Browsing by Subject "Hyperspectral imaging"
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Item Miniature laser scanning micro-endoscopes : multi-modality imaging system and biomedical applications(2013-05) Wang, Youmin, 1986-; Zhang, Xiaojing, Ph. D.; Yu, Edward T.Cancer is a world menace. After years of endeavor seeking the end of it, people started to realize that no matter how powerful the therapy could be, detection at early stage is always a cheaper, easier and more successful solution compared with curative methods for cancer developed onto its advanced stage. However, relatively few early-detection approaches have proven sufficiently effective and practical for mass use as a point-of-care tool. An early-cancer screening tool integrating the desired features of sensitive, informative, portable, and cost-effective is in need for the doctors. The progress in optical imaging and Micro-electro-mechanical system (MEMS) technology offers a promise for an innovative cancer screening alternative that is non-invasive, radiation-free, portable and potentially cost-effective. This dissertation investigates handheld instrumentation as multi-modalities of miniature imaging probes with various designs of MEMS devices, to obtain real-time images of epithelial tissue optical and physiological properties, combining the quantitative advantages of spectral analysis with the qualitative benefits of imaging to distinguish early cancer. This dissertation in sequence presents the handheld instruments in the fashions of Laser-scanning confocal microscopy (LSCM), optical diffuse reflectance imaging, nonlinear optical imaging modalities with their subsequent image-guided managements in oral cancer, skin cancer detection, circulating tumor cell (CTC) imaging, and imaging guided surgeries. One of the main challenges facing miniaturization lies in the mechanism of beam deflection across the sample. This dissertation introduces two generations of MEMS devices desgined, fabricated and incorporated in the imaging probes. A two-axis vertical comb driven silicon micromirror was used in the development of a handheld LSCM for oral cancer detection. Though obtaining numerous advantages, this first generation silicon MEMS micromirror suffers from small aperture size and high voltage requirement for actuation, which result in low collection efficiency in fluorescence imaging and medial safety concerns, respectively. Therefore a stainless steel scanner compatible with electrical discharge machining (EDM) process was fabricated with simplified process, low-voltage magnetic actuation and large fluorescence collection efficiency, with its capability demonstrated in the incorporation and embodiment of a handheld hyperspectral nonlinear imaging probe. Besides, software and controlling innovations for handheld imaging modalities are presented. A feedback controlling system for MEMS scanning status monitoring was developed for stabilized imaging rendering. For the sake of further improved imaging stability in handheld imaging and to enable on-site mosaic for large field viewing, a handheld mosaic system was developed and presented.Item Optical and structural property mapping of soft tissues using spatial frequency domain imaging(2015-08) Yang, Bin, Ph. D.; Tunnell, James W.; Krishnan, Sunil; Reichenberg, Jason S; Yeh, Hsin-Chih; Sacks, MichaelTissue optical properties, absorption, scattering and fluorescence, reveal important information about health, and holds the potential for non-invasive diagnosis and therefore earlier treatment for many diseases. On the other hand, tissue structure determines its function. Studying tissue structural properties helps us better understand structure-function relationship. Optical imaging is an ideal tool to study these tissue properties. However, conventional optical imaging techniques have limitations, such as not being able to quantitatively evaluate tissue absorption and scattering properties and only providing volumetrically averaged quantities with no depth control capability. To better study tissue properties, we integrated spatial frequency domain imaging (SFDI) with conventional reflectance imaging modalities. SFDI is a non-invasive, non-contact wide-field imaging technique which utilizes structured illumination to probe tissues. SFDI imaging is able to accurately quantify tissue optical properties. By adjusting spatial frequency, the imaging depth can be tuned which allows for depth controlled imaging. Especially at high spatial frequency, SFDI reflectance image is more sensitive to tissue scattering property than absorption property. The imaging capability of SFDI allows for studying tissue properties from a whole new perspective. In our study, we developed both benchtop and handheld SFDI imaging systems to accommodate different applications. By evaluating tissue optical properties, we corrected attenuation in fluorescence imaging using an analytical model; and we quantified optical and physical properties of skin diseases. By imaging at high spatial frequency, we demonstrated that absorption in fluorescence imaging can also be reduced because of a reduced imaging depth. This correction can be performed in real-time at 19 frames/second. Furthermore, fibrous structures orientation from the superficial layer can be accurately quantified in a multi-layered sample by limiting imaging depth. Finally, we color rendered SFDI reflectance image at high spatial frequency to reveal structural changes in skin lesions.