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

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

SU-G-IeP1-01: A Novel MRI Post-Processing Algorithm for Visualization of the Prostate LDR Brachytherapy Seeds and Calcifications Based On B0 Field Inhomogeneity Correction and Hough Transform

Purpose: This study aims at developing an MRI-only workflow for post-implant dosimetry of the prostate LDR brachytherapy seeds. The specific goal here is to develop a post-processing algorithm to produce positive contrast for the seeds and prostatic calcifications and differentiate between them on MR images. Methods: An agar-based phantom incorporating four dummy seeds (I-125) and five calcifications of different sizes (from sheep cortical bone) was constructed. Seeds were placed arbitrarily in the coronal plane. The phantom was scanned with 3T Philips Achieva MR scanner using an 8-channel head coil array. Multi-echo turbo spin echo (ME-TSE) and multi-echo gradient recalled echo (ME-GRE) sequences were acquired. Due to minimal susceptibility artifacts around seeds, ME-GRE sequence (flip angle=15; TR/TE=20/2.3/2.3; resolution=0.7×0.7×2mm3) was further processed.The induced field inhomogeneity due to the presence of titaniumencapsulated seeds was corrected using a B0 field map. B0 map was calculated using the ME-GRE sequence by calculating the phase difference at two different echo times. Initially, the product of the first echo and B0 map was calculated. The features corresponding to the seeds were then extracted in three steps: 1) the edge pixels were isolated using “Prewitt” operator; 2) the Hough transform was employed to detect ellipses approximately matching the dimensions of the seeds and 3) at the position and orientation of the detected ellipses an ellipse was drawn on the B0-corrected image. Results: The proposed B0-correction process produced positive contrast for the seeds and calcifications. The Hough transform based on Prewitt edge operator successfully identified all the seeds according to their ellipsoidal shape and dimensions in the edge image. Conclusion: The proposed post-processing algorithm successfully visualized the seeds and calcifications with positive contrast and differentiates between them according to their shapes. Further assessments on more realistic phantoms and patient study are required to validate the outcome.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Three-dimensional (3D) velocity map imaging: from technique to application

The velocity map imaging (VMI) technique was first introduced by Eppink and Parker in 1997, as an improvement to the original ion imaging method by Houston and Chandler in 1987. The method has gained huge popularity over the past two decades and has become a standard tool for measuring high-resolution translational energy and angular distributions of ions and electrons. VMI has evolved gradually from 2D momentum measurements to 3D measurements with various implementations and configurations. The most recent advancement has brought unprecedented 3D performance to the technique in terms of resolutions (both spatial and temporal), multi-hit capability as well as acquisition speed while maintaining many attractive attributes afforded by conventional VMI such as being simple, cost-effective, visually appealing and versatile. Here, in this tutorial, we will discuss many technical aspects of the recent advancement and its application in probing correlated chemical dynamics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

The utility of {sup 82}Rb PET for myocardial viability assessment: Comparison with perfusion-metabolism {sup 82}Rb-{sup 18}F-FDG PET

Background: {sup 82}Rb kinetics may distinguish scar from viable but dysfunctional (hibernating) myocardium. We sought to define the relationship between {sup 82}Rb kinetics and myocardial viability compared with conventional {sup 82}Rb and {sup 18}F-fluorodeoxyglucose (FDG) perfusion-metabolism PET imaging. Methods: Consecutive patients (N = 120) referred for evaluation of myocardial viability prior to revascularization and normal volunteers (N = 37) were reviewed. Dynamic {sup 82}Rb 3D PET data were acquired at rest. {sup 18}F-FDG 3D PET data were acquired after metabolic preparation using a standardized hyperinsulinemic-euglycemic clamp. {sup 82}Rb kinetic parameters K{sub 1}, k{sub 2}, and partition coefficient (KP) were estimated by compartmental modeling Results: Segmental {sup 82}Rb k{sub 2} and KP differed significantly between scarred and hibernating segments identified by Rb-FDG perfusion-metabolism (k{sub 2}, 0.42 ± 0.25 vs. 0.22 ± 0.09 min{sup −1}; P < .0001; KP, 1.33 ± 0.62 vs. 2.25 ± 0.98 ml/g; P < .0001). As compared to Rb-FDG analysis, segmental Rb KP had a c-index, sensitivity and specificity of 0.809, 76% and 84%, respectively, for distinguishing hibernating and scarred segments. Segmental k{sub 2} performed similarly, but with lower specificity (75%, P < .001) Conclusions: In this pilot study, {sup 82}Rb kinetic parameters k{sub 2} and KP, which are readily estimated using a compartmental model commonly used for myocardial blood flow, reliably differentiated hibernating myocardium and scar. Further study is necessary to evaluate their clinical utility for predicting benefit after revascularization. [French] French Abstract: Contexte: La cinétique du {sup 82}Rb pourrait être utilisée pour distinguer la fibrose myocardique des zones viables mais dysfonctionnelles (en hibernation). Dans cette étude, nous avons cherché à définir la relation entre la cinétique du {sup 82}Rb et la viabilité myocardique en comparant les images de perfusion et métabolisme myocardique utilisant le {sup 82}Rb et le {sup 18}F-fluorodésoxyglucose (FDG) Méthodes: les données obtenues chez 120 patients consécutifs (N = 120) référés pour évaluation de la viabilité du myocarde avant revascularisation et 37 volontaires considérés normaux (N = 37) ont été étudieés. Les données TEP 3D dynamiques {sup 82}Rb ont été acquises au repos. Les données TEP 3D au {sup 18}F-FDG ont été acquises après préparation métabolique utilisant une pince hyperinsulémique-euglycémique normalisée. Les paramètres k1, k2 et le coefficient de partage (KP) de la cinétique du {sup 82}R bont été évalues par modélisation compartimentale. Résultats: les paramètres k2 et KP de distribution du {sup 82}Rb se sont révélés significativement différent entre les zones tissulaires cicatricielles fibreuses et celles en hibernation identifiées par étude métabolique au FDG (k2, 0,42 ± 0,25 vs. 0,22 ± 0,09 min{sup −1}; P < 0,0001; KP, 1,33 ± 0,62 vs. 2,25 ± 0,98 ml/g; P < 0,0001). Par rapport aux données FDG, le paramètre KP du rubidium a révélé un indice de concordance de 0,809 et une sensibilité et spécificité de 76% et 84%, pour la distinction des segments en hibernation et cicatrisés. Les résultats du paramètre k2 se sont révélés similaires, mais avec une spécificité plus faible calculée à 75% (P < 0,001). Conclusions: Dans cette étude pilote, les paramètres cinétiques k2 et KP de perfusion myocardique au {sup 82}Rb, qui sont facilement estimés à l’aide d’un modèle compartimental couramment utilisé pour flux sanguin myocardique, ont permis de différencier de manière fiable le myocarde cicatricielle des zones myocardiques hibernantes. Une étude plus approfondie est souhaitable pour valider leur utilité clinique en revacularisation. [Spanish] Spanish Abstract: Antecedentes: La cinética con {sup 82}Rb puede distinguir las cicatrices miocárdicas del tejido viable pero disfuncional (hibernante). Buscamos definir la relación entre la cinética del {sup 82}Rb y la viabilidad miocárdica comparada con las imágenes convencionales de PET con {sup 82}Rb y {sup 18}F-flurodeoxyglucosa (FDG). Métodos: se evaluaron a Pacientes Consecutivos (N = 120) referidos para evaluación de viabilidad miocárdica previos a revascularización y voluntarios normales (N = 37). Los datos de PET 3D dinámico con {sup 82}Rb fueron adquiridos en reposo. Los datos de {sup 18}F-FDG 3D PET fueron adquiridos posterior a la preparación metabólica usando un clamp hiperinsulínico-euglucémico. Los patrones cinéticos K1, k2 y el coeficiente de partición (KP) fueron estimados por el modelo compartimental. Resultados: el k2 y KP del {sup 82}Rb permitueron distinguier el tejido cicatricial de los segmentos hibernados identificados por la vía perfusión metabolismo de Rb-FDG (k{sub 2}, 0.42 ± 0.25 vs. 0.22 ± 0.09 min-1; P < .0001; KP, 1.33 ± 0.62 vs. 2.25 ± 0.98 ml/g; P < .0001). En comparación con el análisis de Rb-FDG, el KP segmentario del Rb tuvo un índice-c, sensbilidad y especificidad de 0.809 76 y 84%, respectivamente, para distinguir segmentos hibernantes y cicatriciales. k2 Segmentario tuvo un desempeño similar pero con una menor especificidad (75%, P < .001). Conclusiones: En este estudio piloto, los parámetros cinéticos k2 y KP del {sup 82}Rb, los cuales son estimados usando un modelo compartimental usado comúnmente para flujo sanguíneo miocárdico, diferenciaron el miocardio hibernante del cicatricial. Se necesita estudiar más a fondo para evaluar la utilidad clínica para la predicción del beneficio posterior a la revascularización [Chinese] Chinese Abstract: 背景: 铷-82({sup 82}Rb)药代动力学可能区分梗死与功能受损但存活的心肌(冬眠心肌)。我们将探讨{sup 82}Rb药代动力学与存活心肌的关系,并与常规的{sup 82}Rb和{sup 18}F-氟脱氧葡萄糖(FDG)灌注-代谢PET显像进行比较。 方法: 连续纳入120名血运重建前评估存活心肌的患者和37名正常志愿者。获得静息{sup 82}Rb 3D-PET动态采集数据;采用标准化的高胰岛素 - 正葡萄糖钳夹试验得到{sup 18}F-FDG 3D PET代谢显像数据; 通过房室模型计算{sup 82}Rb动力学参数k{sub 1},k{sub 2}和分配系数(KP)。 结果: 以Rb-FDG灌注代谢显像鉴定疤痕心肌组和冬眠心肌组,两组的{sup 82}Rb节段性 k{sub 2}值和KP值有明显差异(k{sub 2}, 0.42 ± 0.25 vs 0.22 ± 0.09 min{sup −1}; P < .0001; KP, 1.33 ± 0.62 vs 2.25 ± 0.98 ml/g; P < .0001)。以Rb-FDG灌注代谢显像为诊断标准,{sup 82}Rb节段性 KP对疤痕和冬眠心肌鉴别效能的c指数,敏感性和特异性分别是0.809, 76%和84%。节段性k{sub 2}的鉴别效能与KP相似,但特异性较低(75%,P < .001)。 结论: 在本试验性研究中,通过常规用于{sup 82}Rb心肌血流量测定的房室模型计算出的{sup 82}Rb动力学参数k{sub 2}和KP,可以有效的区分冬眠心肌和瘢痕心肌。 但需要进一步的研究来评估其对预测血运重建是否获益的临床价值。.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

SU-F-J-203: Retrospective Assessment of Delivered Proton Dose in Prostate Cancer Patients Based On Daily In-Room CT Imaging

Purpose: Retrospective calculation of the delivered proton dose in prostate cancer patients based on a unique dataset of daily CT images. Methods: Inter-fractional motion in prostate cancer patients treated at our proton facility is counteracted by water-filled endorectal ballon and bladder filling protocol. Typical plans (XiO, Elekta Instruments AB, Stockholm) for 74 Gy(RBE) sequential boost treatment in 37 fractions include two series of opposing lateral double-scattered proton beams covering the respective iCTV. Stability of fiducial markers and anatomy were checked in 12 patients by daily scheduled in-room control CT (cCT) after immobilization and positioning according to bony anatomy utilizing orthogonal X-ray. In RayStation 4.6 (RaySearch Laboritories AB, Stockholm), all cCTs are delineated retrospectively and the treatment plans were recalculated on the planning CT and the registered cCTs. All fraction doses were accumulated on the planning CT after deformable registration. Parameters of delivered dose to iCTV (D98%>95%, D2%<107%), bladder (V75Gy<15%, V70Gy<25%, V65Gy<30%), rectum (V70Gy<10%, V50Gy<40%) and femoral heads (V50Gy<5%) are compared to those in the treatment plan. Intra-therapy variation is represented in DVH bands. Results: No alarming differences were observed between planned and retrospectively accumulated dose: iCTV constraints were met, except for one patient (D98%=94.6% in non-boosted iCTV). Considered bladder and femoral head values were below the limits. Rectum V70Gy was slightly exceeded (<11.3%) in two patients. First intra-therapy variability analysis in 4 patients showed no timedependent parameter drift, revealed strongest variability for bladder dose. In some fractions, iCTV coverage (D98%) and rectum V70Gy was missed. Conclusion: Double scattered proton plans are accurately delivered to prostate cancer patients due to fractionation effects and the applied precise positioning and immobilization protocols. As a result of rare interventions after daily 3D imaging of the first 12 patients, in-room CT frequency for prostate cancer patients was reduced. The presented study supports this decision. The authors acknowledge the German Federal Ministry for Education and Research for funding the High Precision Radiotherapy Group at the OncoRay - National Center for Radiation Research in Oncology (BMBF- 03Z1N51).

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

(Oxy)hydroxides Formed on Aluminum Fuel Materials After Irradiation and Long-Term Wet Storage - 20354

The aluminum cladding of research-reactor fuel experiences general corrosion when in contact with water during in-reactor service and post-discharge wet storage, resulting in the formation of adherent aluminum (oxy)hydroxide films. These (oxy)hydroxides contain chemically-bound water that poses challenges for extended dry storage due to the risk of thermal or radiolytic decomposition releasing free water and/or hydrogen and oxygen gases. This study describes characterization of the (oxy)hydroxides present on several aluminum materials used in reactor operation and subsequently stored wet in the L-Basin storage facility at the Savannah River Site (SRS) for an extended period. Characterization data providing insight into the loading, composition, and morphology of (oxy)hydroxides to be expected on service-exposed aluminum cladding provides valuable benchmarks for designing adequate drying and dry-storage approaches. This work is part of a broader investigation to address knowledge gaps and technical data needs for dry storage of aluminum-clad spent nuclear fuel (ASNF), which included in-lab growth of (oxy)hydroxide films on aluminum alloy substrates to investigate formation behavior, investigation of drying methods to remove existing (oxy)hydroxides from ASNF cladding, and measurement of radiolytic yield of hydrogen from (oxy)hydroxide powders and films. In this study, (oxy)hydroxide films were characterized for three aluminum-alloy materials used in reactors and subsequently stored wet for up to approximately 40 years in L-Basin at SRS: one cropping from a Missouri University Research Reactor (MURR) fuel element (Al-6061 alloy), one cropping from a Universal Sleeve Housing (USH) (Al-6063 alloy), and one Mark-16B fuel assembly (either Al-6061 or Al- 6063). The USH and Mark-16B were used in SRS production reactors. Characterization of the as-received (oxy)hydroxides included scanning electron microscopy (SEM) in both plan-view and cross-section to characterize the (oxy)hydroxide layer's morphology, thickness, and structure. X-ray diffraction (XRD) was used to identify the chemical composition and distinguish between the various aluminum (oxy)hydroxides known to form under reactor and storage conditions. XRD analysis revealed both bayerite (Al(OH)3) and boehmite (AlOOH) on the surface of the MURR and USH samples, as well as bayerite, boehmite, and gibbsite (another Al(OH)3 polymorph) on the surface of the Mark-16B sample. The aluminum trihydroxides, bayerite and gibbsite, are typically associated with corrosion in low-temperature (<80 deg. C) water, while boehmite is expected to form at higher water temperature (>80 deg. C). The presence of bayerite on the USH, which is believed to have operated close to 90 deg. C, suggests that boehmite formed during in-reactor exposure was not protective against further hydroxide growth in low-temperature wet storage. Cross-section scanning electron microscopy (SEM) showed total (oxy)hydroxide layer thicknesses of ∼5- 10 μm for the MURR and ∼5-15 μm for the Mark-16B. The thickness of the USH's (oxy)hydroxide layer was indiscernible by the current mounting and imaging method, despite plan-view SEM and XRD confirming the presence of an (oxy)hydroxide layer. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

SU-E-I-82: PET Radiopharmaceuticals for Prostate Cancer Imaging: A Review

Purpose: The aim of this work was to review new and clinical practice PET radiopharmaceuticals for prostate cancer imaging. Methods: PET radiopharmaceuticals were reviewed on the main databases. Availability, dosimetry, accuracy and limitations were considered. Results: The following radioisotopes with respective physical half-life and mean positron energy were found: {sup 18}F (109,7 min, 249,8 keV), {sup 89}Zr (78,4 hs, 395,5 keV), {sup 11}C (20,4 min, 385,7 keV) and {sup 68}Ga (67,8 min, 836 keV). {sup 68}Ga was the only one not produced by cyclotron. Radiopharmaceuticals uptake by glucose metabolism ({sup 18}F-FDG), lipogenesis ({sup 11}C-Choline and {sup 11}C-Acetate), amino acid transport (Anti-{sup 18}F-FACBC), bone matrix ({sup 18}F-NaF), prostatespecific membrane antigen ({sup 68}Ga-PSMA and {sup 89}Zr-J591), CXCR receptors ({sup 89}Ga-Pentixafor), adrenal receptors ({sup 18}F-FDHT) and gastrin release peptide receptor (bombesin analogue). Most of radiopharmaceuticals are urinary excretion, so bladder is the critical organ. 11C-choline (pancreas), Anti-{sup 18}FFACBC (liver) and {sup 18}F-FBDC (stomach wall) are the exception. Higher effective dose was seen {sup 18}F-NaF (27 μSv/MBq) while the lowest was {sup 11}CAcetate (3,5 μSv/MBq). Conclusion: Even though {sup 18}F-FDG has a large availability its high urinary excretion and poor uptake to slow growing disease offers weak results for prostate cancer. Better accuracy is obtained when {sup 18}F-NaF is used for bone metastatic investigation although physicians tend to choose bone scintigraphy probably due to its cost and practice. Many guidelines in oncology consider {sup 11}C or {sup 18}F labeled with Choline the gold standard for biochemical relapse after radical treatment. Local, lymph node and distant metastatic relapse can be evaluated at same time with this radiopharmaceutical. There is no consensus over bigger urinary excretion for {sup 18}F labeling. Anti-{sup 18}F-FACBC, {sup 68}Ga-PSMA and {sup 68}Ga-Pentixafor are demonstrating good results but more researches are needed. While PSMA imaging seems to be independent of PSA level, one choline limitation, anti-{sup 18}F-FACBC adds value because imaging any disease stage. {sup 68}Ga-Petixafor is being tested as theranostics marker integrating molecular image and therapy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

The Role of Pretreatment FDG-PET in Treating Cervical Cancer Patients With Enlarged Pelvic Lymph Node(s) Shown on MRI: A Phase 3 Randomized Trial With Long-Term Follow-Up

Purpose: This report is the second analysis of a prospective randomized trial to investigate the impact of {sup 18}F-fluorodeoxyglucose positron emission tomography (FDG-PET) on cervical cancer patients with enlarged pelvic lymph nodes identified by magnetic resonance imaging. Methods and Materials: Patients with newly diagnosed cervical cancer with enlarged pelvic lymph nodes but free of enlarged para-aortic lymph nodes (PALN) were eligible. Patients were randomized to receive either pretreatment FDG-PET (PET arm) or not (control arm). The whole pelvis was the standard irradiation field for all patients except those with FDG-avid extrapelvic findings. Results: In all, 129 patients were enrolled. Pretreatment PET detected extrapelvic metastases in 7 patients. No new patient experienced treatment failure during the additional 4-year follow-up period. There were no significant differences between the PET arm and the control arm regarding overall survival, disease-free survival, and freedom from extrapelvic metastasis. In the control arm, 8 of 10 patients with PALN relapse had limited extrapelvic nodal failures; their 5-year disease-specific survival was 34.3%. By contrast, only 1 of 5 patients with PALN relapse in the PET arm experienced such limited failures; their 5-year survival rate was 0%. Conclusions: Although the pretreatment detection of PALN did not translate into survival benefit, it indeed decreased the need for extended-field concurrent chemoradiation therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

Application of Dislocation Theory to Minimize Defects in Artificial Solids Built with Nanocrystal Building Blocks

Conspectus. Oriented atomic attachment of colloidal inorganic nanocrystals represents a powerful synthetic method for preparing complex inorganic superstructures. Examples include fusion of nanocrystals into dimer and superlattice structures. If the attachment were perfect throughout, then the resulting materials would have single crystal-like alignment of the individual nanocrystals' atomic lattices. While individual colloidal nanocrystals typically are free of many defects, there are a multitude of pathways that can generate defects upon nanocrystal attachment. These attachment generated defects are typically undesirable, and thus developing strategies to favor defect-free attachment or heal defective interfaces are essential. There may also be some cases where attachment-derived defects are desirable. In this Account, we summarize our current understanding of how these defects arise, in order to offer guidance to those who are designing nanocrystal derived solids. The small size of inorganic nanocrystals means short diffusion lengths to the surface, which favor the formation of nanocrystal building blocks with pristine atomic structures. Upon attachment, however, there are numerous pathways that can lead to atomic scale defects, and bulk crystal dislocation theory provides an invaluable guide to understanding these phenomena. As an example, an atomic step edge can be incorporated into the interface leading to an extra half-plane of atoms, known as an edge dislocation. These dislocations can be well described by the Burgers vector description of dislocations, which geometrically identifies planes in which a dislocation can move. Our in situ measurements have verified that bulk dislocation theory predictions for 1D defects hold true at few-nanometer length scales in PbTe and CdSe nanocrystal interfaces. Ultimately, the applicability of dislocation theory to nanocrystal attachment enables the predictive design of attachment to prevent or facilitate healing of defects upon nanocrystal attachment. We applied similar logic to understand formation of planar (2D) defects such as stacking faults upon nanocrystal attachment. Again concepts from bulk crystal defect crystallography can identify attachment pathways that can prevent or deterministically form planar defects upon nanocrystal attachment. The concepts we discuss work well for identifying favorable attachment geometries for nanocrystal pairs ; however it is currently unclear how to translate these ideas to near-simultaneous multiparticle attachment. Geometric frustration, which prevents nanocrystal rotation, and yet-to-be considered defect generation pathways unique to multiparticle attachment complicate defect-free superlattice attachment. New imaging methods now allow for the direct observation of local attachment trajectories and may enable improved understanding of such multiparticle phenomena. With further refinement, a unified framework for understanding and ultimately eliminating structural defects in fused nanocrystal superstructures may well be achievable in coming years.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
NASA NTRS2003

Sprectroscopic and time-resolved optical methods and apparatus for imaging objects in turbed media

Method and apparatus for imaging objects in turbid media. In one embodiment, the method comprises illuminating at least a portion of the turbid medium with substantially monochromatic light of at least two wavelengths in the 600-1500 nm spectral range. A first of the at least two wavelengths is equal to a resonance wavelength for an optical property of an object in the illuminated portion of the turbid medium but is not equal to a resonance wavelength for the turbid medium. A second of the at least two wavelengths is not equal to a resonance wavelength for either the object or the turbid medium. Light emergent from the turbid medium following each of the foregoing illuminations comprises a ballistic component, a snake component and a diffuse component. A direct shadowgram image may be obtained by preferentially passing from the emergent light, following each illumination. the ballistic and snake components thereof and detecting the preferentially passed light. Alternatively, an inverse reconstruction image may be obtained by determining, following each illumination, the intensity of the diffuse component at a plurality of points in time and then using these pluralities of intensity determinations and a mathematical inversion algorithm to form an image of the object in the turbid medium. An image of the object with higher contrast and better quality may be obtained by using the ratio or difference of the images recorded with resonant light and non-resonant light.

Alfano, Robert R.↗
DOE OSTI2016

SU-F-J-85: Evaluation of the Velocity Deformable Image Registration Algorithm

Purpose: To perform validation and commissioning of a commercial deformable image registration (DIR) algorithm (Velocity, Varian Medical Systems) for numerous clinical sites using single and multi-modality images. Methods: In this retrospective study, the DIR algorithm was evaluated for 10 patients in each of the following body sites: head and neck (HN), prostate, liver, and gynecological (GYN). HN DIRs were evaluated from planning (p)CT to re-pCT and pCTs to daily CBCTs using dice similarity coefficients (DSC) of corresponding anatomical structures. Prostate DIRs were evaluated from pCT to CBCTs using DSC and target registration error (TRE) of implanted RF beacons within the prostate. Liver DIRs were evaluated from pMR to pCT using DSC and TRE of vessel bifurcations. GYN DIRs were evaluated between fractionated brachytherapy MRIs using DSC of corresponding anatomical structures. Results: Analysis to date has given average DSCs for HN pCT-to-(re)pCT DIR for the brainstem, cochleas, constrictors, spinal canal, cord, esophagus, larynx, parotids, and submandibular glands as 0.88, 0.65, 0.67, 0.91, 0.77, 0.69, 0.77, 0.87, and 0.71, respectively. Average DSCs for HN pCT-to-CBCT DIR for the constrictors, spinal canal, esophagus, larynx, parotids, and submandibular glands were 0.64, 0.90, 0.62, 0.82, 0.75, and 0.69, respectively. For prostate pCT-to-CBCT DIR the DSC for the bladder, femoral heads, prostate, and rectum were 0.71, 0.82, 0.69, and 0.61, respectively. Average TRE using implanted beacons was 3.35 mm. For liver pCT-to-pMR, the average liver DSC was 0.94 and TRE was 5.26 mm. For GYN MR-to-MR DIR the DSC for the bladder, sigmoid colon, GTV, and rectum were 0.79, 0.58, 0.67, and 0.76, respectively. Conclusion: The Velocity DIR algorithm has been evaluated over a number of anatomical sites. This work functions to document the uncertainties in the DIR in the commissioning process so that these can be accounted for in the development of downstream clinical processes. This work was supported in part by a co-development agreement with Varian Medical Systems.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Self-Assembled Room Temperature Multiferroic BiFeO 3 -LiFe 5 O 8 Nanocomposites

Multiferroic materials have driven significant research interest due to their promising technological potential. Developing new room-temperature multiferroics and understanding their fundamental properties are important to reveal unanticipated physical phenomena and potential applications. Here, a new room temperature multiferroic nanocomposite comprised of an ordered ferrimagnetic spinel α-LiFe 5 O 8 (LFO) and a ferroelectric perovskite BiFeO 3 (BFO) is presented. It is observed that lithium (Li)-doping in BFO favors the formation of LFO spinel as a secondary phase during the synthesis of Li x Bi 1-x FeO 3 ceramics. Multimodal functional and chemical imaging methods are used to map the relationship between doping-induced phase separation and local ferroic properties in both the BFO-LFO composite ceramics and self-assembled nanocomposite thin films. The energetics of phase separation in Li doped BFO and the formation of BFO-LFO composites are supported by first principles calculations. These findings shed light on Li's role in the formation of a functionally important room temperature multiferroic and open a new approach in the synthesis of light element doped nanocomposites for future energy, sensing, and memory applications.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Visualizing Interfacial Jamming Using an Aggregation-Induced-Emission Molecular Reporter

With the interfacial jamming of nanoparticles (NPs), a load-bearing network of NPs forms as the areal density of NPs increases, converting the assembly from a liquid-like into a solid-like assembly. Unlike vitrification, the lineal packing of the NPs in the network is denser, while the remaining NPs can remain in a liquid-like state. It is a challenge to determine the point at which the assemblies jam, since both jamming and vitrification lead to a solid-like behavior of the assemblies. Herein, we show a real-time fluorescence imaging method to probe the evolution of the interfacial dynamics of NP surfactants at the water/oil interface using aggregation-induced emission (AIE) as a reporter for the transition of the assemblies into the jammed state. The AIEgens show typical fluorescence behavior at densities at which they can move and rotate. However, when aggregation of these fluorophores occurs, the smaller intermolecular separation distance arrests rotation, and a significant enhancement in the fluorescence intensity occurs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Depth‐dependent concentrations of hematopoietic stem cells in the adult skeleton: Implications for active marrow dosimetry

Purpose The hematopoietically active (or red) bone marrow is the target tissue assigned in skeletal dosimetry models for assessment of stochastic effects (leukemia induction) as well as tissue reactions (marrow toxicity). Active marrow, however, is in reality a surrogate tissue region for specific cell populations, namely the hematopoietic stem and progenitor cells. Present models of active marrow dosimetry implicitly assume that these cells are uniformly localized throughout the marrow spaces of trabecular spongiosa. Data from Watchman et al. and Bourke et al., however, clearly indicate that there is a substantial spatial concentration gradient of these cells with the highest concentrations localized near the bone trabeculae surfaces. The purpose of the present study was thus to explore the dosimetric implications of these spatial gradients on active marrow dosimetry. Methods Images of several bone sites from a 45‐yr female were retagged to group active marrow voxels into 50 μm increments of marrow depth, after which electron and alpha‐particle depth‐dependent specific absorbed fractions were computed for four source tissues — active marrow, inactive marrow, bone trabeculae volumes, and bone trabeculae surfaces. Corresponding depth‐dependent S values (dose to a target tissue per decay in a source tissue) were computed and further weighted by the relative target cell concentration. These depth‐weighted radionuclide S values were systematically compared to the more traditional volume‐averaged radionuclide S values of the MIRD schema for both individual bones of the skeleton and their skeletal‐averaged quantities. Results For both beta‐emitters and alpha‐emitters localized in the active and inactive marrow, depth‐weighted S values were shown to differ from volume‐averaged S values by only a few percent, as dose gradients across the marrow tissues are nonexistent. For bone volume and bone surface sources of alpha‐emitters and lower energy beta‐emitters, when marrow dose gradients are expected, explicit consideration of target cell spatial concentration gradients are shown to significantly impact marrow dosimetry. Conclusions For medical isotopes currently utilized for treatment of skeletal metastases, namely 153 Sm and 223 Ra, accounting for hematopoietic stem and progenitor cell concentration gradients resulted in maximum percent differences to reference skeletal‐averaged S values of ~21% and 55%, respectively.

Geyer, Amy M.↗
DOE OSTI2015

Evaluation of Liver Stiffness After Radioembolization by Real-Time ShearWave™ Elastography: Preliminary Study

PurposeTo evaluate the effect of ShearWave™ elastography (SWE) for the assessment of liver fibrosis after radioembolization (RE) in patients with liver malignancies.Materials and MethodsWe prospectively examined the effects of SWE before and after RE in 17 adult patients, from June 2012 to September 2013. All patients underwent SWE within 1 month before and 3 months (96.3 ± 22.9 days) after RE. Measurements were taken in segments III, IV, V, and VI (lateral/medial left lobe and anterior/posterior right lobe, respectively). Liver stiffness was studied in the 39 treated segments.ResultsThe mean stiffness of liver tissue according to the pre-RE SWE measurements was not different from the post-RE SWE measurements in the segments that did not undergo RE. Conversely, segments treated with RE were significantly stiffer according to the post-RE SWE measurements (mean SWE 17.4 kPa) than according to the baseline measurements (7.0 kPa) (p < 0.001). Patients with hepatocellular carcinoma and preexisting infection with hepatitis B and C viruses had higher pre-embolization stiffness, and the post-embolization stiffness of the treated segments in these patients was higher than that in the remainder of the study population.ConclusionThese data suggest that SWE measurements of liver stiffness increase as early as the third month after RE. SWE could be used as a noninvasive complementary imaging method for preliminary assessment of liver fibrosis before and after RE.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2025

Characterization of the fractal dimension of helium plumes in laminar to turbulent transition

Abstract Schlieren imaging in conjunction with a high-speed camera was used to observe the behavior of metered helium plumes as they transition from laminar to turbulent flow in an air environment. The plumes were visualized at twelve jet Reynolds numbers ranging from 200 to 2980. The fractal dimension of the flows was obtained by applying a box counting algorithm to the recorded schlieren images. The results were analyzed to determine the correlation between the Reynolds number of the flow and the fractal dimension of the observed turbulence. A trend of increasing fractal dimension with increasing Reynolds number was observed for several different types of schlieren cutoffs including horizontal cutoff, vertical cutoff, circular cutoff, focused shadowgraphy and de-focused shadowgraphy. The vertical cutoff and focused shadowgraphy imaging methods showed the most consistent results for the fractal dimension characterization during the laminar to turbulent transition. For transitional plumes, it was observed that fractal dimension increased with distance from the jet outlet.

42 ENGINEERING↗
DOE OSTI2017

Intracellular in situ labeling of TiO 2 nanoparticles for fluorescence microscopy detection

Titanium dioxide (TiO 2 ) nanoparticles are produced for many different purposes, including development of therapeutic and diagnostic nanoparticles for cancer detection and treatment, drug delivery, induction of DNA double-strand breaks, and imaging of specific cells and subcellular structures. Currently, the use of optical microscopy, an imaging technique most accessible to biology and medical pathology, to detect TiO 2 nanoparticles in cells and tissues ex vivo is limited with low detection limits, while more sensitive imaging methods (transmission electron microscopy, X-ray fluorescence microscopy, etc.) have low throughput and technical and operational complications. In this paper, we describe two in situ posttreatment labeling approaches to stain TiO 2 nanoparticles taken up by the cells. The first approach utilizes fluorescent biotin and fluorescent streptavidin to label the nanoparticles before and after cellular uptake; the second approach is based on the copper-catalyzed azide-alkyne cycloaddition, the so-called Click chemistry, for labeling and detection of azide-conjugated TiO 2 nanoparticles with alkyneconjugated fluorescent dyes such as Alexa Fluor 488. To confirm that optical fluorescence signals of these nanoparticles match the distribution of the Ti element, we used synchrotron X-ray fluorescence microscopy (XFM) at the Advanced Photon Source at Argonne National Laboratory. Titanium-specific XFM showed excellent overlap with the location of optical fluorescence detected by confocal microscopy. Finally and therefore, future experiments with TiO 2 nanoparticles may safely rely on confocal microscopy after in situ nanoparticle labeling using approaches described here.

77 NANOSCIENCE AND NANOTECHNOLOGY↗