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In order to improve the external applicators used for microwave thermotberapy controlled by microwave radiometry in medical applications, we propose specific planar applicators developed for heating: either annular ones to be used at the frequency equal to 915 MHz or in the shape of a horseshoe (short-circuited ring) for 434 MHz. The final goal of this paper is the realization of a honeycomb network for the treatment of larger areas and greater volumes. Index Terms--Finite-difference time-domain (FDTD) method, medical applications, microwave heating, microwave planar applicators.

Coaxial antennas different in their active length have been designed, to be used in a complete 915 MHz hyperthermia system with temperature control by microwave radiometry. Heating patterns are reconstructed from the power deposition associated with the bioheat transfer equation. Temperature control is effected by means of microwave radiometry and used in order to determine bioheat parameters. Phased arrays are studied allowing heated volume expansion.

A surface acoustic wave (SAW) echo method is described and implemented to locate a free or a squeezed liquid droplet from a single interdigital transducer (IDT) actuated by SAW. Findings reveal that the tested platform fitted with one IDT built on a LiNb[O.sub.3] substrate permits the tracking of water droplets actuated by SAW running free or squeezed under a cover for biological treatments in a lab on chip.

Microwave thermotherapy is currently used in clinical routines for benign prostatic hyperplasia treatments. The temperature increase is obtained using an endocavitary microwave applicator placed in the prostatic urethra. This urethral applicator after a technical modification can be placed inside the bladder in order to potentiate the effects of the treatment by chemotherapy of vesical carcinoma. This paper deals with electromagnetic studies of this new endocavitary applicator. First of all, the experimental determination of the dielectric permittivities for the propagation domain characterization is achieved in order to be used in the electromagnetic model. Compared to experimental results, these simulations obtained by the finite-difference time-domain formalism allow us to determine the electromagnetic performance of this applicator. Finally, the in vivo study realized on anesthetized dogs to determine the therapeutic protocol associating chemotherapy and thermotherapy in the treatment of the bladder cancer is presented. Index Terms--Bladder, FDTD, helical applicator, microwaves, radiometry, thermochemotherapy.