is known and recorded prior to the particular use of the system. During use of the system, the wavelength measurements from the reference system are compared to known values. The difference between the known value and the measured value is believed to be due to variations or drifts in electro-optic system 32. Therefore, a correction factor is determined and the sensor optical fibers 20, 21, and 2 are
It is added to the signal received from the device 2, usually in the form of software, to ensure the accuracy and stability of the system of the invention.

In order to extract the angle measurements and thus the shape of the array 18 in this embodiment, the electro-optic system 32 changes the wavelength of the light reflected by the FBG in response to changes in the bending angle of the array 18. taking measurement.

The photodetector 48 is selected to match the light received from the nature filter 50 and provides an electrical signal 44 having a sufficiently high signal to noise ratio. Newpor
t Corporation, New Focus, and Hewlett P
Various photodetectors 48 are currently commercially available from several manufacturers, including ackard.

Typically, it is not necessary to use only one light source 46 and one photodetector 48 for each optical fiber 20, 21, and 22 of array 18, which is not cost effective, but is optional. Appropriate configurations are contemplated. Using multiplexer 40,
Light can be dispersed from the light source 46 into each optical fiber either sequentially or simultaneously.
Multiplexer 40 also receives the reflected light from optical fibers 20, 21, and 22 and directs it to quality filter 50 in a controlled manner, again known. For example, the FBGs 24, 26, 28, and 30 have a plurality of optical fibers 20.
, 21, and 22 when embedded inside, an electrically controlled optical switch can be used to deliver light from the light source 46 to each optical fiber 20, 21, and 22 sequentially. While the light source is "connected" to a particular optical fiber 20, 21 or 22, the light returning from each optical fiber is directed to a property filter 50 to complete the measurement of each FBG in the individual optical fiber.

As shown in FIGS. 6A and 6B, one application of the systems and methods of the present invention is in the shape, orientation, and / or orientation of a catheter placed inside the body of a human or other animal.
Or to find the position. Fiber optic array 18 is inserted inside the lumen of catheter 62 via access port 60. In FIG. 6B, the protective jacket 19
Shown is an exploded view of array 18 covered by and inside catheter 62.

9A-9C sequentially illustrate a mathematical reconstruction of the shape of tubular object 68 as fiber array 18 is advanced into tubular object 68. The fiber array 18 has an active portion 16. Active portion 16 is the area of array 18 in which FBGs 24, 26, 28, and 30 are located. As shown in FIG. 9A, the tubular object 6
Prior to being inserted into the fiber array 18, the fiber array 18 assumes the shape of this first curved section and the system of the present invention displays the linear shape of the active section 16. When the active portion 16 of the array 18 is inserted into the first curved portion of the tubular object 68, the fiber array 18 again exhibits this additional curved shape and the system of the present invention is shown in FIG. 9B. A curved shape of the active portion 16 is generated. The active part 16 is a second tubular object 68
When advanced further into the curved portion of the, the system produces the curved shape of the object 68 and active portion 16 shown in FIG. 9C. By knowing the shape, orientation, and / or position of the active length of the sensor at each of several insertion depths inside the tubular object, the shape of the tubular object can be mathematically determined over a length much greater than the active length of the sensor. Can be reconfigured into

FIG. 7 illustrates a method for determining the shape and orientation of an object such as a catheter inside the body. The active portion 16 of the fiber array 18 is used to determine both shape and orientation.
The azimuth orientation of the proximal end of must be determined. One way to do this indexing is to have the catheter 6 inside a rotary joint 64 that is fixed with respect to the patient's body.
By fixing the proximal ends of the two. By fixing the proximal end of the catheter 62 inside the rotary joint 64, the azimuth angle φ of the catheter 62 can be measured with respect to a fixed reference angle.

In order to determine the shape, orientation and position of the catheter or other tubular object during surveying, it is necessary to determine the azimuth orientation of the proximal end of the catheter and the longitudinal position (insertion depth) of the catheter. is there. This is illustrated in FIG. Indexing the longitudinal position of the catheter can be accomplished by using a series of fiducial marks 66 on the outer surface of the catheter 62, or by any other suitable technique. This allows
The insertion depth of the catheter 62 from the proximal position near the rotary joint 64 to the distal end of the catheter 62 can be determined. The position measuring system can be used statically or dynamically, such as the use of fiducial marks. When using the fiducial mark statically, the catheter 62 is inserted into the patient up to a selected fixed length, which length is indicated by examining the position of the fiducial marking 66 with respect to the fixed rotary joint 64. . When using fiducial mark 66 dynamically, the catheter is inserted to a fixed depth and the orientation and depth measured at fixed rotary joint 64 is recorded. Normally, orientation and depth are recorded automatically and this data is transmitted to the computer system. At this fixed orientation and depth, the shape of the catheter is determined using the fiber optic approach described herein and placed in computer system memory. The catheter 62 is then advanced further into the patient's body. At this time, the orientation of the catheter can be changed from the position calculated in advance. The catheter insertion depth, orientation, and shape are again determined and recorded by the computer system. This process is repeated to mathematically reconstruct the shape of the active portion of fiber array 18 and the portion of the tubular object through which catheter 66 passes.

Note that other optical techniques can be used to determine the bend angle, including varying the intensity of light propagating in the fiber with bend angle, and changing the spectral properties of light with viewing angle. I want to be done. Furthermore, a similar principle can be used with non-optical elements such as strain gauges embedded within the wire filament, which allows the indicated strain to be measured and the corresponding angle to be calculated. it can.

In one alternative embodiment, optical fibers 20, 21, and 22 are made using FBGs.
The long period grating (“L
PG ") can be used. As shown in FIG. 10, the LPG 74 has 1
Contained within a fiber array comprising one or more fibers 70. The core region 72 of the optical fiber 70 comprises LPG, where the longitudinal axis of the LPG is radially offset from the central axis 76 of the optical fiber 70. This offset configuration changes the bend angle of the single optical fiber 70 due to the curvature of the optical fiber 70, which is
It is determined from the corresponding change in the transmission spectrum of the optical signal inside G74. LPG7
The operation of the single fiber bend sensor including 4 is similar to that described above, with the excitation light signal being transmitted from the light source along the optical fiber 70.

In use, the systems and methods of the present invention can be utilized with many medical or non-medical procedures. In medicine, the invention can be used to determine the shape of one section of a catheter or other tubular object placed inside the body of a human or other animal. The present invention is further compatible with any medical device, pointer, or catheter that is placed inside the body of a human or animal and demonstrates the positioning of the tip of the device inside the body. The invention also relates to an endoscopic device,
It can also be used to determine the placement and orientation of an endoscope within a body part such as the bronchus or colon. The present invention can also be used with specific therapies, such as electromagnetic frequency, hyperthermia or cryotherapy, to focus energy on specific anatomical locations.

The present invention can also be tuned using imaging systems such as MRI, CT, and X-ray systems. In doing this, an image of the location of the tip of the fiber optic array 18 or the shape of the active area 16 of the array 18 can be incorporated into the digital image of the human or animal body. This allows the physician to accurately identify the position of the array 18 in real time along the patient's anatomical location when performing the procedure.

Although the principles, preferred embodiments, and preferred operations of the present invention have been described in detail herein, this should not be construed as limited to the particular illustrative forms disclosed. Therefore, it will be apparent to those skilled in the art that various modifications can be made to the preferred embodiments herein without departing from the spirit or scope of the invention as defined by the appended claims.

[Brief description of drawings]

FIG. 1 is a perspective view of an optical fiber including three fiber Bragg gratings along its length.

FIG. 2A is a perspective view of an array of optical fibers geometrically arranged to determine a change in array shape.

FIG. 2B is another perspective view of an array of optical fibers geometrically arranged to determine a change in array shape.

[Figure 3]   1 is a schematic diagram of the system of the present invention.

FIG. 4A is a component of a general electro-optic system for interrogating a fiber optic sensor of the present invention including elements for selecting particular optical properties such as wavelength (frequency), phase, intensity, polarization, or spectral properties. It is a schematic diagram.

FIG. 4B is a schematic diagram of components of an electro-optic system for interrogating a fiber optic sensor of the present invention in which a property selection element is used only between a light source and a multiplexer / demultiplexer system.

FIG. 4C is a schematic diagram of components of an electro-optic system for interrogating a fiber optic sensor of the present invention in which a property selection element is used only between a multiplexer / demultiplexer system and a photodetector.

[Figure 5]   1 is a schematic diagram of an optical fiber array of the present invention.

FIG. 6A is a perspective view of a fiber optic array of the present invention positioned within the lumen of a catheter.

6B is an exploded perspective view of FIG. 6A of a fiber array of the present invention inside the lumen of a catheter.

FIG. 7 is a perspective view of an optical fiber array of the present invention associated with a rotary joint.

FIG. 8 is a perspective view of a fiber optic array of the present invention having fiducial markings and associated with a rotary joint.

9A-C are perspective views of a fiber optic array of the present invention before, during, and after being inserted inside a tubular object.

[Figure 10]   It is a perspective view of the optical fiber in which the long period grating was located inside.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, MZ, SD, SL, SZ, TZ, UG , ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, C H, CN, CR, CU, CZ, DE, DK, DM, DZ , EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, K G, KP, KR, KZ, LC, LK, LR, LS, LT , LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, S E, SG, SI, SK, SL, TJ, TM, TR, TT , TZ, UA, UG, US, UZ, VN, YU, ZA, ZW F term (reference) 2F065 AA01 AA20 AA31 AA45 BB12                       BB17 BB22 CC16 CC23 FF48                       FF49 FF51 FF67 GG22 JJ01                       JJ05 JJ15 LL02 LL03 LL22                       LL32 LL35 LL42 LL67 NN05                       PP22 QQ03 QQ25                 2F103 BA41 CA04 CA06 CA08 EB16                       EC09 EC10 EC14 EC15 EC16                       ED27

Claims (31)

[Claims] 1. A system for measuring the shape of a passage, the sensor element being inserted into the passage, the sensor element being adapted to curve within the passage along the shape of the passage. Wherein the curvature of the element induces a change in a physical property associated with the element, further comprising a device for measuring the physical property and deriving a bend angle from the change in the physical property. system. 2. The system of claim 1, wherein the at least one element comprises an optical fiber. 3. The system of claim 2, wherein the optical fiber is a single mode optical fiber. 4. The system of claim 2, wherein a change in at least one physical property of light transmitted through the optical fiber is utilized to indicate the degree of curvature of the fiber. 5. The at least one physical property of light is wavelength.
The system described in. 6. The system of claim 5, wherein the optical fiber comprises at least one fiber Bragg grating. 7. The apparatus comprises an electro-optic system for receiving an optical signal from the optical fiber and converting the optical signal into a voltage signal and an algorithm to calculate the bend and shape of the optical fiber. Item 4. The system according to Item 4. 8. The system of claim 7, wherein the optical signal is converted to a digital voltage signal. 9. The system of claim 7, wherein the electro-optic system further calculates orientation and positioning of the optical fiber. 10. The electro-optic system comprises:   A light source,   Means for converting changes in the properties of light into changes in the intensity of light;   A photodetector that converts light intensity into voltage,   Analog-digital conversion system,   A digital control system that interfaces with a digital computer The system of claim 7, comprising: 11. The system of claim 5, comprising at least three optical fibers, each fiber comprising at least one fiber Bragg grating positioned at a known location within the fiber. 12. The system of claim 11, wherein the at least three optical fibers are bonded together in a fixed orientation with respect to each other to form an array. 13. The system of claim 12, wherein the bundle is configured such that the fiber Bragg grating is co-located along the length of the bundle. 14. The array is encapsulated within a protective envelope.
The system described in. 15. The instrument comprises an electro-optic system for receiving optical signals from the fiber optic array and converting the optical signals into voltage signals and algorithms to calculate curvature and shape of the array. The system according to claim 14. 16. The system of claim 15, wherein the optical signal is converted to a digital voltage signal. 17. The system of claim 15, wherein the electro-optic system further calculates orientation and positioning of the bundle. 18. The electro-optical system includes a light source, a means for converting a change in the property of light into a change in the intensity of light, a photodetector for converting the light intensity into a voltage, an analog / digital conversion system and a digital device. A system according to claim 15, comprising a digital control system for interfacing with a computer. 19. The system of claim 14, wherein the jacket further comprises a length divider. 20. The fiber includes a plurality of fiber Bragg gratings each positioned at a known length along the fiber.
The system according to 1. 21. The system of claim 20, wherein the plurality of fiber Bragg gratings are co-located along the length of the bundle. 22. The bundle is enclosed within a protective jacket.
0 system. 23. The instrument comprises an electro-optic system to receive an optical signal from the fiber optic bundle and convert the optical signal into a voltage signal and an algorithm to calculate the curvature and shape of the bundle. The system according to claim 20. 24. The system of claim 23, wherein the optical signal is converted to a digital voltage signal. 25. The system of claim 23, wherein the electro-optic system further calculates orientation and positioning of the bundle. 26. The electro-optic system comprises:   A light source,   Means for converting changes in the properties of light into changes in the intensity of light;   A photodetector that converts light intensity into voltage,   Analog-digital conversion system,   A digital control system that interfaces with a digital computer 24. The system of claim 23, comprising. 27. A method of surveying the shape of a passage, comprising the steps of inserting a sensor element into the passage and measuring changes in physical properties of the element when the element conforms to the shape of the passage. And determining a bending angle inside the element from the change in the physical property. 28. The method of claim 27, wherein the element is an optical fiber. 29. The element of claim 28, wherein the element is a single mode optical fiber.
The method described in. 30. A system for measuring characteristics of an optical fiber, the optical fiber having a length having at least one light guiding core having at least one fiber Bragg grating along the length. A light source for selectively introducing light into the light guiding core; and receiving light passing through the light guiding core and the at least one fiber Bragg grating to provide the at least one fiber Bragg grating. And a processor for calculating an arbitrary bend of the light guide core at the position. 31. A fiber optic navigation system as shown and described in the present application and accompanying drawings.