Design and characterization of an intracavitary ultrasound hyperthermia applicator for recurrent or residual lesions in the vaginal cuff

Abstract

For evaluating the feasibility of treating recurrent lesions in the vaginal cuff by hyperthermia, a 2-element ultrasound applicator was designed, constructed and characterized. A half-cylindrical transducer (d=1 cm, length=1 cm) was used to construct the 2-element ultrasound applicator. Each element of this applicator was operated at 1.5 MHz and characterized by measuring transducer efficiency and acoustic power distribution. Thermocouple probes were used to measure the temperature rise in the phantom. The element sizes used in this study were selected to be comparable to a high dose rate brachytherapy colpostat applicator. Each element was powered separately to achieve a desired temperature pattern in a target. The acoustic output power as a function of applied electric power of elements 1 and 2 were linear over this 1-40 W range and efficiencies were 32.2 +/- 3.4% and 46.2 +/- 0.8%, respectively. The temperature measurements in the phantom showed that a 6 degrees C temperature rise was achieved 2 cm from the applicator surface. As a conclusion, the ability of the ultrasound colpostat applicator to be used for hyperthermia was demonstrated by measuring acoustic output power, ultrasound field distribution and temperature rise in the phantom. Based on the characteristics of this applicator, it has the potential to be useful for inducing hyperthermia to the vaginal cuff in the clinic.

Thermal Therapy, Part 2: Hyperthermia Techniques

“…3 Over the years, ultrasound devices capable of improved heating uniformity and controlled depth of penetration, mostly by using multiple applicators with phasing and power steering, have been designed. [127][128][129][130][131][132][133]…”

Integrated Endoscope for Real-Time 3D Ultrasound Imaging and Hyperthermia: Feasibility Study

“…This tech nol ogy could sim plify im ple men ta tion of ra di a tion ther apy, che mo ther apy and other forms of drug de livery while im prov ing tar get vi su al iza tion and con trol of en ergy de po si tion. In par tic u lar, an en do scopic probe for 3D im ag ing and hyperthermia could be ap pli ca ble to cur rent re search in the treat ment of can cers of the cer vix, 10 pros tate 11 and esoph a gus. 12 In ad di tion, dual function al ity probes could be ap plied to in crease drug per me ation across the blood-brain bar rier for de liv ery to the cen tral ner vous sys tem.…”