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DOE OSTI2021

Analysis of Long-Term Quality Control Data for a 137 Cs Dosimetry Calibration Source

Strict quality assurance programs are required for many radiological applications, but these seldom exist for verifying dosimetry calibration sources. After initial characterization of a dosimetry calibration facility, quality control procedures are recommended to ensure the early detection of any changes or malfunctions. These also result in refined knowledge about average dose rate and experimental variations in dose delivery. This paper describes the implementation of a phase I quality control protocol for a 137 Cs dosimetry calibration source and includes an analysis of the resulting data collected over a 24-mo period. During this time, substantial data was collected to establish trial control limits. Air kerma rate measurements were obtained using an ion chamber and were adjusted for decay, corrected for ambient temperature, pressure and humidity, and then analyzed using quality control charts. Three variations of rational subgrouping methods were used in order to find assignable causes of error, and Nelson's Rules were followed to detect any non-random statistical variations. Measurements were subgrouped according to same-day measurements in order to detect positional errors as well as atmospheric correction errors. Additionally, measurements were subgrouped according to analogous experimental setups in order to detect failure in equipment or incorrect settings. Both were analyzed using the X-bar and R chart method. Similarly, individuals and moving ranges charts were used to carefully examine each position in order to observe any situational errors that may occur which include timing, positional, or interference errors. Each method was successful in identifying unique out-of-control data points that occurred during the phase I application of forming control limits. Furthermore, over the 24-mo period, enough data points were deemed in-control to establish reliable trial limits. Future experiments will include the phase II application of gaining more reliable measurements in order to fine-tune the limits, as well as performing a designed experiment, where variables are purposefully changed in order to test the variation of the data.

61 RADIATION PROTECTION AND DOSIMETRY↗

DOE OSTI2012

Cone Beam Computed Tomography Number Errors and Consequences for Radiotherapy Planning: An Investigation of Correction Methods

Purpose: The potential of keV cone beam computed tomography (CBCT) for guiding adaptive replanning is well-known. There are impediments to this, one being CBCT number accuracy. The purpose of this study was to investigate CBCT number correction methods and the affect of residual inaccuracies on dose deposition. Four different correction strategies were applied to the same patient data to compare performance and the sophistication of correction-method needed for acceptable dose errors. Methods and Materials: Planning CT and CBCT reconstructions were used for 12 patients (6 brain, 3 prostate, and 3 bladder cancer patients). All patients were treated using Elekta linear accelerators and XVI imaging systems. Two of the CBCT number correction methods investigated were based on an algorithm previously proposed by the authors but only previously applied to phantoms. Two further methods, based on an approach previously suggested in the research literature, were also examined. Dose calculations were performed using scans of a 'worst' subset of patients using the Pinnacle{sup 3} version 9.0 treatment planning system and the patients' clinical plans. Results: All mean errors in CBCT number were <50 HU, and all correction methods performed well or adequately in dose calculations. The worst single dose discrepancy identified for any of the examined methods or patients was 3.0%. Mean errors in the doses to treatment volumes or organs at risk were negatively correlated with the mean error in CT number. That is, a mean CT number that was too large, averaged over the entire CBCT volume, implied an underdosing in a volume-of-interest and vice versa. Conclusions: Results suggest that (1) the correction of CBCT numbers to within a mean error of 50 HU in the scan volume provides acceptable discrepancies in dose (<3%) and (2) this is achievable with even quite unsophisticated correction methods.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2019

Non-empirical, low-cost recovery of exact conditions with model-Hamiltonian inspired expressions in jmDFT

Density functional theory (DFT) is widely applied to both molecules and materials, but well known energetic delocalization and static correlation errors in practical exchange-correlation approximations limit quantitative accuracy. Common methods that correct energetic delocalization errors, such as the Hubbard U correction in DFT+U or Hartree-Fock exchange in global hybrids, do so at the cost of worsening static correlation errors. We recently introduced an alternate approach [Bajaj et al., J. Chem. Phys. 147, 191101 (2017)] known as judiciously modified DFT (jmDFT), wherein the deviation from exact behavior of semilocal functionals over both fractional spin and charge, i.e., the so-called flat plane, was used to motivate functional forms of second order analytic corrections. In this work, we introduce fully nonempirical expressions for all four coefficients in a DFT+U+J-inspired form of jmDFT, where all coefficients are obtained only from energies and eigenvalues of the integer-electron systems. We show good agreement for U and J coefficients obtained nonempirically as compared with the results of numerical fitting in a jmDFT U+J/J' correction. Incorporating the fully nonempirical jmDFT correction reduces and even eliminates the fractional spin error at the same time as eliminating the energetic delocalization error. We show that this approach extends beyond s-electron systems to higher angular momentum cases including p- and d-electrons. Finally, we diagnose some shortcomings of the current jmDFT approach that limit its ability to improve upon DFT results for cases such as weakly bound anions due to poor underlying semilocal functional behavior.

Delocalization↗

DOE OSTI2016

A method for simultaneous linear optics and coupling correction for storage rings with turn-by-turn beam position monitor data

We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. The fitting results are used for lattice correction. The method has been successfully demonstrated on the NSLS-II storage ring.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2014

Evaluation of overall setup accuracy and adequate setup margins in pelvic image-guided radiotherapy: Comparison of the male and female patients

We evaluated adequate setup margins for the radiotherapy (RT) of pelvic tumors based on overall position errors of bony landmarks. We also estimated the difference in setup accuracy between the male and female patients. Finally, we compared the patient rotation for 2 immobilization devices. The study cohort included consecutive 64 male and 64 female patients. Altogether, 1794 orthogonal setup images were analyzed. Observer-related deviation in image matching and the effect of patient rotation were explicitly determined. Overall systematic and random errors were calculated in 3 orthogonal directions. Anisotropic setup margins were evaluated based on residual errors after weekly image guidance. The van Herk formula was used to calculate the margins. Overall, 100 patients were immobilized with a house-made device. The patient rotation was compared against 28 patients immobilized with CIVCO's Kneefix and Feetfix. We found that the usually applied isotropic setup margin of 8 mm covered all the uncertainties related to patient setup for most RT treatments of the pelvis. However, margins of even 10.3 mm were needed for the female patients with very large pelvic target volumes centered either in the symphysis or in the sacrum containing both of these structures. This was because the effect of rotation (p ≤ 0.02) and the observer variation in image matching (p ≤ 0.04) were significantly larger for the female patients than for the male patients. Even with daily image guidance, the required margins remained larger for the women. Patient rotations were largest about the lateral axes. The difference between the required margins was only 1 mm for the 2 immobilization devices. The largest component of overall systematic position error came from patient rotation. This emphasizes the need for rotation correction. Overall, larger position errors and setup margins were observed for the female patients with pelvic cancer than for the male patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2026

The Art of Automation: Translating Electron Microscopy Workflows Into Automated Processes

Acquiring data using a scanning transmission electron microscope (STEM) is a complex, multi-step process. The intricacy of the process depends on the type of sample, composition of the material, desired results of the experiment, resolution requirement and other experimental factors. Each experiment presents unique complications, such as sample drift and contamination, that the microscopist must consider when acquiring data. All these challenges are handled fluidly and expertly by experienced microscopists, but to reach new levels of innovation in material development, including greater reproducibility, throughput, and precision, the automation of these workflows is essential. The initial phase of this work involved translating intuition-based workflows into discrete, programmable steps. Some common key stages in STEM workflows are the initial tuning, scanning the sample for areas of interest, and then acquiring the data. Each stage can be broken further into specific parameter adjustments, such as aberration correction and dwell time optimization, depending on the experiment. When deconstructing various experiments each step was assessed for automation feasibility based on the amount of real time operator decisions. There are steps that lend themselves to automation more readily than others, such as course focusing and sample screening, but there is potential for full automation of all stages with time. As an initial step, an automated montage routine was developed, allowing for the efficient acquisition of large portions of the sample without requiring continuous intervention from the operator. The automation of this small process of the procedure demonstrates the value of this capability. A major challenge in automation arises from discrepancies between commanded, reported and actual stage movements. Using systematic tests, stage movement was quantified. This error can be corrected algorithmically for more accurate workflows in the future. Expanding automation capabilities would result in larger, more efficient data acquisition which allows for more robust statistical analysis. Additionally, this work lays the groundwork for a closed loop system where machine learning algorithms would intake automatically acquired data and make real time decisions. By progressively automating this instrument, this work establishes the foundation for fully automated experimentation in transmission electron microscopy.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2014

SU-E-T-628: Effect of Dose Rate and Leakage Correction for Dosimetric Leaf Gap Measurement

Purpose: To study the dose rate response of Mapcheck and quantify/correct dose rate/leakage effect on IMRT QA. Evaluate the dose rate/leakage effect on dosimetric leaf gap (DLG) measurement. Methods: Varian Truebeam Linac with HD120 MLC was used for all measurement, it is capable to adjust dose rate from 600MU/min to 5MU/min. Fluke Advanced Therapy Doisemter and PTW 30013 Farmer chamber for chamber measurement; SunNuclear Mapcheck2 with 5cm total buildup for diode measurement. DLG was measured with both chamber and diode.Diode response was measured by varies dose rate, while fixed mapcheck setup and total MU. MLC Leakage was measured with both chamber and diode. Mapcheck measurement was saved as movie file (mcm file), which include measurement updated every 50mSec. The difference between intervals can be converted to dose and dose rate and leakage response correction can be applied to them. Results: DLG measurement results with chamber and diode were showed as follows, the DLG value is 0.36 vs. 0.24mm respectively. Diode dose rate response drops from 100% at 600MU/min to 95.5% at 5MU/min as follows. MLC Leakage measured with diode is 1.021%, which is 9% smaller than 1.112% from chamber measurement. By apply the dose rate and leakage correction, the residue error reduced 2/3. Conclusions: Diode has lower response at lower dose rate, as low as 4.5% for 5MU/min; diode has lower energy response for low energy too, 5% lower for Co-60 than 6MV. It partially explains the leakage difference of 9% between chamber and diode. Lower DLG with diode is because of the lower response at narrower gap, in Eclipse however DLG need to increase to makeup lower response, which is over correction for chamber though. Correction can reduce error by 2/3, the rest 1/3 can be corrected by scatter effect, which is under study.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2018

Author Correction: Energy use and life cycle greenhouse gas emissions of drones for commercial package delivery

In the original version of this Article, the first sentence of the sixth paragraph of the "Comparing emissions" section, the Results originally incorrectly read as 'In the base case, delivery of a small (0.5 kg) package with the small quadrotor drone has lower impacts than delivery by diesel truck, ranging from a 59% reduction in GHGs in California, to a 17% reduction in Missouri'. The correct version states '54%' instead of '59%' and '23%' instead of '17%'.The fourth sentence of the same paragraph originally incorrectly read as 'In the base case, delivery of a medium-sized (8 kg) package has 17% lower GHGs than delivery by truck in California, is about equivalent to delivery trucks for the U.S. average electricity mix, but has 77% higher GHGs than truck delivery in Missouri, which has a carbon-intensive electricity grid'. The correct version states 'In the base case, delivery of a medium-sized (8 kg) package has 9% lower GHGs than delivery by truck in California, is about 24% higher than delivery trucks for the U.S. average electricity mix, and has 50% higher GHGs than truck delivery in Missouri, which has a carbon-intensive electricity grid.The last sentence of the seventh paragraph of the same section originally incorrectly read as 'Because of the importance of electricity used to power the octocopter, charging with low-carbon electricity of 200 g GHG/kWh can reduce delivered package GHGs by 34% compared to diesel trucks'. The correct version states '37%' instead of '34%'.These errors have been corrected in both the PDF and HTML versions of the Article.

Stolaroff, Joshuah K.↗

DOE OSTI2016

Push it to the limit: Characterizing the convergence of common sequences of basis sets for intermolecular interactions as described by density functional theory

With the aim of systematically characterizing the convergence of common families of basis sets such that general recommendations for basis sets can be made, we have tested a wide variety of basis sets against complete-basis binding energies across the S22 set of intermolecular interactions—noncovalent interactions of small and medium-sized molecules consisting of first- and second-row atoms—with three distinct density functional approximations: SPW92, a form of local-density approximation; B3LYP, a global hybrid generalized gradient approximation; and B97M-V, a meta-generalized gradient approximation with nonlocal correlation. We have found that it is remarkably difficult to reach the basis set limit; for the methods and systems examined, the most complete basis is Jensen’s pc-4. The Dunning correlation-consistent sequence of basis sets converges slowly relative to the Jensen sequence. The Karlsruhe basis sets are quite cost effective, particularly when a correction for basis set superposition error is applied: counterpoise-corrected def2-SVPD binding energies are better than corresponding energies computed in comparably sized Dunning and Jensen bases, and on par with uncorrected results in basis sets 3-4 times larger. These trends are exhibited regardless of the level of density functional approximation employed. A sense of the magnitude of the intrinsic incompleteness error of each basis set not only provides a foundation for guiding basis set choice in future studies but also facilitates quantitative comparison of existing studies on similar types of systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

The effect of relative humidity on eddy covariance latent heat flux measurements and its implication for partitioning into transpiration and evaporation

While the eddy covariance (EC) technique is a well-established method for measuring water fluxes (i.e., evaporation or 'evapotranspiration’, ET), the measurement is susceptible to many uncertainties. One such issue is the potential underestimation of ET when relative humidity (RH) is high (> 70%), due to low-pass filtering with some EC systems. Yet, this underestimation for different types of EC systems (e.g. open-path or closed-path sensors) has not been characterized for synthesis datasets such as the widely used FLUXNET2015 dataset. Here, we assess the RH-associated underestimation of latent heat fluxes (LE, or ET) from different EC systems for 163 sites in the FLUXNET2015 dataset. We found that the LE underestimation is most apparent during hours when RH is higher than 70%, predominantly observed at sites using closed-path EC systems, but the extent of the LE underestimation is highly site-specific. We then propose a machine learning based method to correct for this underestimation, and compare it to two energy balance closure based LE correction approaches (Bowen ratio correction, BRC, and attributing all errors to LE). Our correction increases LE by 189% for closed-path sites at high RH (> 90%), while BRC increases LE by around 30% for all RH conditions. Additionally, we assess the influence of these corrections on ET-based transpiration (T) estimates using two different ET partitioning methods. Results show opposite responses (increasing vs. slightly decreasing T-to-ET ratios, T/ET) between the two methods when comparing T based on corrected and uncorrected LE. Overall, our results demonstrate the existence of a high RH bias in water fluxes in the FLUXNET2015 dataset and suggest that this bias is a pronounced source of uncertainty in ET measurements to be considered when estimating ecosystem T/ET and WUE.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2019

(U) Transport Corrections in SENSMG

Truncating the spherical harmonics expansion of the neutron scattering source in the Boltzmann transport equation leads to truncation error. Methods for approximately correcting for this truncation error are called transport corrections . The PARTISN multigroup discrete ordinates neutron transport code has several transport correction options. These options can be used in the SENSMG multigroup neutron sensitivity code, which relies on PARTISN for the neutron transport. However, with one exception, the sensitivities computed by SENSMG do not include the effect of transport corrections. Thus, when certain transport corrections are used, SENSMG results are inconsistent with the transport solutions. This report discusses the issues surrounding computing sensitivities when transport corrections are used. Problems and possible solutions are identified.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2018

Corrigendum: Minimum information about a single amplified genome (MISAG) and a metagenome-assembled genome (MIMAG) of bacteria and archaea.

© 2018 Nature Publishing Group. All rights reserved. In the version of this article initially published, the author A. Murat Eren was listed as A.M. Eren. The corresponding affiliation was given as the Knapp Center for Biomedical Discovery, rather than Department of Medicine, University of Chicago, Chicago, Illinois, USA, and Marine Biological Laboratory, Woods Hole, Massachusetts, USA. The errors have been corrected in the HTML and PDF versions of the article as of 29 November 2017. In the version of this article initially published, the following acknowledgment was omitted: A.L. was supported by the Russian Science Foundation (grant number 14-50-00069). The error has been corrected in the HTML and PDF versions of the article as of 7 December 2017.

Bowers, Robert M↗

DOE OSTI2018

Corrigendum: Minimum information about a single amplified genome (MISAG) and a metagenome-assembled genome (MIMAG) of bacteria and archaea (Nature Biotechnology (2017) 35 (725-731) DOI: 10.1038/nbt.3893)

Bowers, RM↗

DOE OSTI2020

(U) Transport Corrections Implemented in SENSMG

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2015

SU-E-P-54: Evaluation of the Accuracy and Precision of IGPS-O X-Ray Image-Guided Positioning System by Comparison with On-Board Imager Cone-Beam Computed Tomography

Purpose: The purpose of this study is to assess the positioning accuracy and precision of IGPS-O system which is a novel radiographic kilo-voltage x-ray image-guided positioning system developed for clinical IGRT applications. Methods: IGPS-O x-ray image-guided positioning system consists of two oblique sets of radiographic kilo-voltage x-ray projecting and imaging devices which were equiped on the ground and ceiling of treatment room. This system can determine the positioning error in the form of three translations and three rotations according to the registration of two X-ray images acquired online and the planning CT image. An anthropomorphic head phantom and an anthropomorphic thorax phantom were used for this study. The phantom was set up on the treatment table with correct position and various “planned” setup errors. Both IGPS-O x-ray image-guided positioning system and the commercial On-board Imager Cone-beam Computed Tomography (OBI CBCT) were used to obtain the setup errors of the phantom. Difference of the Result between the two image-guided positioning systems were computed and analyzed. Results: The setup errors measured by IGPS-O x-ray image-guided positioning system and the OBI CBCT system showed a general agreement, the means and standard errors of the discrepancies between the two systems in the left-right, anterior-posterior, superior-inferior directions were −0.13±0.09mm, 0.03±0.25mm, 0.04±0.31mm, respectively. The maximum difference was only 0.51mm in all the directions and the angular discrepancy was 0.3±0.5° between the two systems. Conclusion: The spatial and angular discrepancies between IGPS-O system and OBI CBCT for setup error correction was minimal. There is a general agreement between the two positioning system. IGPS-O x-ray image-guided positioning system can achieve as good accuracy as CBCT and can be used in the clinical IGRT applications.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2019

Accounting for errors in quantum algorithms via individual error reduction

Abstract We discuss a surprisingly simple scheme for accounting (and removal) of error in observables determined from quantum algorithms. A correction to the value of the observable is calculated by first measuring the observable with all error sources active and subsequently measuring the observable with each error source reduced separately. We apply this scheme to the variational quantum eigensolver, simulating the calculation of the ground state energy of equilibrium H 2 and LiH in the presence of several noise sources, including amplitude damping, dephasing, thermal noise, and correlated noise. We show that this scheme provides a decrease in the needed quality of the qubits by up to two orders of magnitude. In near-term quantum computing, where full fault-tolerant error correction is too expensive, this scheme provides a route to significantly more accurate calculations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2014

Correcting incompatible DN values and geometric errors in nighttime lights time series images

The Defense Meteorological Satellite Program’s Operational Linescan System (DMSP-OLS) nighttime lights imagery has proven to be a powerful remote sensing tool to monitor urbanization and assess socioeconomic activities at large scales. However, the existence of incompatible digital number (DN) values and geometric errors severely limit application of nighttime light image data on multi-year quantitative research. In this study we extend and improve previous studies on inter-calibrating nighttime lights image data to obtain more compatible and reliable nighttime lights time series (NLT) image data for China and the United States (US) through four steps: inter-calibration, geometric correction, steady increase adjustment, and population data correction. We then use gross domestic product (GDP) data to test the processed NLT image data indirectly and find that sum light (summed DN value of pixels in a nighttime light image) maintains apparent increase trends with relatively large GDP growth rates but does not increase or decrease with relatively small GDP growth rates. As nighttime light is a sensitive indicator for economic activity, the temporally consistent trends between sum light and GDP growth rate imply that brightness of nighttime lights on the ground is correctly represented by the processed NLT image data. Finally, through analyzing the corrected NLT image data from 1992 to 2008, we find that China experienced apparent nighttime lights development in 1992-1997 and 2001-2008 respectively and the US suffered from nighttime lights decay in large areas after 2001.

47 OTHER INSTRUMENTATION↗

DOE OSTI2013

A two-dimensional matrix correction for off-axis portal dose prediction errors

Purpose: This study presents a follow-up to a modified calibration procedure for portal dosimetry published by Bailey et al. ['An effective correction algorithm for off-axis portal dosimetry errors,' Med. Phys. 36, 4089-4094 (2009)]. A commercial portal dose prediction system exhibits disagreement of up to 15% (calibrated units) between measured and predicted images as off-axis distance increases. The previous modified calibration procedure accounts for these off-axis effects in most regions of the detecting surface, but is limited by the simplistic assumption of radial symmetry. Methods: We find that a two-dimensional (2D) matrix correction, applied to each calibrated image, accounts for off-axis prediction errors in all regions of the detecting surface, including those still problematic after the radial correction is performed. The correction matrix is calculated by quantitative comparison of predicted and measured images that span the entire detecting surface. The correction matrix was verified for dose-linearity, and its effectiveness was verified on a number of test fields. The 2D correction was employed to retrospectively examine 22 off-axis, asymmetric electronic-compensation breast fields, five intensity-modulated brain fields (moderate-high modulation) manipulated for far off-axis delivery, and 29 intensity-modulated clinical fields of varying complexity in the central portion of the detecting surface. Results: Employing the matrix correction to the off-axis test fields and clinical fields, predicted vs measured portal dose agreement improves by up to 15%, producing up to 10% better agreement than the radial correction in some areas of the detecting surface. Gamma evaluation analyses (3 mm, 3% global, 10% dose threshold) of predicted vs measured portal dose images demonstrate pass rate improvement of up to 75% with the matrix correction, producing pass rates that are up to 30% higher than those resulting from the radial correction technique alone. As in the 1D correction case, the 2D algorithm leaves the portal dosimetry process virtually unchanged in the central portion of the detector, and thus these correction algorithms are not needed for centrally located fields of moderate size (at least, in the case of 6 MV beam energy).Conclusion: The 2D correction improves the portal dosimetry results for those fields for which the 1D correction proves insufficient, especially in the inplane, off-axis regions of the detector. This 2D correction neglects the relatively smaller discrepancies that may be caused by backscatter from nonuniform machine components downstream from the detecting layer.

60 APPLIED LIFE SCIENCES↗