1. Fiber Optic RS-OCT probe
Advisors: Dr. Patil
Dr. Mahadevan-Jansen
John Acevedo Kelly Thomas Chris Miller

2. 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
Almost all basal cell carcinomas occur on parts of the body excessively exposed to the sun — especially the face, ears, neck, scalp, shoulders, and back. On rare occasions, however, tumors develop on unexposed areas. In a few cases, contact with arsenic, exposure to radiation, open sores that resist healing, chronic inflammatory skin conditions, and complications of burns, scars, infections, vaccinations, or even tattoos are contributing factors.

3. RS and OCT are complimentary
Raman Spectroscopy
Strengths
Biochemical Specificity
Limitations
No spatial Information
Susceptible to sampling error
Optical Coherence Tomography
Strengths
Micron-scale structural resolution
Real-time imaging speeds
Limitations
Insensitive to tissue biochemical composition

4. Procedure 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

5. Dr. Patil’s RS-OCT probe
Problem statement and take out schematic
How it works…

6. 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
Potential endoscopic use, non-invasive
Cost effective
Current skin probe~$4000
Our design ~$700
Product
Price
Fiber Optics
$100
Platinum Alloy coil
Focusing Lens
$200
Polymer block
Electrodes
All Products
$700

7. Miniaturizing sample arm of current RS-OCT probe
Problem Statement
Miniaturizing sample arm of current RS-OCT probe 5” 8”
Therefore, additional diagnostic tools are sought to aid the endoscopist with the identification of pre-cancerous changes so that appropriate treatment can be targeted at an early stage. Ideally these tools would be used in vivo, providing non-invasive, reproducible, real time information on the disease state of the tissue. Such tools could also lead to improved targeting of excisional biopsy, or resection margins, and minimise the number of normal samples collected, thus reducing the burden on busy histopathology departments.
Raman spectroscopy is an inelastic scattering technique which provides a biochemical fingerprint of a tissue sample under interrogation.
Requirements of Raman probes for in vivo endoscopic applications include biocompatibility, miniaturisation to fit down the biopsy channel, well defined depth of field, low backgroun signal and high collection efficiency to enable routine application with spectral acquisition periods of a few seconds. Due to the cost of optical components the probes should be robust enough to withstand sterilisation procedures

8. 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 dB
RS collection efficiency of 10 seconds
Spot size for OCT should be < 50 microns Determined by depth of focus
Beat existing probe performance and beat what current 2 probes do independently

9. RS and OCT existing designs
Raman Spectroscopy
Current Probe Design
Direct light source surrounded by 7 detection fibers
Optical Coherence Tomography
Current Probe Design
Forward facing
Bundle-based
MEMS mirror BP
filter
Notch
filters
785 nm
Spectrograph 7
300 mm
fibers
CCD
Psample = 80 mW
tacq < 5 sec

10. 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
Generalize. Getting materials.

11. 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

12. 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 kV
1310 nm light source - broadband
Diameter of glass was 125 um. Single mode fiber is 9 um.
Munce, N.R. and Yang, V.X.D. et al. (2008).

13. Electrostatic OCT component
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

14. 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
Figure out how to describe it
Collection
OCT
Highest concentration of collection

15. Future work Build prototype Test prototype Evaluate effectiveness
Improve design by adding more collection fibers
Modifying SolidWorks 3D design
Prepare poster presentation

16. 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

17. 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,

18. Questions?

19. Specific Aims
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

20. 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 non-malignant tissue
Gives no spatial information
All sorts of epithelial diseases
Next slide: existing raman probes. CURRENTLY THE BEST WAY IS WITH FIBER OPTIC PROBES..DIRECT LIGHT (picture on experimental methods slide). Problem: no info about space n0 n1
Raman Shift (cm-1) = f ( ) – f ( )

21. 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 5mm
Micron scale resolution (>25µm)
Real-time speed
Current oct design