Home // International Journal On Advances in Systems and Measurements, volume 2, number 1, 2009 // View article
Authors:
G. A. López
A. Valentino
Keywords: image processing, ultrasound, thermochromic liquid crystal
Abstract:
Several methods for the acquisition of bidimensional thermal images of acoustic fields produced by ultrasonic transducers for therapy have been described. A low cost technique used for the characterization of ultrasonic therapy equipment consists in placing a thermochromatic liquid crystal (TLC) film in a cross-section of the ultrasonic beam, forming a colorful image of the temperature distribution. This method gives information about the whole thermal pattern, which is related to the intensity of ultrasound, offering a qualitative measurement. The present paper describes the acquisition of a sequence of thermal images using the TLC technique. Diathermia temperatures were induced by using physiotherapy ultrasound equipment at 1 MHz in polyvinyl chloride and polyurethane copolymer films. Digital image processing and computer graphics were used in order to get the mathematical model of the monotonic relation between temperature and color in TLC films for the temperature range from 35ºC to 40°C. 3D thermal beam-shape reconstruction for the ultrasound therapy transducer was obtained for a future medical parameter analysis such as radiation beam pattern, penetration depth and effective field size. A numerical method based on RGB color model and Euclidean distance for getting a quantitative measurement of temperature rise in thermal images was developed.
Pages: 66 to 75
Copyright: Copyright (c) to authors, 2009. Used with permission.
Publication date: June 7, 2009
Published in: journal
ISSN: 1942-261x