Development of an Estimation Instrument of Acoustic Lens Properties for Medical Ultrasound Transducers

Abstract

In medical ultrasound transducers, the transmission mode (pass-through) approach has been used to estimate the characteristics of the acoustic lens. However, it is difficult to measure the acoustic lens properties with high precision because of human, systemic, or mechanical measurement errors. In this paper, we propose a low-cost estimation instrument for acoustic lens properties connected with a customized database. In the instrument, three-axis and one-axis transmitting and material fixtures accurately align the transmitting and receiving transducers separately. Through the developed instrument, we obtained a precise standard deviation of the attenuation coefficient and velocity of the acoustic lens material of 0.05 dB/cm and 2.62 m/s, respectively. Additionally, the simultaneous alignment between the fixtures is controllable with developed programs, thus generating very accurate information of the acoustic lens about the testing ultrasound transducer. In our instrument, the database could support users in managing the result data efficiently. User programs developed using LabVIEW provide the capability to obtain precise values of the attenuation coefficient and velocity, which represent the fundamental material characteristics of the acoustic lens of the medical ultrasound transducers. The developed review program of the customized database can also search the acoustic lens information and store the experimental results.

Figure 1

Structure of the acoustic lens in the medical ultrasound transducers.

Figure 2

Block diagram of the developed estimation instrument of acoustic lens properties for medical ultrasound transducers.

Figure 3

(a) Schematic diagram of the fixture stages (transmitting, receiving, and material fixtures) and (b) the fixture stages in the water tank.

Figure 4

Automation program flowchart.

Figure 5

Automatic measurement program interface. (a) Original Wave panel, (b) FFT Analyzed panel, (c) Attenuation panel, (d) Instr. Set panel, and (e) ALDRP.

Figure 6

(a) Peak-to-peak voltage of the receiving ultrasound wave depending on the angle of the receiving fixture and (b) the aligned receiving reference wave at 89.5°.

Figure 7

Measurement results of the (a) velocity and (b) attenuation coefficient. Acoustic lens 1, 2, 3, and 4 represent the calculated attenuation coefficient of the receiving ultrasound signal four times (acoustic lens 1, 2, 3, and 4 are represented by red solid, green dashed, purple solid, and blue dashed-dot lines, resp.).