Polyacrylamide gel containing egg white as new model for irradiation experiments using focused ultrasound

A polyacrylamide (PAA) gel containing egg white as a new model for irradiation experiments in high-intensity focused ultrasound HIFU is introduced. The gel is transparent except in thermally necrosed regions which are white. The model is similar to, and has the same benefits as, gels containing bovine serum albumin (BSA) protein, but egg is less expensive than BSA. The acoustic properties of the gel are very favorable, similar to those of soft tissues; density 1.0 g/cm(3), sound speed 1540 m/s and acoustic attenuation 0.4 dB/cm at 2 MHz. We illustrate the usefulness of the gel in visualizing HIFU lesions and introduce a new model of gastric submucosal tumor in a rabbit stomach, showing that this gel can be formed into any desired shape. Our PAA gel containing egg white is an attractive candidate for a disposable acoustic material suitable for experimental applications of HIFU.