We estimate the abundance of Compton-thick (CT) active galactic nuclei (AGN) based on our joint model of X-ray and infrared backgrounds. At Lrest2−10keV > 10 42 erg/s, the CT AGN density predicted by our model is a few ×10 Mpc from z=0 up to z=3. CT AGN with higher luminosity cuts (> 10, 10 & 10 erg/s) peak at higher z and show a rapid increase in the number density from z=0 to z∼2-3. The CT to...

Kisner, Sherman J. Ph.D., Purdue University, December 2013. Image Reconstruction for X-ray Computed Tomography in Security Screening Applications. Major Professor: Charles A. Bouman. X-ray tomographic systems have increasingly widespread use in security screening applications. For example, most major airports now utilize X-ray CT systems for efficient screening of baggage and cargo. While decad...

BACKGROUND Conventional X-ray urography is one of the basic imaging techniques in urinary tract diseases in children. CT urography (CTU) employing standard Filtered Back Projection (FBP) reconstruction algorithms is connected with higher radiation dose. Advanced iterative reconstruction techniques enable lowering the radiation dose to the level comparable with conventional X-ray urography with ...

Pulmonary barotrauma (PBT) is a recognised risk of compressed gas diving. Any reason that causes air trapping in the lung during ascent may cause PBT by increasing intrapulmonary pressure. Chest x ray examination is mandatory for medical certification of the professional divers in many countries, but pulmonary air trapping lesions such as an air cyst in the lungs cannot always be detected by pl...

Heterogeneous catalysis performed in the liquid phase is an important type of catalytic process which is rarely studied in situ. Using microfocus X-ray fluorescence and X-ray diffraction computed tomography (μ-XRF-CT, μ-XRD-CT) in combination with X-ray absorption near-edge spectroscopy (XANES), we have determined the active state of a Mo-promoted Pt/C catalyst (NanoSelect) for the liquid-phase...

X-ray computed tomography (CT) images obtained with a polychromatic X-ray source were simulated by computer for homogeneous solutions and suspensions containing a heavy element. When the K-edge of the element was near the peak energy of the polychromatic X-ray spectrum, the degree of beam hardening in the simulated CT image strongly depended on the atomic number and molar concentration of the ...

BACKGROUND The aim of this study was to evaluate the amount of radiation doses absorbed by soft tissues (entrance skin dose) with a low-dose spiral computed tomography (CT) protocol compared to conventional X-ray techniques commonly used in orthodontics. METHODS The amount of skin dose has been evaluated using a tissue-equivalent head-neck radiotherapy humanoid phantom with thermoluminescent ...

The superiority of magnetic resonance imaging (MRI) over X-ray computed tomography (CT) scanning in terms of sensitivity and specificity for identifying the aetiology of epilepsy in both adults and children is firmly established. The most common abnormalities identified are hippocampal sclerosis (HS), malformations of cortical development (MCD), vascular malformations, tumours, and acquired cor...

Current computed tomography (CT) scanners rotate fast to reduce motion artifact. X-ray tube must work in a high power to make the image clear under short exposure time. However, the life span of such a tube may be shortened. In this paper, we propose a novel double sources CT imaging system, which puts two of the same X-ray sources closely with each other. The system is different from current d...