Maximum depth of penetration (DOP) is among the most relevant parameters in quality assurance programs for Ultrasound (US) scanners. Nowadays, a generally-accepted protocol for DOP estimation is still awaited and, in common practice, DOP is visually assessed despite the low accuracy. To overcome the eye-based assessment subjectivity, automatic image analysis methods have been proposed in literature. The present work focuses on a novel automatic method, namely the adaptive Signal to Noise Ratio (SNR) threshold method (AdSTM), developed in the MATLAB environment, by comparing it with an existing automatic approach, namely the tangent threshold method (TTM), and the mean judgment of eight observers (naked eye method). The three investigated methods were applied on data acquired from four US scanners for general purpose imaging, equipped with linear, convex, and vector array probes. Tests were carried out in two different configuration settings (raw scanner and default preset working conditions). AdSTM outcomes were tested by means of Monte Carlo Simulations. Most of measurement results were compatible despite the fact that the AdSTM seemed to be more sensitive and faster than the TTM. The results analysis confirms the higher dispersion of the naked eye method in DOP assessment with respect to the proposed automatic methods.
<p class="Abstract"><span lang="EN-US">The functional characterization of MEMS devices is relevant today since it aims at verifying the behavior of these devices, as well as improving their design. In this regard, this study focused on the functional characterization of a MEMS microgripper prototype suitable in biomedical applications: the measurement of the angular displacement of the microgripper comb-drive is carried out by means of two novel automatic procedures, based on an image analysis method, SURF-based (Angular Displacement Measurement based on Speeded Up Robust Features, ADM<sub>SURF</sub>) and FFT-based (Angular Displacement Measurement based on Fast Fourier Transform, ADM<sub>FFT</sub>) method, respectively. Moreover, the measurement results are compared with a Semi-Automatic Method (SAM), to evaluate which of them is the most suitable for the functional characterization of the device. The curve fitting of the outcomes from SAM and ADM<sub>SURF</sub>, showed a quadratic trend in agreement with the analytical model. Moreover, the ADM<sub>SURF</sub> measurements below 1° are affected by an uncertainty of about 0.08° for voltages less than 14 V, confirming its suitability for microgripper characterization. It was also evaluated that the ADM<sub>FFT</sub> is more suitable for measurement of rotations greater than 1° (up to 30°), with a measurement uncertainty of 0.02°, at 95% of confidence level.</span></p>
<span lang="EN-GB">Nowadays, Doppler system performance evaluation is a widespread issue because a shared worldwide standard is still awaited. Among the recommended Doppler test parameters, the lowest detectable signal could be considered mandatory in Quality Control (QC) protocols for Pulsed Wave (PW) Doppler. Such parameter is defined as the minimum signal level that can be clearly distinguished from noise and therefore, it is considered as related to PW Doppler sensitivity. The present study focuses on proposing and validating a novel image analysis based method for the estimation of the Lowest Detectable Signal in the spectrogram image (LDS<sub>IMG</sub>), namely Automatic Doppler Sensitivity Measurement Method (ADSMM), as well as to compare its results with the outcomes retrieved from the Naked Eye Doppler Sensitivity Method (NEDSM), based on the mean judgment of three independent observers. Data have been collected from a Doppler flow phantom, through three ultrasound systems for general purpose imaging, equipped with two linear array probes each and with two configuration settings. Results are globally compatible among the proposed methods, US systems and settings. Further studies could be carried out on a higher number of US diagnostic systems, Doppler frequencies and observers, as well as with different probe and phantom models.</span>
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