FIBER OPTIC RSOCT PROBE Advisors Dr Patil Dr
FIBER OPTIC RS-OCT PROBE Advisors: Dr. Patil Dr. Mahadevan-Jansen John Acevedo Kelly Thomas Chris Miller
Epithelial cancer types Epithelium – cells that line hollow organs and make up the outer surface of the body (skin) Basal Cell Carcinoma: 1 million new cases are diagnosed each year in the U. S. � The basal cells line the deepest layer of the epidermis � Squamous Cell Carcinoma: More than 700, 000 new cases are diagnosed every year. � Chronic exposure to sunlight is the cause of most squamous cell carcinoma and basal cell carcinoma. � Optical imaging such as Optical Coherence Tomography (OCT) can noninvasively serve as a diagnostic and monitoring tool of epithelial cancers, and can evaluate therapeutic responses
RS and OCT are complimentary Raman Spectroscopy Strengths � Biochemical Specificity Optical Coherence Tomography Strengths � Micron-scale structural resolution � Real-time imaging speeds Limitations � No spatial Information � Susceptible to sampling error Limitations � Insensitive to tissue biochemical composition
Procedure 1. 2. 3. 4. 5. 6. 7. Turn on OCT component Acquire tomographical map Detect area of interest Turn off OCT component Turn on RS component Acquire biochemical composition of area of interest Turn off RS component
Dr. Patil’s RS-OCT probe
Reason for fiber optic RS-OCT probe Improve detection and diagnosis of cancer Hand held device will facilitate the use RS-OCT probe A fiber optic probe will decrease the size of the current probe Product Price Potential endoscopic use, Fiber Optics $100 non-invasive Platinum Alloy coil $100 Cost effective Focusing Lens $200 � Current skin probe~$4000 � Our design ~$700 Polymer block $200 Electrodes $100 All Products $700
Problem Statement Miniaturizing sample arm of current RS-OCT probe 8” 5”
Design Criteria Meet existing RS-OCT probe performance and functionality � Decrease size of probe to < 1 cm in diameter � Reach a scan rate of RS and OCT to 4 frames per second � Reach a scan range of at least 3 mm depth � OCT sensitivity of -95 d. B � RS collection efficiency of 10 seconds � Spot size for OCT should be < 50 microns Determined by depth of focus
RS and OCT existing designs Raman Spectroscopy Optical Coherence Current Probe Design Tomography � Direct light source Current Probe Design � Forward facing surrounded by 7 � Bundle-based detection fibers BP filter Notch filters 785 nm 7 300 mm fibers Psample = 80 m. W tacq < 5 sec Spectrograph CCD � MEMS mirror
Challenges Quality compensation from combining RS and OCT � RS requires narrow band of light source and multi-mode fibers for optimum specificity � OCT requires broad band of light source and single-mode fibers for optimum specificity Develop scanning technique for the OCT probe in such a small area Spatial registration of RS and OCT data sets Obtaining material for tests
Current Design Forward facing Electrostatic scanning probe for OCT component � Located in the center Fiber-optic array for RS component 270 um 300 um 125 um inner diam
Electrostatic OCT component 125 µm diameter single mode fiber illuminates and detects elastic scattering in the area of interest Fiber placed in 250 µm diameter platinum alloy coil Placed in the center of 400 µm diameter lumen of a triple lumen catheter Two peripheral lumens contain 270 µm diameter wires � One serves as electrode and the other serves as ground leads � Driven by DC power supply, <5 µA, 1 -3 k. V 1310 nm light source - broadband Munce, N. R. and Yang, V. X. D. et al. (2008).
Electrostatic OCT component 1. 2. 3. 4. 5. Electrostatic driven cantilever to create a compact, wide angle, rapid scanning forward viewing probe Cantilever is neutral and is attracted to electrode Cantilever touches electrode and acquires the same potential Charge dissipates through the polymer from the cantilever and repels from electrode Cantilever touches ground and becomes neutral again Process restarts enacting a scanning motion
Fiber Optic Array RS Component Multi-mode fibers (200 µm)set on either side of the OCT scanning fiber One narrow band (785 nm) light sources on one side Light source Collection OCT Highest concentration of collection
Future work Build prototype Test prototype Evaluate effectiveness Improve design by adding more collection fibers Modifying Solid. Works 3 D design Prepare poster presentation
Current Progress Voltage source and optical fibers have been obtained Dissipative Polymer has been ordered Platinum coil or suitable replacement is needed Find a suitable replacement for dissipative polymer if polymer is not effective � Capacitor, resistor, inductor
References Patil, C. A. (2009). Development combined raman spectroscopy-optical coherence tomograpgy for the detection of skin cancer. Disertation submitted to faculty of Graduate school of Vanderbilt University. Munce, N. R. and Yang, V. X. D. et al. (2008). Electrostatic forward-viewing scanning probe for doppler optical coherence tomography using a dissipative polymer catheter. Optical letters, 33, 7, 657 -60.
Questions?
Specific Aims 1. 2. 3. Combine RS-OCT techniques into a fiber optic device to replace sample arm of current probe Maximize Raman detection time efficiency Integrate multi-mode and single-mode fibers into probe without compromising RS-OCT functionality
Raman Spectroscopy Inelastic scattering (Stokes and Anti-Stokes) � Occurs 1 in 10 million compared to elastic Frequency of light scattered from a molecule dependent on structural characteristics of molecular bonds Able to determine malignant from nonmalignant tissue Gives no spatial information Raman Shift (cm n 01 -1) =f( )–f( )
Optical Coherence Tomography (OCT) Sensitivity to microstructural features of disease Measures tissue reflectivity as function of depth � Detects elastic scattering Ability to image over transverse areas of tissue of greater than 5 mm Micron scale resolution (>25µm)
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