Simultaneous measurement of sound velocity and wall thickness of a tube

Metrological Validation of a Measurement Procedure for the Characterization of a Biological Ultrasound Tissue-Mimicking Material

The speed of sound and attenuation are important properties for characterizing reference materials such as biological phantoms used in ultrasound applications. There are many publications on the manufacture of ultrasonic phantoms and the characterization of their properties. However, few studies have applied the principles of metrology, such as the expression of the uncertainty of measurement. The objective of this study is to validate a method for characterizing the speed of sound and the attenuation coefficient of tissue-mimicking material (TMM) based on the expression of the measurement of uncertainty. Six 60-mm-diameter TMMs were fabricated, three 10 mm thick and three 20 mm thick. The experimental setup comprised two ultrasonic transducers, acting as transmitter or receiver depending on the stage of the measurement protocol, both with a nominal center frequency of 5 MHz and an element diameter of 12.7 mm. A sine burst of 20 cycles and 20-V peak-to-peak amplitude at 5 MHz excited the transmitter transducer, producing a maximum pressure of 0.06 MPa. The measurement method was based on the through-transmission substitution immersion technique. The speed of sound measurement system was validated using a calibrated stainless-steel cylinder as reference material, and normalized errors were <0.8. The attenuation coefficient measurement method was validated using replicated measurements under repeatability conditions. The normalized error between the two measurement sets was <1. The proposed uncertainty models for the measurements of the speed of sound and the attenuation coefficient can help other laboratories develop their own uncertainty models. These validated measurement methods can be used to certify a TMM as a reference material for biotechnological applications.

A comparison of methods for the determination of sound velocity in biological materials: a case study

Non-destructive ultrasonic methods for testing biological materials are applied in medicine as well as in food engineering to determine the physical parameters and the quality of agricultural products and raw materials such as meat. The purpose of this work was to identify the simplest and the most accurate of five methods for sound velocity determination across the fibers of the porcine longissimus dorsi muscle. The through-transmission technique (TT) was used for ultrasound signal acquisition with 2MHz transducers. The first two methods (M1, M2) are based on the acquisition of a single ultrasound signal in the analyzed material, another two methods (M3, M4) rely on the acquisition of two ultrasound signals in samples with different thicknesses (two-distance method) and the last method (M5) involves the acquisition of a single ultrasound signal in the analyzed material and the acquisition of a single ultrasound signal in distilled water at the same distance between ultrasonic transducers (relative method). The results were processed by the nonparametric Kruskal-Wallis test and compared with published data. The mean values of sound velocity obtained with the use of the above methods in pork samples at post-storage, room and vital temperatures were as follows: method M1-1549.2/1581.7/1597.4m/s, method M2-1477.7/1509.8/1597.4m/s, method M3-1552.0/1599.0/1623.3m/s, method M4-1557.4/1598.3/1623.6m/s, method M5-1554.3/1583.7/1598m/s. The experiment indicates that the choice of method for determining sound velocity significantly influences the results. Two of the five analyzed methods (namely M3 and M4), which involved measurements of the time of sound wave propagation through samples of the same material with varied thickness, produced velocity values most consistent with published data.

An ultrasonic array technique for material characterization of plate samples

An ultrasonic system with a linear array for characterization of a layered specimen placed in immersion liquid parallel to the aperture of the array is considered. To estimate the longitudinal and transverse wave velocities as well as the thickness and density of the specimen, it is proposed to decompose the spatio-temporal data recorded by the array in a spectrum of plane pulse waves. Based on fitting the developed wave model of the system to the experimental data, it is shown that the relative delays and amplitudes of the spectral responses can be used for the estimation of the velocities and thickness of the layer and its density. The distortions of the plane wave spectrum caused by the spatial discretization of the array data are considered. It is proposed to suppress these distortions using individual interpolating processing of the received pulses separated in the spatio-temporal domain. The developed technique is experimentally verified on a fused quartz plate evaluated with a 17-MHz linear array. The relative reproducibility of the estimation is found to be 0.11% in the longitudinal wave velocity and thickness of the plate, and 0.5% and 5% in the transverse wave velocity and the density, respectively.

An Automated Measurement System of Ultrasonic Properties of Tofu and Acorn Curd (Dotori Muk)

Tofu was suggested as Tissue Mimicking Materials (TMMs) due to its low cost, availability, gelatinous nature, and shape flexibility. However, the similarity in acoustic properties of the different packets of Tofu and acorn curd (Muk) is critical for TMMs but not fully investigated yet. In order to improve the accuracy for time-consuming and multi-stepped measurements of acoustic properties, an automated measurement system was developed. Using the automated system, the acoustic properties Tofu and Muk were measured to know whether they are similar among the different samples. In conclusion, the acoustic properties were measured to be similar among the different packets of Tofu and Muk, suggesting them as potential TMMs.

Directing ultrasound at the cemento-enamel junction (CEJ) of human teeth: I. Asymmetry of ultrasonic path lengths

The diagnosis of degenerative changes in human teeth is of general interest because early detections can avoid greater health problems and further weakening effects. Since the wear of teeth determines their stability and lifetime in relation to the physiological load, an ultrasonic survey of any dimensional changes of the enamel layer and especially of the dentin wall thickness may be very helpful. However, an ultrasonographic diagnosis requires first to determine the anisotropic human tooth properties at clinically relevant locations and to simulate wave propagation phenomena in inhomogeneous tooth models with proper dimensions. The first article of a series that provides modular data of mineralized tissues in human teeth at the cemento-enamel junction (CEJ) deals with an ultrasonic method for measuring the asymmetry of dimensional characteristics of extracted human teeth and their ultrasonic path lengths (UPL). Heavily attenuating tooth halves were investigated with respect to the symmetry of normal and inclined oppositely directed radial ultrasonic paths. The measured UPLs ranged from 1.2 mm to 4.4 mm. The relative difference in inclined UPLs between the left and the right tooth halves reaches almost 30%. This reveals a large asymmetry. The mean difference of angles that represent fastest path lengths was 2.2+/-8.1 degrees, which indicates large asymmetry and anisotropy. Several aspects, which are required for a proper integration of asymmetric data into models designed for medical element engineering and simulation (MEES), are discussed.