Particle image velocimetry of high intensity focused ultrasound (HIFU) field

Abstract

High Intensity Focused Ultrasound (HIFU) is one of thermal ablation techniques that are used to treat the cancer tumors by generating coagulation necrosis in the tumor cells. It is designed to focus a high acoustic intensity at a precisely defined location called Focal Spot leading to increase temperature at this spot to a degree that is sufficient to ablate the cancerous biological tissues. Prostate, renal, bladder, and testicular tumors are examples for the tumors that have been treated with HIFU. Despite its use, until now there is no international standard that accurately describes the field induced by the HIFU. Particle Image Velocimetry (PIV), on the other hand, provides a non-intrusive technique to measure and characterize the fluid flow. It was used in many previous works to measure the Acoustic Particle Velocity of low-frequency sound fields. In this work, a novel PIV procedure that is appropriate for using in high-frequency applications will be introduced. This procedure will be used to investigate a HIFU field that arises in a water bath at and around the focal spot. Moreover, the influence of changing the HIFU intensity on the resulting acoustic particle velocity field will be measured to estimate the availability of using PIV as a calibration tool for the HIFU transducers.