Quantitative Assessment of Penetration Depth in Clinical Ultrasound Systems

2007 ◽  
Author(s):  
Franco Marinozzi ◽  
Fabiano Bini ◽  
Federico Patane` ◽  
Daniele Piras
Keyword(s):  
Penetration Depth ◽  
Correlation Coefficient ◽  
Quantitative Assessment ◽  
Signal To Noise Ratio ◽  
Electronic Noise ◽  
Grey Level ◽  
Signal To Noise ◽  
Time And Space ◽  
Depth Of Penetration ◽  
Speckle Contrast

Most of the recent studies for image uniformity assessment involve signal to noise ratio (SNR) analysis computed over various combinations of mean grey level and variance [1–2] to quantify the speckle contrast and hence the depth of penetration (DOP). Speckle is auto correlated in time but not in space. Electronic noise always present at the bottom of the image, instead, is uncorrelated both in time and space. The extension of the area in which only the speckle is visible, gives an estimate of the penetration depth. The correlation coefficient of two subsequently acquired frames can be computed to quantify image uniformity where depth at which the correlation coefficient falls below a fixed threshold is defined as penetration depth.

scholarly journals Proof-of-Principle of a Cherenkov-Tag Detector Prototype

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3437
Author(s):  
Giuseppe Gallo ◽  
Domenico Lo Presti ◽  
Danilo Luigi Bonanno ◽  
Giovanni Bonanno ◽  
Paola La Rocca ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Preliminary Test ◽  
Correct Identification ◽  
Electronic Noise ◽  
Signal To Noise ◽  
Transparent Material ◽  
Muon Tracking ◽  
The University ◽  
Reduced Scale ◽  
Proof Of Principle

In a recent paper, the authors discussed the feasibility study of an innovative technique based on the directionality of Cherenkov light produced in a transparent material to improve the signal to noise ratio in muon imaging applications. In particular, the method was proposed to help in the correct identification of incoming muons direction. After the first study by means of Monte Carlo simulations with Geant4, the first reduced scale prototype of such a detector was built and tested at the Department of Physics and Astronomy "E. Majorana" of the University of Catania (Italy). The characterization technique is based on muon tracking by means of the prototype in coincidence with two scintillating tiles. The results of this preliminary test confirm the validity of the technique and stressed the importance to enhance the Cherenkov photons production to get a signal well distinguishable with respect to sensors and electronic noise.

Performance Analysis of OFDM Channel System

2011 ◽  
Vol 268-270 ◽  
pp. 1438-1446
Author(s):  
Zhang Lei ◽  
Cong Feng Liu ◽  
Wei Jiang ◽  
Gui Zhou Xu ◽  
Ning Dai
Keyword(s):  
Channel Estimation ◽  
Correlation Coefficient ◽  
Signal To Noise Ratio ◽  
Estimation Error ◽  
Error Model ◽  
Channel Estimation Error ◽  
Ofdm Systems ◽  
Signal To Noise ◽  
Estimation Scheme ◽  
Complex Correlation

OFDM is a promising digital communications technique for high data rate transmissions. In this paper, we have analyzed the performance of mobile OFDM systems in the presence of channel estimation error. A new channel estimation error model is presented. Based on the estimation error model, new and simple expressions for the average bit error probability of M-QAM OFDM systems are derived for zero-forcing, minimum mean square error and maximum likelihood receivers. A complex correlation coefficient is used to quantify the quality of the channel estimation scheme. We have shown that if the complex correlation coefficient is a function of the signal to noise ratio, then the inter-carrier interference caused by channel variations is the dominant source of performance degradation. On the other hand, if the channel estimation scheme produces a constant value for the complex correlation coefficient (estimation quality is not a function of the signal to noise ratio), then the channel estimation error will cause an error floor that is larger than the one caused by the inter-carrier interference, and is considered as one of the dominant causes of degradation. And channel estimation using pilot symbols are discussed in terms of different pilot symbol placement schemes.

scholarly journals Contribution of Statistical Iterative Reconstruction Algorithm For Orthopaedic Applications: A Study With A Cone-Beam CT Prototype

2021 ◽  
Author(s):  
Stéphanie Uk ◽  
Fanny Morin ◽  
Valerie Bousson ◽  
Rémy Nizard ◽  
Guillaume Bernard ◽  
...  
Keyword(s):  
Trabecular Bone ◽  
Orthopaedic Surgery ◽  
Signal To Noise Ratio ◽  
Cone Beam Ct ◽  
Qualitative Assessment ◽  
Cone Beam ◽  
Angular Range ◽  
Grey Level ◽  
Signal To Noise

Abstract Three-dimensional reconstruction for image-guidance in orthopaedic surgery necessitates a high degree of geometrical precision but not necessary structure details. With the aim to reduce as much as possible the dose, a cone beam CT prototype was tested with decreasing intensities, the number of projections or different angular range. We tested two methods of reconstruction: classical Feldkamp-Davis-Kress (FDK) reconstruction and the Simultaneous Algebraic Reconstruction Technic with Total Variation (SART-TV). Based on this protocol, on a knee cadaveric specimen, we combined qualitative assessment performed by radiologists and orthopedic surgeons, objective metrics of image quality such as signal-to-noise ratio, or related to bone geometric contour, grey level restitution and texture of trabecular bone, and finally the quality of joint space segmentation. Objective indicators related to signal-to-noise ratio, the quality of geometry and segmentation have shown better results for SART-TV than FDK in case of decrease projections number and angular range. On the contrary, qualitative assessment, and indexes about grey level restitution and textural quality of trabecular bone produced the best results for FDK reconstruction. These results showed that SART-TV reconstruction has a good capability to restore the geometry in case of low dose protocol and consequently could be a good candidate for orthopaedic surgery.

scholarly journals Planetary radar science case for EISCAT 3D

2021 ◽  
Vol 39 (3) ◽  
pp. 427-438
Author(s):  
Torbjørn Tveito ◽  
Juha Vierinen ◽  
Björn Gustavsson ◽  
Viswanathan Lakshmi Narayanan
Keyword(s):  
High Resolution ◽  
Radio Wave ◽  
Penetration Depth ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Physical Structure ◽  
The Moon ◽  
Signal To Noise ◽  
Resolution Mapping ◽  
Scattering Maps

Abstract. Ground-based inverse synthetic aperture radar is a tool that can provide insights into the early history and formative processes of planetary bodies in the inner solar system. This information is gathered by measuring the scattering matrix of the target body, providing composite information about the physical structure and chemical makeup of its surface and subsurface down to the penetration depth of the radio wave. This work describes the technical capabilities of the upcoming 233 MHz European Incoherent Scatter Scientific Association (EISCAT) 3D radar facility for measuring planetary surfaces. Estimates of the achievable signal-to-noise ratios for terrestrial target bodies are provided. While Venus and Mars can possibly be detected, only the Moon is found to have sufficient signal-to-noise ratio to allow high-resolution mapping to be performed. The performance of the EISCAT 3D antenna layout is evaluated for interferometric range–Doppler disambiguation, and it is found to be well suited for this task, providing up to 20 dB of separation between Doppler northern and southern hemispheres in our case study. The low frequency used by EISCAT 3D is more affected by the ionosphere than higher-frequency radars. The magnitude of the Doppler broadening due to ionospheric propagation effects associated with traveling ionospheric disturbances has been estimated. The effect is found to be significant but not severe enough to prevent high-resolution imaging. A survey of lunar observing opportunities between 2022 and 2040 is evaluated by investigating the path of the sub-radar point when the Moon is above the local radar horizon. During this time, a good variety of look directions and Doppler equator directions are found, with observations opportunities available for approximately 10 d every lunar month. EISCAT 3D will be able to provide new, high-quality polarimetric scattering maps of the nearside of the Moon with the previously unused wavelength of 1.3 m, which provides a good compromise between radio wave penetration depth and Doppler resolution.

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