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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Validation of a virtual source model for Monte Carlo dose calculations of a flattening filter free linac

Purpose: A linac delivering intensity-modulated radiotherapy (IMRT) can benefit from a flattening filter free (FFF) design which offers higher dose rates and reduced accelerator head scatter than for conventional (flattened) delivery. This reduction in scatter simplifies beam modeling, and combining a Monte Carlo dose engine with a FFF accelerator could potentially increase dose calculation accuracy. The objective of this work was to model a FFF machine using an adapted version of a previously published virtual source model (VSM) for Monte Carlo calculations and to verify its accuracy. Methods: An Elekta Synergy linear accelerator operating at 6 MV has been modified to enable irradiation both with and without the flattening filter (FF). The VSM has been incorporated into a commercially available treatment planning system (Monaco Trade-Mark-Sign v 3.1) as VSM 1.6. Dosimetric data were measured to commission the treatment planning system (TPS) and the VSM adapted to account for the lack of angular differential absorption and general beam hardening. The model was then tested using standard water phantom measurements and also by creating IMRT plans for a range of clinical cases. Results: The results show that the VSM implementation handles the FFF beams very well, with an uncertainty between measurement and calculation of <1% which is comparable to conventional flattened beams. All IMRT beams passed standard quality assurance tests with >95% of all points passing gamma analysis ({gamma} < 1) using a 3%/3 mm tolerance. Conclusions: The virtual source model for flattened beams was successfully adapted to a flattening filter free beam production. Water phantom and patient specific QA measurements show excellent results, and comparisons of IMRT plans generated in conventional and FFF mode are underway to assess dosimetric uncertainties and possible improvements in dose calculation and delivery.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

TU-F-18A-09: CT Number Stability Across Patient Sizes Using Virtual-Monoenergetic Dual-Energy CT

Purpose: Virtual-monoenergetic imaging uses dual-energy CT data to synthesize images corresponding to a single photon energy, thereby reducing beam-hardening artifacts. This work evaluated the ability of a commercial virtual-monoenergetic algorithm to achieve stable CT numbers across patient sizes. Methods: Test objects containing a range of iodine and calcium hydroxyapatite concentrations were placed inside 8 torso-shaped water phantoms, ranging in lateral width from 15 to 50 cm, and scanned on a dual-source CT system (Siemens Somatom Force). Single-energy scans were acquired from 70-150 kV in 10 kV increments; dual-energy scans were acquired using 4 energy pairs (low energy: 70, 80, 90, and 100 kV; high energy: 150 kV + 0.6 mm Sn). CTDIvol was matched for all single- and dual-energy scans for a given phantom size. All scans used 128×0.6 mm collimation and were reconstructed with 1-mm thickness at 0.8-mm increment and a medium smooth body kernel. Monoenergetic images were generated using commercial software (syngo Via Dual Energy, VA30). Iodine contrast was calculated as the difference in mean iodine and water CT numbers from respective regions-of-interest in 10 consecutive images. Results: CT numbers remained stable as phantom width varied from 15 to 50 cm for all dual-energy data sets (except for at 50 cm using 70/150Sn due to photon starvation effects). Relative to the 15 cm phantom, iodine contrast was within 5.2% of the 70 keV value for phantom sizes up to 45 cm. At 90/150Sn, photon starvation did not occur at 50 cm, and iodine contrast in the 50-cm phantom was within 1.4% of the 15-cm phantom. Conclusion: Monoenergetic imaging, as implemented in the evaluated commercial system, eliminated the variation in CT numbers due to patient size, and may provide more accurate data for quantitative tasks, including radiation therapy treatment planning. Siemens Healthcare.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2015

Technical Note: Relation between dual-energy subtraction of CT images for electron density calibration and virtual monochromatic imaging

Purpose: For accurate tissue inhomogeneity correction in radiotherapy treatment planning, the author previously proposed a simple conversion of the energy-subtracted computed tomography (CT) number to an electron density (ΔHU–ρ{sub e} conversion), which provides a single linear relationship between ΔHU and ρ{sub e} over a wide ρ{sub e} range. The purpose of the present study was to reveal the relation between the ΔHU image for ρ{sub e} calibration and a virtually monochromatic CT image by performing numerical analyses based on the basis material decomposition in dual-energy CT. Methods: The author determined the weighting factor, α{sub 0}, of the ΔHU–ρ{sub e} conversion through numerical analyses of the International Commission on Radiation Units and Measurements Report-46 human body tissues using their attenuation coefficients and given ρ{sub e} values. Another weighting factor, α(E), for synthesizing a virtual monochromatic CT image from high- and low-kV CT images, was also calculated in the energy range of 0.03 < E < 5 MeV, assuming that cortical bone and water were the basis materials. The mass attenuation coefficients for these materials were obtained using the XCOM photon cross sections database. The effective x-ray energies used to calculate the attenuation were chosen to imitate a dual-source CT scanner operated at 80–140 and 100–140 kV/Sn. Results: The determined α{sub 0} values were 0.455 for 80–140 kV/Sn and 0.743 for 100–140 kV/Sn. These values coincided almost perfectly with the respective maximal points of the calculated α(E) curves located at approximately 1 MeV, in which the photon-matter interaction in human body tissues is exclusively the incoherent (Compton) scattering. Conclusions: The ΔHU image could be regarded substantially as a CT image acquired with monoenergetic 1-MeV photons, which provides a linear relationship between CT numbers and electron densities.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Performance of today’s dual energy CT and future multi energy CT in virtual non-contrast imaging and in iodine quantification: A simulation study

Purpose: To study the performance of different dual energy computed tomography (DECT) techniques, which are available today, and future multi energy CT (MECT) employing novel photon counting detectors in an image-based material decomposition task. Methods: The material decomposition performance of different energy-resolved CT acquisition techniques is assessed and compared in a simulation study of virtual non-contrast imaging and iodine quantification. The material-specific images are obtained via a statistically optimal image-based material decomposition. A projection-based maximum likelihood approach was used for comparison with the authors’ image-based method. The different dedicated dual energy CT techniques are simulated employing realistic noise models and x-ray spectra. The authors compare dual source DECT with fast kV switching DECT and the dual layer sandwich detector DECT approach. Subsequent scanning and a subtraction method are studied as well. Further, the authors benchmark future MECT with novel photon counting detectors in a dedicated DECT application against the performance of today’s DECT using a realistic model. Additionally, possible dual source concepts employing photon counting detectors are studied. Results: The DECT comparison study shows that dual source DECT has the best performance, followed by the fast kV switching technique and the sandwich detector approach. Comparing DECT with future MECT, the authors found noticeable material image quality improvements for an ideal photon counting detector; however, a realistic detector model with multiple energy bins predicts a performance on the level of dual source DECT at 100 kV/Sn 140 kV. Employing photon counting detectors in dual source concepts can improve the performance again above the level of a single realistic photon counting detector and also above the level of dual source DECT. Conclusions: Substantial differences in the performance of today’s DECT approaches were found for the application of virtual non-contrast and iodine imaging. Future MECT with realistic photon counting detectors currently can only perform comparably to dual source DECT at 100 kV/Sn 140 kV. Dual source concepts with photon counting detectors could be a solution to this problem, promising a better performance.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-C-BRA-07: Virtual Bronchoscopy-Guided IMRT Planning for Mapping and Avoiding Radiation Injury to the Airway Tree in Lung SAbR

Purpose: Post-treatment radiation injury to central and peripheral airways is a potentially important, yet under-investigated determinant of toxicity in lung stereotactic ablative radiotherapy (SAbR). We integrate virtual bronchoscopy technology into the radiotherapy planning process to spatially map and quantify the radiosensitivity of bronchial segments, and propose novel IMRT planning that limits airway dose through non-isotropic intermediate- and low-dose spillage. Methods: Pre- and ∼8.5 months post-SAbR diagnostic-quality CT scans were retrospectively collected from six NSCLC patients (50–60Gy in 3–5 fractions). From each scan, ∼5 branching levels of the bronchial tree were segmented using LungPoint, a virtual bronchoscopic navigation system. The pre-SAbR CT and the segmented bronchial tree were imported into the Eclipse treatment planning system and deformably registered to the planning CT. The five-fraction equivalent dose from the clinically-delivered plan was calculated for each segment using the Universal Survival Curve model. The pre- and post-SAbR CTs were used to evaluate radiation-induced segmental collapse. Two of six patients exhibited significant segmental collapse with associated atelectasis and fibrosis, and were re-planned using IMRT. Results: Multivariate stepwise logistic regression over six patients (81 segments) showed that D0.01cc (minimum point dose within the 0.01cc receiving highest dose) was a significant independent factor associated with collapse (odds-ratio=1.17, p=0.010). The D0.01cc threshold for collapse was 57Gy, above which, collapse rate was 45%. In the two patients exhibiting segmental collapse, 22 out of 32 segments showed D0.01cc >57Gy. IMRT re-planning reduced D0.01cc below 57Gy in 15 of the 22 segments (68%) while simultaneously achieving the original clinical plan objectives for PTV coverage and OAR-sparing. Conclusion: Our results indicate that the administration of lung SAbR can Result in significant injury to bronchial segments, potentially impairing post-SAbR lung function. To our knowledge, this is the first investigation of functional avoidance based on mapping and minimizing dose to individual bronchial segments. The presenting author receives research funding from Varian Medical Systems, Elekta, and VisionRT.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-F-BRD-11: A Virtual Simulator Designed for Collision Prevention in Proton Therapy

Purpose: In proton therapy, collisions between patient and nozzle potentially occur in attaining minimal air gap due to the large nozzle structure. Thus, we developed software predicting the collisions of the nozzle and patient by simulating treatments. Methods: 3D modeling of a gantry inner-floor, nozzle and robotic-couch was done by using the SolidWorks based on the manufacturer’s machine data. To obtain patient body information, a 3D-scanner was utilized to scan a patient right before CT scanning. From the acquired images, a 3D-image of the patient’s body contour was reconstructed. The accuracy of the image was confirmed against the CT image for a humanoid phantom. The machine components and the virtual patient were combined on the treatment-room coordinate system, resulting in a virtual simulator. The simulator simulated the motion of its components such as rotation and translation of gantry, nozzle and couch, in real scale. Collision, if any, was examined both in static mode and dynamic mode. The static mode checks only at fixed positions of the machine’s components while dynamic mode examines while one component is in motion. Collision was notified if any voxel of two components, for example a nozzle and a patient or couch, overlapped when calculating volume locations. The event and collision point are visualized and colliding volumes are reported. Results: All components were successfully assembled and the motions could be accurately controlled. The 3D-shape of a phantom agreed with CT images within a deviation of 2 mm. Collision situations can be simulated within minutes and the results are displayed and reported. Conclusion: The developed software will be useful in improving patient safety and clinical efficiency for proton therapy. This work was supported by the National Research Foundation of Korea funded by Ministry of Science, ICT & Future Planning (2012M3A9B6055201, 2013M2A2A7043507), and Samsung Medical Center grant (GFO1130081)

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

MO-D-213-08: Remote Dosimetric Credentialing for Clinical Trials with the Virtual EPID Standard Phantom Audit (VESPA)

Purpose: Report on implementation of a Virtual EPID Standard Phantom Audit (VESPA) for IMRT to support credentialing of facilities for clinical trials. Data is acquired by local facility staff and transferred electronically. Analysis is performed centrally. Methods: VESPA is based on published methods and a clinically established IMRT QA procedure, here extended to multi-vendor equipment. Facilities, provided with web-based comprehensive instructions and CT datasets, create IMRT treatment plans. They deliver the treatments directly to their EPID without phantom or couch in the beam. They also deliver a set of simple calibration fields. Collected EPID images are uploaded electronically. In the analysis, the dose is projected back into a virtual phantom and 3D gamma analysis is performed. 2D dose planes and linear dose profiles can be analysed when needed for clarification. Results: Pilot facilities covering a range of planning and delivery systems have performed data acquisition and upload successfully. Analysis showed agreement comparable to local experience with the method. Advantages of VESPA are (1) fast turnaround mainly driven by the facility’s capability to provide the requested EPID images, (2) the possibility for facilities performing the audit in parallel, as there is no need to wait for a phantom, (3) simple and efficient credentialing for international facilities, (4) a large set of data points, and (5) a reduced impact on resources and environment as there is no need to transport heavy phantoms or audit staff. Limitations of the current implementation of VESPA for trials credentialing are that it does not provide absolute dosimetry, therefore a Level 1 audit still required, and that it relies on correctly delivered open calibration fields, which are used for system calibration. Conclusion: The implemented EPID based IMRT audit system promises to dramatically improve credentialing efficiency for clinical trials and wider applications. VESPA for VMAT will follow soon.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

TU-CD-304-07: Intensity Modulated Electron Beam Therapy Employing Small Fields in Virtual Scanning Mode

Purpose: Dynamic electron radiation therapies such as dynamic electron arc radiotherapy (DEAR) utilize small fields to provide target conformity and fluence modulation. The purpose of this study is to demonstrate the feasibility of virtual scanning mode using small fields. Methods: Monte Carlo simulations (EGSnrc/BEAMnrc/DOSXYZnrc) were performed using validated Varian TrueBeam phase space files for electron beam energies of 6, 9, 12, and 16 MeV and square/circular fields (1×1/1, 2×2/2, 3×3/3, 4×4/4, 5×5/5 cm{sup 2}/cm diameter). Resulting dose distributions (kernels) were used for subsequent calculations. The following analyses were performed: (1) Comparison of composite square fields and reference 10×10 cm{sup 2} dose distributions and (2) Scanning beam deliveries for square and circular fields realized as the convolution of kernels and scanning pattern. Preliminary beam weight and pattern optimization were also performed. Two linear scans of 10 cm with/without overlap were modeled. Comparison metrics included depth and orthogonal profiles at dmax. Results: (1) Composite fields regained reference depth dose profiles for most energies and fields within 5%. Smaller kernels and higher energies increased dose in the build-up and Bremsstrahlung region (30%, 16MeV and 1×1 cm{sup 2}), while reference dmax was maintained for all energies and composite fields. Smaller kernels (<2×2 cm{sup 2}) maintained penumbra and field size within 0.2 cm, and flatness within 2%. Deterioration of penumbra for larger kernels (5×5 cm{sup 2}) were observed. Balancing desirable dosimetry and efficiencies suggests that smaller kernels are used at edges and larger kernels in the center of the target. (2) Beam weight optimization improved cross-plane penumbra (0.2 cm) and increased the field size (0.4 cm) on average. In-plane penumbra and field size remained unchanged. Overlap depended on kernel size and optimal overlap resulted in flatness ±2%. Conclusion: Dynamic electron beam therapy in virtual scanning mode is feasible by employing small fields to achieve desired dose distributions and acceptable efficiencies.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Technical Note: Improved CT number stability across patient size using dual-energy CT virtual monoenergetic imaging

Purpose: The purpose of this study was to evaluate, over a wide range of phantom sizes, CT number stability achieved using two techniques for generating dual-energy computed tomography (DECT) virtual monoenergetic images. Methods: Water phantoms ranging in lateral diameter from 15 to 50 cm and containing a CT number test object were scanned on a DSCT scanner using both single-energy (SE) and dual-energy (DE) techniques. The SE tube potentials were 70, 80, 90, 100, 110, 120, 130, 140, and 150 kV; the DE tube potential pairs were 80/140, 70/150Sn, 80/150Sn, 90/150Sn, and 100/150Sn kV (Sn denotes that the 150 kV beam was filtered with a 0.6 mm tin filter). Virtual monoenergetic images at energies ranging from 40 to 140 keV were produced from the DECT data using two algorithms, monoenergetic (mono) and monoenergetic plus (mono+). Particularly in large phantoms, water CT number errors and/or artifacts were observed; thus, datasets with water CT numbers outside ±10 HU or with noticeable artifacts were excluded from the study. CT numbers were measured to determine CT number stability across all phantom sizes. Results: Data exclusions were generally limited to cases when a SE or DE technique with a tube potential of less than 90 kV was used to scan a phantom larger than 30 cm. The 90/150Sn DE technique provided the most accurate water background over the large range of phantom sizes evaluated. Mono and mono+ provided equally improved CT number stability as a function of phantom size compared to SE; the average deviation in CT number was only 1.4% using 40 keV and 1.8% using 70 keV, while SE had an average deviation of 11.8%. Conclusions: The authors’ report demonstrates, across all phantom sizes, the improvement in CT number stability achieved with mono and mono+ relative to SE.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2016

WE-FG-207B-09: Experimental Assessment of Noise and Spatial Resolution in Virtual Non-Contrast Dual-Energy CT Images Across Multiple Patient Sizes and CT Systems

Purpose: To investigate the noise and spatial resolution properties of virtual non-contrast (VNC) dual-energy CT images compared to true non-contrast (TNC) images across multiple patient sizes and CT systems. Methods: Torso-shaped water phantoms with lateral widths of 25, 30, 35, 40 and 45 cm and a high resolution bar pattern phantom (Catphan CTP528) were scanned using 2nd and 3rd generation dual-source CT systems (Scanner A: Somatom Definition Flash, Scanner B: Somatom Force, Siemens Healthcare) in dual-energy scan mode with the same radiation dose for a given phantom size. Tube potentials of 80/Sn140 and 100/Sn140 on Scanner A and 80/Sn150, 90/Sn150 and 100/Sn150 on Scanner B were evaluated to examine the impact of spectral separation. Images were reconstructed using a medium sharp quantitative kernel (Qr40), 1.0-mm thickness, 1.0-mm interval and 20 cm field of view. Mixed images served as TNC images. VNC images were created using commercial software (Virtual Unenhanced, Syngo VIA Version VA30, Siemens Healthcare). The noise power spectrum (NPS), area under the NPS, peak frequency of the NPS and image noise were measured for every phantom size and tube potential combination in TNC and VNC images. Results were compared within and between CT systems. Results: Minimal shift in NPS peak frequencies was observed in VNC images compared to TNC for NPS having pronounced peaks. Image noise and area under the NPS were higher in VNC images compared to TNC images across all tube potentials and for scanner A compared to scanner B. Limiting spatial resolution was deemed to be identical between VNC and TNC images. Conclusion: Quantitative assessment of image quality in VNC images demonstrated higher noise but equivalent spatial resolution compared to TNC images. Decreased noise was observed in the 3rd generation dual-source CT system for tube potential pairs having greater spectral separation. Dr. McCollough receives research support from Siemens Healthcare.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Some aspects of virtual black holes

We first consider consistently third-quantize modified gravity. We then analyze certain aspects of virtual black holes in this third-quantized modified gravity. We see how a statistical mechanical origin for the Bekenstein-Hawking entropy naturally arises in this model. Furthermore, the area and hence the entropy of a real macroscopic black hole is quantized in this model. Virtual black holes cause a loss of quantum coherence, which gives an intrinsic entropy to all physical systems that can be used to define a direction of time and hence provide a solution to the problem of time.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Study of photon electroproduction on the nucleon at high and low energy by Virtual Compton Scattering

Virtual Compton Scattering (VCS) and Deeply Virtual Compton Scattering (DVCS) on the nucleon are two processes accessed via the photon electroproduction reaction (eN → eγN). In the first part of this paper we are interested by the DVCS on the neutron. We measured the (D(e, eγ)X-H(e, e'γ)X) unpolarized cross section and we extracted, for the first time, a non-zero contribution of (neutron-DVCS + coherent- deuteron-DVCS) at Q{sup 2} = 1.75 GeV{sup 2} and x{sub B} = 36 from Jefferson Lab experiment E08-025. VCS on the proton has been studied at Mainz Microtron MAMI at the four-momentum transfer squared Q{sup 2} = 0.5 GeV{sup 2}, below the pion production threshold. In the second part of this paper we present our preliminary results of the structure functions (P{sub LL} − (P{sub TT}/ε)) and P{sub LT}, and the electric and magnetic generalized polarizabilities α{sub E}(Q{sup 2}) and β{sub M}(Q{sup 2}) extracted from this experiment.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Comparative Studies of AlGaAs/InGaAs Enhancement/Depletion-Mode High Electron Mobility Transistors with Virtual Channel Layers by Hybrid Gate Recesses Approaches

Unlike the conventional GaAs- and InP-based enhancement/depletion-mode (E/D-mode) transistors, the improved gate characteristics of the AlGaAs/InGaAs E-mode high electron mobility transistors (HEMTs) by way of hybrid gate recesses to remove the n-AlAs/i-GaAs/n-AlGaAs virtual channel layers upon 2DEG channels are demonstrated. As compared to the D-mode device (sample A), the gate reverse currents are effectively reduced by 45 and 102 times for the E-mode devices with additional gate recess time of 24 s (sample B) and 30 s (sample C) to remove part of the virtual channel layers, respectively. Under gate forward bias, the hybrid gate recesses also enable the gate turn-on voltages to increase. Furthermore, the threshold voltages of –1.25, 0.09, and 0.22 V are observed in the samples A, B, and C, respectively. The maximum transconductances of 187.3, 209.2, and 243.4 mS/mm and saturation current density of 482.8, 410.6, and 347.4 mA/mm are obtained in the samples A, B, and C, respectively.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

VAIM-CFF: a variational autoencoder inverse mapper solution to Compton form factor extraction from deeply virtual exclusive reactions

We develop a new methodology for extracting Compton form factors (CFFs) from deeply virtual exclusive reactions such as the unpolarized DVCS cross section using a specialized inverse problem solver, a variational autoencoder inverse mapper (VAIM). The VAIM-CFF framework not only allows us access to a fitted solution set possibly containing multiple solutions in the extraction of all 8 CFFs from a single cross section measurement, but also accesses the lost information contained in the forward mapping from CFFs to cross section. We investigate various assumptions and their effects on the predicted CFFs such as cross section organization, number of extracted CFFs, use of uncertainty quantification technique, and inclusion of prior physics information. We then use dimensionality reduction techniques such as principal component analysis to visualize the missing physics information tracked in the latent space of the VAIM framework. Through re-framing the extraction of CFFs as an inverse problem, we gain access to fundamental properties of the problem not comprehensible in standard fitting methodologies: exploring the limits of the information encoded in deeply virtual exclusive experiments.

Accelerator Physics↗
DOE OSTI2022

Tensor Network Quantum Virtual Machine for Simulating Quantum Circuits at Exascale

The numerical simulation of quantum circuits is an indispensable tool for development, verification, and validation of hybrid quantum-classical algorithms intended for near-term quantum co-processors. The emergence of exascale high-performance computing (HPC) platforms presents new opportunities for pushing the boundaries of quantum circuit simulation. Here, we present a modernized version of the Tensor Network Quantum Virtual Machine (TNQVM) that serves as the quantum circuit simulation backend in the eXtreme-scale ACCelerator (XACC) framework. The new version is based on the scalable tensor network processing library ExaTN (Exascale Tensor Networks). It provides multiple configurable quantum circuit simulators that perform either an exact quantum circuit simulation via the full tensor network contraction or an approximate simulation via a suitably chosen tensor factorization scheme. Upon necessity, stochastic noise modeling from real quantum processors is incorporated into the simulations by modeling quantum channels with Kraus tensors. By combining the portable XACC quantum programming frontend and the scalable ExaTN numerical processing backend, we introduce an end-to-end virtual quantum development environment that can scale from laptops to future exascale platforms. We report initial benchmarks of our framework, which include a demonstration of the distributed execution, incorporation of quantum decoherence models, and simulation of the random quantum circuits used for the certification of quantum supremacy on Google’s Sycamore superconducting architecture.

Nguyen, Thien↗
DOE OSTI2017

Quantum Virtual Machine (QVM)

There is a lack of state-of-the-art HPC simulation tools for simulating general quantum computing. Furthermore, there are no real software tools that integrate current quantum computers into existing classical HPC workflows. This product, the Quantum Virtual Machine (QVM), solves this problem by providing an extensible framework for pluggable virtual, or physical, quantum processing units (QPUs). It enables the execution of low level quantum assembly codes and returns the results of such executions.

McCaskey, AlexanderJ.↗
DOE OSTI2021

Comparing perceptions of a dimmable LED lighting system between a real space and a virtual reality display

Over the last several decades, designers have used digital screens to view images of real and simulated spaces and make critical design decisions. Screen technology has improved during this time, as technologies like OLED have replaced legacy displays (CRT, plasma, and LCD). These new screens provide a higher pixel resolution, luminous output and contrast ratio. Immersive head-mounted displays now allow designers to view immersive images, and recent developments in real-time rendering have encouraged the uptake of virtual reality (VR) head-mounted displays in mainstream practice and design education. This paper presents an experiment on lighting perception using a series of LED lighting conditions in a real space and a virtual representation of those conditions captured using a 360° high-dynamic-range camera and presented on an HTC Vive Pro HMD. Fifty-three participants were asked to rate each lighting condition by viewing it in a real space (n = 30) or via immersive HDR photographs displayed in a VR HMD (n = 23). The results show that ratings of visual comfort, pleasantness, evenness, contrast and glare are similar between the HTC Vive Pro HMD and our real space when evaluating well-lit scenes, but significant differences emerge in dim and highly contrasted scenes for a number of rating scales.

Rockcastle, S.↗
DOE OSTI2012

SANE's Measurement of the Proton's Virtual Photon Spin Asymmetry, A p 1 , at Large Bjorken x

The experiment SANE (Spin Asymmetries of the Nucleon Experiment) measured inclusive double polarization electron asymmetries on a proton target at the Continuous Electron Beam Accelerator Facility at the Thomas Jefferson National Laboratory in Newport News Virgina. Polarized electrons were scattered from a solid 14 NH 3 polarized target provided by the University of Virginia target group. Measurements were taken with the target polarization oriented at 80 degrees and 180 degrees relative to the beam direction, and beam energies of 4.7 and 5.9 GeV were used. Scattered electrons were detected by a multi-component novel non-magnetic detector package constructed for this experiment. Asymmetries measured at the two target orientations allow for the extraction of the virtual Compton asymmetries A 1 p and A 2 p as well as the spin structure functions g 1 p and g 2 p . This work addresses the extraction of the virtual Compton asymmetry A 1 p in the deep inelastic regime. The analysis uses data in the kinematic range from Bjorken x of 0.30 to 0.55, separated into four Q 2 bins from 1.9 to 4.7 GeV 2 .

43 PARTICLE ACCELERATORS↗