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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,711 records · Page 95
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Development of interatomic potential for Al–Tb alloys using a deep neural network learning method

An interatomic potential for the Al–Tb alloy around the composition of Al 90 Tb 10 is developed using the deep neural network (DNN) learning method. The atomic configurations and the corresponding total potential energies and forces on each atom obtained from ab initio molecular dynamics (AIMD) simulations are collected to train a DNN model to construct the interatomic potential for the Al–Tb alloy. Here we show that the obtained DNN model can well reproduce the energies and forces calculated by AIMD simulations. Molecular dynamics (MD) simulations using the DNN interatomic potential also accurately describe the structural properties of the Al 90 Tb 10 liquid, such as partial pair correlation functions (PPCFs) and bond angle distributions, in comparison with the results from AIMD simulations. Furthermore, the developed DNN interatomic potential predicts the formation energies of the crystalline phases of the Al–Tb system with an accuracy comparable to ab initio calculations. The structure factors of the Al 90 Tb 10 metallic liquid and glass obtained by MD simulations using the developed DNN interatomic potential are also in good agreement with the experimental X-ray diffraction data. The development of short-range order (SRO) in the Al 90 Tb 10 liquid and the undercooled liquid is also analyzed and three dominant SROs, i.e., Al-centered distorted icosahedron (DISICO) and Tb-centered ‘3661’ and ‘15551’ clusters, respectively, are identified.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Constructing angular distributions of neutrinos in core-collapse supernovae from zeroth and first moments calibrated by full Boltzmann neutrino transport

Two-moment neutrino transport methods have been widely used for developing theoretical models of core-collapse supernovae (CCSN), since they substantially reduce the computational burden inherent in the multidimensional neutrino-radiation hydrodynamical simulations. The approximation, however, comes at a price; the detailed structure of angular distribution of neutrinos is sacrificed, that is the main drawback of this approach. In this paper, we develop a novel method by which to construct angular distributions of neutrinos from the zeroth and first angular moments. In our method, the angular distribution is expressed with two quadratic functions of the neutrino angle in a piecewise fashion. We determine the best parameters in the fitting function by comparing to the neutrino data in a spherically symmetric CCSN model with full Boltzmann neutrino transport. We demonstrate the capability of our method by using our recent 2D CCSN model. In this work, we find that the essential features of the angular distributions can be well reconstructed, whereas the angular distributions of incoming neutrinos tend to have large errors that increase with flux factor ($\textit{κ}$). This issue originates from the insensitiveness of incoming neutrinos to $\textit{κ}$, that is an intrinsic limitation in moment methods. Based on the results of the demonstration, we assess the reliability of electron- neutrinos lepton number (ELN)-crossing searches with the two-moment neutrino transport. This analysis is complementary to our [L. Johns and H. Nagakura arXiv:2104.04106] that scrutinizes the limitation of crossing searches with a few moments. We find that the systematic errors of angular distributions for incoming neutrinos lead to misjudgements of the crossing at $\textit{κ}$ ≳ 0.5. This casts doubt on the results of ELN-crossing searches based on two-moment methods in some previous studies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

rmc-discord : reverse Monte Carlo refinement of diffuse scattering and correlated disorder from single crystals

A user-friendly program has been developed to analyze diffuse scattering from single crystals with the reverse Monte Carlo method. The approach allows for refinement of correlated disorder from atomistic supercells with magnetic or structural (occupational and/or displacive) disorder. The program is written in Python and optimized for performance and efficiency. Refinements of two user cases obtained with legacy neutron-scattering data demonstrate the effectiveness of the approach and the developed program. It is shown with bixbyite, a naturally occurring magnetic mineral, that the calculated three-dimensional spin-pair correlations are resolved with finer real-space resolution compared with the pair distribution function calculated directly from the reciprocal-space pattern. With the triangular lattice Ba 3 Co 2 O 6 (CO 3 ) 0.7 , refinements of occupational and displacive disorder are combined to extract the one-dimensional intra-chain correlations of carbonate molecules that move toward neighboring vacant sites to accommodate strain induced by electrostatic interactions. The program is packaged with a graphical user interface and extensible to serve the needs of single-crystal diffractometer instruments that collect diffuse-scattering data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Mycorrhizal nutrient acquisition strategies shape tree competition and coexistence dynamics

Mycorrhizal fungi with different nutrient acquisition strategies influence plant species performance and physiology, thereby defining their trophic niche. This might drive resource competition dynamics that cumulatively impact tree species coexistence, but few manipulative experiments have directly tested this. Combining surveys and experiments in a modern coexistence theory framework, we tested how variation in mycorrhizal strategies and nutrient conditions affects plant competitive outcomes. We focused on two genera of co-occurring tree species with different mycorrhizal states: Acer (arbuscular mycorrhizal, AM) and Populus (dual mycorrhizal, but often considered predominantly ectomycorrhizal, EM). The EM and AM fungal responsiveness in Populus species varied with latitude and nitrogen (N) limitation. Host-specific soil microbiome conditioning and inorganic N fertilization combined to qualitatively affect coexistence outcomes. Lower N conditions favoured Populus over Acer trees, and N fertilization reversed this outcome for southern species, aligning with regional-scale forest mycorrhizal transitions. Results from the coexistence experiment also predict competitive exclusion between the tree species pairs, which could arise, in part, from their mycorrhizal differences and is consistent with alternative stable states in dominant forest mycorrhizal strategies. Such bistability appears in natural systems as a bimodal distribution of Populus vs. Acer tree species dominance using long-term forest inventory data. Synthesis: The magnitude and outcome of microbially mediated competition between Populus and Acer depends on soil nutrient availability, which likely relates to their mycorrhizal differentiation. These findings support the importance of mycorrhizal symbioses for contributing to large-scale biogeographical patterns of tree species trophic niche separation across soil resource gradients and bistability in forest mycorrhizal structure.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Study of the internal structure, instabilities, and magnetic fields in the dense Z-pinch

Z-pinches are sources of hot dense plasma which generates powerful x-ray bursts and can been applied to various areas of high-energy-density physics (HEDP). The 26-MA Z machine is at the forefront of many of these applications, but important aspects of HEDP have been studied on generators at the 1 MA current level. Recent development of laser diagnostics and upgrade of the Leopard laser at Nevada Terawatt Facility (NTF) give new opportunities for the dense Z-pinch study. The goal of this project is the investigation of the internal structure of the stagnated Z pinch including sub-mm and micron-scale instabilities, plasma dynamics, magnetic fields, and hot spots formation and initiation. New plasma diagnostics will be developed for this project. A 3D structure and instabilities of the pinch will be compared with 3D MHD and spectroscopic modeling and theoretical analysis. The structure and dynamics of stagnated Z pinches has been studied with x-ray self-radiation diagnostics which derive a temperature map of the pinch with a spatial resolution of 70-150 µm. The regular laser diagnostics at 532 nm does not penetrate in the dense pinch due to strong absorption and refraction in trailing plasma. Recent experiments at NTF showed that shadowgraphy at the UV wavelength of 266 nm unfolds a fine structure of the stagnated Z-pinch with unprecedented detail. We propose to develop laser UV diagnostics for Z pinches with a spatial resolution <5 μm to study the small-scale plasma structures, implement two-frame shadowgraphy/interferometry, and develop methods for investigation of strong magnetic fields. New diagnostics will help to understand better basic physical processes in Z pinches. A 3D internal structure of the pinch and characteristic instabilities will be studied in wire arrays with different configurations and compared with 3D MHD simulations and analytical models. Mechanisms of “enhanced heating” of Z-pinch plasma will be studied. Fast dynamics of stagnated plasma will be studied to estimate its contribution to the Doppler broadening of x-ray lines. Development of “necks” and “hot spots” will be studied with high-resolution UV diagnostics, an x-ray streak camera, and x-ray spectroscopy. Laser initiation of hot spots in Z pinches will be tested. A Faraday rotation diagnostic at 266 nm will be applied to 1-10 MG magnetic fields. For magnetic fields B>20 MG, suggested in micropinches, Cotton-Mouton and cutoff diagnostics will be applied. A picosecond optical Kerr shutter will be tested to increase a sensitivity of UV methods for application at multi-MA Z pinches. The proposal is based on the experimental capability of NTF. The Zebra generator produces 1-1.7 MA Z-pinches with electron plasma density of 10 20 -10 21 cm -3 , electron temperature of 0.5-1 keV, and magnetic fields >10 MG. The Leopard laser was upgraded to energy of 90-J at 0.8 ns. This regime will be used for laser initiation of hot spots. A further upgrade to energy of 250-J is suggested for laser-Z-pinch interaction. A picosecond regime will be used for optical gating. A 10-TW Tomcat laser at NTF is available for the high energy UV laser probing of the Z-pinch. Two graduate students will develop new optical and x-ray diagnostics, carry out experiments, and process experimental data. Other students will be involved in the design and fabrication of loads, supporting regular optical and x-ray diagnostics, and data processing. The new plasma diagnostics may be applied to HEDP experiments at NTF and other multi-MA generators. The feasibility of the research plan is based on the experience of the scientific team in Z-pinch plasma physics, laser physics, development of new plasma diagnostics, and the experimental capability of NTF. The experimental group of Dr. V. V. Ivanov (UNR) collaborates with a group for Z pinch MHD modeling of Dr. J. P. Chittenden (Imperial College, London), and theoretical group of Dr. D. D. Ryutov (LLNL). The suggested research ideas are supported by preliminary experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2017

Association of Plages with Sunspots: A Multi-Wavelength Study Using Kodaikanal Ca ii K and Greenwich Sunspot Area Data

Plages are the magnetically active chromospheric structures prominently visible in the Ca ii K line (3933.67 Å). A plage may or may not be associated with a sunspot, which is a magnetic structure visible in the solar photosphere. In this study we explore this aspect of association of plages with sunspots using the newly digitized Kodaikanal Ca ii K plage data and the Greenwich sunspot area data. Instead of using the plage index or fractional plage area and its comparison with the sunspot number, we use, to our knowledge for the first time, the individual plage areas and compare them with the sunspot area time series. Our analysis shows that these two structures, formed in two different layers, are highly correlated with each other on a timescale comparable to the solar cycle. The area and the latitudinal distributions of plages are also similar to those of sunspots. Different area thresholdings on the “butterfly diagram” reveal that plages of area ≥4 arcmin{sup 2} are mostly associated with a sunspot in the photosphere. Apart from this, we found that the cyclic properties change when plages of different sizes are considered separately. These results may help us to better understand the generation and evolution of the magnetic structures in different layers of the solar atmosphere.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

One-point remapping of Lagrangian perturbation theory in the mildly non-linear regime of cosmic structure formation

On the smallest scales, three-dimensional large-scale structure surveys contain a wealth of cosmological information which cannot be trivially extracted due to the non-linear dynamical evolution of the density field. Lagrangian perturbation theory (LPT) is widely applied to the generation of mock halo catalogs and data analysis. In this work, we compare topological features of the cosmic web such as voids, sheets, filaments and clusters, in the density fields predicted by LPT and full numerical simulation of gravitational large-scale structure formation. We propose a method designed to improve the correspondence between these density fields, in the mildly non-linear regime. We develop a computationally fast and flexible tool for a variety of cosmological applications. Our method is based on a remapping of the approximately-evolved density field, using information extracted from N-body simulations. The remapping procedure consists of replacing the one-point distribution of the density contrast by one which better accounts for the full gravitational dynamics. As a result, we obtain a physically more pertinent density field on a point-by-point basis, while also improving higher-order statistics predicted by LPT. We quantify the approximation error in the power spectrum and in the bispectrum as a function of scale and redshift. Our remapping procedure improves one-, two- and three-point statistics at scales down to 8 Mpc/h.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

New CTEQ-Jefferson Lab (CJ) analysis of parton distributions

We present preliminary results of a new global QCD analysis of PDFs from the CTEQ-Jefferson Lab Collaboration (dubbed "CJ15"), which includes several new data sets and recent theoretical developments. In particular, we study the constraints from new D0 data on *W* boson asymmetries on the *d/u* PDF ratio at large *x*, and, indirectly, on the models of nuclear corrections in the deuteron. The analysis also considers for the first time the impact of Jefferson Lab data on the free neutron/deuteron structure function ratio at large *x*, and reanalyzes the light antiquark asymmetry in the proton from Drell-Yan data using more flexible parametrizations and nuclear corrections to deuterium cross sections. The results provide a new set of baseline PDFs which can be used to more reliably calibrate the effect of future data from the LHC.

Keppel, Cynthia↗
DOE OSTI2015

New CTEQ-Jefferson Lab (CJ15) Analysis of Parton Distributions

We present the results of a new global QCD analysis of PDFs from the CTEQ-Jefferson Lab collaboration (dubbed "CJ15"), which includes several new data sets and recent theoretical developments. In particular, we study the constraints from new D0 data on W boson asymmetries on the d/u PDF ratio at large x, and, indirectly, on the models of nuclear corrections in the deuteron. The analysis also considers for the first time the impact of Jefferson Lab data on the free neutron/deuteron structure function ratio at large x, and reanalyzes the light antiquark asymmetry in the proton from Drell-Yan data using more flexible parametrizations and nuclear corrections to deuterium cross sections. The results provide a new set of baseline PDFs which can be used to more reliably calibrate the effects of future data from the LHC.

Melnitchouk, W.↗
DOE OSTI2014

SU-E-I-75: Evaluation of An Orthopedic Metal Artifact Reduction (O-MAR) Algorithm On Patients with Spinal Prostheses Near Spinal Tumors

Purpose: To evaluate the impact of a commercial orthopedic metal artifact reduction (O-MAR) algorithm on CT image quality and dose calculation for patients with spinal prostheses near spinal tumors. Methods: A CT electron density phantom was scanned twice: with tissue-simulating inserts only, and with a titanium insert replacing solid water. A patient plan was mapped to the phantom images in two ways: with the titanium inside or outside of the spinal tumor. Pinnacle and Eclipse were used to evaluate the dosimetric effects of O-MAR on 12-bit and 16-bit CT data, respectively. CT images from five patients with spinal prostheses were reconstructed with and without O-MAR. Two observers assessed the image quality improvement from O-MAR. Both pencil beam and Monte Carlo dose calculation in iPlan were used for the patient study. The percentage differences between non-OMAR and O-MAR datasets were calculated for PTV-min, PTV-max, PTV-mean, PTV-V100, PTV-D90, OAR-V10Gy, OAR-max, and OAR-D0.1cc. Results: O-MAR improved image quality but did not significantly affect the dose distributions and DVHs for both 12-bit and 16- bit CT phantom data. All five patient cases demonstrated some degree of image quality improvement from O-MAR, ranging from small to large metal artifact reduction. For pencil beam, the largest discrepancy was observed for OARV-10Gy at 5.4%, while the other seven parameters were ≤0.6%. For Monte Carlo, the differences between non-O-MAR and O-MAR datasets were ≤3.0%. Conclusion: Both phantom and patient studies indicated that O-MAR can substantially reduce metal artifacts on CT images, allowing better visualization of the anatomical structures and metal objects. The dosimetric impact of O-MAR was insignificant regardless of the metal location, image bit-depth, and dose calculation algorithm. O-MAR corrected images are recommended for radiation treatment planning on patients with spinal prostheses because of the improved image quality and no need to modify current dose constraints. This work was supported by a research grant from Philips Healthcare. Paul Klahr is an employee of Philips Healthcare.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

The State of Demand Flexibility Programs and Rates

This report provides foundational data on programs and rates that promote demand flexibility in residential and commercial buildings in the United States. Leveraging a dataset of 148 programs and 94 rates collected through a review of utility websites, published electricity tariffs, and a database of demand-side programs, we describe the structure of demand flexibility events and the types and levels of incentives offered. For the two most common program types in our dataset—Wi-Fi thermostat and battery storage programs—we provide additional details on program designs. We also report data on program outcomes, including enrollment and participation, energy and demand savings, and costs. Furthermore, we describe the structure of dynamic rate events, report prices for critical peak pricing and variable peak pricing rates, and describe features of technology rates.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2023

NMR relaxometry characterization of water adsorption in corn stover anatomical fractions

Nuclear magnetic resonance (NMR) relaxometry is applied to provide direct measurement of water adsorption in anatomical fractions of corn stover. NMR transverse T 2 relaxation time distribution measurements indicate multiple water populations, which vary with anatomical fraction and water adsorption. Measured T 2 data are used to calculate thermodynamic properties of Brunauer-Emmet-Teller adsorption theory using a model to estimate mono and bilayer relaxation. T 2 data are used directly to determine rotational diffusion correlation times indicating adsorption interaction strength. T 1 -T 2 longitudinal-transverse relaxation time correlation measurements quantify differences in the molecular level structural order of the adsorbate surface water as a function of water activity, i.e. relative humidity or water vapor partial pressure. The T 1 /T 2 ratio provides a measure of the surface energy related to the adsorption strength and surface diffusive mobility of the water adsorbate and differentiates the anatomical fractions. Furthermore, the results indicate that direct measurement of NMR relaxation times can be used to characterize corn stover biomass water adsorption, data relevant to processing and handling considerations.

09 BIOMASS FUELS↗
DOE OSTI2014

Comparative genomic and proteomic analyses of Clostridium acetobutylicum Rh8 and its parent strain DSM 1731 revealed new understandings on butanol tolerance

Highlights: • Genomes of a butanol tolerant strain and its parent strain were deciphered. • Comparative genomic and proteomic was applied to understand butanol tolerance. • None differentially expressed proteins have mutations in its corresponding genes. • Mutations in ribosome might be responsible for the global difference of proteomics. - Abstract: Clostridium acetobutylicum strain Rh8 is a butanol-tolerant mutant which can tolerate up to 19 g/L butanol, 46% higher than that of its parent strain DSM 1731. We previously performed comparative cytoplasm- and membrane-proteomic analyses to understand the mechanism underlying the improved butanol tolerance of strain Rh8. In this work, we further extended this comparison to the genomic level. Compared with the genome of the parent strain DSM 1731, two insertion sites, four deletion sites, and 67 single nucleotide variations (SNVs) are distributed throughout the genome of strain Rh8. Among the 67 SNVs, 16 SNVs are located in the predicted promoters and intergenic regions; while 29 SNVs are located in the coding sequence, affecting a total of 21 proteins involved in transport, cell structure, DNA replication, and protein translation. The remaining 22 SNVs are located in the ribosomal genes, affecting a total of 12 rRNA genes in different operons. Analysis of previous comparative proteomic data indicated that none of the differentially expressed proteins have mutations in its corresponding genes. Rchange Algorithms analysis indicated that the mutations occurred in the ribosomal genes might change the ribosome RNA thermodynamic characteristics, thus affect the translation strength of these proteins. Take together, the improved butanol tolerance of C. acetobutylicum strain Rh8 might be acquired through regulating the translational process to achieve different expression strength of genes involved in butanol tolerance.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Joint Inversion of Body Wave Arrival Times, Surface Wave Dispersion Data and Receiver Functions: Method and Application to South China

In this work, we have developed a new joint inversion method that incorporates body wave arrival times, surface wave dispersion and receiver functions to simultaneously update earthquake locations and constrain three-dimensional P-wave (Vp) and S-wave velocity (Vs) models. Due to complementary sensitivities of the three types of data, the proposed joint inversion algorithm can reduce the intrinsic non-uniqueness of inversions using fewer types of data and better determine smooth velocity variations and velocity discontinuities. Synthetic tests demonstrate the advantages of this new joint inversion algorithm in resolving velocity structures, especially in constraining velocity gradients across the Moho interface. We have applied the proposed joint inversion algorithm to image the lithosphere velocity structure of south China. The inverted Vp and Vs models fit body wave arrival times, surface wave dispersion and receiver functions well. We further analyzed the distribution of Vs gradients across the Moho interface in detail, which helps us better understand tectonics in south China.

58 GEOSCIENCES↗
DOE OSTI2014

Polarizability effects on the structure and dynamics of ionic liquids

Polarization effects on the structure and dynamics of ionic liquids are investigated using molecular dynamics simulations. Four different ionic liquids were simulated, formed by the anions Cl{sup −} and PF{sub 6}{sup −}, treated as single fixed charge sites, and the 1-n-alkyl-3-methylimidazolium cations (1-ethyl and 1-butyl-), which are polarizable. The partial charge fluctuation of the cations is provided by the electronegativity equalization model (EEM) and a complete parameter set for the cations electronegativity (χ) and hardness (J) is presented. Results obtained from a non-polarizable model for the cations are also reported for comparison. Relative to the fixed charged model, the equilibrium structure of the first solvation shell around the imidazolium cations shows that inclusion of EEM polarization forces brings cations closer to each other and that anions are preferentially distributed above and below the plane of the imidazolium ring. The polarizable model yields faster translational and reorientational dynamics than the fixed charges model in the rotational-diffusion regime. In this sense, the polarizable model dynamics is in better agreement with the experimental data.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

In this paper, we compare and contrast the experimental data and the theoretical predictions of the low temperature optical properties of polar and nonpolar InGaN/GaN quantum well structures. In both types of structure, the optical properties at low temperatures are governed by the effects of carrier localisation. In polar structures, the effect of the in-built electric field leads to electrons being mainly localised at well width fluctuations, whereas holes are localised at regions within the quantum wells, where the random In distribution leads to local minima in potential energy. This leads to a system of independently localised electrons and holes. In nonpolar quantum wells, the nature of the hole localisation is essentially the same as the polar case but the electrons are now coulombically bound to the holes forming localised excitons. These localisation mechanisms are compatible with the large photoluminescence linewidths of the polar and nonpolar quantum wells as well as the different time scales and form of the radiative recombination decay curves.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Diffraction pattern simulation of cellulose fibrils using distributed and quantized pair distances

Intensity simulation of X-ray scattering from large twisted cellulose molecular fibrils is important in understanding the impact of chemical or physical treatments on structural properties such as twisting or coiling. This paper describes a highly efficient method for the simulation of X-ray diffraction patterns from complex fibrils using atom-type-specific pair-distance quantization. Pair distances are sorted into arrays which are labelled by atom type. Histograms of pair distances in each array are computed and binned and the resulting population distributions are used to represent the whole pair-distance data set. These quantized pair-distance arrays are used with a modified and vectorized Debye formula to simulate diffraction patterns. This approach utilizes fewer pair distances in each iteration, and atomic scattering factors are moved outside the iteration since the arrays are labelled by atom type. As a result, this algorithm significantly reduces the computation time while maintaining the accuracy of diffraction pattern simulation, making possible the simulation of diffraction patterns from large twisted fibrils in a relatively short period of time, as is required for model testing and refinement.

09 BIOMASS FUELS↗
DOE OSTI2015

SU-E-T-318: Dosimetric Evaluation of ArcCHECK and 3DVH System Using Customized Polymer Gel Dosimeter

Purpose: ArcCHECK and 3DVH system (Sun Nuclear) can reconstruct the three-dimensional (3D) dose distribution and provide the DVH analysis in a patient. The aim of this study was to evaluate dosimetric accuracy of this system using customized polymer gel dosimeter, and also Gafchromic EBT3 films. Methods: Polyacrylamide-based gel contained magnesium chloride as a sensitizer (iPAGAT) was used in this study. Volumetric-modulated arc therapy (VMAT) plan was performed for the C-shape structure by the Eclipse treatment planning system (Varian) and used to irradiate the ArcCHECK by the Novalis Tx linear accelerator (Varian/BrainLAB). The cubic phantom filled with iPAGAT and EBT3 films placed in three orthogonal planes (axial, sagittal, and coronal) inserted into the I’mRT Phantom (IBA Dosimetry) simulated a patient were irradiated with the same VMAT plan. The measurement-guided 3D dose distribution was reconstructed using 3DVH software from the measured data of the ArcCHECK. The 3D dose distribution in iPAGAT was read out by Signa 1.5 T MRI system (GE), and 2D dose distribution on EBT3 was read out by color scanner (Epson). The comparison of all the dose distributions was performed with dose profiles and gamma index analysis in orthogonal planes using in-house developed software. Results: A good agreement was observed by overlaying the dose profiles of 3DVH, EBT3, and iPAGAT. The mean pass rates by gamma index analysis with 3%/3 mm criteria in orthogonal planes were 94.3% (3DVH vs EBT3), 91.1% (3DVH vs iPAGAT), and 96.4% (iPAGAT vs EBT3), respectively. Conclusion: 3D dose distribution reconstructed by ArcCHECK and 3DVH system was estimated accurately in a patient. However, slightly differences were observed between 3DVH and iPAGAT because of MRI noise, therefore further study is required to improve the accuracy of MRI based polymer gel dosimetry for the DVH analysis.

60 APPLIED LIFE SCIENCES↗