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Swept Source Frequency Domain Optical Coherence Tomography Anurag Gupta University of Rochester, BS: Biomedical Engineering Dr. Zhongping Chen, Dr. Jun Zhang and Dr. Qiang Wang The University of California, Irvine Department of Biomedical Engineering Beckman Laser Institute and Medical Clinic.

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  1. Swept Source Frequency Domain Optical Coherence TomographyAnurag GuptaUniversity of Rochester, BS: Biomedical EngineeringDr. Zhongping Chen, Dr. Jun Zhang and Dr. Qiang Wang The University of California, IrvineDepartment of Biomedical Engineering Beckman Laser Institute and Medical Clinic

  2. Outline • Define OCT • Clinical Applications • Advantage of OCT Over Other Imaging Modalities • Types of OCT Systems • Motivations for Designing an FDOCT Imaging Modality • Sample OCT Image • Acknowledgements

  3. What Is Optical Coherence Tomography? As Defined in 2005 by the Inventor, Dr. James Fujimoto: “Optical coherence tomography (OCT) is an emerging imaging modality which can generate high resolution, cross-sectional images of microstructure in biological systems...by measuring the echo time delay of optical backscattering in the tissue as a function of transverse position.” http://www.fitzpatrick.duke.edu/Events/Seminars/2005SpringSeminars/Fujimoto.html

  4. Clinical Applications • Ophthalmology • Diagnosing retinal diseases and other abnormalities of the eye • Dermatology • Early detection of skin cancer • Diagnosing skin diseases and other problems • Cardiovascular • Imaging of the blood vessels and other cardiovascular areas for early detection of diseases

  5. Standardclinical Resolution (log) Ultrasound 1 mm Highfrequency 100 µm 10 µm Confocalmicroscopy OCT 1 µm Penetration depth (log) 1 mm 1 cm 10 cm Advantage of OCT http://www.risoe.dk/ofd/oct/OCT_apps.htm

  6. Histology Versus “Optical” Biopsy of aNormal Hamster Cheek Pouch Woonggyu Jung, Jun Zhang, Jungrae Chung, Petra Wilder-Smith, Matt Brenner, J. Stuart Nelson, and Zhongping Chen. "Advances in Oral Cancer Detection Using Optical Coherence Tomography." IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 11.4 (2005): 811-817. July-Aug. 2006 <http://chen.bli.uci.edu/publications/J83_Cancer%20IEEE.pdf>.

  7. Size of OCT Device OCT can be designed to be: compact, portable, relatively inexpensive, and can be easily connected to any number of image acquisition scanners This is a picture of our system in final stages

  8. Stationary mirror Mirror Beam splitter Beam splitter Sample Sample Swept Source SLD Photodetecter Photodetector Time Domain OCT Frequency Domain OCT Elimination of Scanning Mirror Scanning Reference Mirror

  9. Swept Source Laser System http://www.santec.com/pdf/lasers/HSL-2000.pdf

  10. Motivations Can You Have a Signal Without Noise? NO!

  11. Signal to Noise Ratio (SNR) • A High SNR Ratio: Higher Image Quality • Images are more distinguishable • A Low SNR Ratio: Lower Image Quality • Images are less distinguishable

  12. SNR of FDOCT Versus TDOCT FDOCT: acquire signal in the time window of T Signal term # of photons = Noise term # of photons = Fei Wang EE131 Presentation at Caltech Where N is the # of pixels per depth scan We see that the SNR of FDOCT is N times better than that of TDOCT

  13. Dispersion Control Dispersion is the separation of white or compound light into its respective colors, as in the formation of a spectrum by a prism. http://en.wikipedia.org/wiki/Dispersion_(optics) This can cause the resolution of an image to decrease. In FDOCT, Dispersion can be controlled rather easily whereas in other imaging modalities its very difficult.

  14. Before Dispersion Control 40 - 50 µm Resolution

  15. After Dispersion Control 8 µm Resolution

  16. Image Acquisition Speed • Programmed Using Microsoft Visual C++ • Speed: 15 / 16 Frames Per Second • Images can be Acquired In-Vivo or Ex-Vivo • This makes it a viable option for use during surgery

  17. 3D Image Acquisition Scanner This is a picture of our 3D Image Acquisition Scanner

  18. 3D Image Acquisition Scanner Movie

  19. 3D FDOCT Movie of the Retina

  20. Acknowledgments The National Science Foundation The University of California, Irvine (UROP) Dr. Zhongping Chen, Dr. Jun Zhang, Dr. Qiang Wang, and Mr. Bin Rao The Beckman Laser Institute and Medical Clinic The Air Force Research Laboratory The IM-SURE Fellows

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