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?
Une image / un lien ci-dessous est fourni (tel quel) pour télécharger la présentation
Politique de téléchargement : le contenu du site vous est fourni TEL QUEL pour votre information et votre usage personnel ; il ne peut être vendu, concédé sous licence ni partagé sur d’autres sites sans l’accord de son auteur.Le contenu vous est fourni TEL QUEL, pour votre information et votre usage personnel uniquement.Téléchargez la présentation en cliquant sur ce lien.Lors du téléchargement, si vous ne parvenez pas à télécharger une présentation, l’éditeur a peut-être supprimé le fichier de son serveur.Pendant le téléchargement, si vous ne parvenez pas à obtenir une présentation, le fichier a peut-être été supprimé par l’éditeur.
Outline What is microwaves? Why microwaves useful? What microwaves used for? use of microwaves, applications in medical .Research at Other Universities Research at BAMU
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
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
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
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)
Connexion au compte
Connectez-vous pour publier votre contenu sur SlideServe.
