545 research outputs found
Advantages of quasi-monochromatic X-ray sources in absorption mammography
No full textMammography is a challenging field of medical imaging. Early detection of breast cancer requires identifying small contrast details. The choice of the appropriate monochromatic energy enhances the visibility of such details. Thomson scattering source can provide tunable quasi-monochromatic X-ray beams. In this work, we investigate by Monte Carlo simulations the optimal monochromatic energy to image mammographic phantoms. In order to mimic a Thomson scattering source, we consider the effect on image quality of the presence of an energy spread and of the presence of higher-order harmonics
Sant’Imbenia (Alghero): further archaeometric evidence for an Iron Age market square
No full textLead isotope compositions were determined for 18 metal objects from the archaeological site of Sant'Imbenia, NW Sardinia, dating to the end of the 9th 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
New Techniques in Diagnostic X-ray Imaging: A Simulation Tool and Experimental Findings
No full textAbstractAbsorption 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
Visibility of tumor-like details in inline phase contrast mammography using quasi monochromatic X-ray sources
No full text
Visibility of tumor-like details in inline phase contrast mammography using quasimonochromatic X-ray sources
No full textA new generation of quasimonochromatic high-flux X-ray sources, based on the X-ray radiation
produced through Compton scattering between an electron beam and a laser beam, is under
development. One of the possible applications of this source is inline phase contrast mammography,
based on the observation of the edge-enhancement effect that can be observed at the border of structures
inside the breast in images produced using a partially or totally coherent X-ray beam. In this work we
present the results of a set of simulations of inline phase contrast mammography using typical inverse
Compton scattering sources parameters. The simulated sample was a tumour-like mass having spherical
shape, diameter between 200 mm and 5 mm, placed inside a breast-like matrix, 4 cm thick, and a
standard composition of 50% glandular tissue and 50% adipose tissue. We discuss the minimum
requirements for mammography using inverse Compton scattering sources and we discuss how the
working parameters of the experimental setup (focal spot size, source–object distance, object–detector
distance, detector point spread function, mean energy, energy bandwidth) affect the image quality, and
specifically the edge-enhancement visibility. In particular, we show that the energy bandwidth does not
significantly affect the visibility up to several keV. On the other hand, the edge-enhancement visibility
depends substantially on other parameters such as source–object distance and detector point spread
function
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