1,721,066 research outputs found
Generalized diffraction enhanced imaging to retrieve absorption, refraction and scattering effects
No full text
Three-image diffraction enhanced imaging algorithm to extract absorption, refraction, and ultrasmall-angle scattering
No full textAs different methods to improve diffraction enhanced imaging are proposed, the authors introduce a simple algorithm that follows the original idea of Chapman et al. (Phys. Med. Biol. 42, 2015, 1997), but extend it to a general object featuring absorption, refraction, and ultrasmall-angle scattering. The information relative to the three effects is decoupled, requiring only three images in input. Simulation and experiment give accurate results, provided the refraction and scattering angles are small compared to the rocking curve width. The proposed algorithm can be readily and fruitfully implemented in several applications, particularly when time and dose constraints are relevant
Spectral micro-CT for simultaneous gold and iodine detection, and multi-material identification
Full text linkMultiple energy bin spectral micro-CT (SμCT) 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 SμCT 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.
On the possibility of utilizing scattering-based contrast agents in combination with diffraction enhanced imaging
No full text
Position-sensitive multi-wavelength photon detectors based on epitaxial InGaAs/InAlAs quantum wells
No full textBeam monitoring in synchrotron radiation or free electron laser facilities is extremely important for calibration and diagnostic issues. Here we propose an in-situ detector showing fast response and homogeneity for both diagnostics and calibration purposes. The devices are based on In0.75Ga0.25As/In0.75Al0.25As QWs, which offer several advantages due to their direct, low-energy band gap and high electron mobility at room temperature. A pixelation structure with 4 quadrants was developed on the back surface of the device, in order to fit commercially available readout chips.
The QW devices have been tested with collimated monochromatic X-ray beams from synchrotron radiation. A rise in the current noise with positive bias was observed, which could be due to deep traps for hole carriers. Therefore, an optimized negative bias was chosen to minimize dark currents and noise. A decrease in charge collection efficiency was experienced as the beam penetrates into deeper layers, where a dislocation network is present. The prototype samples showed that individual currents obtained from each quadrant allow the position of the beam to be monitored for all the utilized energies. These detectors have a potential to estimate the position of the beam with a precision of about 10 μm
Development and validation of a simulation tool for K-edge Subtraction imaging with polychromatic spectra and X-ray photon counting detectors
No full textIn K-Edge Subtraction (KES) imaging the K-edge of a high-Z contrast medium is used to generate a differential image in which, in principle, only the contrast agent is visible, suppressing any background. A possible approach to KES imaging is by using polychromatic spectra and spectral X-ray photon counting detectors (XPCD). In this paper we present the development and validation of a simulation tool for KES imaging with spectral XPCD. In addition an analytical formula, based on theoretical considerations, is derived, that further supports the simulation results. The validation is made on experimental data obtained with an X-ray tube, an iodine-based contrast agent, and Pixirad-1/Pixie-III detection system
- …
