Beamforming for Therapy with High Intensity Focused Ultrasound (hifu) Using Quantitative Schlieren

The requirements for beamforming in high intensity focused ultrasound (HIFU) for tissue destruction are substantially different than those for diagnostic imaging. High numerical aperture and CW efficiency are desirable for tissue destruction, while depth of focus and broadband sensitivity are key to good imaging. When the same transducer must be used for ablation and imaging some compromises must be made, resulting in non-ideal beam patterns. Predicting the dosage in tissue that results from actual beam patterns becomes a key element in designing such systems. Quantitative schlieren images in CW mode are used to provide fast, high dynamic range field maps in water. The image data are then corrected for attenuation, resulting in simulated beam profiles and absorbed dose rates for tissue.