Integrated temperature sensor for determination of ultrasound interstitial applicator heating effects

We discuss the feasibility of temperature determination with an integrated sensor in ultrasound (US) interstitial heating. The sensor, a 230-μm diameter microthermistor, was epoxied at the tip of the 1.22-mm diameter antenna of the US waveguide applicator. Incorporation of the sensor into the applicator caused about 10% drop in the acoustic output. While the temperatures read with the integrated sensor were much higher compared to microthermistors around the antenna, the shape of the heating curves was very similar. Measurements show that the volume temperature can be inferred from the readings of the integrated sensor using short, 1.5-min interruptions in delivered US power.