CHARACTERIZATION OF FOCUSED ULTRASOUND BEAM GEOMETRIES USING THERMOCHROMIC LIQUID CRYSTAL FILMS

Abstract

Focused ultrasound (FUS) applications are gaining more attention from clinicians for being able to provide effective, non-invasive treatments to almost any region of the body. In-house development of FUS devices require characterization and quality assurance methods to verify acoustic pressure fields, focal zone geometry, location, and validate proper function. Conventional techniques (hydrophones, gel phantoms) are limited by expensive and inaccessible equipment, time-consuming procedures, and use of toxic reagents. We developed a process for using thermochromic liquid crystal (TLC) films, sensors which undergo color transition when exposed to a range of specific temperatures, as a low-cost and readily adaptable characterization method for FUS transducers. A proof-of-concept experiment showed reproducibility in detecting ultrasound beams. Tests with two FUS transducers demonstrated that the technique was able to approximate axial dimensions of the focal region and depth of the focal region, characteristics that are significant in FUS treatment planning.