314 research outputs found
Comparative evaluation of two methods for automatic evaluation of the accuracy in distance measurement performed by medical ultrasound scanners
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Preliminary study on a remote system for diagnostic-therapeutic postural measurements
No full textThe study refers to an experimental set up to achieve the remote control of a therapeutic-diagnostic system composed of (a) a local host, connected with (b) a rotating platform, (c) a helmet instrumented with transducers, (d) an audio-video acquisition system and (e) a webcam with microphone. The whole system is able to collect acquired signals related to some diagnostic parameters of a patient submitted to a body rotation applied by in an integrated service of home care assistance. On the basis of available scientific literature, the requirements of measuring and control remote system are investigated and some methods for the optimal data transmission between client (diagnostic station at hospital) and server (measurement station in home care assistance) were implemented by means of a set of virtual tools on Labview and the performances are evaluated. Sinusoidal signals were used to test the proposed device during operative conditions. Frequency sweep test signals were applied to the file server and the comparison between transmitted and received signals was adopted to estimate the effective
bandwidth of the whole system. Measurements are carried out in different experimental conditions within city areas. In
particular various connection types were tested, such as analogue telephone line and an asymmetric digital subscriber line: results confirm that by an appropriate bandwidth limit can be reached in order to fulfill the diagnostic system requirements
Use of phantoms and test objects for local dynamic range evaluation in medical ultrasounds: A preliminary study
No full textIn the ultrasound image the relationship between echo amplitudes and gray levels is expressed by means of the Grayscale Mapping Function (GMF), that is the greyscale transfer function associated with the echo displayed. The GMF allows the determination of some image quality parameters and quantities, among which the Local Dynamic Range (LDR) is relevant, since it is defined as the 20·log10 of the ratio of the minimum echo amplitude that yields the maximum grey level in the digitized image to that of the echo that yields the lowest grey level at the same location in the image and the same settings. This study reports the implementation of a method for the automatic determination of the LDR on medical ultrasound scanners and its application by means of a commercial grayscale ultrasound phantom, nevertheless it can be used also with general purpose phantoms: the LDR is obtained from the estimation of the GMF, based on processing of a sequence of uncompressed bidimensional ultrasound images provided by the scanner. In the manuscript, some theoretical considerations have been done to determine the GMF and its fitting model, as well as the LDR values, after that an experimental setup is described and some results are shown for an ultrasound system equipped with two different probes
Preliminary evaluation of a fiber-optic sensor for flow measurements in pulmonary ventilators
No full textA novel optical fiber air flow sensor was developed for monitoring flow rates supplied by infant ventilators. The device is based on a fiber optic sensing technique and overcomes some important shortcomings of biomedical applications, such as electromagnetic interference and possible electrical hazard. The sensing principle is based on measuring the displacement of an emitting optical fiber cantilever by means of a photodiode linear array: the detection of the illumination pattern makes the developed system less sensitive to light intensity source variations than intensity-based sensors. A preliminary evaluation of the relationship between displacement and flow rate is theoretically and experimentally conducted, as well as a measurement range up to 3.00•10-4 m3/s (18.0 l/min) has been verified, in accordance to the flow range usual for tidal breathing of infants
Functional and Metrological Issues in Arterial Simulators for Biomedical Testing Applications: A Review
No full textArterial simulators are a useful tool to simulate the cardiovascular system in many different
fields of application and to carry out in vitro tests that would constitute a danger when performed in
in vivo conditions. In the literature, a thriving series of in vitro experimental set-up examples can be
found. Nevertheless, in the current scientific panorama on this topic, it seems that organic research
from a metrological and functional perspective is still lacking. In this regard, the present review study
aims to make a contribution by analyzing and classifying the main concerns for the cardiovascular
simulators proposed in the literature from a metrological and functional point of view, according to
their field of application, as well as for the transducers in the arterial experimental set-ups, measuring
the main hemodynamic quantities in order to study their trends in specific testing conditions and to
estimate some parameters or indicators of interest for the scientific community
Optimisation of a sensor cluster for supersonic object trajectory and velocity determination
No full textAn evaluation of errors for a method for determination of trajectories and velocities of supersonic objects is conducted. The analytical study of a cluster, composed of three pressure transducers and generally used as an apparatus for cinematic determination of parameters of supersonic objects, is developed. Furthermore, detailed investigation into the accuracy of this cluster on determination of the slope of an incoming shock wave is carried out for optimization of the device. In particular, a specific non-dimensional parameter is proposed in order to evaluate accuracies for various values of parameters and reference graphs are provided in order to properly design the sensor cluster. Finally, on the basis of the error analysis conducted, a discussion on the best estimation of the relative distance for the sensor as a function of temporal resolution of the measuring system is presented
Fiber-optic flow sensor for the measurement of inspiratory efforts in mechanical neonatal ventilation
No full textA novel fiber-optic flow sensor has been developed for monitoring inspiratory efforts during neonatal mechanical ventilation. The considered sensor is based on fiber-optic sensing techniques, allowing the reduction of the effects due to electromagnetic interferences and a possible improvement of the electrical safety conditions. In the arrangement described here, the fiber-optic sensor is able to measure, with an accuracy of 5 %, flow variations in the range between 0.5 l/min and 5 l/min that are the typical flow variations due to infants' inspiratory attempts and typical flow trigger levels set during assist-control ventilation (ACV). Moreover, a good agreement (r 2 = 0.998) between experimental data and the parabolic theoretical model can be deduced. The metrological characteristics confirm that the novel proposed configuration for the optical fiber air flow sensor is suitable for monitoring flow variations due to infants' inspiratory attempts
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