Invasive and non-invasive feedback for ultrasound phased array thermometry

The use of high-intensity focused ultrasound for cancer therapy and tissue ablation has been receiving increased attention recently. Currently, fine-wire thermocouple sensors represent the only practical means of feedback for these treatments. Difficulties in placing thermocouples in many clinical situations represent a major limitation on the amount feedback that can be obtained with these versatile sensors. For this purpose, invasive and non-invasive feedback methods for ultrasound thermotherapy have been developed. Invasive methods for acoustic feedback are based on implantable hydrophone arrays, and non-invasive methods for temperature feedback are based on signal processing of the backscattered diagnostic ultrasound pulse. Experimental results demonstrating quantitative, non-invasive, tissue temperature change measurements are shown. The methods for temperature change estimation presented are independent of the heating modality.