Self-adaptive ultrasonic beam amplifiers: application to transcostal shock wave therapy.

Self-adaptive ultrasonic beam amplifiers: application to transcostal shock wave therapy. Phys Med Biol. 2018 Aug 13;: Authors: Robin J, Simon A, Arnal B, Tanter M, Pernot M Abstract Ultrasound shock wave therapy is increasingly used for non-invasive surgery. It requires the focusing of very high pressure amplitude in precisely controlled focal spots. In transcostal therapy of the heart or the liver the high impedance mismatch between the bones and surrounding tissues gives rise to strong aberrations and attenuation of the therapeutic wavefront, with potential risks of injury at the tissue - bone interface. An adaptive propagation of the ultrasonic beam through the intercostal spaces would be required. Several solutions have been developed so far, but they require a prior knowledge of the patient's anatomy or an invasive calibration process, not applicable in clinic. Here, we develop a non-invasive adaptive focusing method for ultrasound therapy through the ribcage using a time reversal cavity (TRC) acting as an ultrasonic beam amplifier. This method is based on ribcage imaging through the TRC and a projection orthogonally to the strongest identified reflectors. The focal pressure of our device was improved by up to 30 % using such self-adaptive processing, without degrading the focal spots size and shape. This improvement allowed lesions formation in an Ultracal® phantom through a ribcage without invasive calibration of the device. ...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research