Abstract Multiple energy bin spectral micro-CT (S μ CT) is an advanced imaging technique that allows multi-material decomposition according to their specific absorption patterns at a sub-100 μm ...scale. Typically, iodine is the preferred CT contrast agent for cardiovascular imaging, while gold nanoparticles have gained attention in recent years owing to their high absorption properties, biocompatibility and ability to target tumors. In this work, we demonstrate the potential for multi-material decomposition through S μ CT imaging of a test sample at the PEPI lab of INFN Trieste. The sample, consisting of gold, iodine, calcium, and water, was imaged using a Pixirad1/PixieIII chromatic detector with multiple energy thresholds and a wide spectrum (100 kV) produced by a micro-focus X-ray tube. The results demonstrate the simultaneous detection and separation of the four materials at a spatial scale of 35 μm, suggesting the potential of this technique in improving material detectability and quantification in a range of pre-clinical applications, including cardiovascular and oncologic imaging.
Abstract Spectral K-edge subtraction (SKES) is an imaging technique that takes advantage of the sharp rise in the mass attenuation coefficient of specific elements within an object at their K-edge to ...produce separate and quantifiable distributions of each element. In this paper, a high-sensitivity and wide bandwidth SKES imaging system for computed tomography applications on biological samples is presented. X-ray images are acquired using a wide and continuous energy spectrum that encompasses the absorption edges of the target materials. System characterization shows that high energy resolution (approximately 3 × 10 − 3 ) and unprecedented large energy bandwidth (around 15%) are achieved over a field-of-view of several centimeters. Imaging results obtained on contrast elements relevant for biomedical applications, namely silver, iodine, xenon, and barium, demonstrate the system sensitivity to concentrations down to 0.5 mg ml −1 . The achievement of a large energy bandwidth allowed the simultaneous imaging of the K-edges of iodine, xenon, and barium and provided an accurate concentration estimation and distinction of co-localized contrast elements, leading the way for future simultaneous cardiovascular (iodine), pulmonary (xenon), and gastrointestinal/inflammatory (barium) imaging applications.
Abstract
The PEPI project is developing a new experimental facility integrating a chromatic photon-counting detector within an edge-illumination (EI) phase-contrast setup. In this context, a novel ...Geant4-based simulation tool has been introduced with the aim of defining the optimal design of the experimental setup. The code includes a custom X-ray refraction process and allows simulating the whole EI system, comprising a polychromatic and extended source, absorbing masks, substrates, their movement during acquisition, and X-ray detection. In this paper, a realistic spectral detector model is introduced and its energy response validated against experimental data acquired with synchrotron radiation at energies between 26 and 50 keV. Moreover, refraction and transmission images of a plastic phantom are reconstructed from simulation data and successfully compared with theoretical predictions. Finally, an optimization study aiming at finding the effect of the X-ray focal spot size (i.e. spatial coherence) on image quality is presented; the results suggest that, in the considered configuration, the system can tolerate source sizes up to 30 μm, while, for a fixed exposure time, the best signal-to-noise ratio in refraction images is found for source sizes in the order of 10 to 15 μm.
The mammography project at the SYRMEP beamline Dreossi, D; Abrami, A; Arfelli, F ...
European journal of radiology,
12/2008, Volume:
68, Issue:
3
Journal Article, Conference Proceeding
Peer reviewed
Abstract A clinical program for X-ray phase contrast (PhC) mammography with synchrotron radiation (SR) has been started in March 2006 at the SYRMEP beamline of Elettra, the SR facility in Trieste, ...Italy. The original beamline layout has been modified substantially and a clinical facility has been realized. In order to fulfill all security requirements, dedicated systems have been designed and implemented, following redundancy criteria and “fail safe” philosophy. Planar radiographic images are obtained by scanning simultaneously the patient and the detector through the stationary and laminar SR beam. In this first phase of the project a commercial screen-film system has been used as image receptor. Upon approval by the respective authorities, the mammography program is about half way to conclusion. Up to now about 50 patients have been examined. The patients are volunteers recruited by the radiologist after conventional examinations at the hospital resulted in an uncertain diagnosis. As an example one case of PhC SR mammography is shown and compared to conventional digital mammography. Preliminary analysis shows the high diagnostic quality of the PhC SR images that were acquired with equal or less delivered dose compared to the conventional ones.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Abstract
A state of the art commercial detector, a PCO Edge 4.2 bi based on a back illuminated sCMOS sensor developed for applications in the visible light/ultra violet regime has been adapted for ...ultra-high vacuum operations and has been characterized using soft X-ray in the energy range from 30 eV to 1000 eV. The imager features 2048 × 2048 pixel with a pixel size of 6.5 μm × 6.5 μm and allows full frame acquisitions at 48 Hz with a dynamic range of 88 dB at a noise level of 1.9
e
−
. Spatial resolution and quantum efficiency have been elucidated in the aforementioned energy range at a soft X-ray beam line at Elettra Sincrotrone Trieste. The handiness of the camera as well as its Python library package allows easy and fast integration into the beam line environments of synchrotron sources and free electron lasers.
In analyzer based imaging (ABI) scattering can be efficiently separated from refraction and absorption effects by acquiring three images of the sample. In the scattering image the lungs appear as ...areas of high intensity signal (area contrast), which is modulated by the local thickness of the scattering tissue intersecting the X-ray path. The scattering signal is also included in the so-called apparent absorption image, where it adds to the absorption contrast thanks to the extinction of rays which are deviated outside the analyzer crystal's acceptance window. The presence of scattering can be emphasized in the ratio between two images acquired with a strongly detuned and a perfectly tuned analyzer crystal, respectively: we name this ratio as the amplified scatter image. In this paper we present ABI scattering methods applied to postmortem mouse lung imaging to assess their diagnostic value. For this purpose images have been acquired at the SYRMEP beamline of the ELETTRA synchrotron in Trieste (Italy) with the Argus time delay integration CCD detector at a photon energy of 25 keV . Subsequently the parametric images, including the amplified scatter image have been obtained, and contrast and signal-to-noise ratio have been evaluated. It is noteworthy that images have been acquired with a radiation dose of some mGy, thus are compatible with dose restricted medical imaging settings such as mammography.
Abstract
III-V-compound semiconductors offer many advantages over silicon-based technologies traditionally used in solid-state photodetectors, especially in hard X-ray applications that require high ...detection efficiency and short response times. Amongst them, gallium arsenide (GaAs) has very promising characteristics in terms of X-ray absorption and high carrier velocity. Furthermore, implementing charge-multiplication mechanisms within the sensor may become of critical importance in cases where the photogenerated signal needs an intrinsic amplification before being acquired by the front-end electronics. This work reports on the experimental characterization by means of lasers and synchrotron radiation of gain, noise, and charge collection efficiencies of GaAs avalanche photodiodes (APDs), realized by molecular beam epitaxy (MBE), featuring separate absorption and multiplication regions (SAM) and different absorption region thicknesses. These devices have been fabricated to investigate the role of the thickness of the absorption region and of possible traps or defects at the metal-semiconductor interfaces in the collection efficiency in order to lay the groundwork for the future development of thicker GaAs devices for detection of hard X-rays.
We report the results of a systematic study of phase-contrast x-ray computed tomography in the propagation-based and analyser-based modes using specially designed phantoms and excised breast tissue ...samples. The study is aimed at the quantitative evaluation and subsequent optimization, with respect to detection of small tumours in breast tissue, of the effects of phase contrast and phase retrieval on key imaging parameters, such as spatial resolution, contrast-to-noise ratio, x-ray dose and a recently proposed 'intrinsic quality' characteristic which combines the image noise with the spatial resolution. We demonstrate that some of the methods evaluated in this work lead to substantial (more than 20-fold) improvement in the contrast-to-noise and intrinsic quality of the reconstructed tomographic images compared with conventional techniques, with the measured characteristics being in good agreement with the corresponding theoretical estimations. This improvement also corresponds to an approximately 400-fold reduction in the x-ray dose, compared with conventional absorption-based tomography, without a loss in the imaging quality. The results of this study confirm and quantify the significant potential benefits achievable in three-dimensional mammography using x-ray phase-contrast imaging and phase-retrieval techniques.
The PERCIVAL detector: first user experiments Correa, J.; Mehrjoo, M.; Battistelli, R. ...
Journal of synchrotron radiation,
January 2023, 2023-Jan-01, 2023-01-01, 20230101, 2023, Volume:
30, Issue:
1
Journal Article
Peer reviewed
Open access
The PERCIVAL detector is a CMOS imager designed for the soft X‐ray regime at photon sources. Although still in its final development phase, it has recently seen its first user experiments: ...ptychography at a free‐electron laser, holographic imaging at a storage ring and preliminary tests on X‐ray photon correlation spectroscopy. The detector performed remarkably well in terms of spatial resolution achievable in the sample plane, owing to its small pixel size, large active area and very large dynamic range; but also in terms of its frame rate, which is significantly faster than traditional CCDs. In particular, it is the combination of these features which makes PERCIVAL an attractive option for soft X‐ray science.
PERCIVAL is a detector system specifically designed for the soft X‐ray regime. Although still in a development phase, it has already served its first user experiments at both a storage ring and also a free‐electron laser. The device performed remarkably well in all the different techniques tested: ptychography, holography and also X‐ray photon correlation spectroscopy. The results of these tests are presented.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
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