Reusable Ultrasonic Tissue Mimicking Hydro-Gels Containing Non-Ionic Surface Active Agents for Visualizing Thermal Lesions. [JOURNAL ARTICLE]
IEEE Trans Biomed Eng 2009 Sep 18.
The present study aims to identify a new recipe for reusable tissue mimicking phantoms that allows the optical visualization of thermal lesions produced in various applications of therapeutic ultrasound where thermal mechanisms are important. The phantom was made of polyacrylamide hydro-gel containing a non-ionic surface active agent (NiSAA) as a temperature sensitive indicator. Threshold temperature above which a thermal lesion is regarded to be formed in the phantom is controlled by selecting a NiSAA. In the present study, three NiSAAs of polyoxyethylene alkyl ehter series with nominal clouding points of 66$\circ$C, 70$\circ$C and 80$\circ$C were chosen. Test phantoms were prepared with polyacrylamide hydro-gel, corn syrup and NiSAAs (5% w/v). Key acoustic properties of the 3 NiSAA hydro-gels were found to be similar to those of human liver. The phantoms were optically transparent at room temperature (25$\circ$C) adn became opaque after exceeding the clouding points. The transparency was recovered on cooling, although the system demonstrated hysteresis. The phantoms were tested both in their ability to provide visualization of thermal lesions produced by high intensity focused ultrasound and also to examine any characteristic differences in the shape of the lesions formed at different threshold temperatures. The present study suggests that the NiSAA polyacrylamide hydro-gel will be of a practical use in quality assurance in various applications of therapeutic ultrasound where thermal mechanisms are important.
More from this journal |
