23,092 research outputs found
The clinical application of PET/CT: a contemporary review
The combination of positron emission tomography (PET) scanners and x-ray computed tomography (CT) scanners into a single PET/CT scanner has resulted in vast improvements in the diagnosis of disease, particularly in the field of oncology. A decade on from the publication of the details of the first PET/CT scanner, we review the technology and applications of the modality. We examine the design aspects of combining two different imaging types into a single scanner, and the artefacts produced such as attenuation correction, motion and CT truncation artefacts. The article also provides a discussion and literature review of the applications of PET/CT to date, covering detection of tumours, radiotherapy treatment planning, patient management, and applications external to the field of oncology
Image quality and dosimetry of a dual source computed tomography scanner with special emphasis on radiation dose of lung in a chest examination
The purpose of the current study was to evaluate the Dual Source Computed Tomography scanner in terms of Image quality and dosimetry with special emphasis of radiation dose of lung in a Chest examination.Zielsetzung der Studie war die Evaluation eines Dual-Source-Computertomographen hinsichtlich Bildqualität und Dosimetrie mit speziellem Fokus auf der Lungendosis in Thoraxuntersuchungen
A LEKID-based CMB instrument design for large-scale observations in Greenland
We present the results of a feasibility study, which examined deployment of a
ground-based millimeter-wave polarimeter, tailored for observing the cosmic
microwave background (CMB), to Isi Station in Greenland. The instrument for
this study is based on lumped-element kinetic inductance detectors (LEKIDs) and
an F/2.4 catoptric, crossed-Dragone telescope with a 500 mm aperture. The
telescope is mounted inside the receiver and cooled to K by a
closed-cycle He refrigerator to reduce background loading on the detectors.
Linearly polarized signals from the sky are modulated with a metal-mesh
half-wave plate that is rotated at the aperture stop of the telescope with a
hollow-shaft motor based on a superconducting magnetic bearing. The modular
detector array design includes at least 2300 LEKIDs, and it can be configured
for spectral bands centered on 150~GHz or greater. Our study considered
configurations for observing in spectral bands centered on 150, 210 and
267~GHz. The entire polarimeter is mounted on a commercial precision rotary air
bearing, which allows fast azimuth scan speeds with negligible vibration and
mechanical wear over time. A slip ring provides power to the instrument,
enabling circular scans (360 degrees of continuous rotation). This mount, when
combined with sky rotation and the latitude of the observation site, produces a
hypotrochoid scan pattern, which yields excellent cross-linking and enables
34\% of the sky to be observed using a range of constant elevation scans. This
scan pattern and sky coverage combined with the beam size (15~arcmin at
150~GHz) makes the instrument sensitive to in the angular
power spectra
Multi-Energy Blended CBCT Spectral Imaging Using a Spectral Modulator with Flying Focal Spot (SMFFS)
Cone-beam CT (CBCT) spectral imaging has great potential in medical and
industrial applications, but it is very challenging as scatter and spectral
effects are seriously twisted. In this work, we present the first attempt to
develop a stationary spectral modulator with flying focal spot (SMFFS)
technology as a promising, low-cost approach to accurately solving the X-ray
scattering problem and physically enabling spectral imaging in a unified
framework, and with no significant misalignment in data sampling of spectral
projections. Based on an in-depth analysis of optimal energy separation from
different combinations of modulator materials and thicknesses, we present a
practical design of a mixed two-dimensional spectral modulator that can
generate multi-energy blended CBCT spectral projections. To deal with the
twisted scatter-spectral challenge, we propose a novel scatter-decoupled
material decomposition (SDMD) method by taking advantage of a scatter
similarity in SMFFS. A Monte Carlo simulation is conducted to validate the
strong similarity of X-ray scatter distributions across the flying focal spot
positions. Both numerical simulations using a clinical abdominal CT dataset,
and physics experiments on a tabletop CBCT system using a GAMMEX multi-energy
CT phantom, are carried out to demonstrate the feasibility of our proposed SDMD
method for CBCT spectral imaging with SMFFS. In the physics experiments, the
mean relative errors in selected ROI for virtual monochromatic image (VMI) are
0.9\% for SMFFS, and 5.3\% and 16.9\% for 80/120 kV dual-energy cone-beam scan
with and without scatter correction, respectively. Our preliminary results show
that SMFFS can effectively improve the quantitative imaging performance of
CBCT.Comment: 10 pages, 13 figure
Scanning protocol optimisation for dual-energy computed tomography angiography in peripheral artery stenting
In this thesis, a novel approach has been proposed to evaluate the optimal scanning protocol for dual energy computed tomography angiography in peripheral arterial stents. This new approach includes evaluation of different protocols and image reconstructions at different energy level, development of the optimal protocol based on lowest radiation dose and acceptable image quality. Furthermore, an optimal contrast medium protocol has been identified in imaging peripheral arterial disease
Snowmass CF1 Summary: WIMP Dark Matter Direct Detection
As part of the Snowmass process, the Cosmic Frontier WIMP Direct Detection
subgroup (CF1) has drawn on input from the Cosmic Frontier and the broader
Particle Physics community to produce this document. The charge to CF1 was (a)
to summarize the current status and projected sensitivity of WIMP direct
detection experiments worldwide, (b) motivate WIMP dark matter searches over a
broad parameter space by examining a spectrum of WIMP models, (c) establish a
community consensus on the type of experimental program required to explore
that parameter space, and (d) identify the common infrastructure required to
practically meet those goals.Comment: Snowmass CF1 Final Summary Report: 47 pages and 28 figures with a 5
page appendix on instrumentation R&
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