Patent Application
20190133448
The present disclosure relates generally to optical coherence tomography, methods for minimally invasive procedures, and image guided medical procedures.
Optical coherence tomography (OCT) enables imaging of tissue with depth limited to typically 1-2 mm due to the light absorption and scattering property of tissue.
When building an OCT probe, the probe should be made as small as possible to minimize openings required in the surgical field for probe insertion so that the risk of any possible damage to the patient is reduced. A smaller probe also allows for ease of use inside surgical cavities. Presently, OCT scan heads use a large objective lens and galvanometers, which are large and limit its use to outside the surgical field. This prevents OCT to be used for surgeries that utilize minimal invasive techniques and surgeries that are typically access through endoscopes.
Multichannel optical coherence systems are disclosed in which optical coherence tomography subsystems are operably and respectively connected to optical fibers of a multichannel optical probe, such that each optical fiber forms at least a distal portion of a sample beam path of a respective optical coherence tomography subsystem. The optical fibers are in optical communication with distal optical elements such that external beam paths associated therewith are directed towards a common spatial region external to the housing. In some example embodiments, image processing computer hardware is employed to process optical coherence tomography signals obtained from the plurality of optical coherence tomography subsystems to generate an optical coherence tomography image dataset comprising a plurality of optical coherence tomography A-scans and process the optical coherence tomography image dataset to generate volumetric image data based on known positions and orientations of the external beam paths associated with the optical coherence tomography subsystems.
Accordingly, in a first aspect, there is provided a multichannel optical coherence system comprising:
a plurality of optical coherence tomography subsystems, each optical coherence tomography subsystem comprising a respective optical source and optical detector; and
a multichannel optical probe comprising:
wherein said plurality of single mode optical fibers and said plurality of distal optical elements are configured such that the external beam paths associated therewith are directed towards a common spatial region residing external to said housing.
In another aspect, there is provided a multichannel optical coherence system comprising:
a plurality of optical coherence tomography subsystems, each optical coherence tomography subsystem comprising a respective optical source and optical detector; and
a multichannel optical probe comprising:
image processing computer hardware configured to:
In another aspect, there is provided a multi-fiber optical probe comprising:
A further understanding of the functional and advantageous aspects of the disclosure can be realized by reference to the following detailed description and drawings.
Various embodiments and aspects of the disclosure will be described with reference to details discussed below. The following description and drawings are illustrative of the disclosure and are not to be construed as limiting the disclosure. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure.
As used herein, the terms “comprises” and “comprising” are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in the specification and claims, the terms “comprises” and “comprising” and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components.
As used herein, the term “exemplary” means “serving as an example, instance, or illustration,” and should not be construed as preferred or advantageous over other configurations disclosed herein.
As used herein, the terms “about” and “approximately” are meant to cover variations that may exist in the upper and lower limits of the ranges of values, such as variations in properties, parameters, and dimensions. Unless otherwise specified, the terms “about” and “approximately” mean plus or minus 25 percent or less.
It is to be understood that unless otherwise specified, any specified range or group is as a shorthand way of referring to each and every member of a range or group individually, as well as each and every possible sub-range or sub-group encompassed therein and similarly with respect to any sub-ranges or sub-groups therein. Unless otherwise specified, the present disclosure relates to and explicitly incorporates each and every specific member and combination of sub-ranges or sub-groups.
As used herein, the term “on the order of”, when used in conjunction with a quantity or parameter, refers to a range spanning approximately one tenth to ten times the stated quantity or parameter.
The systems and methods described herein may be useful in the field of neurosurgery, including oncological care, neurodegenerative disease, stroke, brain trauma and orthopedic surgery; however persons of skill will appreciate the ability to extend these concepts to other conditions or fields of medicine. It should be noted that the surgical process is applicable to surgical procedures for brain, spine, knee and any other suitable region of the body.
Various example embodiments of the present disclosure provide fiber optic probe heads having multiple optical fibers. As shown below, the inclusion of multiple optical fibers in a probe head may be employed to achieve a compact probe head with a effective volumetric scan region while eliminating the need for large motors and/or MEMS scanners. In some example embodiments described below, the multiple fibers may be provided within a probe head and interfaced with one or more optical coherence tomography systems, where the multiple fibers are spatially arranged to probe a plurality of longitudinal spatial segments that can be integrated to provide volumetric information.
The example OCT system shown in
This signal then propagates into the detector 110 where it may be subsequently detected, and converted from an analog to digital signal and input into a processor (not shown). The processor may be programmed with instructions to process the input data into a useable format such as a visualization or graphical representation to be provided to a user. Methods which may be employed to process the OCT data are known in the art, an example of which is provided in the paper [Proc. SPIE 8369, Sensing for Agriculture and Food Quality and Safety IV, 83690F (5 May 2012); doi:10.1117/12.919347].
Similar to the sample arm the light entering the reference arm reflects back to the fiber coupler after passing through a similar arrangement of optical components the main difference being that in the case of the reference arm the final element from which the reflected signal is generated is a mirror element 224 as opposed to the sample 210 such as that in the sample arm. The components in the reference arm similar to the sample arm include a collimator 228 and a quarter wave plate 222 at 22.5 degrees in addition the reference arm also includes an iris 220. The quarter wave plate splits the reference arm power equally between the two orthongonally polarized channels while the iris maximizes the signal-to-noise and resolution of the interferometric signal.
After both signals from the reference and sample arm are generated the fiber coupler 206 then interferes the reflected reference light beam signal and the reflected sample light beam signal and propagates it to a polarizing beam splitter 201 that separates the now interfered light signals into two orthongonal polarization states. Each of the split polarized signals are channeled their respective detectors 242 for conversion from interferometric optical signals into electrical signals. The electrical signals are then subsequently converted into digital signals through a Data Acquisition card (DAQ) 250 which are then stored and processed in the connected computer 255 to generate PSOCT images.
It is noted that the quarter waveplates in the reference and sample arm may be interchanged with a polarization controller or polarization modulator to module the light polarization into other states for tissue imaging.
Presently there exists two fundamental operational modes for OCT systems, the first being Time Domain Optical Coherence Tomography (TDOCT) and the second being Fourier Domain Optical Coherence Tomography (FDOCT) both of which are known in the art. Both of these modes of operation are integratable with the OCT probe arrangement shown in
An SDOCT system functions by illuminating the sample with broadband interrogating illumination (typical bandwidth of ≈100 nm). This illumination interacts with the sample through a combination of transmission, absorption, scattering, and reflection phenomena. A proportion of this interrogating illumination is returned to the sample arm optical terminal and directed through fiber optic channels (or an equivalent) to an interferometer. The interferometer then combines this signal with the reference signal reflected from the reference mirror and channels the combined signal to a spectrometer which includes, in general, a grating to separate light into the different wavelength spatially, and a camera for detection, for example a CCD (charge coupled devices) or CMOS camera. The intensity at each wavelength forms a distribution that is spatially encoded with information regarding the amount of illumination that returns from varying depths through the tissue along the scan axis. A Fourier transform may then be applied to this signal to decode the spatial information and determine the amount of return illumination which is reflected from the varying depths.
To integrate an SDOCT mode of operation into the OCT probe arrangement shown in
To enable the OCT probe shown in
In some implementations, especially those involving fiber optic delivery, the components of OCT systems (including SDOCT, SSOCT, TDOCT, or any other applicable OCT arrangement), such as the interferometer, the fiber optics, the detector, the reference mirror, and any other applicable elements may be configured or customized for a particular wavelength band (usually determined by the specific wavelength band emitted by the chosen light source 300). This is due to the practical limitation of the designs in each of the optical components. Thus, the interferometer 350, the fiber optics 335, the detector 340, and the reference mirror 320, of the at least one of the n constituent OCT subsystems may have optical components chosen to facilitate the specific wavelength band emitted by the light source 300. More specifically, in order to employ this wavelength band, the fiber optic elements 335 used to transfer the illumination throughout the constituent OCT subsystem may be chosen such that the loss of the optical elements are sufficiently low to allow enough propagation of this specific broadband illumination.
For example, a fiber optic cable having a cutoff wavelength of 1200±70 nm and insertion loss less than 0.5 dB could be used for a light source emitting a broadband illumination of operating wavelength of 1270-1625 nm with center wavelength around 1310 nm. In addition the optical properties of the interferometer element 350 are also chosen to allow for the coupling and splitting of illumination signals at this bandwidth illumination. For example, a 2×2 fiber coupler having an operation band between 1200+/−70 nm is optimized for a laser operating at 1200+/−70 nm and is ideal for OCT image. For detection, a silicon based spectrometer, for example, would be applicable for a light source emitting a broadband illumination of between 190 nm to 1100 nm. As an aside it should be noted that in addition to the spectrometer, a camera, for example a CCD (charge coupled devices) or CMOS camera, may also be used to detect the chosen wavelength range. It should also be noted that the aforementioned wavelength and wavelength ranges are given as examples only and are not to be construed as limiting embodiments of the OCT probe system as described herein. The wavelength and wavelength ranges described may be adjusted for the particular application of the OCT Probe as disclosed herein by commonly known configuration adjustments.
A system configured to acquire SSOCT scans functions in substantially the same way as an SDOCT system in that the raw detected signal to be processed is the same, essentially being a distribution of signal strengths for each wavelength. Although the acquired signal and its subsequent processing to decipher its encoded spatial information is essentially the same the main difference lies in the manner in which this signal is acquired. Whereas an SDOCT scan uses a broadband illumination source and a spectrometer, a SSOCT scan uses a narrow band swept illumination source and a simple photodetector capable of detecting all of the narrow bands swept through by the source. The difference in source illumination is highlighted in
With respect to an OCT subsystem such as that depicted in
As noted above,
The light in the reference arm passes back to the non-polarizing beam splitter after passing through optical components. These components include a collimator, quarter wave plate at 22.5 degrees, dispersion compensation unit, iris and/or neutral density filter. The quarter wave plate splits the reference arm power equally between the two orthongonally polarized channels while the dispersion compensation unit, iris and neutral density filter maximizes the signal-to-noise of the interferometric signal.
The non-polarizing beam splitter then combines the reflected reference light beam and the reflected and back-scattered sample light beam. The combined interferometric signal then propagates to the top to another non-polarizing beam splitter that splits the power equally into two orthongonal directions. Each of the split powers goes through a polarizing beam splitter that splits the the interferometric signal into two othogonal polarization channels. The same polarization channels from the two polarizing beam splitters then propagates to a balanced detector for converting the interferometric signals into electrical analog signals. These electrical analog signals are then converted to a digital signal through a Data Acquisition card (DAQ) which is then stored and processed in the connected computer to generate PSOCT images in this particular example.
In the system diagram shown in
In some embodiments a processor may amalgamate the optical coherence tomography image dataset of A-scans into a single OCT image (visualization). This may be accomplished by stitching the A-scans into a common image space wherein the individual's A-scan projections in the image space are dependent on the spatial orientation of the individual fiber optics from which they were acquired. This knowledge of the positions and orientations of the external beam paths can therefore be employed to generate, based on the A-scans, a composite volumetric image. In some embodiments the A-scans may overlap in the image space, in such a case further processing may be executed as described below to clarify the particular regions where this occurs. In some cases this may be a desirable result as more data about the overlapped region is available which may potentially provide a more accurate representation of the region also described in further detail below. In one example implementation, the image data from the multiple A-scans may be spatially interpolated when generating the composite volumetric image.
Referring now to
The optical terminal mentioned above may include one or more polarization optics, lenses and/or collimators that are provided to interrogate the sample with a specific spot size, resolution and polarization state. In some embodiments the optical terminal may include a GRIN lens that is used to alter the direction of the light upon exiting and entering the probe head.
Several different example OCT probe designs have been realized using different optical elements. In one example configuration, an optical terminal may take the form of a graded index (GRIN) lens as shown in
An extension of the GRIN lens design has been demonstrated through using two GRIN lens as described in the paper [Wu, Jigang, et al. “Paired-angle-rotation scanning optical coherence tomography forward-imaging probe.” Optics letters 31.9 (2006): 1265-1267.] By rotating two angled GRIN lens that are placed at the output of the fiber optics, the light output beam can be collimated and focused at a location with an angle that is different with respect to the forward direction of the light output from the optic fiber. Such a configuration enables the scanning mechanism, for example a motor or a galvanometer, to be mounted away from the tip of the fiber probe to enable a small probe tip design while enabling the light beam to be directed at different location of the samples.
In another configuration, a spherical ball lens could be used in the place of a GRIN lens to collimate and focus the light output from the optic fiber. An example is described in the paper [Singh, Kanwarpal, Daisuke Yamada, and Guillermo Tearney. “Common Path Side Viewing Monolithic Ball Lens Probe for Optical Coherence Tomography.” Medical Technologies in Medicine/Sovremennye Tehnologii v Medicine 7.1 (2015).]. The advantage of using a ball lens is that the entire probe could be made monolithic. The cost of the probe can be potentially cheaper compared to the GRIN lens design.
As is apparent from
Furthermore, the acquisition array 600 may be replicated in a repeating concentric manner to form an A-scan acquisition array which acquires OCT imaging in a conical volume (i.e. not a surface volume). An example of such a configuration is shown in
It should be noted that although the examples involve a cylindrical probe head acquiring a conical surface volume or conical volume, that any applicable shape of probe head, surface volume, and volume may be acquired. Examples of such being a rectangular prism shaped probe head, a rectangular prism shaped probe head, or etc. acquiring a rectangular surface, a planar surface, or etc. or acquiring a cubic volume, a rectangular prism shaped volume, or etc.
As mentioned above, the design of the example OCT probes as disclosed herein allows the user to individually configure the elements of the probe. In one example embodiment, the parameters or type of the light source elements 300 of each of the n constituent OCT subsystems may be altered such that they are optimized for imaging tissue.
Presently the effectiveness of OCT (SDOCT, SSOCT, TDOCT, PSOCT, and etc.) imaging of tissues at subsurface levels is highly dependent on the center wavelength and bandwidth chosen for the interrogation. The effectiveness is dependent on the interrogating illuminations' ability to penetrate the surface of the tissue, interact with its molecular structure and return to the detector with a high enough interference signal to form OCT images with meaningful resolution. For example, absorption spectra are relatively high for hemoglobin (and deoxyhemoglobin) for wavelengths below ≈700 nm, and for water for wavelengths above ≈950 nm, both of which form a substantial proportion of almost all tissue but can vary between types. It may therefore be beneficial or advantageous to provide illumination light having a wavelength that penetrates as deep into the tissue as possible while still providing significant return illumination to form a resolved OCT image.
In order to determine the wavelength that best approximates this situation, the optical properties of the tissue should be taken into consideration. These optical properties may be determined from scientific analysis and indeed the literature provides many such papers outlining the relevant information. One such paper is provided by Steven L Jacques et al entitled “Optical properties of biological tissues: a review” [Jacques, Steven L. “Optical properties of biological tissues: a review.” Physics in medicine and biology 58.11 (2013): R37.] in which the optical properties of tissue varying between subject and between tissue type are modelled and the data provided. For example, as shown in
Using these exemplary plots or those found in the paper [Jacques, Steven L. “Optical properties of biological tissues: a review.” Physics in medicine and biology 58.11 (2013): R37.] in addition to other available information it is possible to determine the center wavelength of an incident illumination that would maximize the penetration depth into a tissue of interest while still providing significant return illumination to form a resolved OCT image. Resultantly the one or more of the light sources 300 of the n constituent OCT subsystems contained within the OCT probe as disclosed herein may be configured to emit illumination at this center wavelength allowing the interrogation A-scan parameters to be optimized for the tissue being scanned.
For example, if the OCT probe is being used to image breast one or more of the light sources 300 may be centered at a wavelength of ≈720 nm. This value can be arrived at by analyzing the scattering and absorption spectra of breast tissue from the example plots provided in
In addition when forming a universal variant of an OCT probe as disclosed herein different sets of OCT arrays may be configured to have differing interrogation wavelength ranges for different tissues. For example, given the OCT probe illustrated in
In addition to being able to configure the light source elements 300 of each of the n constituent OCT subsystems of the OCT probe as disclosed herein in some cases it may be advantageous to alter the reference mirror elements 320 of each of the n constituent OCT subsystems to optimize it for viewing the sample at a particular distance to the surface of the sample being scanned. More specifically the reference mirror is ideally located at a distance from the from the reference arm 310 such that the elapsed time taken by the illumination to travel to the reference mirror 320 and back to the reference arm 310 therefrom should be the same as the elapsed time taken by the illumination to travel from the sample arm 330 to the surface of the sample 170 and back to the sample arm 330. Given that different wavelengths of light travel at different speed through dispersive media such as air, liquid, or solid media. In order to ascertain the same elapsed time for each trip from the reference arm to the reference mirror and back and from the sample arm to the sample surface and back, the distance of the reference mirror from the reference arm may be configured (or optimized) to account for the speed of a particular wavelength of light in a specific medium described by the following equation.
where vλ is the velocity of the light at wavelength λ, c is the speed of light in a vacuum, and nλ is the refractive index of a medium for a light at wavelength λ. Thus the elapsed time taken for the reference trip relative to the sample trip must take into account these factors to be optimized.
For example, a first set of OCT subsystems interfaced with a first set of optical fibers of a multi-fiber OCT probe may be configured such that their respective reference arms are set such that the sensitivity is maximized within 500 um, in the axial direction, from a pre-selected external location (which may be a focal point). A second set of OCT subsystems interfaced with a second set of optical fibers of the multi-fiber OCT probe may be configured with reference arms set at a different location relative to the pre-selected external location, for example, such that the sensitivity is maximized 1 mm from the pre-selected external location, in a direction that is proximal to the probe. Similarly, a third set of OCT subsystems interfaced with a third set of optical fibers of the OCT probe may be configured such that their respective reference arms are set such that the sensitivity is maximized a 1 mm from the pre-selected external location, in a direction that is distal to the probe.
It is noted that each set of optical fibers can have associated focusing elements (e.g. lenses) that focus the light emitted therefrom at different working distances, which improves the sensitivity of the imaging range they are focused on and at different part of a stationary sample being imaged. Alternatively, every optical fiber of the probe can configured, by way of spatial positioning of the fibers and/or the selection of the associated focusing elements, to focus the light emitted therefrom at a common location.
In some example implementations, due to Fresnel reflection and the irregular contour of the sample, strong reflections produced from the sample may be directed in a direction that is different from the incident angle. In such a case, an OCT subsystem interfaced with the optical probe may be interfaced with two optical fibers, such that a first optical fiber of the optical probe is employed to direct incident light onto the sample, and a second optical fiber is employed to collect reflected light. The second optical fiber of the multi-fiber probe may be oriented at angle in which a strong reflected signal is expected to result based on light incident from the first optical fiber, provided the reference arm has an optical path length based on the round-trip delay through both the first and second fibers. For example, brain tissue is also a highly scattering tissue in which incident light can scatter within the tissue and exit the tissue surface at angle that is different than the incident angle and the Fresnel reflection angle.
In one example embodiment, a multiple 1-D scanning probe can be used capture signals from different angles of the tissue and either (1) display all signals from the different beam angles to the user or (2) select the best data to display to the user or (3) combine data (i.e. weighted average the data) for display. Due to the optical path difference between the probe facet and the point, a different focusing optics might be used to focus the light onto the same common point.
Referring again to
The choice of fiber optic cable element may be chosen to minimize optical losses when propagating through said element is also an important consideration when forming the OCT probe system disclosed herein, especially when acquiring a PSOCT scan. The choice of fiber optic cable in this case must have parameters specifically defined for the two orthogonal polarizations. Particularly when employing a PSOCT system a specific fiber optic cable might be used to preserve a particular polarization. For example, a ‘Panda’ style polarization maintaining fiber or a ‘Bow-tie’ style polarization maintaining fiber could be used to preserve two orthogonal linearly polarizing states. The choice of detector is an important consideration as well and may be optimized not only for the SSOCT and SDOCT scan type systems as described above but also varying wavelengths or additional features such as hyperspectral imaging, or overlapping acquisition arrays, and PSOCT imaging and various other imaging features of the OCT probe as further disclosed in this document.
As is apparent from
In addition, if phase retardation imaging is performed, the ‘true birefringence’, defined as the greatest birefringence value of the material here, and the direction of the optical axis can be more accurately measured in three-dimensional space through measuring the phase retardation of the same location at multiple angles. In tissue imaging with OCT, the retardation measured is only the ‘apparent birefringence’ in which the birefringence value is only valid at the specific angle being measure because the optical axis of the organized tissue (i.e. tissue with birefringence property) is not always parallel to the surface of the tissue nor perpendicular the k-vector (i.e. propagation direction) of the incident light. This ‘apparent birefringence’ is a reduced value compared to the ‘true birefringence’ that is obtained when the k-vector is perpendicular to the optic axis of the tissue. This is because the magnitude of birefringence depends not only on the degree of optical anisotropy of the material (i.e. the organize tissue) but also on how the organize tissue is oriented relative to the k-vector of the propagating light wave. The phase retardation is related to birefringence of the material by the following relations:
Phase retardation=L*Δn
where L is the length of the material in which light travels through and Δn is the ‘apparent birefringence’. The apparent birefringence is Δn=|n−no| where no is refractive index of the ordinary and
where θc is the angle between the k-vector and the optic axis
When the k-vector is perpendicular to the optic axis, θc=90°, in which n=ne and Δn=|ne−no|. However, when the k-vector is parallel to the optic axis, then θc=0°, in which n=no and Δn=0. In reality, k-vector is likely to be at some angle to the optic axis most of the time; therefore, the birefringence is in between 0 and |ne−no|. In other words, when the birefringence values of the tissue is measured at angle non-perpendicular to the optical axis, the birefringence is reduced compared to the maximum value and therefore the image contrast between organize and non-organized tissue is reduced. By measuring the birefringence of the sample at multiple angles, the maximum or the strong birefringence of the tissue can be determined to maximize the phase retardation contrast. An example is demonstrated from the reference N. Ugryumova, S. V. Gangnus, S. J. Matcher Variable-angle-of-incidence polarization-sensitive optical coherence tomography: its use to study the 3-D collagen structure of equine articular cartilage Proc Soc Photo Opt Instrum Eng, 6079 (2006) 60792C-1.
One benefit that may be derived from having multiple data sets corresponding to the same region is if the scans are acquired sequentially then the SNR of that particular region may improve by data averaging at common points. Alternatively, having multiple data sets corresponding to the same region would enable selectively filtering the data sets for the one with the best SNR providing a clearer image of the region than its counterparts.
Yet another benefit that may be derived from having multiple data sets corresponding to the same region when employing a constituent OCT system that acquires a PSOCT image as described above, would be the ability to acquire directional data that is not available from one acquisition direction in another acquisition direction. This would result in further enhancement of the image due to the acquisition of further accurate, or otherwise absent, retardance information at the region.
When generating a PSOCT image from a multi-fiber probe, the directional orientation of the A-scans relative to the region is taken into consideration and the received signals are processed to account for such a directional orientation difference among the different fibers.
An example of the OCT Probe disclosed herein being used in such a manner is shown in
As is apparent from the figure, the fibers that terminate on the right side of the probe may be employed to generate a PSOCT scan of the sample 1120. The A-scans acquired by the fibers can be seen to overlap at the region 1140. Given that the polarized illumination used to acquire the A-scan by the fiber 1100 is substantially parallel to the surface of the sample at region 1140 its A-scan would likely be lacking a reflectance signal containing the information required to visualize the tissues flat surface at the acquisition point 1140. However since the three other fibers are also capable of scanning the same point 1140 at different angles, the reflectance signal they may acquire can be used to augment the A-scan acquired via the fiber 1100 to provide a more complete scan of the region.
Furthermore the four scans acquired via the fibers may be combined and compared, or averaged to produce a more interpretable anisotropic map of the portion of the region 1140 in which the beams from the fibers spatially overlap.
In addition to acquiring multiple datasets of the same region simultaneously, other acquisition schemes may be employed to improve imaging of the overlapped region. For example, given the diagram shown in
In one example implementation, the best image data set for that region 1140 could be used by comparing the signal-to-noise ratio amongst the many available data sets at that region and choosing the data set with the highest value. It should be noted that although the region 1140 is referred to as a region this is merely an example case and this region may actually be a point in space, and may be represented by a voxel (or pixel) or group of voxels (or pixels) in a 3D (or 2D or 1D) visualization of the OCT image data acquired by the OCT probe as disclosed herein.
In one example embodiment, the different OCT subsystems may have different associated wavelengths (or wavelength bands), permitting the acquisition of hyperspectral OCT data. For example, in the example embodiment shown in
An example embodiment of the OCT probe as disclosed herein which capitalizes on this benefit is shown in
Although any wavelength range may be chosen to interrogate the sample, given that the illumination is to penetrate the surface of the sample to participate in OCT interferometry this may prevent the acquisition of Hyperspectral data using wavelengths that cannot penetrate the surface of the sample. Thereby potentially limiting the spectral range over which the Hyperspectral signature may be acquired in the sample volume. However spectral signatures need not be exhaustive and thus, even a limited spectral signature may be of use in benefiting the user for example when identifying tissue, or the presence of various pathologies. It should be noted that the probe head shown in the figure is a cross-section of a rectangular prism type probe head having rows of fibers in the same orientation as the cross-section only stacked along the normal direction to the plane of the cross section shown. It should be noted further that having this rectangular prism type probe head would allow for the acquisition of Hyperspectral data on a volumetric subsurface region in a sample of the form of the elongated volume 1210.
As mentioned above in some embodiments a processor 115 may amalgamate the A-scans into a single OCT image visualization to be displayed on a display 125. This may be accomplished by superimposing the scans into a common image space wherein the individual's A-scan projections in the image space are dependent on the spatial position and orientation of the individual optical fibers from which they were acquired. In some embodiments, the A-scans may spatially overlap over one or more regions in the image space, and in such a case, further processing may be employed to provide a composite image of the overlapping region.
For example, as shown in
In the case of overlapping A-scans such as at the region 1420 shown in
Referring now to
As shown in the example embodiment illustrated in
The aforementioned example methods for processing OCT image data received by the OCT subsystems 1130 can be implemented via processor 1510 and/or memory 1515. As shown in
The methods described herein can be partially implemented via hardware logic in processor 1510 and partially using the instructions stored in memory 1515. Some embodiments may be implemented using processor 1510 without additional instructions stored in memory 1515. Some embodiments are implemented using the instructions stored in memory 1515 for execution by one or more microprocessors. Thus, the disclosure is not limited to a specific configuration of hardware and/or software.
It is to be understood that the example system shown in the figure is not intended to be limited to the components that may be employed in a given implementation. For example, the system may include one or more additional processors. Furthermore, one or more components of control and processing hardware 1500 may be provided as an external component that is interfaced to a processing device. Furthermore, although the bus 1505 is depicted as a single connection between all of the components, it will be appreciated that the bus 1505 may represent one or more circuits, devices or communication channels which link two or more of the components. For example, the bus 305 may include a motherboard. The control and processing hardware 1500 may include many more or less components than those shown.
Some aspects of the present disclosure can be embodied, at least in part, in software, which, when executed on a computing system, transforms an otherwise generic computing system into a specialty-purpose computing system that is capable of performing the methods disclosed herein, or variations thereof. That is, the techniques can be carried out in a computer system or other data processing system in response to its processor, such as a microprocessor, executing sequences of instructions contained in a memory, such as ROM, volatile RAM, non-volatile memory, cache, magnetic and optical disks, or a remote storage device. Further, the instructions can be downloaded into a computing device over a data network in a form of compiled and linked version. Alternatively, the logic to perform the processes as discussed above could be implemented in additional computer and/or machine readable media, such as discrete hardware components as large-scale integrated circuits (LSI's), application-specific integrated circuits (ASIC's), or firmware such as electrically erasable programmable read-only memory (EEPROM's) and field-programmable gate arrays (FPGAs).
A computer readable storage medium can be used to store software and data which when executed by a data processing system causes the system to perform various methods. The executable software and data may be stored in various places including for example ROM, volatile RAM, nonvolatile memory and/or cache. Portions of this software and/or data may be stored in any one of these storage devices. As used herein, the phrases “computer readable material” and “computer readable storage medium” refers to all computer-readable media, except for a transitory propagating signal per se.
The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2016/050469 | 4/22/2016 | WO | 00 |
