Metrological aspects on therapeutic ultrasound parameters: effective radiating area and non-uniformity ration

This paper discloses the infra-structure developed aiming the implementation of the US pressure field mapping system of Inmetro’s Laboratory of Ultrasound (Labus), based on current standards, which provides Brazilian traceability to related quantities. As a reliability proof of system’s adequacy, the uncertainties of the effective radiating area (AER) and the beam non-uniformity ratio (RBN) were assessed for US transducers in the range of 1.0 MHz to 3.5 MHz, and diameters of 1.27 cm and 2.54 cm. The calculation protocol was developed based on Standard IEC 61689:2007. Type A uncertainty was estimated from 4 repetitions of the full procedure for the determination of AER and RBN, and type B uncertainty was estimated from the mathematical model for both calculation, obtained based on IEC 61689:2007 and the GUM. All results are presented herein, being maximum expanded uncertainties (95% confidence level) 6.8% for AER and 14.9% for RBN.