Modelling and Cross-Correlation Analysis of Two Sets of Ideal Ultrasonic Signals for Non-invasive Temperature Estimation in Ablation Temperatures

Hyperthermia (40-45 °C) and ablation (≥60°C) have become a common treatment procedure for cancerous tumors. At the present time, there is no easily affordable and robust instrument for noninvasive estimation of temperature changes. Ultrasound is one of the most feasible alternatives for non-invasive temperature change estimation during thermotherapy due to its simplicity of processing, tissue penetration capability, relative low cost, and its non-invasive and non-ionizing nature, suggesting a promising prospective of this technique to be used in clinical therapy. A temporal analysis is presented comparing the time delays suffered by two sets of ideal signals generated using a theoretical mathematical description. The cross- correlation method was used to calculate the time lags of the signals as they pass through a medium containing scatterers with temperature increments. The linear regressions conducted for all the four data windows in which the two sets of signals were divided show a linear and growing behavior, which implies that the higher the temperature, the greater the time delay between the signals of the same window.