Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Microwave imaging technique for biomedical application


Published on

Published in: Education, Technology, Business
  • Be the first to comment

  • Be the first to like this

Microwave imaging technique for biomedical application

  1. 1. Microwave Imaging Technique for Biomedical Application Gunjan Gupta Nirma University
  2. 2. Introduction • The penetration through opaque media makes microwaves a convenient agent for non invasive testing, evaluating cold measurements • Microwaves have been considered for medical applications involving the detection of organ movements and changes in tissue water content • Cardiopulmonary interrogation via microwaves has resulted in various sensors for monitoring various movements and changes inside human body 2
  3. 3. Introduction • In all these applications, microwave sensors perform local measurements and need to be displaced for obtaining an image reproducing the spatial variations of a given quantity • Recently advances in the area of inverse scattering theory and microwave technology have made possible the development of microwave imaging and tomographic instruments 3
  4. 4. What Paper Covers ? • Equipments developed at Supelec and UPC Barcelona, within the frame of successive French-Spanish PICASSO cooperation programs • Brief historical survey for both technological and numerical aspects • Capabilities of the existing equipment, as well as difficulty in dealing with clinical situations • Expected development of microwave imaging techniques for biomedical applications 4
  5. 5. Reconstruction Algorithm • Main difficulty in producing microwave images of quality was to compensate for complex diffraction mechanisms • Two Approaches: • First , Efficient reconstruction algorithms used with X-ray CT • Second, Scattering Mechanism with more rigorous nature in Reconstruction Process 5
  6. 6. Reconstruction Algorithm X-Ray CT Reconstruction • Compensate the effect of Scattering Phenomenon • Neglect Multiple Scattering • Approach, imported from Ultrasound Imaging technique , is known as Diffraction Topography Scattering Reconstruction • Scattering mechanism are formally taken into account with more rigorous nature • Linearize the inverse scattering problem, scattered field are linearly related to equivalent current induced by interrogating beam 6
  7. 7. Reconstruction Algorithm X-Ray CT Reconstruction • Fast Fourier Transform Algorithm • Efficient under computational aspect & suited for real time op • Does not allow quantitative imaging • Reproduce shape of structure Scattering Reconstruction • Fourier Transform Algorithm • Allow quantitative imaging, even for high contrast targets 7
  8. 8. Iterative Reconstruction Algorithm 8
  9. 9. Iterative Reconstruction Algorithm • At each step , the measured scattered field is compared to the scattered field calculated from a numerical model • Such an approach, equivalently known as Distorted Born Method or Newton Kantorovitch Technique (NKT) , has been developed at the end of the 80’s and has been shown to be able to deal with high contrasted structures • Spatial resolution is not so strictly related to the wavelength 9
  10. 10. Equipments • Equipment differ from the geometry of the transmitter receiver arrangement • Designed for operation according to a transmission mode in water, at a frequency of the order of 2 GHz • Provides a satisfactory optimization between a desired investigation depth of about 20 cm, and a spatial resolution comprised between 5 and 10 mm 10
  11. 11. Equipments Planer Microwave Camera @2.45 GHz Circular Microwave Scanner @2.33 GHz 11
  12. 12. Result • Microwave camera has been initially designed for non-invasive thermometry (NIT) purposes during hyperthermia sessions • Hyperthermia is demanding for an accurate control of the temperature distribution in the heated tissues • Such a control is impossible to obtain in case of deep seated tumors, except with invasive thermometric probes 12
  13. 13. Result • In all trials, the time required for reconstructing images was too long for obtaining interactivity between operator and equipment • However, very recently, the microwave camera has been made compatible with real time constraints • Images can now be produced at the rate of more than 10 images per second, which is enough for most biological processes 13
  14. 14. Result Fig : Microwave image of a human hand. Mono-view reconstruction with a diffraction tomography algorithm 14
  15. 15. Human for-arm reconstructed from Microwave scanner data Linear Diffraction Tomography Non-linear Iterative Technique 15
  16. 16. Conclusion • From the beginning of the 80’s , microwave imaging techniques for biomedical applications have been drastically improved • Various assessments conducted with preliminary Equipments have confirmed the sensitivity of microwave images to factors of medical relevance • Even if operational and clinical efficacy is not yet achieved, different steps for succeeding are now well identified 16
  17. 17. Indeed, without a significant development effort, microwave imaging techniques will still have to wait a long time before being recognized and accepted by their potential users Thank You ! 17
  18. 18. Reference IEEE Paper 18