Uma aplicação médica de micro-ondas: diatermia e hipertermia.

Abstract

In this dissertation a bibliographical review is made on the modalities of thermotherapy known as DIATHERMY and HIPERTHERMY, as well as a description of the main techniques and applicators used in these treatements. Aiming to set the object of study in an electromagnetic context, some underlying principles on the behaviour of a biological tissue in terms of frequency of the applied field are presented, besides the main effects of non-ionizing radiation on them. Some relevant aspects of safety standards adopted in Brazil are discussed, concerning level and exposure time of non-ionizing electromagnetic energy. A review of antenna theory is presented and special emphasis is given to helical antennas, antenna arrays, passive reflectors and Geometric Optics. These theoretical considerations are then used in writing a computer program for the design of a primary helical antenna radiating in the axial mode. Increased directivity and the effects of plane, conic and elliptical reflectors on it are considered by the program. A second program allows the determination of the shape of a reflector, given the characteristics of the primary antenna (feeder) and of the desired secondary aperture field. A good agreement is found between theoretical and experimental results. Some conclusions are drawn from the dissertation and we hope i t will open new avenues for future work on medical applications of electromagnetic fields.