Tentative Uncertainty Evaluation of Thermal and Mechanical Indices Used for Medical Ultrasound

Abstract

Tentative estimations of uncertainties of thermal index (TI) and mechanical index (MI) are described. Recently, high power and high pressure ultrasound has become an important tool for increasing quality of medical ultrasound required in the diagnosis and treatments. Precise control of ultrasonic power or acoustic pressure is required to contain the hazards to the human body caused by high power and high acoustic pressure and frequency of ultrasound. Due to this reason, TI and MI are very important parameters as indices, which denote the effects of ultrasonic power and acoustic pressure to human body. The uncertainties of TI and MI are based on the measured quantities such as ultrasonic power, acoustic pressure and frequency. The uncertainties of these measured values are usually calculated by measurers. When TI and MI are estimated, uncertainties of these indices also should be evaluated as same as other quantities for checking the validity of the values. Actually, these uncertainties have not been discussed. In this paper, relative expanded uncertainties of TI and MI which include the uncertainty caused by the bandwidth are estimated.