1. PHOTOACOUSTIC PROBE FOR TUMOR DETECTION
HAIFENG WANG
SUBHASHINI PAKALAPATI
VU TRAN
Department of Electrical and Computer Engineering
University of Massachusetts Lowell

2. OUTLINE Introduction Principle of Ultrasound
What is Photoacoustic (PA)
Fiber-optic Source and Receiver
System of PA
How to fabricate
How PA system can detect tumor
Advantages and Disadvantages
Timeline
Tasks
Reference

3. INTRODUCTION Cancer killed ~570 000 people in 2010 in the USA.
Lot of methods to detect/predict tumor: US, x-ray, CT, MRI, PET, SPECT, etc.
Photoacoustic (PA) takes advantage of fiber optic and ultrasound to detect tumor

4. PRINCIPLE OF ULTRASOUND
Transducer emit ultrasound wave and get signals back from object
D= t.v
Scan volume to get image

5. WHAT IS PHOTOACOUSTIC?
Conversion of photons to acoustic wave due to absorption and localized thermal excitation.
Pulses of light is absorbed, energy will be radiated as heat.
Heat causes detectable sound waves due to pressure variation.

6. PHOTOACOUSTIC (Cont.)

7. DIAGRAM OF A TYPICAL PA SYSTEM
Themo-elastic Ultrsound Generation
Extrinsic fiber hydrophone, based on a Fabry-Perot interferometer

8. FIBER OPTIC ULTRASONIC SOURCE BASED ON OPTO-ACOUSTIC CONVERSION

9. FIBER OPTIC ULTRASONIC RECEIVER BASED ON ACOUSTO-OPTIC CONVERSION

10. TRANSMISSION STRUCTURE
2D gold nanoparticle array sandwiched between a transparent substrate and a PDMS layer

11. GOLD NANOSTRUCTURE
The top view (a) and sketch of the side view( b) of the gold nanostructure.

12. DETECTION OF TUMOR USING PAI
Tumors have dense and unorganized vasculature.
High density of blood vessels in tumors enhances PAI contrast.

13. DETECTION OF TUMOR (CONT.)
Endogenous PA contrast:
Melanin
Oxy Hemoglobin
Deoxy Hemoglobin
Exogenous PA contrast (Highly sensitive to deeply situated tumors):
Au NP
Alexa Fluor
Indocyanine Green

14. ADVANTAGES DISADVANTAGES
Ability to detect deeply situated tumor and its vasculature
Monitors angiogenesis
High resolution
Compatible to Ultra Sound
High Penetration depth
1. Limited Path length
2. Temperature Dependence
3. Weak absorption at short wavelengths

15. TIMELINE

16. TASKS HAIFENG WANG Principle of Photoacoustic Fabricate PA structure
SUBHASHINI PAKALAPATI
Principle and procedure of tumor detection using PA
AuNP enhanced
VU TRAN
Compare other methods to detect tumor

17. REFERENCES
[1] Jemal,A. et al. Cancer Statistics, CA CancerJ.Clin. 60, 277–300
[2] Hou, Y., et al., Optical generation of high frequency ultrasound using two-dimensional gold nanostructure. Applied Physics Letters, (9): p
[3] Mallidi, S., G.P. Luke, and S. Emelianov, Photoacoustic imaging in cancer detection, diagnosis, and treatment guidance. Trends Biotechnol, 2011.
[4] Tang, M.X., et al., Photoacoustics, thermoacoustics, and acousto-optics for biomedical imaging. Proc Inst Mech Eng H, (2): p
[5] Wang, X., et al., Photoacoustic tomography: a potential new tool for prostate cancer. Biomed Opt Express, (4): p

18. THANK YOU