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Medical Applications of Microwaves Suresh C. Mehrotra UGC-BSR Faculty Fellow Dr.Babasaheb Ambedkar Marathwada University, Aurangabad. Interdisciplinary research involving. Medical doctors Physics Chemistry Computer Science Electronic Engineers. Outline. What is microwaves?
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Medical Applications of MicrowavesSuresh C. MehrotraUGC-BSR Faculty FellowDr.BabasahebAmbedkarMarathwada University, Aurangabad
Interdisciplinary research involving Medical doctors Physics Chemistry Computer Science Electronic Engineers
Outline What is microwaves? Why microwaves useful? What microwaves used for? use of microwaves, applications in medical .Research at Other Universities Research at BAMU
What is Microwaves Ocean Waves
Why are microwaves useful? They can Travel Through Various Types of Media
Why are microwaves useful? Earth Observation: Radio Detection and Ranging (RADAR)
Why are microwaves useful? Earth Observation: Radio Detection and Ranging (RADAR)
Information from Interstellar Medium Microwaves received from far space gives information regarding types of molecules there H, He, Water , formaldehyde etc and also their temperayures
Why are microwaves useful? Telecommunications: Mobile Phones
Microwave Applications In Medicine Why Use Microwaves? Sometimes they can travel through the body Sometimes they can heat the body
Microwave Applications In Medicine Why Use Microwaves?
Microwave Applications In Medicine Why Use Microwaves?
Microwave Applications In Medicine Example Cont..
Microwave Applications In Medicine Example: Brain Temperature Monitoring
Microwave Applications In Medicine Example:
Microwave Applications In Medicine Before After adding Microwave
Microwave Applications In Medicine Example: Microwave Cancer Detection
Microwave Applications In Medicine Example: Microwave Cancer Detection
Microwave breast tumordetection • Microwave tomography – Inverse scattering, non-linear relationship between the acquired data and imagined pattern, non-unique solution. – Early solutions - linear approximation, more recent accurate solutions based on optimization. • Ultra-wideband microwave radar techniques • Hybrid microwave – acoustic imaging
Breast tissue electrical properties • Early (before 2000) published data – Are not all in agreement – Limited sample sizes and frequency ranges – Do not consistently distinguish between different normal tissue types
Breast tissue Dielectric Spectroscopy • Comprehensive study to characterize malignant, benign, and normal breast tissues • U. Wisconsin-Madison (S. C. Hagness) and • U. Calgary, Canada (M. Okoniewski) • Frequencies 0.5 - 20 GHz • Total number of patients 93, samples 490; ages 17-65 • Tissue composition determined by pathologists • Normal breasts: percentage adipose, fibrous connective, and glandular
Results: normal breast tissue Source: Drs.Hagness & Okoniewski
radar-based detection - historical • 1998/1999: S. C. Hagness, A. Taflove & J. Bridges (Northwestern U.): concept proposed and demonstrated with FDTD models of planar antenna array system • 2000: E.C. Fear & M.A. Stuchly (U. Victoria): cylindrical system, skin subtraction - FDTD • Today: two main groups pursue simulations & experiments – Susan C. Hagness, U. Wisconsin – Elise C. Fear, U. Calgary – Other groups
Radar-based detection - basic • Ultra-wideband pulse: modulated Gaussian or frequency contents optimized (1 - 10 GHz) • Small broadband antennas • Signal processing – Calibration: removal of the antenna artifacts – Skin surface identification and artifact removal: reduce dominant reflection from skin - various algorithms – Compensation: of frequency dependent propagation effects – Tumor detection • Basic algorithm: compute time delays from antennas to focal • point, add together corresponding signals, scan focal point • through volume • Additional complex signal processing
Utrecht Hyperthermia System • 3 T MRI system, RF = 128 MHz • Radio frequency within the range optimal for regional hyperthermia of abdomen • Efficient 3T MRI requires tuned antenna array instead of traditional coils • The same antenna array for hyperthermia and MRI monitoring • Water (de-ionized) bolus – Optimal power coupling & surface cooling of the patient – Shorter antennas (more elements): better control of focus and uniformity of B field in imaging – No significant effect on S/N in imaging
Principle of TDR A fast rising (20 ps) pulse is transmitted in the sample of interest. The sample is placed in transmission line The reflected pulse is recorded Fourier Transform is used to extract the information. Experiments have been perfoemed in vitro as well as in vivo
Values of permittivity, conductivity & relaxation time for the control and oral squamous cell carcinoma groups
Values of permittivity, conductivity & relaxation time for the control and oral squamous cell carcinoma groups
The mean permittivity and conductivity values were higher in the OSCC group as compared to the control group. The mean relaxation time value was higher in the control group as compared to the OSCC group. Statistically significant correlation was not observed between values of dielectric parameters and the different clinical stages of OSCC. The mean values of permittivity and conductivity were higher in histopathological grade II as compared to grade I. Grade I had a higher relaxation time compared to grade II. Thus, the values of dielectric parameters correlated well with the histopathological grades of OSCC and the difference was found to be extremely statistically significant (p<0.0001)
Software for TDR Interface To Laptop PROBE Fig.1a:Instruments and Set up to acquire data from TDR
The feature vectors p are extracted for each set of measurements. These feature vectors are used as inputs to Linear Discriminate Analysis (LDA). The measurements have been classified in three categories as follows: Category 1. Subjects with no tobacco eating habits Category 2: Subjects with tobacco eating habits Category 3: Subjects with known cases of cancer (grade -1) Category 4: Subjects with known cases of cancer (grade -2) Category 5: Subjects with known cases of cancer (grade -3)