The importance of the analysis of the radiofrequency signal is by now recognized in the field of tissue characterization via ultrasound. The RF signal contains a wealth of information and structural details that are usually lost in the B-Mode representation. The HyperSPACE (Hyper SPectral Analysis for Characterization in Echography) algorithm presented by the authors in previous papers for clinical applications is based on the radiofrequency ultrasonic signal. The present work describes the method in detail and evaluates its performance in a repeatable and standardized manner, by using two test objects: a commercial test object that simulates the human parenchyma, and a laboratory-made test object consisting of human blood at different dilution values. In particular, the sensitivity and specificity in discriminating different density levels were estimated. In addition, the robustness of the algorithm with respect to the signal-to-noise ratio was also evaluated.
In literature, it is known that a Light Emitting Diode (LED) could be used as a light sensor. It is also known that its emitted light spectrum and sensitivity spectrum can be partially overlapped. This work presents how commercial LEDs can be used as light emitters and simultaneously as sensors of the reflected portion of the light emitted by themselves. The realized devices present a unique characteristic: the transmitter and the receiver coincide spatially as they are the same device. This ensures the perfect overlapping between transmission and reception radiation lobes that could provide many benefits in several applications like as distance measurements or image sensors. Some simple electronic configurations that use LEDs as detectors of their own emitted light are presented. It has been also demonstrated how these LEDs Tx-Rx can work as image sensors by acquiring an image of a simple test object, and how they can realize distance sensors with respect to other known techniques. Further advantages can be obtained by realizing LED Tx-Rx array in single integrated devices. With the realization of such devices, it will be also possible to experiment new constructive solutions for commonly used applications, without the need of using separate emitter and receiver.
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