Patent Application
20180149464
This disclosure relates to optical coherence tomography (OCT), and more specifically, to systems and methods for automated OCT scanning.
Surgery often involves precise removal of tissue or placement of incisions. Various surgical procedures require highly precise targeting of tissues or structures below the surface to ensure the operation is successful and to cause minimal damage to nearby tissue and structures. In ophthalmic surgery, in particular, visualization of internal structures below the surface of the eye is critical to planning and completing the procedure. In such situations, microscopes and other similar devices are insufficient to visualize the internal structures to the extent necessary to perform the procedure. One way to visualize tissues and structures deeper below the surface of the eye is through the use of OCT scanning. OCT scanning uses a beam of light to penetrate into the tissue, and a detector to detect light reflected back from the eye. The reflected light provides data relating to internal structures of the eye and surrounding tissues that the beam of light penetrating the tissue passed through.
The present disclosure provides a system for automated OCT scanning. The system includes an OCT imaging head coupled to a processor, the OCT imaging head operable to generate an OCT source beam, a reference mirror, a beam splitter operable to split the OCT source beam into a sample beam directed to a target and a reference beam directed to the reference mirror, a detector operable to detect an interference pattern of a reflected OCT beam, the reflected OCT beam containing a component reflected from the reference mirror and a component reflected from the target, and generate data relating to the interference pattern, an input device coupled to the processor and operable to specify a starting position or modify the starting position of the OCT source beam, a display operable to present a pictorial representation of internal target structures the sample beam passed through, and a processor configured to direct the OCT source beam to continuously scan a defined area, receive data from the detector relating to the interference pattern, process data relating to the interference pattern, generate a pictorial representation of internal target structures the sample beam passed through, using the data relating to the interference pattern, transmit the pictorial representation to the display.
In additional embodiments, which may be combined with one another unless clearly exclusive: the detector is a spectrophotometer; the input device is a coordinate input device, a tool tracking device, a joystick, or a touchscreen device; the input device is operable to specify or modify a defined area that is an irregular shape; the defined area to scan is an area adjacent to or offset from a starting position specified by the input device; the processor is further configured to direct the OCT source beam to continuously scan a defined area in a specified scanning pattern; the specified scanning pattern is a rectangular scanning pattern; the specified scanning pattern is a circular full circumference sweeping scanning pattern or a circular partial circumference sweeping scanning pattern; the processor is further configured to generate and transmit, and the display is further operable to present, the pictorial representation of internal target structures the sample beam passed through in real time; the pictorial representation of internal target structures the sample beam passed through is a three-dimensional image; the processor is further configured to generate and transmit, and the display is further operable to present, a pictorial representation that incorporates prior pictorial representations generated during the continuous scan to render a three-dimensional image; and the processor is further configured to generate and transmit, and the display is further operable to present the pictorial representation in real time.
The present disclosure further provides a method for performing automated OCT scanning. The method includes specifying a starting position to direct an OCT source beam, specifying a defined area for the OCT source beam to continuously scan, directing the OCT source beam to continuously scan the defined area, detecting an interference pattern of a reflected OCT beam by using a detector, the reflected OCT beam containing a component reflected from the reference mirror and a component reflected from a target, and generating data relating to the interference pattern, receiving data from the detector relating to the interference pattern, processing the data relating to the interference pattern to generate a pictorial representation of internal target structures a sample beam component of the OCT source beam passed through, and transmitting the pictorial representation to a display.
In additional embodiments, which may be combined with one another unless clearly exclusive: the defined area is continuously scanned in a specified scanning pattern; the specified scanning pattern is a rectangular scanning pattern, a partial circumference circular scanning pattern, or a full circumference circular scanning pattern; the pictorial representation of internal target structures the sample beam passed through is presented in real time; the pictorial representation of internal target structures the sample beam passed through is a three-dimensional image; and the pictorial representation incorporates prior pictorial representations generated during the continuous scan to render a three-dimensional image.
The above systems may be used with the above methods and vice versa. In addition, any system described herein may be used with any method described herein and vice versa.
For a more complete understanding of the present invention and its features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, which are not to scale, in which like numerals refer to like features, and in which:
In the following description, details are set forth by way of example to facilitate discussion of the disclosed subject matter. It should be apparent to a person of ordinary skill in the field, however, that the disclosed embodiments are exemplary and not exhaustive of all possible embodiments.
OCT is an interferometric analysis technique for structural examination of a sample that is at least partially reflective to light. The sample may be called a “target.” In OCT scanning, an OCT imaging head produces an OCT light beam (an “OCT source beam”) that is directed toward a beam splitter. The beam splitter splits the source beam into one beam directed at a reference mirror (the “reference beam”) and one beam directed at a sample material (the “sample beam”). When the reference beam is reflected from the reference mirror and the sample beam is reflected from the sample, the two reflected beams are recombined (forming a “reflected OCT beam”), and directed toward a detector. When recombined, the reflected beam from the sample interferes with the reflected beam from the reference mirror. This generates an interference pattern.
Sample characteristics may be determined by analysis of such interference patterns. An interference pattern may be processed to generate an electronic OCT image of the sample. The electronic OCT image is then presented on a display. The sample may be a tissue and the image may be of the tissue. The sample may be a biological tissue, such as a human eye. OCT techniques may image fine structures in a human eye to assist in diagnosis of an opthalmological health condition, development of a suitable treatment plan, and performance of a surgical procedure. The OCT source beam may be supplied in pulses, sweeping wavelengths, or a broad band light.
The electronic OCT image of the sample, such as a tissue, is presented on a display in any of a variety of images, such as in a one-dimensional (“1D”) image, such as an A-Scan image, a 2D image, such as a B-Scan image, or a three-dimensional (“3D”) volume.
An A-scan image is a 1D image of the OCT light scattering profile of tissue as a function of depth into the tissue roughly parallel to the sample beam. A-Scan images can be used to generate a B-Scan image and a 3D volume data set. A B-Scan image is a 2D cross-sectional image of tissue obtained by laterally combining a series of A-Scan images. Alternatively, a B-Scan image can be obtained from a 3D volume data set.
Each B-Scan image corresponds to a line B-Scan. A line B-Scan is a cross-sectional scan created by moving the OCT source beam in a linear direction, along the cross-section. For each line B-Scan, the user specifies the starting position of the OCT source beam. Depending on the clinical application of a B-Scan image, each line B-Scan across a cross-section of tissue may have the same or a different size, length, width, and shape. For example, a first line B-Scan of a tissue may be 1 millimeter (mm) long, and another line B-Scan of the same tissue may be 16 mm long. Line B-Scans may be arranged in any pattern. For example, line B-Scans may be arranged parallel to each other, they may be arranged in a radius from a common crossing point to create the image of a circular area, or they may be arranged as a rectangular raster scan. A collection of consecutive B-Scan images can be used to construct a 3D volume image.
In ophthalmic surgery, for example, a user may have interest in visualizing a broad area instead of a specific position or cross-section. The present disclosure provides a system for automated OCT scanning in which a scanning pattern for a defined area is implemented to direct the OCT source beam to continuously perform a line B-scan in the defined area without intervening user input. The system provides an input device for the user to specify a starting position from which a scanning pattern for the OCT source beam is initiated. Once the scanning pattern, which may be pre-set or specified by a user via an input device, is initialized, the OCT source beam performs automated line B-scanning within the defined area. The defined area may be of any shape, for example a circle, rectangle, or square surrounding or near an area of interest of an eye. The defined area may be a pre-set size or shape, or may be any user-specified size or shape. The two-dimensional B-Scans are collected across time and combined to provide a pseudo-3D OCT image display in real time. Real time may mean in less than half a second, in less than one second, or otherwise in less than the normal reaction time of a user of the visual information.
Referring now to the drawings,
As shown in
The user may specify the point at which sample beam 108 contacts sample 130 by controlling the starting position of OCT source beam 106. System 100 provides input device 150, which may be used to specify a starting position of the OCT source beam, modify the starting position, specify a defined area to scan, or modify the defined area to scan, the defined area specified in relation to the starting position of the OCT source beam. Input device 150 may be any input device, for instance, a joystick, a coordinate input device, a tool tracking device, or a touchscreen device. Input device 150 may be one or multiple input devices that may be coupled to each other and in communication with processor 140. Input device 150 may be further used to initialize, cancel, specify or modify a scanning pattern. When a scanning pattern is initialized, processor 140 may direct the OCT source beam to perform an automated scan within the defined area, according to the scanning pattern specified. The defined area may be of any shape, preferably relating to an area of interest of the eye. Input device 150 may be used to specify or modify a defined area that is a regular or an irregular shape. For example, a coordinate input device may be used to specify a circle or rectangle as the defined area, or a touchscreen device may be used to draw an irregular shape as the defined area to scan. The defined area may be an area surrounding the starting position. The defined area to scan may also be an area adjacent to or offset from the starting position. For example, the defined area may be a circle of a particular diameter surrounding the starting position of the OCT source beam. In another example, the defined area may be a circle of a particular diameter, but with the center point of the circle being adjacent to or offset from the starting position of the OCT source beam.
Once a starting position for the OCT source beam and a defined area to scan are specified via input device 150, a scanning pattern may be initiated via input device 150. Processor 140, which is coupled to OCT imaging head 105, may direct the OCT source beam to perform an automated scan according to the scanning pattern. The scanning pattern may be a pre-set scanning pattern or any scanning pattern specified by the user, for example, a rectangular sweeping scan, a circular partial circumference sweeping scan, or a circular full circumference sweeping scan. Processor 140 may direct the OCT source beam to perform the automated scanning pattern for any duration of time, for example, throughout the duration of surgery. As OCT imaging head 105 performs the specified scanning pattern, processor 140 may use the data received from detector 120, relating to the interference pattern, to generate a pictorial representation of the of internal target structures the sample beam passed through. The pictorial representation may be in the form of a 2D B-Scan image. Processor 140 may present subsequently generated 2D B-Scan images in real time. Processor 140 may also combine multiple 2D B-Scan images collected over time to provide a pseudo 3D OCT image display in real time.
The pictorial representation generated by processor 140 may be transmitted to display 145 and presented to the user. Display 145 may be configured to present such pictorial representations with display persistence. Display persistence, which may also be referred to as image persistence, is characterized by a display image that fades with time and is replaced or overwritten by a subsequently generated image. Even if the previous display image is not replaced or overwritten by a subsequently generated image, it still fades away. For example, a display may present a 2D B-Scan image and replace portions of the image with a subsequently generated 2D B-Scan image, in a manner similar to a airport radar display. In this example, the first 2D scan image fades and is gradually replaced by a second 2D scan image in a clockwise or counterclockwise manner. In another example, display persistence may be enabled using 3D scan images. Aspects of display persistence may be controlled by the user. For example, replacement of a presented image with a subsequently generated image may be paused, a previously-presented image may be recalled, and the refresh rate or “persistence rate” of replacing a presented image may be varied. The persistence rate may be defined as the rate at which a subsequently generated image replaces a previously displayed image, and may be adjusted from zero to any duration of time. For example, the persistence rate may be selected as 0.2 seconds.
A processor 140 may include, for example a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), field-programmable gate array (FPGA), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, processor 140 may interpret and/or execute program instructions and/or process data stored in memory 142. Memory 142 may be configured in part or whole as application memory, system memory, or both. Memory 142 may include any system, device, or apparatus configured to hold and/or house one or more memory modules. Each memory module may include any system, device or apparatus configured to retain program instructions and/or data for a period of time (e.g., computer-readable media). The various servers, electronic devices, or other machines described may contain one or more similar such processors or memories for storing and executing program instructions for carrying out the functionality of the associated machine.
At step 520, an interference pattern of the reflected OCT beam is detected by a detector. The reflected OCT beam includes the recombined beams reflected from the sample and the reference mirror. At step 525, data relating to the interference pattern may be generated and transmitted, the data indicating the internal target structures the sample beam passed through. At step 530, data relating to the interference pattern may be received and processed at step 535 to generate a pictorial representation of the internal target structures the sample beam passed through. At step 540, the pictorial representation may be transmitted to a display and may be presented to a user, for example, during a surgical procedure.
Such pictorial representations may be displayed continuously in real time or may be displayed sequentially, as directed by the user. For example, each pictorial representation may be displayed and continuously replaced with the next pictorial representation generated in real time. In another example, each pictorial representation may be displayed but only replaced with the next pictorial representation generated upon user confirmation (such as by pressing a button to provide confirmation on an input device).
The pictorial representations may also be displayed with display persistence. As described in
Method 500 may be implemented using the system of
For the purposes of this disclosure, computer-readable media may include any instrumentality or aggregation of instrumentalities that may retain data and/or instructions for a period of time. Computer-readable media may include, without limitation, storage media such as a direct access storage device (e.g., a hard disk drive or floppy disk), a sequential access storage device (e.g., a tape disk drive), compact disk, CD-ROM, DVD, random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), and/or flash memory; as well as communications media such wires, optical fibers, and other electromagnetic and/or optical carriers; and/or any combination of the foregoing.
The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.
| Number | Date | Country | |
|---|---|---|---|
| 62428347 | Nov 2016 | US |
