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At least 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

SU-E-T-226: Junction Free Craniospinal Irradiation in Linear Accelerator Using Volumetric Modulated Arc Therapy : A Novel Technique Using Dose Tapering

Purpose: Spatially separated fields are required for craniospinal irradiation due to field size limitation in linear accelerator. Field junction shits are conventionally done to avoid hot or cold spots. Our study was aimed to demonstrate the feasibility of junction free irradiation plan of craniospinal irradiation (CSI) for Meduloblastoma cases treated in linear accelerator using Volumetric modulated arc therapy (VMAT) technique. Methods: VMAT was planned using multiple isocenters in Monaco V 3.3.0 and delivered in Elekta Synergy linear accelerator. A full arc brain and 40° posterior arc spine fields were planned using two isocentre for short (<1.3 meter height ) and 3 isocentres for taller patients. Unrestricted jaw movement was used in superior-inferior direction. Prescribed dose to PTV was achieved by partial contribution from adjacent beams. A very low dose gradient was generated to taper the isodoses over a long length (>10 cm) at the conventional field junction. Results: In this primary study five patients were planned and three patients were delivered using this novel technique. As the dose contribution from the adjacent beams were varied (gradient) to create a complete dose distribution, therefore there is no specific junction exists in the plan. The junction were extended from 10–14 cm depending on treatment plan. Dose gradient were 9.6±2.3% per cm for brain and 7.9±1.7 % per cm for spine field respectively. Dose delivery error due to positional inaccuracy was calculated for brain and spine field for ±1mm, ±2mm, ±3mm and ±5 mm were 1%–0.8%, 2%–1.6%, 2.8%–2.4% and 4.3%–4% respectively. Conclusion: Dose tapering in junction free CSI do not require a junction shift. Therefore daily imaging for all the field is also not essential. Due to inverse planning dose to organ at risk like thyroid kidney, heart and testis can be reduced significantly. VMAT gives a quicker delivery than Step and shoot or dynamic IMRT.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-E-T-263: Development of Dose Monitor Unit Calculation Using Clarkson Integration for Proton Beam Therapy Using Beam-Wobbling System

Purpose: The purpose of the present study is to develop a calculation method of dose-calibration-factor using Clarkson integration for proton therapy employing the wobbling system and to evaluate accuracy of the calculation by comparison between calculations and measurements. Methods: CF and CALF stand for a dose-calibration-factor and a dose per monitor unit (MU), respectively. A measured dose-calibration-factor CFmeas is defined as a ratio of the measured dose per monitor unit in a patient-specific condition CALFpat to the measured dose per MU in a reference beam condition CALFref. The CFcalc is a product of three factors: CF1, CF2 and CF3. The CF1 and CF2 are a factor reflecting the effect of common beam delivery devices and that of patient specific devices and parameter (an aperture collimator, a range compensator and an air gap), respectively. The CF1 was obtained by interpolation using measured data. The CF2 was calculated using the Simplified Monte Carlo (SMC) method. The SMC method calculates a dose distribution by tracing individual protons and by using a measured Bragg curve in water. The CF3 representing the correction factor of field size effect was obtained by using the Clarkson integration. We compared the calculated and measured CF values for 20 prostate cases. Results: Field size correction was found to be important. The calculations reproduce the measurement results within an error of ±2.0%, except for a few cases. The error was about –3.1% for the small field area of less than19 square centimeters. Conclusion: We have developed a calculation method of dose-calibration-factor. Calculations agreed with measurements within ±2.0% for 90% of 20 prostate cases. Except for a small field size cases, the calculation method can be applied to determine the dose-calibration–factor for majority cases of prostate cancer.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-E-T-783: Using Matrixx to Determine Transit Dose Contribution Over Clinically Useful Limits of HDR Source Activity

Purpose: Most HDR brachytherapy treatment planning systems (TPS) use TG-43 formalism to calculate dose without including transit dose corrections. Historically, measurement of this contribution has required sophisticated apparatus unavailable in most hospitals. We use Matrixx to investigate several scenarios where transit dose contribution may effect a clinical treatment. Methods: Treatment plans were generated using Oncentra Brachy TPS (Version 4.3.0.410, Nucletron ) on a CT scan of a 24-catheter Freiburg applicator (Nucletron ) laid flat on the MatriXX (IBA) detector. This detector is an array of 1020 parallel plate ion chambers. All 24 catheters were digitized and dwells within a central square region of 5×5cm of the applicator were activated. Each of the active catheters had 6 dwells in increments of 1.0cm. The plans were normalized to 10mm. This places the 100% isodose line at the correct effective point of measurement, which lies half-way between the parallel plates of the ion chambers. It is also within the clinically relevant treatment depth for superficial applications. A total of 6 plans were delivered for 3 prescription doses, 1Gy, 2Gy and 4Gy using source activities of 2.9Ci and 11.2Ci. The MatriXX array was operated to capture dosimetric snaps every 500ms and yielded an integral dose at the end of treatment. Results: A comparison of integral dose from 2 different source activities shows that the transit dose contribution is larger when the source activity is higher. It is also observed that the relative transit dose contribution decreases as prescription dose increases. This is quantified by the Gamma analysis. Conclusion: We have demonstrated that the Matrixx detector can be used to evaluate the contribution for a HDR source during transit from the HDR afterloader to a dwell location, and between adjacent dwell locations.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

TU-G-303-00: Radiomics: Advances in the Use of Quantitative Imaging Used for Predictive Modeling

‘Radiomics’ refers to studies that extract a large amount of quantitative information from medical imaging studies as a basis for characterizing a specific aspect of patient health. Radiomics models can be built to address a wide range of outcome predictions, clinical decisions, basic cancer biology, etc. For example, radiomics models can be built to predict the aggressiveness of an imaged cancer, cancer gene expression characteristics (radiogenomics), radiation therapy treatment response, etc. Technically, radiomics brings together quantitative imaging, computer vision/image processing, and machine learning. In this symposium, speakers will discuss approaches to radiomics investigations, including: longitudinal radiomics, radiomics combined with other biomarkers (‘pan-omics’), radiomics for various imaging modalities (CT, MRI, and PET), and the use of registered multi-modality imaging datasets as a basis for radiomics. There are many challenges to the eventual use of radiomics-derived methods in clinical practice, including: standardization and robustness of selected metrics, accruing the data required, building and validating the resulting models, registering longitudinal data that often involve significant patient changes, reliable automated cancer segmentation tools, etc. Despite the hurdles, results achieved so far indicate the tremendous potential of this general approach to quantifying and using data from medical images. Specific applications of radiomics to be presented in this symposium will include: the longitudinal analysis of patients with low-grade gliomas; automatic detection and assessment of patients with metastatic bone lesions; image-based monitoring of patients with growing lymph nodes; predicting radiotherapy outcomes using multi-modality radiomics; and studies relating radiomics with genomics in lung cancer and glioblastoma. Learning Objectives: Understanding the basic image features that are often used in radiomic models. Understanding requirements for reliable radiomic models, including robustness of metrics, adequate predictive accuracy, and generalizability. Understanding the methodology behind radiomic-genomic (’radiogenomics’) correlations. Research supported by NIH (US), CIHR (Canada), and NSERC (Canada)

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Land and Water Use Characteristics and Human Health Input Parameters for use in Environmental Dosimetry and Risk Assessments at the Savannah River Site 2017 Update

Operations at the Savannah River Site (SRS) result in releases of relatively small amounts of radioactive materials to the atmosphere and to the Savannah River. For regulatory compliance purposes, potential offsite radiological doses are estimated annually using computer models that follow U.S. Nuclear Regulatory Commission (NRC) regulatory guides. Within the regulatory guides, default values are provided for many of the dose model parameters, but the use of site-specific values is encouraged. Detailed surveys of land-use and water-use parameters were conducted in 1991, 2008, 2010, and 2016 and are being concurred with or updated in this report. These parameters include local characteristics of meat, milk, and vegetable production; river recreational activities; and meat, milk, and vegetable consumption rates, as well as other human usage parameters required in the SRS dosimetry models. In addition, the preferred elemental bioaccumulation factors and transfer factors (to be used in human health exposure calculations at SRS) are documented. The intent of this report is to establish a standardized source for these parameters that is up to date with existing data, and that is maintained via review of future-issued national references (to evaluate the need for changes as new information is released). These reviews will continue to be added to this document by revision.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Design Optimization of A generic Fissile Solution for Mo99 production using Electron Beam-based Neutron Generator using MCNP+CFD

Molybdenum-99 ( 99 Mo) is a medical isotope used in 80% of all medical imaging procedures today. However, 99 Mo is not directly administered to patients for imaging; its decay product, technetium-99m ( 99 mTc), is a metastable isotope with a half-life of ~6 hours. Such a short half-life does not allow for production, separation, and application to a patient before decaying further. Therefore, the solution is to produce the precursor to 99 mTc, 99 Mo. 99 Mo has a half-life of 66 hours, long enough to produce the material and send it to the desired location before it fully decays. Under National Nuclear Security Administration’s (NNSA) highly enriched uranium (HEU) minimization mission, the Material Management and Minimization (M3) office leads the Molybdenum-99 (Mo-99) program. A major goal of the Mo-99 program is to develop methods of producing 99 Mo using low enriched uranium (LEU) opposed to the traditionally used HEU domestically in the U.S. Internationally, LEU is the new standard for use in research reactors and isotope production facility. In this study, we introduce a generic fissile solution system for 99 Mo production facility meeting the design requirement of 1) LEU usage as fissile material and 2) subcritical fissile system coupled with a horizontal electron beam (E-beam) accelerator. The focus of this research is to optimize a fissile solution configuration for maximum 99 Mo production yield using MCNP model, and ultimately implement the optimized design with computational fluid dynamics (CFD) model to understand thermal hydraulic behavior and solution convection characteristic. The report consists of two parts: 1) isotope yield calculation and criticality analysis with a wide range of parametric test matrix, and 2) thermal hydraulic analysis for solution mixing and cooling assessment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Using Pilot Jobs and CernVM File System for Simplified Use of Containers and Software Distribution

High Energy Physics (HEP) experiments entail an abundance of computing resources, i.e. sites, to run simulations and analyses by processing data. This requirement is fulfilled by local batch farms, grid sites, private/commercial clouds, and supercomputing centers via High Throughput Computing (HTC). The growing needs of such experiments and resources being prone to trends of heterogeneity make it difficult for physicists to handle these resources directly. Additionally, HEP collaborations heavily rely on data and software releases, typically in the order of tens of gigabytes, while conducting simulations and analyses. Hence, aspects of scalability, reliability, and maintenance become crucial with regards to the distribution of the necessary data and software stack. The GlideinWMS [4] framework helps with the resource management problem by using pilot jobs, aka Glideins, to provision reliable elastic virtual clusters. Glideins are submitted to unreliable heterogeneous resources which are validated and customized by the Glideins to make the worker nodes available for end-user job execution. On the other hand, the CernVM File System (CernVM-FS or CVMFS) [1] helps with data distribution. It is a write-once, read-everywhere filesystem used to deploy scientific software to thousands of nodes on a worldwide distributed computing infrastructure. CVMFS is based on the Hyper Text Transfer Protocol and has been widely used within the particle physics community for (1) distributing experiment software and data such as calibrations, and (2) facilitating containerization by efficiently hosting container images along with providing containerization software, especially Singularity [3] GlideinWMS relies on CVMFS installed locally on the computing resources to satisfy the experiments' software needs. This requires system administrators' effort to install and maintain CVMFS at the sites and limits the use of sites, especially HPC resources, that do not have CVMFS installed. This poster presents a solution, taking advantage of Glideins to provide CVMFS at most sites without the need for a local installation. Doing so expands the pool of resources available for HEP experiments and reduces the effort of system administrators for current resources. Additionally, the proposed solution allows GlideinWMS to also start Singularity [3], a containerization software that can run unprivileged, on sites where neither CVMFS nor Singularity are available, including HPC sites. The benefits provided by this solution are: (1) lower overhead for site administrators in that they have less software to install, (2) an expanded pool of resources that run user jobs with easy access to software and data provided by CVMFS, thus making life easier for the scientists, and (3) improved flexibility to use HPC resources by enabling GlideinWMS pilot jobs to support HPC sites.

Urs, Namratha↗
DOE OSTI2022

End-Use Load Profiles for the U.S. Building Stock: Practical Guidance on Accessing and Using the Data

This report describes example applications and considerations for using the National Renewable Energy Lab’s ResStock and ComStock end use load profiles (EULP). The report begins with an introduction to the three year project, and then provides instructions on accessing the EULP data and considerations for using the EULP and limitations of the data. The remainder of the report is on EULP use cases, including a variety of electricity planning use cases.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2019

First Cosmology Results using Type Ia Supernovae from the Dark Energy Survey: Constraints on Cosmological Parameters

We present the first cosmological parameter constraints using measurements of type Ia supernovae (SNe Ia) from the Dark Energy Survey Supernova Program (DES-SN). The analysis uses a subsample of 207 spectroscopically confirmed SNe. Ia from the first three years of DES-SN, combined with a low-redshift sample of 122 SNe from the literature. Our "DES-SN3YR" result from these 329 SNe. Ia is based on a series of companion analyses and improvements covering SN. Ia discovery, spectroscopic selection, photometry, calibration, distance bias corrections, and evaluation of systematic uncertainties. For a flat Lambda CDM model we find a matter density Omega(m) = 0.331 +/- 0.038. For a flat wCDM model, and combining our SN. Ia constraints with those from the cosmic microwave background (CMB), we find a dark energy equation of state w = -0.978 +/- 0.059, and Omega(m) = 0.321 +/- 0.018. For a flat w(0)w(a)CDM model, and combining probes from SN. Ia, CMB and baryon acoustic oscillations, we find w(0) = -0.885 +/- 0.114 and w(a) = -0.387 +/- 0.430. These results are in agreement with a cosmological constant and with previous constraints using SNe. Ia (Pantheon, JLA).

dark energy↗
DOE OSTI2018

Land surface model parameter optimisation using in situ flux data: comparison of gradient-based versus random search algorithms (a case study using ORCHIDEE v1.9.5.2)

Land surface models (LSMs), which form the land component of earth system models, rely on numerous processes for describing carbon, water and energy budgets, often associated with highly uncertain parameters. Data assimilation (DA) is a useful approach for optimising the most critical parameters in order to improve model accuracy and refine future climate predictions. In this study, we compare two different DA methods for optimising the parameters of seven plant functional types (PFTs) of the ORCHIDEE LSM using daily averaged eddy-covariance observations of net ecosystem exchange and latent heat flux at 78 sites across the globe. We perform a technical investigation of two classes of minimisation methods – local gradient-based (the L-BFGS-B algorithm, limited memory Broyden–Fletcher–Goldfarb–Shanno algorithm with bound constraints) and global random search (the genetic algorithm) – by evaluating their relative performance in terms of the model–data fit and the difference in retrieved parameter values. We examine the performance of each method for two cases: when optimising parameters at each site independently (“single-site” approach) and when simultaneously optimising the model at all sites for a given PFT using a common set of parameters (“multi-site” approach). We find that for the single site case the random search algorithm results in lower values of the cost function (i.e. lower model–data root mean square differences) than the gradient-based method; the difference between the two methods is smaller for the multi-site optimisation due to a smoothing of the cost function shape with a greater number of observations. The spread of the cost function, when performing the same tests with 16 random first-guess parameters, is much larger with the gradient-based method, due to the higher likelihood of being trapped in local minima. When using pseudo-observation tests, the genetic algorithm results in a closer approximation of the true posterior parameter value in the L-BFGS-B algorithm. We demonstrate the advantages and challenges of different DA techniques and provide some advice on using it for the LSM parameter optimisation.

58 GEOSCIENCES↗
NASA NTRS1972

Mapping of terrain by computer clustering techniques using multispectral scanner data and using color aerial film

Two clustering techniques were used for terrain mapping by computer of test sites in Yellowstone National Park. One test was made with multispectral scanner data using a composite technique which consists of (1) a strictly sequential statistical clustering which is a sequential variance analysis, and (2) a generalized K-means clustering. In this composite technique, the output of (1) is a first approximation of the cluster centers. This is the input to (2) which consists of steps to improve the determination of cluster centers by iterative procedures. Another test was made using the three emulsion layers of color-infrared aerial film as a three-band spectrometer. Relative film densities were analyzed using a simple clustering technique in three-color space. Important advantages of the clustering technique over conventional supervised computer programs are (1) human intervention, preparation time, and manipulation of data are reduced, (2) the computer map, gives unbiased indication of where best to select the reference ground control data, (3) use of easy to obtain inexpensive film, and (4) the geometric distortions can be easily rectified by simple standard photogrammetric techniques.

Smedes, H. W.↗
NASA NTRS1971

Monitoring the evolving land use patterns using remote sensing

The urbanization of Walnut Valley from 1953-71 prompted land use change from intensive von Thunen market-oriented patterns to extensive, disinvested, production-factor-minimized patterns. Shortrun, interim land use planning, has allowed agriculture to persist but only in the form of barley farming and grazing. Aerial photography used synoptically recorded six periods of land use change that bracketed dates before and after the freeway was announced and built. Interpretations of these changes help recognize potential conversions to urban uses which allow guidelines to be established that deal with rural-urban transition problems before they arise.

Goehring, D. R.↗
NASA NTRS1974

A detailed procedure for the use of small-scale photography in land use classification

A procedure developed to produce accurate land use maps from available high-altitude, small-scale photography in a cost-effective manner is presented. An alternative procedure, for use when the capability for updating the resultant land use map is not required, is also presented. The technical approach is discussed in detail, and personnel and equipment needs are analyzed. Accuracy percentages are listed, and costs are cited. The experiment land use classification categories are explained, and a proposed national land use classification system is recommended.

Vegas, P. L.↗
NASA NTRS1975

A procedure for automated land use mapping using remotely sensed multispectral scanner data

A system of processing remotely sensed multispectral scanner data by computer programs to produce color-coded land use maps for large areas is described. The procedure is explained, the software and the hardware are described, and an analogous example of the procedure is presented. Detailed descriptions of the multispectral scanners currently in use are provided together with a summary of the background of current land use mapping techniques. The data analysis system used in the procedure and the pattern recognition software used are functionally described. Current efforts by the NASA Earth Resources Laboratory to evaluate operationally a less complex and less costly system are discussed in a separate section.

Whitley, S. L.↗
NASA NTRS1976

Toward the modeling of land use change: A spatial analysis using remote sensing and historical data

It was hypothesized that the chronological observation of land use change could be shown to follow a predictable pattern and these patterns could be correlated with other statistical data to develop transition probabilities suitable for modeling purposes. A literature review and preliminary research, however, indicated a totally stochastic approach was not practical for simulating land use change and thus a more deterministic approach was adopted. The approach used assumes the determinants of the land use conversion process are found in the market place, where land transactions among buyers and sellers occur. Only one side of the market transaction process is studied, however, namely, the purchaser's desires in securing an ideal or suitable site. The problem was to identify the ideal qualities, quantities or attributes desired in an industrial site (or housing development), and to formulate a general algorithmic statement capable of identifying potential development sites. Research procedures involved developing a list of variables previously noted in the literature to be related to site selection and streamlining the list to a set suitable for statistical testing. A sample of 157 industries which have located (or relocated) in the 16-county Knoxville metropolitan region since 1950 was selected for industrial location analysis. Using NASA color infrared photography and Tennessee Valley Authority historical aerial photography, data were collected on the spatial characteristics of each industrial location event. These data were then subjected to factor analysis to determine the interrelations of variables.

Honea, R. B.↗
NASA NTRS1977

Techniques for land use change detection using Landsat imagery

A variety of procedures were developed for the delineation of areas of land use change using Landsat Multispectral Scanner data and the generation of statistics revealing the nature of the changes involved (i.e., number of acres changed from rural to urban). Techniques of the Image Based Information System were utilized in all stages of the procedure, from logging the Landsat data and registering two frames of imagery, to extracting the changed areas and printing tabulations of land use change in acres. Two alternative methods of delineating land use change are presented while enumerating the steps of the entire process. The Houston, Texas urban area, and the Orlando, Florida urban area, are used as illustrative examples of various procedures.

Angelici, G. L.↗
NASA NTRS1983

Urban land use classification using synthetic aperture radar

Several approaches to the use of radar imagery for land use classification of urban and near-urban areas are presented. The use of L band, horizontal transmit, and horizontal receive data is emphasized because of their general availability. For urban area studies using imaging radar, the effects of processing in an off-zero Doppler or squint mode, of the presence of large diffuse scatters, and of the possibility of height measurements are discussed. Data from the Los Angeles area are illustratively used.

Bryan, M. L.↗