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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

GLOBAL PROPERTIES OF FULLY CONVECTIVE ACCRETION DISKS FROM LOCAL SIMULATIONS

We present an approach to deriving global properties of accretion disks from the knowledge of local solutions derived from numerical simulations based on the shearing box approximation. The approach consists of a two-step procedure. First, a local solution valid for all values of the disk height is constructed by piecing together an interior solution obtained numerically with an analytical exterior radiative solution. The matching is obtained by assuming hydrostatic balance and radiative equilibrium. Although in principle the procedure can be carried out in general, it simplifies considerably when the interior solution is fully convective. In these cases, the construction is analogous to the derivation of the Hayashi tracks for protostars. The second step consists of piecing together the local solutions at different radii to obtain a global solution. Here we use the symmetry of the solutions with respect to the defining dimensionless numbers—in a way similar to the use of homology relations in stellar structure theory—to obtain the scaling properties of the various disk quantities with radius.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Development of High Alumina Glass Property Data for Hanford High-Level Waste Glass Models - 16231

Roughly half of the projected Hanford high-level waste batches will have waste loadings limited by relatively high concentration of Al{sub 2}O{sub 3}. Individual glasses have been formulated and tested to demonstrate that it is possible to increase the loading of these high-Al{sub 2}O{sub 3} wastes in glass by as much as 50%. To implement such increases in waste loading in the Hanford Tank Waste Treatment and Immobilization Plant, the impact of composition on the properties of high-Al{sub 2}O{sub 3} waste glasses must be quantified in the form of validated glass property-composition models. To collect the data necessary for glass property-composition models, a multi-phase experimental approach was developed. In the first phase of the study, a set of 46 glass compositions were statistically designed to most efficiently backfill existing data in the composition region for high-Al{sub 2}O{sub 3} (15 to 30 wt%) waste glasses. The glasses were fabricated and key glass properties were tested: - Product Consistency Test (PCT) on quench (Q) and canister centerline cooled (CCC) samples - Toxicity Characteristic Leaching Procedure (TCLP) on Q and CCC samples - Crystallinity as a function of temperature (T) at equilibrium and of CCC samples - Viscosity and electrical conductivity as a function of T The measured properties of these glasses were compared to predictions from previously existing models developed over lower Al{sub 2}O{sub 3} concentration ranges. Areas requiring additional testing and modeling were highlighted. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

Forward fitting of experimental data from a NE213 neutron detector installed with the magnetic proton recoil upgraded spectrometer at JET

In this paper, we present the results obtained from the data analysis of neutron spectra measured with a NE213 liquid scintillator at JET. We calculated the neutron response matrix of the instrument combining MCNPX simulations, a generic proton light output function measured with another detector and the fit of data from ohmic pulses. For the analysis, we selected a set of pulses with neutral beam injection heating (NBI) only and we applied a forward fitting procedure of modeled spectral components to extract the fraction of thermal neutron emission. The results showed the same trend of the ones obtained with the dedicated spectrometer TOFOR, even though the values from the NE213 analysis were systematically higher. This discrepancy is probably due to the different lines of sight of the two spectrometers (tangential for the NE213, vertical for TOFOR). The uncertainties on the thermal fraction estimates were from 4 to 7 times higher than the ones from the TOFOR analysis.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Development of a 3D optical scanning-based automatic quality assurance system for proton range compensators

Purpose: A new automatic quality assurance (AutoRCQA) system using a three-dimensional scanner (3DS) with system automation was developed to improve the accuracy and efficiency of the quality assurance (QA) procedure for proton range compensators (RCs). The system performance was evaluated for clinical implementation. Methods: The AutoRCQA system consists of a three-dimensional measurement system (3DMS) based on 3DS and in-house developed verification software (3DVS). To verify the geometrical accuracy, the planned RC data (PRC), calculated with the treatment planning system (TPS), were reconstructed and coregistered with the measured RC data (MRC) based on the beam isocenter. The PRC and MRC inner surfaces were compared with composite analysis (CA) using 3DVS, using the CA pass rate for quantitative analysis. To evaluate the detection accuracy of the system, the authors designed a fake PRC by artificially adding small cubic islands with side lengths of 1.5, 2.5, and 3.5 mm on the inner surface of the PRC and performed CA with the depth difference and distance-to-agreement tolerances of [1 mm, 1 mm], [2 mm, 2 mm], and [3 mm, 3 mm]. In addition, the authors performed clinical tests using seven RCs [computerized milling machine (CMM)-RCs] manufactured by CMM, which were designed for treating various disease sites. The systematic offsets of the seven CMM-RCs were evaluated through the automatic registration function of AutoRCQA. For comparison with conventional technique, the authors measured the thickness at three points in each of the seven CMM-RCs using a manual depth measurement device and calculated thickness difference based on the TPS data (TPS-manual measurement). These results were compared with data obtained from 3DVS. The geometrical accuracy of each CMM-RC inner surface was investigated using the TPS data by performing CA with the same criteria. The authors also measured the net processing time, including the scan and analysis time. Results: The AutoRCQA system accurately detected all fake objects in accordance with the given criteria. The median systematic offset of the seven CMM-RCs was 0.08 mm (interquartile range: −0.25 to 0.37 mm) and −0.08 mm (−0.58 to 0.01 mm) in the X- and Y-directions, respectively, while the median distance difference was 0.37 mm (0.23–0.94 mm). The median thickness difference of the TPS-manual measurement at points 1, 2, and 3 was −0.4 mm (−0.4 to −0.2 mm), −0.2 mm (−0.3 to 0.0 mm), and −0.3 mm (−0.6 to −0.1 mm), respectively, while the median difference of 3DMS was 0.0 mm (−0.1 to 0.2 mm), 0.0 mm (−0.1 to 0.3 mm), and 0.1 mm (−0.1 to 0.2 mm), respectively. Thus, 3DMS showed slightly better values compared to the manual measurements for points 1 and 3 in statistical analysis (p < 0.05). The average pass rate of the seven CMM-RCs was 97.97% ± 1.68% for 1-mm CA conditions, increasing to 99.98% ± 0.03% and 100% ± 0.00% for 2- and 3-mm CA conditions, respectively. The average net analysis time was 18.01 ± 1.65 min. Conclusions: The authors have developed an automated 3DS-based proton RC QA system and verified its performance. The AutoRCQA system may improve the accuracy and efficiency of QA for RCs.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2016

SHARP User Manual

SHARP is an advanced modeling and simulation toolkit for the analysis of nuclear reactors. It is comprised of several components including physical modeling tools, tools to integrate the physics codes for multi-physics analyses, and a set of tools to couple the codes within the MOAB framework. Physics modules currently include the neutronics code PROTEUS, the thermal-hydraulics code Nek5000, and the structural mechanics code Diablo. This manual focuses on performing multi-physics calculations with the SHARP ToolKit. Manuals for the three individual physics modules are available with the SHARP distribution to help the user to either carry out the primary multi-physics calculation with basic knowledge or perform further advanced development with in-depth knowledge of these codes. This manual provides step-by-step instructions on employing SHARP, including how to download and install the code, how to build the drivers for a test case, how to perform a calculation and how to visualize the results. Since SHARP has some specific library and environment dependencies, it is highly recommended that the user read this manual prior to installing SHARP. Verification tests cases are included to check proper installation of each module. It is suggested that the new user should first follow the step-by-step instructions provided for a test problem in this manual to understand the basic procedure of using SHARP before using SHARP for his/her own analysis. Both reference output and scripts are provided along with the test cases in order to verify correct installation and execution of the SHARP package. At the end of this manual, detailed instructions are provided on how to create a new test case so that user can perform novel multi-physics calculations with SHARP. Frequently asked questions are listed at the end of this manual to help the user to troubleshoot issues.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS2019

Predictive Modeling for Differential Diagnosis and Mortality Risk Assessment

The prevalence of electronic health record (EHR) systems has brought prodigious biomedical informatics opportunity. Automated machine learning methods can effectively utilize such data and have become common tools for healthcare predictive modeling. Researches in medical informatics have explored the potential of deep learning and classical models in emergent care scenarios. In particular, predicting differential diagnoses for admissions have proven useful in decreasing unnecessary lab tests and improving inpatient triage decision-making. Moreover, identification of high-risk patients for in-hospital mortality is vitally important to maximize allocation of medical resources.The Medical Information Mart for Intensive Care (MIMIC-III) database, containing de-identified critical care inpatient was used in our study. This data set captures hospital patient laboratory measurements, pharmacologic prescriptions, diagnostic data and procedure event recordings. When considering adult patients and discounting admissions with ICU length of stay less than 24 hours, there were 37,787 unique admissions and 30,414 total patients. We examined the top 25 most prevalent ICD-9 group-level disease specificities in MIMIC-III using a multi-label classification model. In-hospital mortality was modeled as binary classification with 4,155 (13%) adult patients that expired, of which 3,138 (75.5%) were in the ICU setting. The metrics AUC, F1 score, sensitivity and specificity values calculated for each disease label measured prediction performance.The usage of ICD-9 group codes reduced feature dimension from 14,567 to 942 and greatly improved distribution of patient diagnostic categories. Disease temporal patterns were captured by considering the most frequently sampled 6 vital signs and 13 laboratory values. Missing data were imputed at each time-stamp. Time-series raw hourly average values were converted into 5 summary features (mean, standard deviation, number of observations, min & max values). Patient demographic variables such as age, gender, marital status and ethnicity were also factored into the modeling. Choi et al showed that contextual embedding of medical data, diagnostic and procedural codes alone can predict future diagnoses with sensitivity as high as 0.79. We utilized an embedding technique called word2vec which allowed sparse representations of medical history to be transformed into dense word vectors. The mappings captured contextual information by treating each admission as a sentence and learning the most likely neighboring words in a sliding window fashion. Binary and multi-label classification was achieved via collapse models, which do not consider temporal information, as well as recurrent neural networks with regularization, Softmax output layer activation together with categorical cross-entropy as the loss function.

US Army collaboration↗
DOE OSTI2016

Experimental study of the downstream effect of LOCA-generated debris on the pressure drop of full scale fuel assembly

The emergency core cooling system (ECCS) works to cool the reactor core in the event of a postulated loss-of-coolant accident (LOCA). The long-term reactor cooling water of ECCS comes from containment sump. Usually, the containment sump contains one or more screens to prevent the components of the ECCS from debris which could be washed into the sump. Large debris is blocked by the sump screens. However, some of the debris, such as fibrous, chemical precipitates and small particles may be ingested into the ECCS and subsequently into the reactor coolant systems (RCS), which would challenge the long-term core cooling (LTCC) and threaten the reactor core safety. NRC address this concern Generic Letter 2004-02. Westinghouse has evaluated the AP1000 1/4 height fuel assembly head-loss test in response to the issue. AVERA also perform the scaled 1/3 height mock-up fuel assembly test. The debris effect on the pressure drop of half-length mock-up PLUS7 fuel assembly of APR1400 were performed in KHNP. Numerical simulation by RELAP5-3D were performed for the debris-generated core blockage and full core as well as core bypass blockage condition were considered. However, the test in the works mentioned above use the scaled down FA (1/4, 1/3 or 1/2 length of a full FA), and didn't give the relationship between pressure drop and debris batches. The purpose of this study was to extend the debris effect to the full scale PWR fuel assembly, and identified batch by batch effect of debris to head loss of FA. The specific experimental procedure is concluded. The pressure drop test without adding debris is performed at the beginning and then three kinds of debris are added to the test loop step by step to test their effect on the pressure drop of fuel assembly. Two kinds of tests have been carried out, and the quantitative pressure data are obtained and analysis is provided. This work provides reliable and quantitative data for nuclear power plant (NPP) downstream effect analysis and safety analysis program, which is important to for licensing of NPP and further benchmark exercise. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2014

Reconstruction of the primordial power spectrum of curvature perturbations using multiple data sets

Detailed knowledge of the primordial power spectrum of curvature perturbations is essential both in order to elucidate the physical mechanism ('inflation') which generated it, and for estimating the cosmological parameters from observations of the cosmic microwave background and large-scale structure. Hence it ought to be extracted from such data in a model-independent manner, however this is difficult because relevant cosmological observables are given by a convolution of the primordial perturbations with some smoothing kernel which depends on both the assumed world model and the matter content of the universe. Moreover the deconvolution problem is ill-conditioned so a regularisation scheme must be employed to control error propagation. We demonstrate that 'Tikhonov regularisation' can robustly reconstruct the primordial spectrum from multiple cosmological data sets, a significant advantage being that both its uncertainty and resolution are then quantified. Using Monte Carlo simulations we investigate several regularisation parameter selection methods and find that generalised cross-validation and Mallow's C{sub p} method give optimal results. We apply our inversion procedure to data from the Wilkinson Microwave Anisotropy Probe, other ground-based small angular scale CMB experiments, and the Sloan Digital Sky Survey. The reconstructed spectrum (assuming the standard ΛCDM cosmology) is not scale-free but has an infrared cutoff at k∼<5 × 10{sup −4} Mpc{sup −1} (due to the anomalously low CMB quadrupole) and several features with ∼ 2σ significance at k/Mpc{sup −1} ∼ 0.0013–0.0025, 0.0362–0.0402 and 0.051–0.056, reflecting the 'WMAP glitches'. To test whether these are indeed real will require more accurate data, such as from the Planck satellite and new ground-based experiments.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

CT-Guided Percutaneous Radiologic Gastrostomy for Patients with Head and Neck Cancer: A Retrospective Evaluation in 177 Patients

PurposeThe purpose of this study was to assess the technical success rate and adverse events (AEs) associated with computed tomography (CT)-guided percutaneous gastrostomy for patients with head and neck cancer (HNC).Materials and MethodsThis retrospective study included patients with HNC who had undergone CT-guided percutaneous gastrostomy between February 2007 and December 2013. Information regarding the patients’ backgrounds, CT-guided percutaneous gastrostomy techniques, technical success rate, and AEs were obtained from the medical records. In all patients, the stomach was punctured under CT fluoroscopy with a Funada gastropexy device.ResultsDuring the study period, 177 patients underwent CT-guided percutaneous gastrostomy. The most common tumor location was the oral cavity, followed by the pharynx and maxilla. The indication for CT-guided percutaneous gastrostomy were tumor obstruction in 78 patients, postoperative dysphagia in 55 patients, radiation edema in 43 patients, and cerebral infarction in 1 patient. The technical success rate was 97.7 %. The overall mean procedure time was 25.3 min. Major AEs occurred in seven patients (4.0 %), including bleeding (n = 4), colonic injury (n = 1), gastric tear (n = 1), and aspiration pneumonia (n = 1). Minor AEs occurred in 15 patients (8.5 %), which included peristomal leakage (n = 6), irritation (n = 4), inadvertent removal (n = 2), peristomal hemorrhage (n = 1), peristomal infection (n = 1), and wound granulation (n = 1). The mean follow-up period was 111 days (range 1–1106 days).ConclusionOur study suggests that CT-guided gastrostomy may be suitable in patients with HNC.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Novel utilization of 3D technology and the hybrid operating theatre: Peri-operative assessment of posterior sterno-clavicular dislocation using cone beam CT

A patient with a medial and posterior dislocation of the right sterno-clavicular (SC) joint and displacement of the trachea and brachiocephalic artery by the medial head of the clavicle underwent general anaesthetic in the operating theatre for an open reduction procedure. The surgeon initially attempted a closed reduction, but this required imaging to check SC alignment. The patient was transferred to an adjacent hybrid operating theatre for imaging. Cone beam computed tomography (CBCT) was performed, which successfully demonstrated a significant reduction in the dislocation of the SC joint. The trachea and brachiocephalic artery were no longer compressed or displaced. This case study demonstrates an alternative to the patient being transferred to the medical imaging department for multi-slice CT. It also describes a novel use of the hybrid operating theatre and its CBCT capabilities.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Modern sensitivity analysis - 15651

Sensitivity analysis has been applied to complex models, such as performance assessment models, since at least the advent of computational tools to support such an approach to model evaluation. Initially, sensitivity analysis methods were applied to deterministic models and focused on changing one input variable at a time. Probabilistic modeling opened the door to evaluating changes in all input variables simultaneously. Standardized rank regression methods were primarily used in the last century to evaluate probabilistic models. These methods assume linearity in the rank response of the model to the inputs. At the very least this assumes monotonicity in the response, but for the most part the response needs to be near-linear. This is highly unlikely for performance assessment models that are based on differential equations, multiplication and division of variables that are usually not correlated, and conservatism that is not well understood. There are better statistical methods for evaluating highly non-linear and dynamic probabilistic models. Some of these methods were founded in the data mining industry. This century has seen a rapid development of the internet that led directly to the development of data mining techniques for massive databases. Although the goals were different, these techniques can be adapted to sensitivity analysis for complex probabilistic models, which, also, form large, or even massive, databases. These modern sensitivity analysis procedures assess the importance of every explanatory variable (input parameters) used in a probabilistic model. In practice, this means that for each endpoint of interest, every explanatory variable in the model is associated with a quantitative measure of importance. For a given explanatory variable, the importance value depends on the endpoint of interest. This global approach to sensitivity analysis allows all levels of interactions to be evaluated, so that the variation in the output can be measured at every level of possible interaction. The effects are collected together during sensitivity analysis processing, and then separated out to attribute the overall contribution of each input parameter to the model output. These global sensitivity analysis procedures have the ability to characterize non-linear and non-monotonic relationships between explanatory variables and endpoints of interest. This is critically important because of the need to characterize complex interactions among multiple explanatory variables in PA models that often have non-linear and non-monotonic effects. The options for sensitivity analysis are fully explored, including an evaluation of several methods when applying them to a well-known complex non-linear non-monotonic model. The results clearly demonstrate the relative benefit of using data mining methods over simple statistical approaches such as standardized rank regression. (authors)

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Incidence and Consequence of Nontarget Embolization Following Bland Hepatic Arterial Embolization

Purpose: Estimate the incidence of nontarget embolization (NTE) as identified on immediate post-hepatic artery embolization CT. Materials and Methods: Two hundred hepatic embolizations performed with particles alone (bland embolization) in 147 patients between August 16, 2013 and August 26, 2014 with immediate post-procedure CT were retrospectively reviewed. Arterial anatomy, vessels treated, imaging findings of NTE, patient demographics, length of hospital stay following embolization, and procedure-related complications were recorded. The data were analyzed using two-sided t-tests and chi-squared tests. Results: Evidence of NTE was seen on post-procedure CT in 64 of 200 cases (64/200, 32%). Six organs were affected, with 69 discrete sites in 64 patients. The majority (49/69, 71.0%) involved the gallbladder. The mean length of hospital stay (LOS) for patients with and without NTE was 2.9 ± 1.5 nights (range 1–7) and 2.9 ± 2.3 nights (range 0–21), respectively (P = 0.81). NTE was more common following embolization of replaced or accessory hepatic vessels. There were three complications in the NTE group (3/64, 4.7%) following the embolization procedure, one of which was cholecystitis directly related to NTE. The other two were one incidence each of contrast-induced nephropathy and pneumonia. In the group without NTE, seven complications occurred (7/136, 5.1%, P = 0.889), including one death resulting from hepatic failure, two gastrointestinal bleeds, two hepatic abscesses, flash pulmonary edema, and pancreatitis. Conclusion: Unanticipated NTE is not uncommon after bland hepatic artery embolization, particularly after treating accessory or replaced vessels, but does not increase complications or LOS. Level of Evidence: Level 2b, Retrospective Cohort.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Optimized mirror shape tuning using beam weightings based on distance, angle of incidence, reflectivity, and power

For glancing-incidence optical systems, such as short-wavelength optics used for nano-focusing, incorporating physical factors in the calculations used for shape optimization can improve performance. Wavefront metrology, including the measurement of a mirror's shape or slope, is routinely used as input for mirror figure optimization on mirrors that can be bent, actuated, positioned, or aligned. Modeling shows that when the incident power distribution, distance from focus, angle of incidence, and the spatially varying reflectivity are included in the optimization, higher Strehl ratios can be achieved. Following the works of Maréchal and Mahajan, optimization of the Strehl ratio (for peak intensity with a coherently illuminated system) occurs when the expectation value of the phase error's variance is minimized. We describe an optimization procedure based on regression analysis that incorporates these physical parameters. This approach is suitable for coherently illuminated systems of nearly diffraction-limited quality. Mathematically, this work is an enhancement of the methods commonly applied for ex situ alignment based on uniform weighting of all points on the surface (or a sub-region of the surface). It follows a similar approach to the optimization of apodized and non-uniformly illuminated optical systems. Significantly, it reaches a different conclusion than a more recent approach based on minimization of focal plane ray errors.

47 OTHER INSTRUMENTATION↗
DOE OSTI2012

A method to estimate the effect of deformable image registration uncertainties on daily dose mapping

Purpose: To develop a statistical sampling procedure for spatially-correlated uncertainties in deformable image registration and then use it to demonstrate their effect on daily dose mapping. Methods: Sequential daily CT studies are acquired to map anatomical variations prior to fractionated external beam radiotherapy. The CTs are deformably registered to the planning CT to obtain displacement vector fields (DVFs). The DVFs are used to accumulate the dose delivered each day onto the planning CT. Each DVF has spatially-correlated uncertainties associated with it. Principal components analysis (PCA) is applied to measured DVF error maps to produce decorrelated principal component modes of the errors. The modes are sampled independently and reconstructed to produce synthetic registration error maps. The synthetic error maps are convolved with dose mapped via deformable registration to model the resulting uncertainty in the dose mapping. The results are compared to the dose mapping uncertainty that would result from uncorrelated DVF errors that vary randomly from voxel to voxel. Results: The error sampling method is shown to produce synthetic DVF error maps that are statistically indistinguishable from the observed error maps. Spatially-correlated DVF uncertainties modeled by our procedure produce patterns of dose mapping error that are different from that due to randomly distributed uncertainties. Conclusions: Deformable image registration uncertainties have complex spatial distributions. The authors have developed and tested a method to decorrelate the spatial uncertainties and make statistical samples of highly correlated error maps. The sample error maps can be used to investigate the effect of DVF uncertainties on daily dose mapping via deformable image registration. An initial demonstration of this methodology shows that dose mapping uncertainties can be sensitive to spatial patterns in the DVF uncertainties.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2015

TU-AB-303-03: CBCT-Based On-Site Simulation, Planning, and Delivery (OSPD) for Whole Brain Radiotherapy

Purpose: To demonstrate the feasibility of a CBCT-based on-site simulation, planning, and delivery (OSPD) for whole brain radiotherapy, in which all steps from imaging, planning to treatment delivery are performed at the treatment unit in one appointment time slot. This work serves as the proof of concept for future OSPD single fraction radiation therapy. Methods: An integrated on-site imaging, planning and delivery workflow was developed and tested for whole brain radiotherapy. An automated two-opposed-oblique-beam plan is created by utilizing the treatment planning system scripting and simple field-in-field IMRT. The IMRT plan is designed with maximum 8 control points to cover the target volume consisting of the brain to C1/C2 of the spinal cord, with dose homogeneity criteria from −5% to +7% of the prescription dose. Due to inaccuracy of reconstructed Hounsfield unit numbers in CBCT images, the dose distribution is calculated with non-heterogeneity correction introducing only clinically insignificant dose discrepancy. A coherent and synchronized workflow was designed for a team of attending physician, physicist, therapists, and dosimetrist to work closely with the ability to quickly modify, approve, and implement the treatment. Results: Thirty-one patients have been treated with this OSPD treatment, without compromising the plan quality compared to our regular clinically used parallel apposed 2D plans. The average time for these procedures are 48.02 ±11.55 minutes from the time patient entered the treatment room until s/he exited, and 35.09 ±10.35 minutes from starting CBCT until last beam delivered. This time duration is comparable to the net time when individual tasks are summed up during our regular CT- based whole brain planning and delivery. Conclusions: The OSPD whole brain treatment has been tested to be clinically feasible. The next step is to further improve the efficiency and to streamline the workflow. Other disease sites will be also tested with this new technology.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Energy and momentum preserving Coulomb collision model for kinetic Monte Carlo simulations of plasma steady states in toroidal fusion devices

A kinetic Monte Carlo model suited for self-consistent transport studies is proposed and tested. The Monte Carlo collision operator is based on a widely used model of Coulomb scattering by a drifting Maxwellian and a new algorithm enforcing the momentum and energy conservation laws. The difference to other approaches consists in a specific procedure of calculating the background Maxwellian parameters, which does not require ensemble averaging and, therefore, allows for the use of single-particle algorithms. This possibility is useful in transport balance (steady state) problems with a phenomenological diffusive ansatz for the turbulent transport, because it allows a direct use of variance reduction methods well suited for single particle algorithms. In addition, a method for the self-consistent calculation of the electric field is discussed. Results of testing of the new collision operator using a set of 1D examples, and preliminary results of 2D modelling in realistic tokamak geometry, are presented.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Connecting CO intensity mapping to molecular gas and star formation in the epoch of galaxy assembly

Intensity mapping, which images a single spectral line from unresolved galaxies across cosmological volumes, is a promising technique for probing the early universe. Here we present predictions for the intensity map and power spectrum of the CO(1–0) line from galaxies at z∼2.4–2.8, based on a parameterized model for the galaxy–halo connection, and demonstrate the extent to which properties of high-redshift galaxies can be directly inferred from such observations. We find that our fiducial prediction should be detectable by a realistic experiment. Motivated by significant modeling uncertainties, we demonstrate the effect on the power spectrum of varying each parameter in our model. Using simulated observations, we infer constraints on our model parameter space with an MCMC procedure, and show corresponding constraints on the L{sub IR}–L{sub CO} relation and the CO luminosity function. These constraints would be complementary to current high-redshift galaxy observations, which can detect the brightest galaxies but not complete samples from the faint end of the luminosity function. By probing these populations in aggregate, CO intensity mapping could be a valuable tool for probing molecular gas and its relation to star formation in high-redshift galaxies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Percutaneous Biopsy and Radiofrequency Ablation of Osteoid Osteoma with Excess Reactive New Bone Formation and Cortical Thickening Using a Battery-Powered Drill for Access: A Technical Note

PurposeTo report our experience with the use of a battery-powered drill in biopsy and radiofrequency ablation of osteoid osteoma with excess reactive new bone formation. The battery-powered drill enables obtaining the sample while drilling.Materials and MethodsDuring the last 18 months, 14 patients suffering from painful osteoid osteoma with excess reactive new bone formation underwent CT-guided biopsy and radiofrequency ablation. In order to assess and sample the nidus of the osteoid osteoma, a battery-powered drill was used. Biopsy was performed in all cases. Then, coaxially, a radiofrequency electrode was inserted and ablation was performed with osteoid osteoma protocol. Procedure time (i.e., drilling including local anesthesia), amount of scans, technical and clinical success, and the results of biopsy are reported.ResultsAccess to the nidus through the excess reactive new bone formation was feasible in all cases. Median procedure time was 50.5 min. Histologic verification of osteoid osteoma was performed in all cases. Radiofrequency electrode was coaxially inserted within the nidus and ablation was successfully performed in all lesions. Median amount CT scans, performed to control correct positioning of the drill and precise electrode placement within the nidus was 11. There were no complications or material failure reported in our study.ConclusionsThe use of battery-powered drill facilitates access to the osteoid osteoma nidus in cases where excess reactive new bone formation is present. Biopsy needle can be used for channel creation during the access offering at the same time the possibility to extract bone samples.

62 RADIOLOGY AND NUCLEAR MEDICINE↗