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At least 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Rapid design of bacteriophage cocktails to suppress the burden and virulence of gut-resident carbapenem-resistant Klebsiella pneumoniae

Antibiotic use can lead to the expansion of multi-drug-resistant pathobionts within the gut microbiome that can cause life-threatening infections. Selective alternatives to conventional antibiotics are in dire need. Here, in this work, we describe a Klebsiella PhageBank for the tailored design of bacteriophage cocktails to treat multi-drug-resistant Klebsiella pneumoniae. Using a transposon library in carbapenem-resistant K. pneumoniae, we identify host factors required for phage infection in major Klebsiella phage families. Leveraging the diversity of the PhageBank, we formulate phage combinations that eliminate K. pneumoniae with minimal phage resistance. Optimized cocktails selectively suppress the burden of K. pneumoniae in the mouse gut and drive the loss of key virulence factors that act as phage receptors. Phage-mediated diversification of bacterial populations in the gut leads to co-evolution of phage variants with higher virulence and broader host range. Altogether, the Klebsiella PhageBank charts a roadmap for phage therapy against a critical multidrug-resistant human pathogen.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Effect of various post-extrusion tempering on performance of AA2024 tubes fabricated by shear assisted processing and extrusion

In this report aluminum alloy 2024 (AA2024) tubes were extruded using the shear assisted processing and extrusion (ShAPE) method. As a ubiquitous aerospace alloy, AA2024 has reached a high degree of maturity with respect to manufacturing processes, alloy chemistry and heat treatment to maximize material strength. Therefore, over the eight decades since the introduction of this alloy, the mechanical properties have plateaued, and the extrusion speed has reached a 3.5 m/min ceiling using conventional extrusion. The ShAPE technique enabled an extrusion speed of AA2024 up to 7.4 m/min at 480 °C which is surpassing the extrudability chart of this alloy. Variation of the standard T3510 and T8510 post extrusion heat treatments were applied to improve the mechanical performance of the ShAPE extruded AA2024 tube. The ultimate tensile strength and yield strength of AA2024-T8510 ShAPE extruded tube are 522.0 ± 3.3 MPa and 510.7 ± 3.3 MPa, which are respectively 18% and 32% higher than ASM-typical and ASTM minimum values. The elongation at break of ShAPE extruded AA2024-T8510 tubes is two times higher than the ASM-typical and ASTM-minimum values. This improved ductility is attributed to the refinement of grain size and secondary phases as well as due to the uniform dispersion of sub-micron strengthening precipitates formed during the ShAPE process.

42 ENGINEERING↗
DOE OSTI2026

Computational methods in solution-based plastics purification

Plastic waste can be recycled into resins with near-virgin properties by solution-based purification processes that selectively dissolve polymers, remove contaminants, or detach printing residues. Here, in this review, we examine computational methods for predicting the behavior governing solution-based plastic purification, motivated by the vast polymer–solvent–contaminant compositional space. We discuss thermodynamic and machine learning methods for predicting polymer–solvent and polymer–contaminant interaction and review physics-based molecular dynamics simulations that resolve molecular-scale phenomena within polymer matrices inaccessible to screening methods. We highlight how these methods have informed experimental design for dissolution-based recycling and solvent-based contaminant removal. Finally, we discuss the prospective role of agentic AI in integrating these computational tools with real-time sorting data to adapt purification conditions to the compositional variability of real post-consumer feedstocks. This review charts a path toward computationally guided solution-based purification workflows that can respond to the complexity inherent in plastic waste streams.

Altamimi, Ali [Univ. of Wisconsin, Madison, WI (Un↗
DOE OSTI2019

Toward scalable many-body calculations for nuclear open quantum systems using the Gamow Shell Model

Drip-line nuclei have very different properties from those of the valley of stability, as they are weakly bound and resonant. Therefore, the models devised for stable nuclei can no longer be applied therein. Hence, a new theoretical tool, the Gamow Shell Model (GSM), has been developed to study the many-body states occurring at the limits of the nuclear chart. GSM is a configuration interaction model based on the use of the so-called Berggren basis, which contains bound, resonant and scattering states, so that inter-nucleon correlations are fully taken into account and the asymptotes of extended many-body wave functions are precisely handled. However, large complex symmetric matrices must be diagonalized in this framework, therefore the use of very powerful parallel machines is needed therein. So, in order to fully take advantage of their power, a 2D partitioning scheme using hybrid MPI/OpenMP parallelization has been developed in our GSM code. The specificities of the 2D partitioning scheme in the GSM framework will be described and illustrated with numerical examples. It will then be shown that the introduction of this scheme in the GSM code greatly enhances its capabilities.

2D partitioning↗
DOE OSTI2018

An optimization method for flexural bearing design for high-stroke high-frequency applications

A method for optimization of a high-stroke, high-frequency flexural bearing was completed. The main goal was to design a flexural bearing system as the energy restoration component of a one kW free piston linear engine alternator (LEA) operating at 90 Hz and maximum targeted displacement of 22 mm. Defined electricity output of 1 kW, with more than 30% efficiency, required engine operation under high speed and high stroke conditions. Under such challenging stroke and frequency requirements, a method of design was required to select between a wide range of parameters in flexural bearing design. A parametric CAD model was prepared and used in the optimization package of a finite element analysis (FEA) software. Four main parameters of flexural bearing geometry were identified and included the outer diameter, thickness, number of arms, and sweep angle of spiral cuts. Other design parameters including spiral gap width, shape factor and spiral start points angle were shown to be less important compared to these four main parameters in primary design and were examined separately. A neural network algorithm was used to investigate the interactions and effects of design parameters. The sensitivity of each parameter on output criteria such as maximum stress and natural frequency was examined and design charts developed. Methods for further modification of the spiral curve at end points were introduced to reduce the maximum stress level by up to 20%. Several steel alloys and a titanium-based alloy were identified as proper material candidates for high cycle applications and the final designed spring was manufactured and tested to validate the FEA results of axial stiffness and strain level throughout the flexure arms. The percent of the flexure’s moving mass was estimated to be 29% with FEA analysis and compared well with the experimental value of 31%. The stress/strain results of the FEA analysis matched with the experimental results – within ±5%.

42 ENGINEERING↗
DOE OSTI2022

Understanding and improving anode performance in an alkaline membrane electrolyzer using statistical design of experiments

The behavior of the oxygen-evolving positive electrode (i.e. anode) in the anion exchange membrane water electrolyzer (AEMEL) is complex and influenced by several factors. Very few studies have been performed to understand oxygen evolution reaction (OER) behavior by optimizing the individual factors that influence performance. Here, this study highlights the effects of catalyst loading, catalyst selection, porous transport layer (PTL) type and conductive additive content. The influence of each factor is elucidated through a design of experiments (DoE) approach with a full statistical analysis. Electrochemical data, alongside Pareto charts, parametric trends and their mutual interactions are discussed. This DoE approach is also helpful in making useful predictions and discovering new combinations to be tested. The end result was a high-performance AEMEL able to operate at a current density of 1.0 A/cm 2 at 1.80 V with IrOx OER and PtNi hydrogen evolution reaction (HER) catalysts using 0.3 M KOH fed to the anode. Even lower operating voltage was observed with PbRuOx catalyst at the anode, 1.64 V @ 1.0 A/cm 2 , though the cell decay rate was higher. Lastly, a IrOx/PtNi cell was stably operated continuously for 30 days (720 h) at 1.0 A/cm 2 . This study can serve as a guide for optimal electrode design with insights into component-performance compromises, which can aid in making design choices and performing techno-economic analyses.

08 HYDROGEN↗
DOE OSTI2021

Computation-guided discovery of coating materials to stabilize the interface between lithium garnet solid electrolyte and high-energy cathodes for all-solid-state lithium batteries

All-solid-state batteries with a lithium metal anode, enabled by lithium garnet solid electrolytes such as Li 7 La 3 Zr 2 O 12 (LLZO), are a promising next-generation energy-storage technology. The further development of all-solid-state battery requires the integration of high-energy cathodes such as LiNi 1-x-y Mn x Co y O 2 (NMC) with the garnet solid electrolyte with stable and low-resistance interfaces, which requires a coating layer to stabilize the interface during high-temperature sintering and electrochemical cycling. In order to guide the future development of interfacial coatings, we perform high-throughput thermodynamic analyses based on first-principles computation to investigate the stability of LLZO garnet and high-energy NMC cathodes with a wide range of materials chemistries. Here our study reveals the factors governing the materials stability with LLZO garnet and NMC cathodes, and identifies the mechanisms of good coating layers stable with LLZO and NMC. In addition to classifying known coating layers, our study provides detailed guiding charts and multiple new materials systems as promising coatings for stabilizing LLZO—NMC interfaces to enable high-energy-density garnet-based all-solid-state batteries. Our demonstrated computation scheme and high-throughput analyses are generally applicable to investigate and screen coating materials for stabilizing interfaces in energy-related applications.

25 ENERGY STORAGE↗
DOE OSTI2023

Suspending democratic (dis)belief: Nonliberal energy polities of solar power in Morocco and Tanzania

This paper proposes the concept of technodemocratic imaginaries (TDIMs) to supplement the widely-used framework of sociotechnical imaginaries (STIMs) for analyzing nonliberal political contexts in energy social science research. Taking the power of coproductionist analysis of STIMs seriously, TDIMs highlight the inherent instabilities within overarching STIMs by arguing that not only are particular groups marginalized and excluded but that they continue to practice and mobilize their own imaginaries of collective governance and justice vis-à-vis energy systems. In contrast, the existing idea of contested STIMs, in which a shared mode of knowledge politics undergirds different imaginaries, casts aside subaltern modes of political engagement and knowledge-making. TDIMs expand conceptions of democracy to include shared practices of credibility in nonliberal political orders. The intent is not to promote democratic relativism but rather to ask scholars and international energy-access practitioners to suspend their democratic disbelief when studying energy matters in so-called nonliberal contexts. We develop the concept of TDIMs by comparing two African nation-states–Morocco and Tanzania–to show how the states and subaltern groups do (or do not) develop TDIMs related to solar power. While international governance organizations often portray Morocco as authoritarian and Tanzania corrupt, each state differently experienced colonization and decolonization and practices different relationships with domestic subaltern groups. Whereas low-income citizens and indigenous groups seek integration into the Moroccan state’s STIM, the Maasai in Tanzania chart their own TDIM separate from the state and international development groups.

14 SOLAR ENERGY↗
DOE OSTI2026

Holistic energy analysis method for thermal management architectures of data centers

Modern high-performance computing (HPC) data centers (DCs), particularly those supporting energy-intensive artificial intelligence (AI) workloads, face escalating thermal management challenges that degrade performance through thermal throttling and drive up cooling power consumption and operational costs. To address this challenge, many have developed a wide variety of thermal management solutions (single-phase, two-phase, direct, indirect, hybrid, and more) which attempt to cool HPC DCs effectively while attempting to minimize overall system power consumption. However, the analysis of these solutions and methods to effectively compare one with another is lacking. Overall power usage effectiveness (PUE) and total-power usage effectiveness (TUE) provide a metric to quantify power consumption but fail to identify components in the system which require further optimization. To address this, we propose a holistic analytical framework – the waterfall diagram (WFD) – which leverages a waterfall chart methodology, offering a comprehensive visualization of both the thermal management system loop and heat flow pathways from individual server components to the outdoor ambient. Use of the WFD enables graphical estimations of power efficiency and cooling performance across each component of a DC cooling system and complements Sankey-style energy flow visualizations by additionally resolving stage-wise temperature changes and incremental TUE contributions. The framework is used in conjunction with simulation-based approaches, to conduct a detailed pressure drop and flow distribution analysis aimed at identifying the optimal coolant distribution architecture for a single-phase direct-to-chip water-cooled DC, which serves as the baseline for subsequent WFD analysis. Among the evaluated architectures, the 3 U modular coolant distribution architecture is found to demonstrate the best performance, considering minimal pressure drop and uniform flow distribution. In addition, TUE is calculated for each cooling loop component based on its associated pressure drop and corresponding pumping power, which are integrated into the WFD. This correlation between TUE and local temperature offers immediate insight into the power efficiency and thermal performance contributions of individual components, facilitating further development and optimization. Examples of WFD applications are presented under varying thermal loads and ambient conditions, demonstrating reasonable cooling strategies. Notably, the 3 U modular architecture maintains a consistent chip case temperature of 85°C, achieving a TUE of 1.016 at ambient temperature of 47°C, and a TUE of 1.026 at ambient temperature of 52°C. The WFD methodology provides an efficient, holistic, and streamlined framework for DC thermal management architecture assessment and enables design optimization which is important for addressing the thermal-fluidic energy challenges of current and next-generation DCs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

Rapid high density cryogenic pressure vessel filling to 345 bar with a liquid hydrogen pump

Cryogenic pressurized hydrogen (H 2 ) vessels promise maximum storage density with potential to enabling practical H 2 vehicles with maximum driving autonomy and minimum cost of ownership. This paper adds a more complete evaluation of the benefits of cryogenic vessel technology by establishing a methodology for evaluating fill density for any initial vessel thermodynamic state. This is accomplished by assessing 24 cryogenic pressure vessel fill experiments with a liquid hydrogen (LH 2 ) pump manufactured by Linde and installed at the Lawrence Livermore National Laboratory (Livermore, CA) campus. The LH 2 piston pump takes LH 2 from the station Dewar at near ambient pressure (3 bar) and very low temperature (24.6 K) and pressurizes it to the vessel pressure in two stages of compression, up to 875 bar, although the rating of the cryogenic vessel used for these experiments limits fill pressure to 345 bar. Experiments spanned initial vessel temperatures from ambient to 22 K, enabling pump testing over a broad range of conditions. Experimental results validate many of the virtues that make LH 2 pumping a promising technology for H 2 dispensing, both for filling cryogenic as well as ambient temperature vessels: high throughput (1.67 kg/min, 100 kg/h), unlimited capacity for back to back refueling, low electricity consumption at the station due to high density of LH 2 minimizing compression work, and highest fill density, up to 80 g/L (estimated) when dispensing cryogenic hydrogen at 700 + bar. Analysis of the experiments shows that fill density can be predicted with reasonable accuracy (±0.7 g/L) by assuming 10 kJ/kg K cryogenic vessel inlet entropy (pump delivery hose outlet entropy). Fill lines are finally generated on a H 2 phase diagram, producing charts that can be used for rapidly determining fill density for any vessel condition at the moment of fill initiation.

08 HYDROGEN↗
DOE OSTI2013

Precision masses for studies of the astrophysical r process

Half of the elements heavier than iron (Z > 26) are thought to be created through the astrophysical r process, whereby nuclides are produced via a rapid series of nuclear reactions that are postulated to occur in high temperature and neutron density environments such as supernovae or merging neutron stars. The nucleosynthetic path that describes the sequence of reactions through the chart of nuclides strongly depends on the neutron-separation energies of the nuclei. Until recently, however, almost all of these neutron-rich nuclei were not within reach of accelerator facilities, and therefore simulations of the r process had to rely on mass models for input into the calculations. Now, with the advent of facilities such as CARIBU at Argonne National Laboratory, the masses of many nuclides along the r-process path can be determined precisely with Penning trap mass spectrometers coupled to these facilities. More than 70 nuclides have been measured with the Canadian Penning Trap mass spectrometer alone in the past year, which overlap and complement results from other Penning trap mass spectrometers, and first calculations with these new masses suggest the timescale of the r process through the tin isotopes is delayed much more strongly than mass models would suggest.

Clark, Jason↗
DOE OSTI2012

Modern Outcomes of Inflammatory Breast Cancer

Purpose: To report contemporary outcomes for inflammatory breast cancer (IBC) patients treated in the modern era of trastuzumab and taxane-based chemotherapy. Methods and Materials: We retrospectively reviewed the charts of 104 patients with nonmetastatic IBC treated between January 2000 and December 2009. Patients who received chemotherapy, surgery, and radiation therapy were considered to have completed the intended therapy. Kaplan-Meier curves estimated locoregional control (LRC), distant metastases-free survival (DMFS), and overall survival. Results: The median follow-up time was 34 months; 57 (55%) patients were estrogen receptor progesterone receptor (ER/PR) negative, 34 (33%) patients were human epidermal growth factor receptor 2 (her2)/neu amplified, and 78 (75%) received definitive postoperative radiation. Seventy-five (72%) patients completed all of the intended therapy, of whom 67 (89%) received a taxane and 18/28 (64%) of her2/neu-amplified patients received trastuzumab. For the entire cohort, the 5-year rates of overall survival, LRC, and DMFS were 46%, 83%, and 44%, respectively. The ER/PR-negative patients had a 5-year DMFS of 39% vs. 52% for ER/PR-positive patients (p = 0.03). The 5-year DMFS for patients who achieved a pathologic complete response compared with those who did not was 83% vs. 44% (p < 0.01). Those patients who received >60.4 Gy (n = 15) to the chest wall had a 5-year LRC rate of 100% vs. 83% for those who received 45 to 60.4 Gy (n = 49; p = 0.048). On univariate analysis, significant predictors of DMFS included achieving a complete response to neoadjuvant chemotherapy (hazard ratio [HR] = 5.8; 95% confidence interval [CI] = 1.4-24.4; p = 0.02) and pathologically negative lymph nodes (HR = 4.1; 95% CI = 1.4-11.9; p < 0.01), but no factor was significant on multivariate analysis. Conclusions: For IBC patients, the rate of distant metastases is still high despite excellent local control, particularly for patients who received >60.4 Gy to the chest wall. Despite the use of taxanes and trastuzumab, outcomes remain modest, particularly for those with ER/PR-negative disease and those without a pathologic complete response.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

The Impact of New Technologies on Radiation Oncology Events and Trends in the Past Decade: An Institutional Experience

Purpose: To review the type and frequency of patient events from external-beam radiotherapy over a time period sufficiently long to encompass significant technology changes. Methods and Materials: Ten years of quality assurance records from January 2001 through December 2010 were retrospectively reviewed to determine the frequency of events affecting patient treatment from four radiation oncology process steps: simulation, treatment planning, data entry/transfer, and treatment delivery. Patient events were obtained from manual records and, from May 2007 onward, from an institution-wide database and reporting system. Events were classified according to process step of origination and segregated according to the most frequently observed event types. Events from the institution-wide database were evaluated to determine time trends. Results: The overall event rate was 0.93% per course of treatment, with a downward trend over time led by a decrease in treatment delivery events. The frequency of certain event types, particularly in planning and treatment delivery, changed significantly over the course of the study, reflecting technologic and process changes. Treatments involving some form of manual intervention carried an event risk four times higher than those relying heavily on computer-aided design and delivery. Conclusions: Although the overall event rate was low, areas for improvement were identified, including manual calculations and data entry, late-day treatments, and staff overreliance on computer systems. Reducing the incidence of pretreatment events is of particular importance because these were more likely to occur several times before detection and were associated with larger dosimetric impact. Further improvements in quality assurance systems and reporting are imperative, given the advent of electronic charting, increasing reliance on computer systems, and the potentially severe consequences that can arise from mistakes involving complex intensity-modulated or image-guided treatments.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Brachial Plexopathy in Apical Non-Small Cell Lung Cancer Treated With Definitive Radiation: Dosimetric Analysis and Clinical Implications

Purpose: Data are limited on the clinical significance of brachial plexopathy in patients with apical non-small cell lung cancers (NSCLC) treated with definitive radiation therapy. We report the rates of radiation-induced brachial plexopathy (RIBP) and tumor-related brachial plexopathy (TRBP) and associated dosimetric parameters in apical NSCLC patients. Methods and Materials: Charts of NSCLC patients with primary upper lobe or superiorly located nodal disease who received {>=}50 Gy of definitive conventionally fractionated radiation or chemoradiation were retrospectively reviewed for evidence of brachial plexopathy and categorized as RIBP, TRBP, or trauma-related. Dosimetric data were gathered on ipsilateral brachial plexuses (IBP) contoured according to Radiation Therapy Oncology Group atlas guidelines. Results: Eighty patients were identified with a median follow-up and survival time of 17.2 and 17.7 months, respectively. The median prescribed dose was 66.6 Gy (range, 50.4-84.0), and 71% of patients received concurrent chemotherapy. RIBP occurred in 5 patients with an estimated 3-year rate of 12% when accounting for competing risk of death. Seven patients developed TRBP (estimated 3-year rate of 13%), comprising 24% of patients who developed locoregional failures. Grade 3 brachial plexopathy was more common in patients who experienced TRBP than RIBP (57% vs 20%). No patient who received {<=}78 Gy to the IBP developed RIBP. On multivariable competing risk analysis, IBP V76 receiving {>=}1 cc, and primary tumor failure had the highest hazard ratios for developing RIBP and TRBP, respectively. Conclusions: RIBP is a relatively uncommon complication in patients with apical NSCLC tumors receiving definitive doses of radiation, while patients who develop primary tumor failures are at high risk for developing morbid TRBP. These findings suggest that the importance of primary tumor control with adequate doses of radiation outweigh the risk of RIBP in this population of patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Role of Salvage Radiation Therapy for Patients With Relapsed or Refractory Hodgkin Lymphoma Who Failed Autologous Stem Cell Transplant

Purpose: To analyze, through chart review, the efficacy of salvage radiation therapy (sRT) for relapsed or progressive Hodgkin lymphoma (HL) patients who failed autologous stem cell transplant (ASCT). Patients and Methods: Among 347 patients with recurrent/refractory HL who received ASCT from 1986-2006, 163 had post-ASCT progression or relapse. Of these, 56 received sRT and form the basis of this report. Median age at sRT was 30 years (range, 17-59 years). Disease was confined to lymph nodes in 27 patients, whereas 24 had both nodal and extranodal disease. Salvage radiation therapy alone was given in 34 patients (61%), and sRT plus chemotherapy was given in 22 (39%). Median interval from ASCT to sRT was 0.8 years (range, 0.1-5.6 years). The median dose was 35 Gy (range, 8-40.3 Gy). The sRT technique was extended-field in 14 patients (25%) and involved-field in 42 (75%). Results: The median follow-up from sRT was 31.3 months (range, 0.2-205.5 months). Overall response rate was 84% (complete response: 36%; partial response: 48%). The median overall survival was 40.8 months (95% confidence interval, 34.2-56.3 months). The 5-year overall survival was 29% (95% confidence interval, 14%-44%). The 2-year progression-free survival (PFS) was 16%; the 2-year local PFS was 65%, whereas the 2-year systemic PFS was 17%. The 1-year PFS was higher in patients in whom all diseased sites were irradiated (49%) compared with those in whom only the symptomatic site was treated (22%, P=.07). Among 20 alive patients, 5 were disease free (at 6.4, 6.8, 7.4, 7.9, and 17.1 years). Conclusion: For patients with HL who fail ASCT, a selective use of RT provides a durable local control rate of 65% at 2 years and should be considered as part of the standard management plan for the palliation of incurable HL. Occasionally irradiation of truly localized disease can lead to long-term survival.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Quality Control Quantification (QCQ): A Tool to Measure the Value of Quality Control Checks in Radiation Oncology

Purpose: To quantify the error-detection effectiveness of commonly used quality control (QC) measures. Methods: We analyzed incidents from 2007-2010 logged into a voluntary in-house, electronic incident learning systems at 2 academic radiation oncology clinics. None of the incidents resulted in patient harm. Each incident was graded for potential severity using the French Nuclear Safety Authority scoring scale; high potential severity incidents (score >3) were considered, along with a subset of 30 randomly chosen low severity incidents. Each report was evaluated to identify which of 15 common QC checks could have detected it. The effectiveness was calculated, defined as the percentage of incidents that each QC measure could detect, both for individual QC checks and for combinations of checks. Results: In total, 4407 incidents were reported, 292 of which had high-potential severity. High- and low-severity incidents were detectable by 4.0 {+-} 2.3 (mean {+-} SD) and 2.6 {+-} 1.4 QC checks, respectively (P<.001). All individual checks were less than 50% sensitive with the exception of pretreatment plan review by a physicist (63%). An effectiveness of 97% was achieved with 7 checks used in combination and was not further improved with more checks. The combination of checks with the highest effectiveness includes physics plan review, physician plan review, Electronic Portal Imaging Device-based in vivo portal dosimetry, radiation therapist timeout, weekly physics chart check, the use of checklists, port films, and source-to-skin distance checks. Some commonly used QC checks such as pretreatment intensity modulated radiation therapy QA do not substantially add to the ability to detect errors in these data. Conclusions: The effectiveness of QC measures in radiation oncology depends sensitively on which checks are used and in which combinations. A small percentage of errors cannot be detected by any of the standard formal QC checks currently in broad use, suggesting that further improvements are needed. These data require confirmation with a broader incident-reporting database.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

PSA Response to Neoadjuvant Androgen Deprivation Therapy Is a Strong Independent Predictor of Survival in High-Risk Prostate Cancer in the Dose-Escalated Radiation Therapy Era

Purpose: The aim of the study was to evaluate the prognostic value of prostate-specific antigen (PSA) response to neoadjuvant androgen deprivation therapy (ADT) prior to dose-escalated radiation therapy (RT) and long-term ADT in high-risk prostate cancer. Methods and Materials: We reviewed the charts of all patients diagnosed with high-risk prostate cancer and treated with a combination of long-term ADT (median, 24 months) and dose-escalated (median, 75.6 Gy) RT between 1990 and 2007. The associations among patient, tumor, and treatment characteristics with biochemical response to neoadjuvant ADT and their effects on failure-free survival (FFS), time to distant metastasis (TDM), prostate cancer-specific mortality (PCSM) and overall survival (OS) were examined. Results: A total of 196 patients met criteria for inclusion. Median follow-up time for patients alive at last contact was 7.0 years (range, 0.5-18.1 years). Multivariate analysis identified the pre-RT PSA concentration (<0.5 vs {>=}0.5 ng/mL) as a significant independent predictor of FFS (P=.021), TDM (P=.009), PCSM (P=.039), and OS (P=.037). On multivariate analysis, pretreatment PSA (iPSA) and African-American race were significantly associated with failure to achieve a pre-RT PSA of <0.5 ng/mL. Conclusions: For high-risk prostate cancer patients treated with long-term ADT and dose-escalated RT, a pre-RT PSA level {>=}0.5 ng/mL after neoadjuvant ADT predicts for worse survival measures. Both elevated iPSA and African-American race are associated with increased risk of having a pre-RT PSA level {>=}0.5 ng/mL. These patients should be considered for clinical trials that test newer, more potent androgen-depleting therapies such as abiraterone and MDV3100 in combination with radiation.

62 RADIOLOGY AND NUCLEAR MEDICINE↗