Patent Application
20150355413
The present disclosure relates to optical coherence tomography (OCT), and in particular relates to an integrated torque jacket systems and methods for use in an OCT.
The entire disclosure of any publication or patent document mentioned herein is incorporated by reference, including U.S. Patent Application Publication No. 2013/0223787 and the article entitled “Optical coherence tomography,” by Huang et al., Science, New Series, Vol. 254, No. 5035 (Nov. 22, 1991), 1178-1181.
Optical coherence tomography (OCT) is used to capture a high-resolution cross-sectional image of scattering biological tissues using fiber-optic interferometry. The core of an OCT system is a Michelson interferometer, wherein a first optical fiber is used as a reference arm and a second optical fiber is used as a sample arm. The sample arm includes the sample to be analyzed as well as an optical probe that includes optical components. An upstream light source provides the imaging light. A photodetector is arranged in the optical path downstream of the sample and reference arms.
Optical interference of light from the sample arm and the reference arm is detected by the photodetector only when the optical path difference between the two arms is within the coherence length of the light from the light source. Depth information from the sample is acquired by axially varying the optical path length of the reference arm and detecting the interference between light from the reference arm and scattered light from the sample arm that originates from within the sample.
A three-dimensional image requires high-speed rotation as well as axial translation of the optical probe. This rotation and axial translation carried out in conventional OCT systems through the use of a metal torque tube that is mechanically connected to the probe at a distal end. The torque tube is threaded through a guide tube, which is referred to in the art as an “inner lumen.” The torque tube is driven to rotate and axially translate at its proximal end by a rotary and axial translation actuator and transmits the rotational and axial translation motion to the optical probe at the distal end.
Conventional torque tubes are made of a stainless steel and have a multi-coil spring assembly, which is a relatively complex design and does not offer very good dimensional control. Further, the torque tube must be feed into the inner lumen over long distances, which is difficult to do because of the flexibility of the spring coil. In addition, there is a large amount of surface area contact that can occur between the torque tube and the inner lumen. This surface area contact represents a source of friction that impacts the rotation and axial translation of the optical probe.
It is therefore desirable to simply the mechanism used to impart rotation to the optical probe so that the OCT system is less expensive and easier to use while also reducing the potential contact area and frictional forces.
An aspect of the disclosure is an integrated torque jacket (ITJ) system for use with a guide tube of an optical coherence tomography (OCT) system that utilizes a rotating optical probe. The ITJ system includes: an optical fiber cable of diameter DC. The optical fiber cable has an optical fiber surrounded by a jacket and having a length, a proximal end, and a distal end configured to attach to an optical probe. The ITJ system also has a plurality of low-friction bearings operably disposed on the optical fiber cable along its length. The bearings each have a diameter DB>DC. The bearings are sized so that the optical fiber cable and low-friction bearings can be inserted into and rotate within an interior of the flexible guide tube in a close-fit configuration.
Another aspect of the disclosure is OCT assembly that includes: the bearing-based ITJ system described above, and the guide tube, wherein the guide tube has an inner wall that defines the guide tube interior, and wherein the ITJ system resides within the guide tube interior in the tight-fit configuration.
Another aspect of the disclosure is a method of rotating and axial translating an optical probe in an OCT system. The method includes: operably disposing a plurality of low-friction bearings along a length of an optical fiber cable that has a proximal end and a distal end, wherein the optical probe is operably connected to the optical fiber cable at the distal end; inserting the optical fiber cable and low-friction bearings into an interior of a flexible guide tube in a close-fit configuration; and causing a rotation and axial translation of the optical fiber cable at its proximal end so that the optical fiber cable and low-friction bearings and optical probe rotate and axially translate within the interior of the flexible guide tube.
Another aspect of the disclosure is an ITJ system for use with a guide tube of an optical coherence tomography system that utilizes a rotating optical probe. The ITJ system includes: an optical fiber cable having an optical fiber surrounded by a jacket and having a length, a proximal end and a distal end configured to attached to an optical probe; and a spiral member operably disposed on the optical fiber cable along its length, the spiral member having a diameter sized so that the optical fiber cable and spiral can be inserted into and rotate within an interior of the flexible guide tube in a close-fit configuration.
Another aspect of the disclosure is an OCT assembly that includes the spiral-based ITJ system as described above, and the guide tube, wherein the ITJ system resides within the guide tube interior in the close-fit configuration.
Another aspect of the disclosure is a method of rotating and axially translating an optical probe in an OCT system. The method includes: operably disposing a spiral member along a length of an optical fiber cable that has a proximal end and a distal end, wherein the optical probe is operably connected to the optical fiber cable at the distal end; inserting the optical fiber cable and low-friction bearings into an interior of a flexible guide tube in a close-fit configuration; and causing a rotation and axial translation of the optical fiber cable at its proximal end so that the spiral member and optical probe within the interior of the flexible guide tube.
Additional features and advantages are set forth in the Detailed Description that follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings. It is to be understood that both the foregoing general description and the following Detailed Description are merely exemplary, and are intended to provide an overview or framework to understand the nature and character of the claims.
The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the Detailed Description serve to explain principles and operation of the various embodiments. As such, the disclosure will become more fully understood from the following Detailed Description, taken in conjunction with the accompanying Figures, in which:
Reference is now made in detail to various embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Whenever possible, the same or like reference numbers and symbols are used throughout the drawings to refer to the same or like parts. The drawings are not necessarily to scale, and one skilled in the art will recognize where the drawings have been simplified to illustrate the key aspects of the disclosure.
The claims as set forth below are incorporated into and constitute part of this Detailed Description.
The entire disclosure of any publication or patent document mentioned herein is incorporated by reference.
An end portion 22 of probe 20 is attached to an end portion 42 of the torque tube. In an example, the end portion 22 of probe 20 is made of metal, e.g., stainless steel. The torque tube 40 resides within a guide tube (or inner lumen) 50 and is free to rotate and axially translate therein, though there is typically some contact between the torque tube and guide tube, i.e., there is a close-fit between the torque tube and guide tube. Torque tube 40 has a constant diameter and thus represents a configuration that presents a maximum amount of surface area to guide tube 50.
Guide tube 50 is transparent to light 60 at least at probe-end portion 12. In an example, a (transparent) balloon (not shown) is used to create space for the probe-end portion 12 within tissue or vessel 70. The probe-end portion 12 of OCT system 10 is inserted into a catheter or endoscope (not shown) for insertion into the body to be examined.
The light 60 originates from a light source (not shown) and travels down optical fiber 30 to end 32. This light exits end 32 of optical fiber 30 and is directed by probe 20 to the surrounding tissue or vessel 70. Light 60 generates scattered light 60S from the tissue or vessel 70, and some of this scattered light returns to and is captured by probe 20 and directed back to optical fiber end 32. This returned light travels back down optical fiber 30 toward the light source and is then interferometrically processed to generate the OCT image according to methods known in the art.
As noted above, this configuration based on the use of torque tube 40 and guide tube 50 is relatively complicated and experiences frictional forces between the torque tube and the guide tube that adversely impact the operation of OCT system 10.
The ITJ system 150 is formed from an optical fiber cable 110. Optical fiber cable 110 includes an optical fiber 112 (shown in phantom in
The process for forming optical fiber cables 110 are well known in the art. In particular, optical fiber cable 110 is formed using a manufacturing operation that forms the optical fiber 112 and outer jacket 114 as part of the same manufacturing operation, i.e., a drawing operation to form the optical fiber and a coating operation that forms the outer jacket on the optical fiber. In an example, outer jacket 114 is formed from a single dielectric material. Further in an example, outer jacket 114 contains no support elements or other structural elements so that the optical fiber cable 110 is maximally flexible in all directions, i.e., does not have a preferred bending direction. Optical fiber cables 110 are known to be flexible.
In one example, ITJ system 150 includes bearing elements (“bearings”) 120 operably disposed along the length of optical fiber cable 110. Bearings 120 have a low-friction outer surface 122. The bearings 120 have a diameter DB and an axial length LB. In an example, the bearing diameter DB is in the range 700 microns≦DB≦1300 microns, with the condition that DB>DC.
Adjacent bearings 120 are shown as having a center-to-center axial spacing LS. In one example, the spacing LS is uniform (i.e., bearings 120 have a constant pitch), while in another example the spacing LS can vary along the length of optical fiber cable 110 (i.e., bearings 120 can have a variable pitch). Likewise, the axial length LB of bearings 120 can all be the same or can vary between some or all of the bearings.
In an example, bearings 120 are fixed, secured, attached, etc. to optical fiber cable 110 using conventional means. In one example, bearings 120 are fixed to optical fiber cable 110 using an adhesive, while in another example the bearings are crimped to the optical fiber cable, while in yet another example are thermally attached (e.g., via heat shrinking). In an example, bearings 120 have rounded or chamfered edges 123 (see
With reference again to
The clearance C=(DG−DB) of bearings 120 within guide tube 50 is selected as a balance between preventing uncontrolled lateral movement (“lashing”) of the bearings during rotation and axial translation and of ITJ system 150 within guide tube interior 54 with low-friction between bearings 120 and inner wall 152 of the guide tube, including when the guide tube is bent or flexed during the OCT procedure. Thus, the bearings 120 and the interior 54 of guide tube 50 define a close fit, i.e., one in which there is sufficient space for the bearings to rotate within guide tube interior 54 but insufficient space for the bearings to be laterally displaced to a substantial extent, e.g., no more than a few percent of the bearing diameter DB. Thus, in the close fit configuration, the outer surface 122 of bearings 120 loosely contact inner wall 52 of guide tube 50. It is also noted that the amount of area presented by bearings 120 to inner wall 52 of guide tube 50 is substantially less than for a prior art torque tube 40 discussed above that has a constant diameter.
Random manufacturing variations in guide tube 50 and ITJ system 150 can cause an increase in the frictional forces or an increase in lashing of the ITJ system within the guide tube. These variations can lead to non-uniform rotation of probe 20 and can put stress on the various components. This stress can lead to a system failure, e.g., probe 20 becoming disconnected from ITJ system 150. Thus, in an example, the clearance C=(DG−DB) is in the range from 100 μm to 150 μm to define the close-fit configuration and reduce or minimize the adverse effects of the random manufacturing variations.
In an example, guide tube 50 can be formed from polymer using an extrusion or a drawing process. The extrusion processes provides good dimensional control, thereby reducing the potential adverse effects of the aforementioned random manufacturing errors.
The pitch of bearings 120 can be selected to provide minimum contact area between bearing outer surfaces 122 and the inner wall 52 of guide tube 50 while also optimizing torsional rigidity without comprising flexibility.
In an example embodiment, one or more components of OCT system 100 can include a low-friction coating. For example,
Example low-friction materials include polytetrafluorotethylene, polyimide, polyamide, polyethylene, polysilicone, fluorosilane, fluoroether silanes, silicones, etc. In an example, bearing outer surface 122 (or the low-friction coating 126 thereon) has a coefficient of static friction μs<0.5, while in another example, μs<0.1, while yet in another example, μs<0.05.
Low-friction coating 126 can be made from any of the known low-friction materials and can be spray coated, spin-coated, dipped, etc. In one example, a TEFLON-based low-friction coating 126 was prepared using 1% TEFLON AF in a fluoroether solvent FC-40 and combined with a solution of adhesion binder (1 Wt % in HFE7200) to produce a solution that was 1 wt % total in polymer mass. The solution was filtered through a coarse paper filter prior to use. An example of using an adhesion binder and the preparation details for non-stick coating materials are described in U.S. Patent Application Publication No. 2012/0189843.
In an example, low-friction coating 126 is applied to metal (e.g., stainless steel) components of OCT system 100. In one example, this can be accomplished by first removing any organic contaminants from the metal surface. Such cleaning can be performed by using an ethanol-soaked wipe and then allowing the surface to dry. In an example, low-friction coating 126 can be applied (e.g., immersion or spraying or dipping) and then cured in an oven by ramping the temperature from 100° C. to 165° C. at 5° C./minute, holding at 165° C. for 15 minutes, and then ramping to 280° C. at 5°/minute, and then holding at 280° C. for 60 minutes.
In another example, low-friction coating can be made from heptadecafluoro-tetrahydrodecyl-trichlorosilane (C10H4F17Si Cl3) by combining perfluorosilane with anhydrous heptane. The metal surfaces can then be cleaned and then immersed in the coating solution for 1 minute. Upon removal, the coated metal surfaces can be rinsed with heptane and then ethanol.
In an example, low-friction coating 126 includes one or more low-friction enhancements, such as low-friction particles and/or additives. The particles and/or additives can also be added to inner surface 52 of guide tube 50 and/or jacket 114 of optical fiber cable 110 during their fabrication.
An aspect of the disclosure is a method of rotating and axially translating optical probe 20 in OCT system 100. The method includes operably disposing a plurality of the low-friction bearings 120 along the length of optical fiber cable 110, with optical probe 20 being operably connected to the optical fiber cable at the distal end 118. This forms the ITJ system 150 as discussed above. The ITJ system 150 is then inserted into interior 54 of flexible guide tube 50 in a close-fitting configuration. The method further includes causing a rotation and an axial translation of ITJ system 150 at its proximal end, e.g., by activating actuator 150 operably connected thereto. This causes rotation and axial translation of the optical fiber cable 110, the low-friction bearings 120 thereon and the optical probe 20 attached thereto within the interior 54 of the flexible guide tube. Thus, ITJ system 150 transfers the torque and axial translation generated by actuator 150 at the proximal end of optical fiber cable 110 to its distal end, thereby causing the rotation and axial translation of the optical probe. In examples of the method, one or more low-friction coatings 126 are employed on at least one of: the inner wall 52 of guide tube 50; bearings 120; and at least an end portion 22 of optical probe 20.
In
In an examples, spiral member 250 includes a low-friction coating 126, as illustrated in the example ITJ system 150 of
Another aspect of the disclosure is a method of rotating and axially translating optical probe 20 in OCT system 100 using the spiral-based ITJ system 150. The method includes operably disposing spiral member 250 along the length of optical fiber cable 110, with optical probe 20 being operably connected to the optical fiber cable at the distal end 118. This forms the spiral-based ITJ system 150 as discussed above. The ITJ system 150 is then inserted into interior 54 of flexible guide tube 50 in a close-fitting configuration, thereby defining an OCT assembly. The method further includes causing a rotation and axial translation of ITJ system 150 at its proximal end, e.g., by activating actuator 150 operably connected thereto. This causes rotation and axial translation of the optical fiber cable 110, the spiral member 250 thereon and the optical probe 20 attached thereto within the interior 54 of the flexible guide tube. Thus, ITJ system 150 transfers the torque and axial translation generated by rotary and axial translation actuator 150 at the proximal end of optical fiber cable 110 to its distal end, thereby causing the rotation and axial translation of the optical probe. In examples of the method, one or more low-friction coatings 126 are employed on at least one of: the inner wall 52 of guide tube 50; spiral member 250; and at least an end portion 22 of optical probe 20.
It will be apparent to those skilled in the art that various modifications to the preferred embodiments of the disclosure as described herein can be made without departing from the spirit or scope of the disclosure as defined in the appended claims. Thus, the disclosure covers the modifications and variations provided they come within the scope of the appended claims and the equivalents thereto.
This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Ser. No. 62/007,512 filed on Jun. 4, 2014 the contents of which are relied upon and incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62007512 | Jun 2014 | US |
