Image-guided phased array system for ultrasound thermotherapy

An image-guided ultrasonic phased array system for non-invasive tissue ablation is described. Image guidance is provided by processing beamformed RF-data from a commercially available scanner. Two dimensional estimates of tissue temperature are obtained in real-time by implementing a high-speed displacement tracking algorithm. Experimental results validate our approach for image guidance in which the therapy array is initially driven at low (non-destructive) intensity sufficient to cause a small change in temperature at the focus. Two-dimensional non-invasive temperature data is then used to localize and assess the quality of the focus. If the extent and location of the focal spot are consistent with expected values, a high-intensity pulse capable of causing tissue ablation is delivered. Preliminary in-vitro beef muscle experiments are reported, showing successful visualization of the location and quality of the HIFU focus followed by an ablative pulse. Dissection revealed lesion formation (~2 mm dia., 12 mm long, 30 mm deep within the tissue) at the expected location