Ultrasonic attenuation and speed in phantoms made of polyvinyl chloride-plastisol and graphite powder

Abstract

Biological phantoms are very useful for controlled experiments on biomedical ultrasound. Nevertheless they are normally made of organic materials with short time-duration. We have studied the ultrasonic properties of test-blocks made of polyvinyl chloride-plastisol (PVCP) that are very stable in time. In this work, we analyzed ultrasonic (US) attenuation and speed at 1 MHz, as a function of temperature (15–45°C) of five phantoms made with PVCP and different concentrations of graphite powder (0, 0.5, 1, 2, and 5%) using the classical transmission method. US speed diminishes almost linearly (from 1408 to 1333 m.s−1) as temperature increases. In general attenuation lied between 0.73 and 0.09 dB.cm−1, but presenting a more complex behavior. For graphite concentrations of 0.5 and 1%, attenuation was lower than for 0% and for the other two phantoms (2 and 5% concentrations) attenuation was higher. This behavior can be perhaps due to the fact that the fabrication temperature for 0.5 and 1% was 140°C and for the other was 170°C. Although the standard recipe is 170°C, we observed that smaller temperatures may add in adjusting the attenuation values and it is a very useful property to mimic different biological tissues. We are now working on multilayer phantoms of PVCP.