Integrated Microwave Thermal Imaging System with Mechanically Steerable HIFU Therapy Device<br />Tian Zhou<br />01/26/09 <...
Outline <br />Purpose<br />Principles of Microwave Imaging<br />Dielectric Properties vs. Temperature Change<br />Integrat...
Purpose <br />3<br />
Principles in Microwave Imaging<br />Dielectric Properties<br />Permittivity, ɛ<br />a measurement of energy storage in a ...
Principles in Microwave Imaging<br />5<br />
Relationship between Dielectric Properties and Temperature<br />In literature<br />Liver tissue<br />ex vivo<br />@915MHz<...
Integrating MW Imaging and HIFU Heating<br />Temperature change will alter the dielectric properties of a phantom or tissu...
HIFU Heating<br />13 W<br />8 W<br />Cyril Lafon et al. (2001)<br />8<br />
Microwave imaging system<br />9<br />
Integrating MW Imaging and HIFU Heating<br />10<br />
System Setup<br />11<br />Phantom <br />
Difference Image<br />12<br />      T = tiT = t0                    Difference Image<br />
Difference image<br />Circle<br />Conductivity Difference Image <br />Courtesy of ShireenGeimer<br />13<br />
Difference image<br />C-circle<br />14<br />Conductivity Difference Image <br />
Difference image<br />Spirals <br />15<br />Conductivity Difference Image <br />
Spatial Registration<br />16<br />Conductivity Difference Image <br />
Temporal Registration<br />Temperature<br />Normalized<br />	conductivity<br />     (1100MHz)<br />17<br />
Conductivity vs. Temperature Change<br />Conductivity<br />Temperature (°C)<br />18<br />
New Configuration for Integration<br />Waveform<br />Generator<br />Power<br />Amp.<br />MW antenna<br />Temp.<br />Meter<...
New Configuration for Integration<br />20<br />Phantom <br />Transducer<br />heated<br />plane<br />focal zone scan path<b...
Steerable HIFU Transducer<br />21<br />
Cross Section of a Focal Beam<br />22<br />1X power level<br />1.5X power level<br />
Cross Section of a Focal Zone<br />23<br />Permittivity<br />Conductivity<br />Permittivity<br />Conductivity<br />
Animal Experiment<br />24<br />
Challenges<br />25<br />Spatial Resolution<br />Better with higher frequency, but higher attenuation<br />Compromise betwe...
Acknowledgement <br />Thayer School, Dartmouth College<br />Paul Meaney, PH.D	<br />	Keith Paulsen, PH.D<br />	Shireen Gei...
Phantom experiment<br />Relationship between Dielectric Constant and Temperature<br />27<br />Temperature (C)<br />Tempera...
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Microwave imaging for thermal therapy

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Use microwave tomographic imaging for temperature monitoring in thermal therapy

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Microwave imaging for thermal therapy

  1. 1. Integrated Microwave Thermal Imaging System with Mechanically Steerable HIFU Therapy Device<br />Tian Zhou<br />01/26/09 <br />
  2. 2. Outline <br />Purpose<br />Principles of Microwave Imaging<br />Dielectric Properties vs. Temperature Change<br />Integration of Microwave Thermal Imaging and HIFU Heating (Configuration I, II)<br />Challenges<br />2<br />
  3. 3. Purpose <br />3<br />
  4. 4. Principles in Microwave Imaging<br />Dielectric Properties<br />Permittivity, ɛ<br />a measurement of energy storage in a material from an external electric field<br />Conductivity, σ (siemens/m)<br />how dissipative or lossy a material is to an external electric field*<br />*Agilent tech notes <br />4<br />
  5. 5. Principles in Microwave Imaging<br />5<br />
  6. 6. Relationship between Dielectric Properties and Temperature<br />In literature<br />Liver tissue<br />ex vivo<br />@915MHz<br />@2.45GHz<br />Susan C. Hagness et al.<br /> (2006)<br />6<br />
  7. 7. Integrating MW Imaging and HIFU Heating<br />Temperature change will alter the dielectric properties of a phantom or tissues<br />Microwave imaging is able to capture the change of the dielectric properties<br />Microwave imaging can be a potential non-invasive tool to provide feedback of the thermal profile in HIFU heating<br />7<br />
  8. 8. HIFU Heating<br />13 W<br />8 W<br />Cyril Lafon et al. (2001)<br />8<br />
  9. 9. Microwave imaging system<br />9<br />
  10. 10. Integrating MW Imaging and HIFU Heating<br />10<br />
  11. 11. System Setup<br />11<br />Phantom <br />
  12. 12. Difference Image<br />12<br /> T = tiT = t0 Difference Image<br />
  13. 13. Difference image<br />Circle<br />Conductivity Difference Image <br />Courtesy of ShireenGeimer<br />13<br />
  14. 14. Difference image<br />C-circle<br />14<br />Conductivity Difference Image <br />
  15. 15. Difference image<br />Spirals <br />15<br />Conductivity Difference Image <br />
  16. 16. Spatial Registration<br />16<br />Conductivity Difference Image <br />
  17. 17. Temporal Registration<br />Temperature<br />Normalized<br /> conductivity<br /> (1100MHz)<br />17<br />
  18. 18. Conductivity vs. Temperature Change<br />Conductivity<br />Temperature (°C)<br />18<br />
  19. 19. New Configuration for Integration<br />Waveform<br />Generator<br />Power<br />Amp.<br />MW antenna<br />Temp.<br />Meter<br />Stepper<br />Controller<br />HIFU transducer<br />Thermal couples<br />DMAS<br />System<br />Beam focus<br />19<br />
  20. 20. New Configuration for Integration<br />20<br />Phantom <br />Transducer<br />heated<br />plane<br />focal zone scan path<br />Focus<br />
  21. 21. Steerable HIFU Transducer<br />21<br />
  22. 22. Cross Section of a Focal Beam<br />22<br />1X power level<br />1.5X power level<br />
  23. 23. Cross Section of a Focal Zone<br />23<br />Permittivity<br />Conductivity<br />Permittivity<br />Conductivity<br />
  24. 24. Animal Experiment<br />24<br />
  25. 25. Challenges<br />25<br />Spatial Resolution<br />Better with higher frequency, but higher attenuation<br />Compromise between spatial res. and SNR <br />Registered with images which have fine anatomic details<br />Temporal Resolution<br />Currently reconstructed offline<br />Understanding the Relationship between Dielectric Properties and Temperature Change <br />Nonlinear in vivo<br />
  26. 26. Acknowledgement <br />Thayer School, Dartmouth College<br />Paul Meaney, PH.D <br /> Keith Paulsen, PH.D<br /> Shireen Geimer<br /> Margaret Fanning <br /> Lincoln Potwin<br /> Tim Raynolds<br />Dartmouth Hitchcock Medical Center<br />P. Jack Hoopes, D.V.M., PH.D<br /> Susan Kane<br />NIH<br />26<br />
  27. 27. Phantom experiment<br />Relationship between Dielectric Constant and Temperature<br />27<br />Temperature (C)<br />Temperature (C)<br />

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