Cavitation-enhanced back projection for acoustic detection of attenuating structures

Current methodology for the detection of attenuating structures in abdominal HIFU interventions requires lengthy, elaborate image analysis, which is undesired in a clinical setting. In this work, a method for the acoustic detection of attenuating structures in the beam path of the therapeutic HIFU array is described. The proposed method is used to determine binary apodizations that can be applied to the HIFU transducer for intercostal shot positions. Such a binary apodization was determined in vivo on an anesthetized pig under controlled breathing. Validation of the proposed method was done by comparing the binary apodization based on the proposed method to a binary apodization obtained using methodology based on MR image analysis and a collision detection algorithm. The proposed acoustical method provided a binary apodization that was over 90% similar to the apodization obtained using the image analysis-based method. Additionally, the proposed method can provide a measure of the amount of attenuation that each respective transducer element encounters in its beam path towards the focus.