The Importance of Proper Storage of Agar Phantom on the Water-Glycerol-benzalkonium Chloride Mixture to Maintain the Ultrasonic Group Velocity

The present paper studied the metrological impact on the ultrasound group velocity in not storing the agar phantoms in the water-glycerol-benzalkonium chloride maintenance mixture. The ultrasonic velocity and the phantom’s thickness were measured by the pulse-echo technique seven times within 44 days, whereas four replicates were carried out under repeatability conditions. The phantom’s thickness did not differ statistically along the days since the normalized error was less than 1.0. Based on the results obtained, one can conclude that the ultrasound group velocity decreased in a logarithmic function along the days.