Microwave prostatic hyperthermia: interest of urethral and rectal applicators combination-theoretical study and animal experimental results

Abstract

Microwave thermotherapy systems used for benign prostatic hyperplasia treatment generally operate with urethral or rectal applicator to deliver the microwave energy in the prostate. This technique does not allow an efficient heating of all the gland particularly in the case of large adenoma or when the treatment is limited to only one heating session. A solution to this problem is given by using simultaneously the rectal and urethral applicators [l]. A complete 915-MHz microwave thermotherapy system is presented with two applicators which can operate independently or simultaneously to deliver the microwave energy in the prostate. Electromagnetic and thermal modeling have been developed for the applicator antenna optimization, to calculate the specific absorption rate (SAR) and the thermal pattern in the prostate for each applicator alone and when they operate together in phase. Different canine experiments have been performed to prove the interest of using the two applicators simultaneously as compared when they operate alone. Hystological examination cuts of the prostate gland after heating have been carried out. I. INTRODUCTJONHE efficiency of microwave thermotherapy to treat benign prostatic hyperplasia has been demonstrated: many medical teams use this technique in clinical routine [2]- [5].Nevertheless urologists still do not agree about the type of applicators. In order to increase the heating volume and above all to homogenize the temperature within the prostate (in the case of prostatic tumors) it is necessary to combine urethral and rectal heating.The aim of this work is to make a thermoregulated focusing rectal applicator to be used simultaneously with an omnidirectional urethral applicator.Radiation diagrams of urethral and rectal applicators are computed out by the finite-difference time-domain (FDTD) method, and determined by experimental measurements. The

Detection of Vesicoureteral Reflux Using Microwave Radiometry—System Characterization With Tissue Phantoms

“…Among the most widely investigated applications are breast cancer detection [12-14], brain temperature monitoring in new born infants after hypoxia ischemia [15, 16], tissue temperature monitoring for feedback power control of superficial hyperthermia [17-19] and interstitial MW applicators [20, 21], and noninvasive thermometry for intracranial focused deep brain hyperthermia [22, 23]. MW radiometry involves collecting thermal noise power emitted by the body in the EM spectrum (typically 1–4 GHz) using an antenna.…”

Non-invasive vesicoureteral reflux detection: Heating risk studies for a new device

“…A pulsed power heating protocol with 30 Watts alternately to each antenna and 75% duty cycle for the first 3–4 minutes followed by 25% duty cycle for the next 20minutes was determined based on heating cycles delivered to several protocol determination pigs. The high electrical conductivity of urine contained inside the bladder leads to preferential power absorption when irradiated using a microwave hyperthermia applicator [5, 15]. At our advantage, the lack of blood perfusion and the presence of a thermal barrier inside the bladder result in heat retention by the urine.…”

Microwave heating for treatment of bile duct carcinoma — Evaluations on influence of metallic stent

“…They are microwave hyperthermia [2], [3] and microwave coagulation therapy (MCT) [4], [5] for thermal treatment of cancer, cardiac catheter ablation for ventricular arrhythmia treatment [6], [7], thermal treatment for benign prostatic hypertrophy (BPH) [8], [9], etc. Until now, the authors have been studying microwave antennas for hyperthermia.…”