How OCT Works?
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Principles of Operation
Niris® is a highly sensitive and specific imaging tool. The System produces a lateral sweeping image of the tissue microstructure in real time at a depth of 2 – 3 millimeters and a spatial resolution of approximately 10 – 20 micrometers (um). The resolution of Niris imaging is 100 times that of conventional ultrasound and 10 times that of high frequency ultrasound. Niris images are often comparable to biopsy in diagnostic value but do not require removal of tissue.
Harmless, near-infrared light is directed from the console through the probe into the patient’s tissue. The reflected (backscattered) light is collected by the probe and combined with an internal reference signal. There are natural differences in light backscattering properties of the various tissue elements. The intensity of the light reflected back is a function of tissue structure and content, and in turn can be used for differentiating between normal and abnormal tissue.
Many diseases such as cervical cancer are accompanied by early structural alterations of tissue that up until now could only be identified by an invasive procedure – biopsy and histologic examination. Typically, biopsies are obtained from visually suspicious areas to diagnose a condition and decide on treatment. Currently biopsies are guided by visual inspection using white light (endoscopy, colposcopy, laryngoscopy, cystoscopy) with or without visual aids such as magnification and fluorescence. These methods are only able to identify changes of the tissue surface, not the underlying 2 – 3 mm where the earliest changes of malignancy (dysplasia) occur. In addition, the established imaging modalities, such as ultrasound and CT, lack the spatial resolution to identify these early changes.
"Cross Sectional Optical Imaging"
The Niris Imaging System employs Optical Coherence Tomography (OCT), to construct high spatial resolution [~ 10-20 micrometers], cross-sectional images of tissue microstructure. The principle of OCT is similar to B-mode ultrasound imaging, except that OCT uses light instead of sound.
In OCT, the image is constructed by first measuring the in-depth profile of the backscattered light intensity in the axial (depth) direction. In-depth profiling is performed by measuring the echo time delay and intensity of backscattered or reflected light. Distance or spatial information is determined from the time delay of reflected echoes according to the formula z = Δ T · v, where z is the distance the echo travels, Δ T is the echo delay, and v is the wave propagation velocity of wave (light or sound). Because light travels at such a high speed (~ 300,000,000 m/s), as compared to sound (~1500 m/s), a light echo time delay system would require ultrafast time resolution, which would be impractical and expensive to achieve with modern electronics. For example, an in-depth spatial resolution of 10 micrometers corresponds to a time resolution of approximately 30 femtoseconds (fs). Instead, the Niris Imaging System measures OCT echo time delays by comparing the backscattered or backreflected light signal to a controlled reference signal.
To create a two-dimensional image, the fiber optic beam is moved laterally across the surface (x-axis) and in-depth profiles (z-axis) are obtained at discrete points along the surface. By obtaining these profiles over a lateral distance, a two-dimensional, cross-sectional image is constructed.
To perform a lateral scan, the Imalux Niris Imaging System’s proprietary engineering design incorporates a miniaturized electromagnetic mechanism, coupled with an optical lens system, which moves the Probe’s internal fiber optic tip and enables the optical beam to scan laterally over a 2 mm range while maintaining a small (2.7 mm) outer diameter. This mechanism is localized at the Probe’s tip, and the light is delivered back and forth by an optical fiber, which allows the Probe to have convenient access to a tissue – facilitating image acquisition at the tissue site and permitting use with various endoscope procedures.
The Niris Probe, which is attached to the Image Management Console, is used to direct light to and from the patient’s tissue. A small electromechanical scanning mechanism in the Probe moves the optical beam laterally across the tissue surface while simultaneously acquiring in-depth backscattering profile at each lateral position. For certain applications, the Probe may be covered by a Niris Probe Sheath that is a purchased accessory to provide physical stability and prevent cross-contamination.
The information provided on this website is for the purpose of educating potential users about the Niris Imaging System and related technology. Pictures contained on this website are for demonstration purposes only and should not be construed to accurately depict the body part, condition, or disease described. Nothing contained on this website is intended to be instructional for medical diagnosis or treatment. The information contained herein should not be considered complete, or take the place of thoroughly reading all inserts and labels pertaining to and included with the Niris Imaging System and Accessories.
Imalux shall not be liable for any improper use of the Niris technology and makes no representations or warranties as to the Niris technology’s efficacy, except as described in the labeling and inserts included with the product. Imalux makes no representations or warranties as to the use of the Niris technology in the event that the user attempts to service or repair the machine without using a technician certified by Imalux or uses any accessories other than those recommended by Imalux.
Caution: Federal law restricts this device to sale by or on the order of a physician.