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11 pages, 1427 KiB

Open AccessFeature PaperArticle

Optical Characterization of an Intra-Arterial Light and Drug Delivery System for Photodynamic Therapy of Atherosclerotic Plaque

by Matthieu Zellweger, Ying Xiao, Manish Jain, Marie-Noëlle Giraud, Andreas Pitzschke, Matthieu de Kalbermatten, Erwin Berger, Hubert van den Bergh, Stéphane Cook and Georges Wagnières

Appl. Sci. 2020, 10(12), 4304; https://doi.org/10.3390/app10124304 - 23 Jun 2020

Cited by 3 | Viewed by 2708

Abstract

Although the versatility of photodynamic therapy (PDT) is well established, the technical aspects of light delivery systems vary significantly depending on the targeted organ. This article describes the optical properties of a light and drug delivery system (catheter and light diffuser) suitable for [...] Read more.

Although the versatility of photodynamic therapy (PDT) is well established, the technical aspects of light delivery systems vary significantly depending on the targeted organ. This article describes the optical properties of a light and drug delivery system (catheter and light diffuser) suitable for intra-arterial PDT by using a planar imaging goniometer to measure the full radiance longitudinal and angular profiles at the surface of the diffuser at 652 nm. The results show that the system emits almost Lambertian and “top hat” profiles, an interesting feature to determine the light dosimetry in the many vascular applications of PDT. Full article

(This article belongs to the Special Issue Optical Devices and Systems for Biomedical Applications)

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15 pages, 5292 KiB

Open AccessFeature PaperArticle

Spectral Domain Optical Coherence Tomography Imaging Performance Improvement Based on Field Curvature Aberration-Corrected Spectrometer

by Seung Seok Lee, Woosub Song and Eun Seo Choi

Appl. Sci. 2020, 10(10), 3657; https://doi.org/10.3390/app10103657 - 25 May 2020

Cited by 9 | Viewed by 4455

Abstract

We designed and fabricated a telecentric f-theta imaging lens (TFL) to improve the imaging performance of spectral domain optical coherence tomography (SD-OCT). By tailoring the field curvature aberration of the TFL, the flattened focal surface was well matched to the detector plane. Simulation [...] Read more.

We designed and fabricated a telecentric f-theta imaging lens (TFL) to improve the imaging performance of spectral domain optical coherence tomography (SD-OCT). By tailoring the field curvature aberration of the TFL, the flattened focal surface was well matched to the detector plane. Simulation results showed that the spot in the focal plane fitted well within a single pixel and the modulation transfer function at high spatial frequencies showed higher values compared with those of an achromatic doublet imaging lens, which are commonly used in SD-OCT spectrometers. The spectrometer using the TFL had an axial resolution of 7.8 μm, which was similar to the theoretical value of 6.2 μm. The spectrometer was constructed so that the achromatic doublet lens was replaced by the TFL. As a result, the SD-OCT imaging depth was improved by 13% (1.85 mm) on a 10 dB basis in the roll-off curve and showed better sensitivity at the same depth. The SD-OCT images of a multi-layered tape and a human palm proved that the TFL was able to achieve deeper imaging depth and better contrast. This feature was seen very clearly in the depth profile of the image. SD-OCT imaging performance can be improved simply by changing the spectrometer’s imaging lens. By optimizing the imaging lens, deeper SD-OCT imaging can be achieved with improved sensitivity. Full article

(This article belongs to the Special Issue Optical Devices and Systems for Biomedical Applications)

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10 pages, 2314 KiB

Open AccessArticle

Angiographic Imaging of an In Vivo Mouse Brain as a Guiding Star for Automatic Digital Refocusing in OCT

by Kwan Seob Park, Ju Wan Kim, Byeong Ha Lee and Tae Joong Eom

Appl. Sci. 2020, 10(4), 1210; https://doi.org/10.3390/app10041210 - 11 Feb 2020

Cited by 1 | Viewed by 2917

Abstract

A method allows the extraction of the recovery factor that maximizes the image contrast of OCT (optical coherence tomography) and/or OCTA (OCT angiography) of a living subject is proposed in this study. Due to the finite depth of focus in imaging optics, the [...] Read more.

A method allows the extraction of the recovery factor that maximizes the image contrast of OCT (optical coherence tomography) and/or OCTA (OCT angiography) of a living subject is proposed in this study. Due to the finite depth of focus in imaging optics, the volume OCT imaging suffers from blurriness in the lateral resolution. By utilizing the digital hologram method or angular spectrum method, the blurred image can be refocused. However, for in vivo OCT imaging, evaluation of the image focus is not easy, owing to the cloudy structure of the brain. In the proposed method, the blood flow signals were used as a guiding star to find the recovery factor. The propagation distance to a focal plane was automatically determined by evaluating the contrast of a cross-sectional OCTA image. The performance was examined though in vivo mouse brain OCT/OCTA imaging. The image singularity of the blood flow in OCTA was very effective at evaluating the contrast of the image. Full article

(This article belongs to the Special Issue Optical Devices and Systems for Biomedical Applications)

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10 pages, 3137 KiB

Open AccessArticle

Development and Effect Analysis of UVB-LED General Lighting to Support Vitamin D Synthesis

by Seung-Taek Oh and Jae-Hyun Lim

Appl. Sci. 2020, 10(3), 889; https://doi.org/10.3390/app10030889 - 29 Jan 2020

Cited by 5 | Viewed by 4027

Abstract

Ultraviolet rays from sunlight are involved in vitamin D synthesis, which is essential in maintaining health. Most in vivo vitamin D synthesis occurs via exposure to sunlight, whereas a small portion is obtained through diet. Therefore, appropriate exposure to sunlight is recommended to [...] Read more.

Ultraviolet rays from sunlight are involved in vitamin D synthesis, which is essential in maintaining health. Most in vivo vitamin D synthesis occurs via exposure to sunlight, whereas a small portion is obtained through diet. Therefore, appropriate exposure to sunlight is recommended to satisfy vitamin D requirement. However, vitamin D deficiency still poses a serious issue to numerous people. To resolve this problem, artificial lighting has been studied to provide rays of UV light with characteristics similar to that of sunlight. The present study introduced vitamin D synthesis stimulating UVB-LED light via the general diffusion lighting type to indoor dwellers. However, despite the strides of advancement made in this type of lighting, studies on UVB with relation to vitamin D synthesis are limited. This study aimed to suggest UVB-LED lighting for indoor dwellers and confirm the effectiveness of vitamin D stimulation through animal testing. For this, a UVB-LED providing safe UVB dosage was developed based on the photobiological safety (IEC 62471) of lighting. Next, a comparison study of the suggested lighting and general lighting was executed in an isolated system. The study continued for two weeks and the vitamin D levels within the animal test subject (Rat, Wistar, male) were measured. At this time, the lighting was turned on for 06:00~22:00 considering the sunrise timing and average lighting time for modern people, and blood was collected from the caudal veins of the rats and analyzed for the amount of 25-hydroxyvitamin D [25(OH)D]. Analysis results showed that the amount of 25-hydroxyvitamin D [25(OH)D] in blood was higher, on average, by 6.8% (0.97 ng/mL) and 7.3% (0.9 ng/ml) in rats reared under UVB-LED lighting on the seventh and fourteenth experimental days, respectively, than those under general lighting. It was, therefore, confirmed that vitamin D synthesis in the human body can be supported by the proposed lighting in this study. Full article

(This article belongs to the Special Issue Optical Devices and Systems for Biomedical Applications)

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11 pages, 2939 KiB

Open AccessArticle

Development of Dual-Scale Fluorescence Endoscopy for In Vivo Bacteria Imaging in an Orthotopic Mouse Colon Tumor Model

by Su Woong Yoo, Dinh-huy Nguyen, Suhyeon Park, Hyeri Lee, Chang-Moon Lee, Changho Lee and Jung-Joon Min

Appl. Sci. 2020, 10(3), 844; https://doi.org/10.3390/app10030844 - 24 Jan 2020

Cited by 6 | Viewed by 4362

Abstract

Colorectal cancer is a representative cancer where early diagnosis and proper treatment monitoring are important. Recently, cancer treatment using bacteria has actively progressed and has been successfully monitored using fluorescence imaging techniques. However, because subcutaneous tumor models are limited in reflecting the actual [...] Read more.

Colorectal cancer is a representative cancer where early diagnosis and proper treatment monitoring are important. Recently, cancer treatment using bacteria has actively progressed and has been successfully monitored using fluorescence imaging techniques. However, because subcutaneous tumor models are limited in reflecting the actual colorectal cancer situation, new imaging approaches are needed to observe cancers growing in the colon. The fluorescence endoscopic approach is an optimal monitoring modality to evaluate the therapeutic response of bacteria in orthotopic colon cancer. In this study, we developed dual-scaled fluorescence endoscopy (DSFE) by combining wide-field fluorescence endoscopy (WFE) and confocal fluorescence endomicroscopy (CFEM) and demonstrated its usefulness for evaluating bacterial therapy. Firstly, the endoscopic probe of DSFE was developed by integrating the CFEM probe into the guide sheath of WFE. Secondly, colorectal cancer tumor growth and tumors infiltrating the fluorescent bacteria were successfully monitored at the multi-scale using DSFE. Finally, the bacterial distribution of the tumor and organs were imaged and quantitatively analyzed using CFEM. DSFE successfully exhibited fluorescent bacterial signals in an orthotopic mouse colon tumor model. Thus, it can be concluded that the DSFE system is a promising modality to monitor bacterial therapy in vivo. Full article

(This article belongs to the Special Issue Optical Devices and Systems for Biomedical Applications)

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12 pages, 23447 KiB

Open AccessArticle

Detection of Choroidal Neovascularization by Optical Coherence Tomography Angiography with Assistance from Use of the Image Segmentation Method

by Yuan-Shao Cheng, Shih-Huan Lin, Chih-Yu Hsiao and Chia-Jen Chang

Appl. Sci. 2020, 10(1), 137; https://doi.org/10.3390/app10010137 - 23 Dec 2019

Cited by 4 | Viewed by 3467

Abstract

Optical coherence tomography angiography (OCTA) is a popular medical imaging technology that can quickly establish a three-dimensional model of the fundus without dye injection. However the number of images in a model is quite large, so finding the lesions through image processing technology [...] Read more.

Optical coherence tomography angiography (OCTA) is a popular medical imaging technology that can quickly establish a three-dimensional model of the fundus without dye injection. However the number of images in a model is quite large, so finding the lesions through image processing technology can greatly reduce the time required for the judgment of the condition. This paper proposes a method for finding choroidal neovascularization (CNV) in OCTA images. Among the several characteristics of CNV, the larger turning angle of blood vessels is a relatively clear feature, so we will use this property to find out whether there is CNV in an OCTA image. We will transform the color space to CIELAB space, and extract the L-channel prior to preceding to the next step. We will then use some image segmentation methods to find the clearer vessel region. Finally, we will detect the CNV through certain morphology methods. The experimental result shows that our proposed method can effectively find the CNV in the OCTA image, meaning that we can make automated judgments through this method in the future and reduce the time necessary for human judgment. Full article

(This article belongs to the Special Issue Optical Devices and Systems for Biomedical Applications)

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9 pages, 4928 KiB

Open AccessFeature PaperLetter

Post-Processing Method for Image Reconstruction Enhancement in Integrating-Bucket-Based Full-Field Optical Coherence Tomography

by Juhyung Lee, Taeil Yoon and Byeong Ha Lee

Appl. Sci. 2020, 10(3), 830; https://doi.org/10.3390/app10030830 - 24 Jan 2020

Cited by 2 | Viewed by 3669

Abstract

An integrating-bucket method is widely used as a reconstruction tool for full-field optical coherence tomography (FF-OCT). However, it requires high-precision adjustments of the phase modulation parameters. If the parameters are not optimal, the reconstructed tomogram will incur severe artifacts. We propose a post-processing [...] Read more.

An integrating-bucket method is widely used as a reconstruction tool for full-field optical coherence tomography (FF-OCT). However, it requires high-precision adjustments of the phase modulation parameters. If the parameters are not optimal, the reconstructed tomogram will incur severe artifacts. We propose a post-processing method for removing or reducing such artifacts by utilizing a correction factor extracted from a pre-reconstructed tomogram. FF-OCT imaging created using a coin verifies the effectiveness of the method not only for a single en face image but also for an entire 3-D image. It is expected that the proposed method will expand the application of FF-OCT from biomedical imaging to semiconductor wafers or display panel inspections. Full article

(This article belongs to the Special Issue Optical Devices and Systems for Biomedical Applications)

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8 pages, 1517 KiB

Open AccessFeature PaperLetter

Narrowing Linewidth of Wavelength-Swept Active Mode Locking Laser Based on Cross Gain Modulation

by Se Jin Park, Gyeong Hun Kim, Hwi Don Lee, Chang-Seok Kim and Minsik Jo

Appl. Sci. 2019, 9(19), 4029; https://doi.org/10.3390/app9194029 - 26 Sep 2019

Cited by 3 | Viewed by 2788

Abstract

We demonstrate a novel narrow-linewidth configuration of a wavelength-swept active mode locking (AML) fiber laser. The frequency response of the modulation depth of a semiconductor optical amplifier can be improved in a higher modulation frequency region by adapting the cross gain modulation (XGM) [...] Read more.

We demonstrate a novel narrow-linewidth configuration of a wavelength-swept active mode locking (AML) fiber laser. The frequency response of the modulation depth of a semiconductor optical amplifier can be improved in a higher modulation frequency region by adapting the cross gain modulation (XGM) configuration, compared to that of the conventional direct gain modulation (DGM) configuration. As a sufficient modulation depth is implemented for an AML at higher modulation frequencies at around gigahertz order, it results in a narrower linewidth of lasing output. For the same modulation frequency of 1361.25 MHz, the linewidth of 0.25 nm with DGM becomes narrower up to 0.113 nm with XGM, which corresponds to an improved point spread function with 1.41 mm of 6-dB roll-off. Full article

(This article belongs to the Special Issue Optical Devices and Systems for Biomedical Applications)

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