Knowledge-Based Quality Assurance and Model Maintenance in Lung Cancer Radiation Therapy in a Statewide Quality Consortium of Academic and Community Practice Centers.

PURPOSE: Locally advanced lung cancer (LALC) treatment planning is often complex due to challenging tradeoffs related to large targets near organs at risk, making the judgment of plan quality difficult. The purpose of this work was to update and maintain a multi-institutional knowledge-based planning (KBP) model developed by a statewide consortium of academic and community practices for use as a plan quality assurance (QA) tool. METHODS AND MATERIALS: Sixty LALC volumetric-modulated arc therapy plans from 2021 were collected from 24 institutions. Plan quality was scored, with high-quality clinical (HQC) plans selected to update a KBP model originally developed in 2017. The model was validated via automated KBP planning, with 20 cases excluded from the model. Differences in dose-volume histogram metrics in the clinical plans, 2017 KBP model plans, and 2022 KBP model plans were compared. Twenty recent clinical cases not meeting consortium quality metrics were replanned with the 2022 model to investigate potential plan quality improvements. RESULTS: Forty-seven plans were included in the final KBP model. Compared with the clinical plans, the 2022 model validation plans improved 60%, 65%, and 65% of the lung V20Gy, mean heart dose, and spinal canal D0.03cc metrics, respectively. The 2022 model showed improvements from the 2017 model in hot spot management at the cost of greater lung doses. Of the 20 recent cases not meeting quality metrics, 40% of the KBP model-replanned cases resulted in acceptable plans, suggesting potential clinical plan improvements. CONCLUSIONS: A multi-institutional KBP model was updated using plans from a statewide consortium. Multidisciplinary plan review resulted in HQC model training plans and model validation resulted in acceptable quality plans. The model proved to be effective at identifying potential plan quality improvements. Work is ongoing to develop web-based training plan review tools and vendor-agnostic platforms to provide the model as a QA tool statewide.

Evaluation of Dose Accuracy in the Near-Surface Region for Whole Breast Irradiation Techniques in a Multi-institutional Consortium.

PURPOSE: To assess the accuracy of dose calculations in the near-surface region for different treatment planning systems (TPSs), treatment techniques, and energies to improve clinical decisions for patients receiving whole breast irradiation (WBI). METHODS AND MATERIALS: A portable custom breast phantom was designed for dose measurements in the near-surface regions. Treatment plans of varying complexities were created at 8 institutions using 4 different TPSs on an anonymized patient data set (50 Gy in 25 fractions) and peer reviewed by participants. The plans were recalculated on the phantom data set. The phantom was aligned with predetermined shifts and laser marks or cone beam computed tomography, and the irradiation was performed using a variety of linear accelerators at the participating institutions. Dose was measured with radiochromic film placed at 0.5 and 1.0 cm depth and 3 locations per depth within the phantom. The film was scanned and analyzed >24 hours postirradiation. RESULTS: The percentage difference between the mean of the measured and calculated dose across the participating centers was -0.2 % ± 2.9%, with 95% of measurements within 6% agreement. No significant differences were found between the mean of the calculated and measured dose for all TPSs, treatment techniques, and energies at all depths and laterality investigated. Furthermore, no significant differences were observed between the mean of measured dose and the prescription dose of 2 Gy per fraction. CONCLUSION: These results demonstrate that dose calculations for clinically relevant WBI plans are accurate to within 6% of measurements in the near-surface region for various complexities, TPSs, linear accelerators, and beam energies. This work lays the necessary foundation for future studies investigating the correlation between near-surface dose and acute skin toxicities.

Influence of Silver as a Catalyst on the Growth of ß-Ga2O3 Nanowires on GaAs.

A simple and inexpensive thermal oxidation process was performed to synthesize gallium oxide (Ga2O3) nanowires using Ag thin film as a catalyst at 800 °C and 1000 °C to understand the effect of the silver catalyst on the nanowire growth. The effect of doping and orientation of the substrates on the growth of Ga2O3 nanowires on single-crystal gallium arsenide (GaAs) wafers in atmosphere were investigated. A comprehensive study of the oxide film and nanowire growth was performed using various characterization techniques including XRD, SEM, EDS, focused ion beam (FIB), XPS and STEM. Based on the characterization results, we believe that Ag thin film produces Ag nanoparticles at high temperatures and enhances the reaction between oxygen and gallium, contributing to denser and longer Ga2O3 nanowires compared to those grown without silver catalyst. This process can be optimized for large-scale production of high-quality, dense, and long nanowires.

A Novel CO2-Based Insect Sampling Device and Associated Field Method Evaluated in a Strawberry Agroecosystem.

There is high demand for accurate insect sampling methods to inform integrated pest management strategies. Despite widespread application, existing sampling methods, such as portable aspirating and sweep netting, can result in overrepresentation of prominent pests, underrepresentation of natural enemies, and damage to plants. In this study, we test a novel device for insect sampling via anesthetization. Specifically, we test the effect of CO2 (application pressure and duration of exposure) on Lygus hesperus Knight (Hemiptera: Miridae) anesthetization in the laboratory and on insect community density in a strawberry agroecosystem. Carbon dioxide application proves an effective means of anesthetization compared to negative controls, and an increase in net CO2 exposure results in a decrease in time until L. hesperus anesthetization. Field results indicate the CO2 method collects more parasitoids and thrips than a portable aspirator, and at the 50 PSI application pressure and 15-s exposure, the CO2 method results in a comparable number of pests collected as the research standard, a portable aspirator with 8-s aspiration time. Benefits of the CO2 method include minimal plant damage, highly explicit spatial and temporal data, and scalability.

Recent Time Trends and Predictors of Heart Dose From Breast Radiation Therapy in a Large Quality Consortium of Radiation Oncology Practices.

PURPOSE: Limited data exist regarding the range of heart doses received in routine practice with radiation therapy (RT) for breast cancer in the United States today and the potential effect of the continual assessment of the cardiac dose on practice patterns. METHODS AND MATERIALS: From 2012 to 2015, 4688 patients with breast cancer treated with whole breast RT at 20 sites participating in a state-wide consortium were enrolled into a registry. The importance of limiting the cardiac dose has been emphasized in the consortium since 2012, and the mean heart dose (MHD) has been reported by each institution since 2014. The effects on the MHD were estimated for both conventional and accelerated fractionation using regression models, with technique (intensity modulated RT [IMRT] vs 3-dimensional conformal RT), deep inspiration breath hold use, patient position (supine vs prone), nodal RT (if delivered), and boost (yes vs no) as covariates. RESULTS: For left-sided breast cancer treated with conventional fractionation, the median MHD in 2012 was 2.19 Gy versus 1.65 Gy in 2015 (P<.001). The factors that significantly increased the MHD for conventional fractionation were increased separation relative to 22 cm (1.5%/1 cm), supraclavicular or infraclavicular nodal RT (17.1%), internal mammary nodal RT (40.7%), use of a boost (20.9%), treatment year before 2015 (7.7%), and use of IMRT (20.8%). For left-sided BC treated with accelerated fractionation, the median MHD in 2012 was 1.70 Gy versus 1.22 Gy in 2015 (P<.001). The factors that significantly increased the MHD for accelerated fractionation were separation (1.7%/1 cm), use of a boost (20.0%), year before 2015 (8.5%), and use of IMRT (19.2%). The factors for both conventional fractionation and accelerated fractionation that significantly reduced the MHD were the use of deep inspiration breath hold and prone positioning. CONCLUSIONS: The MHD for left-sided breast cancer decreased during a recent 4-year period, coincident with an increased focus on cardiac sparing in the radiation oncology community in general and a state-wide consortium specifically. These data suggest a positive effect of systematically monitoring the heart dose delivered.

Nanowire formation is preceded by nanotube growth in templated electrodeposition of cobalt hybrid nanostructures.

Cobalt fluted nanowires, novel nanostructures with a diameter of 200 nm consisting of a solid nanowire base and a thin, nanotubular flute shape, were grown in track-etched polycarbonate membranes via templated electrodeposition. The structures were characterized electrochemically via cyclic voltammetry, chronoamperometry, and charge stripping, and structurally via  scanning electron microscopy, transmission electron microscopy, and focused ion beam cross-sectioning. Electrochemical and structural analysis reveals details of their deposition kinetics, structure, and morphology, and indicate possible mechanisms for their formation and control. These unique structures provide inspiration for an array of possible applications in electronics, photonics, and other fields.

Template-based syntheses for shape controlled nanostructures.

A variety of nanostructured materials are produced through template-based synthesis methods, including zero-dimensional, one-dimensional, and two-dimensional structures. These span different forms such as nanoparticles, nanowires, nanotubes, nanoflakes, and nanosheets. Many physical characteristics of these materials such as the shape and size can be finely controlled through template selection and as a result, their properties as well. Reviewed here are several examples of these nanomaterials, with emphasis specifically on the templates and synthesis routes used to produce the final nanostructures. In the first section, the templates have been discussed while in the second section, their corresponding synthesis methods have been briefly reviewed, and lastly in the third section, applications of the materials themselves are highlighted. Some examples of the templates frequently encountered are organic structure directing agents, surfactants, polymers, carbon frameworks, colloidal sol-gels, inorganic frameworks, and nanoporous membranes. Synthesis methods that adopt these templates include emulsion-based routes and template-filling approaches, such as self-assembly, electrodeposition, electroless deposition, vapor deposition, and other methods including layer-by-layer and lithography. Template-based synthesized nanomaterials are frequently encountered in select fields such as solar energy, thermoelectric materials, catalysis, biomedical applications, and magnetowetting of surfaces.

Adhesive interactions of geckos with wet and dry fluoropolymer substrates.

Fluorinated substrates like Teflon® (poly(tetrafluoroethylene); PTFE) are well known for their role in creating non-stick surfaces. We showed previously that even geckos, which can stick to most surfaces under a wide variety of conditions, slip on PTFE. Surprisingly, however, geckos can stick reasonably well to PTFE if it is wet. In an effort to explain this effect, we have turned our attention to the role of substrate surface energy and roughness when shear adhesion occurs in media other than air. In this study, we removed the roughness component inherent to commercially available PTFE and tested geckos on relatively smooth wet and dry fluoropolymer substrates. We found that roughness had very little effect on shear adhesion in air or in water and that the level of fluorination was most important for shear adhesion, particularly in air. Surface energy calculations of the two fluorinated substrates and one control substrate using the Tabor-Winterton approximation and the Young-Dupré equation were used to determine the interfacial energy of the substrates. Using these interfacial energies we estimated the ratio of wet and dry normal adhesion for geckos clinging to the three substrates. Consistent with the results for rough PTFE, our predictions show a qualitative trend in shear adhesion based on fluorination, and the quantitative experimental differences highlight the unusually low shear adhesion of geckos on dry smooth fluorinated substrates, which is not captured by surface energy calculations. Our work has implications for bioinspired design of synthetics that can preferentially stick in water but not in air.

van der Waals Interactions on the Mesoscale: Open-Science Implementation, Anisotropy, Retardation, and Solvent Effects.

The self-assembly of heterogeneous mesoscale systems is mediated by long-range interactions, including van der Waals forces. Diverse mesoscale architectures, built of optically and morphologically anisotropic elements such as DNA, collagen, single-walled carbon nanotubes, and inorganic materials, require a tool to calculate the forces, torques, interaction energies, and Hamaker coefficients that govern assembly in such systems. The mesoscale Lifshitz theory of van der Waals interactions can accurately describe solvent and temperature effects, retardation, and optically and morphologically anisotropic materials for cylindrical and planar interaction geometries. The Gecko Hamaker open-science software implementation of this theory enables new and sophisticated insights into the properties of important organic/inorganic systems: interactions show an extended range of magnitudes and retardation rates, DNA interactions show an imprint of base pair composition, certain SWCNT interactions display retardation-dependent nonmonotonicity, and interactions are mapped across a range of material systems in order to facilitate rational mesoscale design.

Optical properties and electronic transitions of DNA oligonucleotides as a function of composition and stacking sequence.

The role of base pair composition and stacking sequence in the optical properties and electronic transitions of DNA is of fundamental interest. We present and compare the optical properties of DNA oligonucleotides (AT)10, (AT)5(GC)5, and (AT-GC)5 using both ab initio methods and UV-vis molar absorbance measurements. Our data indicate a strong dependence of both the position and intensity of UV absorbance features on oligonucleotide composition and stacking sequence. The partial densities of states for each oligonucleotide indicate that the valence band edge arises from a feature associated with the PO4(3-) complex anion, and the conduction band edge arises from anti-bonding states in DNA base pairs. The results show a strong correspondence between the ab initio and experimentally determined optical properties. These results highlight the benefit of full spectral analysis of DNA, as opposed to reductive methods that consider only the 260 nm absorbance (A260) or simple purity ratios, such as A260/A230 or A260/A280, and suggest that the slope of the absorption edge onset may provide a useful metric for the degree of base pair stacking in DNA. These insights may prove useful for applications in biology, bioelectronics, and mesoscale self-assembly.

Dielectric response variation and the strength of van der Waals interactions.

Small changes in the dielectric response of a material result in substantial variations in the Hamaker coefficient of the van der Waals interactions, as demonstrated in a simplified approximate model as well as a realistic example of amorphous silica with and without an exciton peak. Variation of the dielectric response spectra at one particular frequency influences all terms in the Matsubara summation, making the total change in the Hamaker coefficient depend on the spectral changes not only at that frequency but also at the rest of the spectrum, properly weighted. The Matsubara terms most affected by the addition of a single peak are not those close to the position of the added peak, but are distributed doubly non-locally over the entire range of frequencies. A possibility of eliminating van der Waals interactions or at least drastically reducing them by spectral variation in a narrow regime of frequencies thus seems very remote.