The biggest clinical benefit of OCT as a diagnostic tool for retinal disorders is that it enables the discrimination of subtle pathologic changes in vivo. Though a large number of researches have been done to expand its applications, few of them proved sufficient utility in clinical settings. In laryngology, an OCT system attachable to and working in tandem with an operating microscope may provide solid clinical benefits. Nevertheless, such a system has not been introduced yet, while it is more common to find an OCT system with a hand-held type probe. Hence, we developed a phonomicrosurgical OCT with a long working distance and attachable to an existing operating microscope. The OCT also has a dichroic mirror which splits the coherent IR laser and visual projection to enable dual imaging. We evaluated the efficacy of the system in evaluating subepithelial tissue structure, especially in the Reinke’s space of vocal fold. We tested its imaging capability with excised canine larynx and eyeball. Then, we assessed the surgical margin with the OCT images after treating a live canine larynx with a CO2 laser under general anesthesia. In addition, we compared the images with corresponding histopathologic findings to confirm the diagnostic feasibility. The OCT and histopathologic images showed a significant correlation to identify the epithelial layer, lamina propria, subepithelial glandular structures and vessels from the OCT images. This is the first OCT system attachable to an operating microscope which may provide a promising alternative to frozen biopsies for intraoperative laryngeal cancer margin assessment.
KEYWORDS: Optical coherence tomography, Imaging systems, Microscopes, Visualization, Tissues, 3D microstructuring, In vivo imaging, 3D visualizations, Retina, Skin
Optical Coherence Tomography (OCT) is a promising non-invasive in vivo imaging technology visualizing the 3-dimensional microanatomy of retina, skin and vocal fold. In the field of laryngology, OCT probes installed in an existing laryngoscope have been widely studied. However, there are still a number of critical issues to be resolved to develop a successful phonomicrosurgical OCT system including high-resolution, long working distance (≥400 mm) and rapid 3D image reconstruction, etc. Here we introduce a long working distance OCT with 35µm lateral and 13µm axial resolutions. To the best of our knowledge, this is the first OCT with up to 450mm of working distance as well as µm-level resolutions to identify subepithelial tissue structure of vocal fold. The main purpose of this study is to investigate the feasibility and efficacy of the system in ex-vivo microstructure imaging of vocal fold, especially the Reinke’s space. We tested the imaging capability of the system with the freshly excised canine eyeball and larynx samples before proceeding the study with fresh human laryngectomized specimens. The acquired OCT images were then compared with the corresponding H&E stained histological sections. This correlation study allowed the identification of the epithelial layer, lamina propria, subepithelial glandular structures and vessels of the canine and human specimens from both the OCT and the microscope images ensuring solid correspondence between two different types of visual tissue assessment. This OCT system is developed to directly confirm the lesions during phonomicrosurgeries enabling the clinicians to reduce the number of intraoperative biopsies.
Background and Objective: Noninvasive middle and inner ear imaging using optical coherence tomography
(OCT) presents some unique challenges for real-time, clinical use in animals and humans. The goal of this study
was to investigate whether OCT provides information about the middle and inner ear microstructures by
examining extratympanic structures.
Materials and Methods: Five mice and rats were included in the experiment, and the swept-source OCT system
was tested to identify the middle and inner ear microstructures and to measure the length or thickness of various
structures.
Results: It was possible to see middle ear structures through the tympanic membrane with the OCT instrument
located extratympanically in both rats and mice. We could also obtain the inner ear images through the otic
capsule in the mice, but the bulla needed to be removed to visualize the inner ear structures in the rats. The
whole apical, middle and basals of the cochlea and the thickness of the otic capsule covering the cochlea could
be visualized simultaneously.
Conclusions: OCT is a promising technology to assess middle ear and inner ear microanatomy noninvasively in
both mice and rats. OCT imaging could provide additional diagnostic information about the diseases of the
middle and inner ear.
KEYWORDS: LIDAR, Sensors, Avalanche photodetectors, 3D image processing, Receivers, Signal processing, Digital signal processing, Robots, Pulsed laser operation, 3D acquisition
The purpose of this research is to develop a new 3D LIDAR sensor, named KIDAR-B25, for measuring 3D image
information with high range accuracy, high speed and compact size. To measure a distance to the target object, we
developed a range measurement unit, which is implemented by the direct Time-Of-Flight (TOF) method using TDC chip,
a pulsed laser transmitter as an illumination source (pulse width: 10 ns, wavelength: 905 nm, repetition rate: 30kHz, peak
power: 20W), and an Si APD receiver, which has high sensitivity and wide bandwidth. Also, we devised a horizontal and
vertical scanning mechanism, climbing in a spiral and coupled with the laser optical path. Besides, control electronics
such as the motor controller, the signal processing unit, the power distributor and so on, are developed and integrated in a
compact assembly.
The key point of the 3D LIDAR design proposed in this paper is to use the compact scanning mechanism, which is
coupled with optical module horizontally and vertically. This KIDAR-B25 has the same beam propagation axis for
emitting pulse laser and receiving reflected one with no optical interference each other.
The scanning performance of the KIDAR-B25 has proven with the stable operation up to 20Hz (vertical), 40Hz
(horizontal) and the time is about 1.7s to reach the maximum speed. The range of vertical plane can be available up to
±10 degree FOV (Field Of View) with a 0.25 degree angular resolution. The whole horizontal plane (360 degree) can be
also available with 0.125 degree angular resolution. Since the
KIDAR-B25 sensor has been planned and developed to be
used in mobile robots for navigation, we conducted an outdoor test for evaluating its performance. The experimental
results show that the captured 3D imaging data can be usefully applicable to the navigation of the robot for detecting and
avoiding the moving objects with real time.
Crosstalk of CMOS Image Sensor (CIS) causes degradation of spatial resolution, color mixing and leads to image noise.
Crosstalk consists of spectral, optical and electrical components, but definition of each component is obscure and
difficult to quantify. For the first time, quantifiable definition of each component is proposed to perform crosstalk
analysis in this paper. Contribution of each component to the total crosstalk is analyzed using opto-electrical simulation.
Simulation is performed with an internally developed 2D finite difference time domain (FDTD) simulator coupled to a
commercial device simulator. Simulation domain consists of set of four pixels. Plane wave propagation from micro-lens
to the photodiode is analyzed with FDTD and the optical simulation result is transformed into the photo-current in the
photodiode using electrical simulation. The total crosstalk consists of 43% of spectral crosstalk, 14% of optical cross talk,
and 43% of electrical crosstalk at the normal incident light. Spectral crosstalk can be suppressed through careful
selection of color filter materials with good selectivity of color spectrum. Characteristics of crosstalk and
photosensitivity show contrary trend to one another as a function of color filter thickness. Therefore, the crosstalk target
is fixed and simulation is performed to determine the minimum color filter thickness that satisfies the crosstalk target. By
color filter material and thickness optimization, 10% increase in photosensitivity and 7% decrease spectral crosstalk were
obtained. Electrical crosstalk showed 11% and 9% improvement through applying to new implantation process and
stacking multi-epi layer on the p-type substrate, respectively.
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