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Visualizing Real Tim E Vasomotion in Vivo Using Optical Coherence A Visualizing real time vasomotion in vivo using Optical Coherence Tom ography Suhir Abuhajar 2012 Lancaster University-Physics Department-Nonlinear Biomedical Physics Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in Physics ProQuest Number: 11003436 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 11003436 Published by ProQuest LLC(2018). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C ode Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 - 1346 C ontents Declaration v Abstract vi Acknowledgment vii 1 Introduction 1 1.1 Motivation .................................................................................................... 1 1.2 Structure of the th esis ............................................................................. 2 1.3 Physiology of the skin ............................................................................. 5 1.3.1 Functions of the s k i n ................................................................... 7 1.3.2 Structure of human s k i n ............................................................ 9 1.3.3 V aso m o tio n.................................................................................... 11 1.3.4 Optical properties of the s k in................................................... 15 1.4 Current imaging techniques for skin’s v essel ..................................... 18 2 Optical Coherence Tomography (OCT) 24 2.1 In tro d u ctio n ................................................................................................. 24 2.2 Main characteristic of OCT ................................................................... 25 2.3 Application of OCT................................................................................... 26 2.4 Principles of operation............................................................................. 27 2.4.1 Different OCT versions................................................................ 29 2.5 SROCT Experimental set-up................................................................... 32 2.6 Theory of SROCT ................................................................................... 35 i CONTENTS ii 2.6.1 The Sensitivity of O C T ................................................................. 39 3 The Phantom 43 3.1 In tro d u ctio n ................................................................................................. 43 3.2 Construction of phantom s ....................................................................... 43 3.3 Experimental set-up ...................................................................... 46 3.4 Data Recording and results ..................................................................... 48 3.4.1 First images of the phantom...................................................... 48 3.4.2 Protocols for the assessment of the accuracy of SROCT measurements ................................................................................ 50 3.4.2.1 Using a polystyrene tube ............................................ 50 3.4.2.2 Using Aluminum steps in the different media . 58 3.4.3 Reduction of intensity with dep th ............................................ 64 3.4.4 Calculating a correction factor ................................................... 67 3.4.5 C o n to u r ........................................................................................... 73 3.4.5.1 Calculating the area of the contour ........................ 75 3.4.6 Instrumental noise for a sequence of images ........................ 78 3.4.6.1 D ata processing and r e s u l ts ..................................... 79 3.4.7 Three dimensional images (3 D ) ............................................... 88 3.5 Conclusion .................................................................................................... 90 4 Measurements on human skin 92 4.1 In tro d u ctio n ................................................................................................. 92 4.2 Experimental set-up.............. ...................................................................... 93 4.3 Data Recording and results ..................................................................... 94 4.3.1 First human skin im ages ............................................................. 95 4.3.2 Reduction of intensity with depth ............................................ 97 4.3.3 Calculating the correction factor ................................................... 100 4.3.4 Montage sequence images ............................................................. 102 4.3.5 Contour of vessel ..............................................................................104 CONTENTS iii 4.3.6 Vasomotion under skin ................................................................106 4.3.6.1 Comparing the vessel oscillation with the noise level 109 4.3.7 Fourier Transform for experimental d a ta ................................... I l l 4.3.7.1 Fourier transform for human d ata .................................I l l 4.3.7.2 Fourier transform for phantom data ..........................116 4.3.8 Wavelet transform for experimental d a ta.................................. 118 4.3.8.1 Wavelet transform for human d a ta ............................. 119 4.3.8.2 Wavelet transform for phantom d a ta..........................122 4.3.9 Three dimensional im ages............................................................ 125 4.4 Conclusion ......................................................................................................126 5 Effect of temperature on vasomotion 130 5.1 In tro d u ctio n .................................................................................................. 130 5.2 Methodology and experimental set-up....................................................131 5.2.1 A model of Melcor Thermoelectric Temperature Controller (MTTC) with SROCT ...................................................................132 5.2.2 D ata re c o rd in g ................................................................................134 5.2.3 D ata pre-processing......................................................................... 135 5.3 R esu lts ............................................................................................................ 136 5.4 Conclusion ......................................................................................................144 6 Summary of the results and future work 145 6.1 Summary of the re s u lts .............................................................................. 145 6.2 Further work ...............................................................................................149 Appendix A: MatLab Images Prossesing toolbox 151 A-l: Display an im age........................................................................................ 152 A-2: Measure the d is ta n c e ..................................................................................153 A-3: Define the intensity by d ep th : ................................................................. 154 A-4: Plot several intensity changes by d e p th :.................................................155 A-5: Apply the correction factor to the im age............................................. 155 CONTENTS iv A-6: Define the contour function ......................................................................156 A-7: Calculate the area of the c o n to u r ............................................................156 A-8: Montage im ag es.............................................................................................158 A-9: Create a m o v ie .............................................................................................159 A-10: Fourier tra n s fo r m ...................................................................................... 161 A-ll: Wavelet transform ...................................................................................... 164 Appendix B: Create 3D images by using Image J 168 Appendix C: The The area vibrations of Phantom and vessel 170 Bibliography 171 Declaration I declare that this thesis is my own original work, under the guidance of Professor. Aneta Stefanovska, and Dr Oleg Kolosov and it has not been submitted in sub­ stantially the same form for the award of a higher degree at any other university. Nor does it contain, to the best part of my knowledge, any material published or written by another person, except as acknowledged in the text. v A bstract As blood vessel imaging techniques facilitate the fundamental understanding in vascular performance diagnosis and biomedical research improvement, we aimed to visualize and understand the blood vessels dynamics under human skin and their underlying mechanisms in real time. In this study, a noninvasive imag­ ing system was selected to provide an investigation of the real time oscillation of blood vessels in vivo, using Spectral Radar Optical Coherence Tomography (SROCT). This main goal was achieved by evaluating the precision and confi­ dence in recorded data by using a
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