65 research outputs found
New Techniques in Diagnostic X-ray Imaging: A Simulation Tool and Experimental Findings
Abstract Absorption X-ray imaging is a well-established technique. However it is still a challenging task in its search for a compromise between the need for high spatial resolution and high contrast and the request to keep the dose delivered to the patient within acceptable values. New imaging techniques are under investigation, like the use of new X-ray sources, phase contrast imaging or K-edge imaging. Monte Carlo or analytic simulations are often the best way to test and predict the effectiveness of these techniques. A new simulation tool for X-ray imaging will be presented together with some applications to the characterization of new X-ray sources, in-line phase contrast effect and angiographic K-edge imaging. Simulation results will be compared also with experimental dat
Optimization of the energy for Breast monochromatic absorption X-ray Computed Tomography
The limits of mammography have led to an increasing interest on possible alternatives such as the
breast Computed Tomography (bCT). The common goal of all X-ray imaging techniques is to achieve the
optimal contrast resolution, measured through the Contrast to Noise Ratio (CNR), while minimizing the
radiological risks, quantified by the dose. Both dose and CNR depend on the energy and the intensity
of the X-rays employed for the specific imaging technique. Some attempts to determine an optimal
energy for bCT have suggested the range 22keV\u201334keV, some others instead suggested the range
50keV\u201360keV depending on the parameters considered in the study. Recent experimental works, based
on the use of monochromatic radiation and breast specimens, show that energies around 32keV give
better image quality respect to setups based on higher energies. In this paper we report a systematic
study aiming at defining the range of energies that maximizes the CNR at fixed dose in bCT. The
study evaluates several compositions and diameters of the breast and includes various reconstruction
algorithms as well as different dose levels. The results show that a good compromise between CNR and
dose is obtained using energies around 28keV
A New automatic system of cell colony counting
The counting process of cell colonies is always a long
and laborious process that is dependent on the judgment and ability
of the operator. The judgment of the operator in counting can vary in
relation to fatigue. Moreover, since this activity is time consuming it
can limit the usable number of dishes for each experiment. For these
purposes, it is necessary that an automatic system of cell colony
counting is used. This article introduces a new automatic system of
counting based on the elaboration of the digital images of cellular
colonies grown on petri dishes. This system is mainly based on the
algorithms of region-growing for the recognition of the regions of
interest (ROI) in the image and a Sanger neural net for the
characterization of such regions. The better final classification is
supplied from a Feed-Forward Neural Net (FF-NN) and confronted
with the K-Nearest Neighbour (K-NN) and a Linear Discriminative
Function (LDF). The preliminary results are shown
Sant'Imbenia (Alghero): further archaeometric evidence for an Iron Age market square
AbstractLead isotope compositions were determined for 18 metal objects from the archaeological site of Sant'Imbenia, NW Sardinia, dating to the end of the ninth century BCE onwards. The provenance of some objects is unambiguously traced to SW Sardinia; other objects could derive either from central Sardinia or the Iberian coastal ranges. The variety of the provenances attests to a wide trade network that spanned the entire island of Sardinia and extended to the Iberian sites
Correction to: Sant'Imbenia (Alghero): further archaeometric evidence for an Iron Age market square
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Imaging spectroscopic performances for a Si based detection system
We present the imaging and spectroscopic capabilities of a system based on a single photon counting chip (PCC) bump-bonded on a Si pixel detector. The system measures the energy spectrum and the flux, produced by a standard mammographic tube. We have also made some images of low contrast details, achieving good results
Evaluation of Altered Functional Connections in Male Children with Autism Spectrum Disorders on Multiple-Site Data Optimized with Machine Learning
Phase-contrast breast CT: the effect of propagation distance
X-ray phase imaging has the potential to dramatically improve soft tissue contrast sensitivity, which is a crucial requirement in many diagnostic applications such as breast imaging. In this context, a program devoted to perform in-vivo phase-contrast synchrotron radiation breast computed tomography is ongoing at the Elettra facility (Trieste, Italy). The used phase-contrast technique is the propagation-based configuration, which requires a spatially coherent source and a sufficient object-to-detector distance. In this work the effect of this distance on image quality is quantitatively investigated scanning a large breast surgical specimen at 3 object-to-detector distances (1.6, 3, 9 m) and comparing the images both before and after applying the phase-retrieval procedure. The sample is imaged at 30 keV with a 60 \ub5m pixel pitch CdTe single-photon-counting detector, positioned at a fixed distance of 31.6~m from the source. The detector fluence is kept constant for all acquisitions. The study shows that, at the largest distance, a 20-fold SNR increase can be obtained by applying the phase-retrieval procedure. Moreover, it is shown that, for phase-retrieved images, changing the object-to-detector distance does not affect spatial resolution while boosting SNR (4-fold increase going from the shortest to the largest distance). The experimental results are supported by a theoretical model proposed by other authors, whose salient results are presented in this paper
Experimental study of Compton scattering reduction in digital mammographic imaging
In mammography, the first cause of image contrast reduction arises from the photons scattered inside the examined organ. The amount of Compton scattering strongly depends on the irradiation area and on the distance between the organ and the X-ray detector. We have experimentally evaluated how these geometrical conditions affect the scattering fraction. Our experimental setup includes a single photon counting device based on a silicon pixel detector as X-ray sensor; a lucite cylinder to simulate the breast tissue, and a lead collimator to define the irradiation area. We have evaluated the contrast and the signal-to-noise ratio for images acquired in different conditions
Muonic atom X-ray spectroscopy for non-destructive analysis of archeological samples
The implementation in the RIKEN-RAL negative muons facility of a new muon beamline monitoring and novel digital data acquisition system for gamma and X-ray spectroscopy are presented. This work also shows the high potential of the muonic atoms X-ray spectroscopy technique in non-destructive elemental characterization of archaeological samples
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