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Lattice Radiation Therapy (LRT), a 3-dimentional format of Spatially Fractionated Radiation Therapy, is generally characterized by large differences in peak and valley doses. It has been shown in the literature that LTR administered before conventional external beam radiation treatment results in debulking effect, increased cell killing, and increased tumor growth delay. Traditionally, LRT is delivered by Linac-based radiation system. Particle-based LRT is in the experimental stages. LRT has never been applied to brain tumor. We present a new approach using Gamma Knife (GK) radiosurgery system to advance the application of lattice radiation therapy for tumors in brain. GK has superior localization accuracy, intrinsic spherical shape of the radiation shot, and sharp dose fall-off gradient, which are suitable to deliver LRT. Five cases of brain metastasis with large tumor volumes, previously treated with 2-stage GK SRS, were selected for LTR planning. The tumor volumes range from 14 to 31.8 mL. New Gamma Knife LRT (GKLRT) plans were generated in Leksell Gamma Plan v11.3. Based on the literature, 15Gy to the vertices was elected in this study, which is high enough to induce tumor immunogenic response. The valley dose of 5Gy between vertices were chosen as constraint during planning to preserve tumor perfusion integrity for circulation of immunogenic factors and increasing the therapeutic ratio. Vertices in the lattice were considered as targets in the plan. Multiple targets with single 4 mm shot were placed inside the GTV. The prescription for each target was 15Gy at 100%. These shots were placed manually in such pattern that every shot was at least 4 mm from GTV boundary, the spacing between shots in Z direction was 8 mm, and the spacing in X and Y direction was more than 12 mm. The goal of the manual planning was to place maximum number of shots, and maintain the 5Gy lines around each shot not connected and within GTV. Dose coverage for GTV was not in consideration during planning. In the new GKLRT plans, the point dose at each vertex was exactly 15Gy. The minimal valley dose between any two vertices was less than 5Gy. The maximum dose at GTV surface was less than 5Gy. On average, every 1.6 mL GTV can fit one vertex. Given dose rate of 2.5Gy/min, the treatment time for 30 vertices GKLRT plan is 221 minutes for instance. Dosimetric feasibility of using GKLRT to treat brain tumors is demonstrated. A phase I protocol is under development to introduce one fraction of GKLRT before routine brain SBRT for intact brain metastases. This new approach has promising potential to significantly improve the outcome of patients with bulky brain tumors. [ABSTRACT FROM AUTHOR]

Introduction and Aim: Epidural analgesia is an effective technique for postoperative pain relief following thoracoabdominal surgeries. Lower limb motor weakness is a well-known complication of epidural analgesia with local anesthetics and delays postoperative rehabilitation. Our aim in conducting this observational study was to assess the frequency of lower limb motor weakness in patients receiving epidural analgesia following upper abdominal surgery and the factors associated with it. Materials and Methods: All adult patients, aged 20-70 years, who underwent upper abdominal surgery and received postoperative analgesia with an epidural infusion of bupivacaine with fentanyl, were included. Data were collected over 4 months from notes entered by acute pain service after each round. Data collected included level of epidural placement, drug solution and volume, degree of lower limb motor weakness and measures taken to relieve it. Bromage scale was used to assess motor weakness. Results: Data were collected on 123 patients. Bupivacaine 0.1% with fentanyl 2 µg/mL was used in 113 (92%) patients. Lower limb motor weakness developed in 45 patients (36.5%). The highest frequency was seen in patients with epidural at L2-L3 level. The common management steps were a change of patient's position or decrease in concentration of local anesthetic. These measures produced improvement in 39 (87%) patients whereas the local anesthetic was stopped temporarily in the remaining six patients. Conclusion: Lower limb motor weakness occurred in 36.5% patients. It was more common with a lumbar epidural. It was successfully managed in all patients. Lower thoracic epidurals are recommended for abdominal surgeries. [ABSTRACT FROM AUTHOR]

Abstract: In-plane and out-of-plane crushing properties of the honeycomb core were investigated experimentally and with Digital Image Correlation. The out-of-plane direction of the core was found as the strongest direction which absorbed significant amount of energy during deformation. The ribbon direction was found two times stronger as compared to the transverse direction. Local deformation response in in-plane crushing was analyzed with Digital Image Correlation. It was found that the local plastic strain in the core was mainly in the shear band regime. Additionally, the local plastic strain was found higher as compared to the global stress level. The combination of experimental and Digital Image Correlation results worked excellently well in the determination of global and local deformation mechanism of the honeycomb core. [Copyright &y& Elsevier]

Purpose/objective(s): Ureteral stenosis (US) is an underreported complication of brachytherapy for cervical cancer, with limited data regarding dose constraints to reduce risk of toxicity. Previous work from our institution demonstrated that an EQD2 ≥ 77 Gy to 0.1 cm3 of ureter correlated with development of US. We sought to determine whether we can reduce ureter dose EQD2 ≤77 Gy while maintaining similar HR-CTV coverage. We also sought to determine if anatomical factors would limit achieving ureter dose constraints.Materials/methods: We identified patients with locally advanced cervical cancer treated with external beam radiation therapy plus HDR MRI-guided brachytherapy boost without hydronephrosis at diagnosis who had single or bilateral ureter dose EQD2 ≥ 77 Gy to 0.1 cm3, regardless of subsequent US. Replan was attempted for each individual brachytherapy fraction, aiming to achieve HR-CTV D90 ≥ 80-85 Gy without significant reduction in coverage, while maintaining rectal D2cc ≤65 Gy, bowel D2cc ≤65-70 Gy, sigmoid D2cc ≤70 Gy, and bladder D2cc ≤80 Gy. Distance of each ureter from lateral margin of HR-CTV and tandem were recorded, with mean values calculated on a per patient basis. Dependent samples T-test was performed to compare highest ureteral dose from original plan to replan ureteral dose and original plan HR-CTV D90 to replan HR-CTV D90. Independent samples T-test was performed to compare the mean distance of closest ureter to HR-CTV and tandem in patients for whom ureteral dose reduction was feasible to those for whom reduction was not feasible.Results: 25 patients met inclusion criteria, with all patients receiving 45 Gy in 25 fractions to the pelvis plus/minus paraaortic lymph nodes and 20 of 25 patients receiving mean parametrial dose of 5.4 Gy. Replan meeting ureteral dose of ≤77 Gy was feasible in 18 of 25 patients, with significant reduction in highest mean ureteral dose from 85.3 Gy to 76.7 Gy (P < 0.001). Mean original plan HR-CTV dose of 85.06 Gy decreased by 0.94 Gy to replan dose of 84.12 Gy in successfully replanned patients. Mean distance of closest ureter to HR-CTV margin was 1.5mm in patients for whom achieving ureter dose constraints was not feasible compared to 8.2mm for patients for whom replan was feasible (P = 0.038). Mean distance of closest ureter to tandem was 14.5mm for patients whom achieving ureter dose constraints was not feasible compared to 24.7mm for patients for whom replan was feasible (P < 0.001). Replan achieved ureter dose ≤77 Gy in the majority of patients who experienced US (56%), and 100% of unilateral US cases occurred in the ureter closest to HR-CTV.Conclusion: When ureters are contoured, optimization to reduce ureter dose to ≤77 Gy is feasible, potentially allowing for reduction in US risk without significant compromise in HR-CTV D90. Anatomic variation of ureter position may impact this optimization. Ureters may be considered as potential organs at risk during MRI-based brachytherapy treatment if visualization is feasible to reduce risk of US.Author Disclosure: S.A. Koerner: Stock; Novavax, Pfizer, Inovio Pharmaceuticals, Ocugen, Teladoc, ADC Therapeutics, CVS, Viatris Inc. T. Baig: None. H. Kim: None. J.L. Rodriguez-Lopez: None. A. Keller: None. S. Beriwal: None. [ABSTRACT FROM AUTHOR]

Measurement of the scattered light spectrum from hydrogen plasmas containing small amounts of heavy impurity ions confirms the predictions of theory that the low-frequency ion-acoustic scattered light feature consists of the normal profile due to scattering from a pure hydrogen plasma, with a narrow peak superimposed that is attributed to the impurity. The intensity of the impurity peak scales as the square of a mean charge Z*. Measurements are reported for electron densities of 1–3×1018 cm-3 and electron temperatures ranging from 10 to 80 eV. [ABSTRACT FROM AUTHOR]

A typical workflow for complex cervical HDR brachytherapy planning at most institutions includes delineation of Organ at Risk (OAR) contours on a CT acquired after device placement. Additionally, at our institution, an MRI is obtained for HR CTV delineation. Then the plan is finalized and the treatment is delivered. Due to limited MRI slots, the completion of the MRI can take place up to six hours after the CT. This study aims to assess the potential deviations in OAR delineation and resulting dose statistics caused by variations in the time between CT and MRI scans. Data were acquired through an IRB-approved retrospective review of cervical cancer patients treated with HDR brachytherapy, utilizing both CT and MRI scans for treatment planning. OARs were delineated by our institution's radiation oncologists for 17 cases. Contours for rectum, bladder, bowel, and sigmoid were delineated on both CT and MRI. The MRI was fused to the CT based on the HR CTV and applicator and approved by the physician. The RT doses from the delivered clinical plans were overlaid to assess dose statistics for the two contour sets. Analysis was employed to determine differences in OAR doses between MRI and CT-based contours. The average time between CT and MRI scans was 4.34 ± 1.88 hrs (0.46-6.87 hrs). The mean ± STDev of D2cc for each OAR on CT and MRI, p value, and mean ± STDev of the percent difference of the two were determined for a single fraction. Rectum D2cc on CT and MRI was 3.40 ± 1.54 Gy and 3.64 ± 1.24 Gy respectively with p = 0.39 and average D2cc 34.5 ± 124% higher on MRI. This large STDev is attributed to 2 cases where the rectum moved significantly closer to the HR CTV. Without these 2 outliers, the average percent difference in D2cc was 0.68 ± 9.65%. Bladder D2cc on CT and MRI was 5.10 ± 1.35 Gy and 4.62 ± 1.37 Gy respectively with p = 0.02 and average D2cc 9.46 ± 16.3% lower on MRI. Sigmoid D2cc on CT and MRI was 2.68 ± 1.20 Gy and 2.70 ± 1.22 Gy respectively with p = 0.84 and average D2cc 3.17 ± 27.35% lower on MRI. D2cc for bowel was not evaluable for 6 cases (contours were outside of the 10x10cm dose grid). Bowel D2cc on CT and MRI was 3.63 ± 1.36 Gy and 2.90 ± 1.47 Gy respectively with p = 0.03 and average D2cc 20.2 ± 27.4% lower on MRI. The data show a significant decrease in D2cc to bladder and bowel when contoured on MRI as opposed to CT. There was no correlation between scan time difference and OAR D2cc percent difference between scans. The time difference between CT and MRI scans does not significantly impact dose to OAR contours in HDR brachytherapy treatment planning for cervical cancer. However, there was a small but significant decrease in D2cc to bowel and bladder when contoured on CT versus MRI independent of scan time difference. This may be due to improved delineation of these OARs on MRI. Contouring OARs on CT appears to have a conservative impact, implying it is safe to continue to contour OARs on the CT and the HR CTV on MRI. [ABSTRACT FROM AUTHOR]

Abstract A wet chemical route was followed for the synthesis of Mg 1-x Ni x O (x = 0.5) nano-solid solution. The nanoparticles were characterized by using PXRD, SEM and EDX analytical techniques. The nano particles were crystallized in NaCl structure type with crystallite size range; 10–30 nm with spherical geometry and average particle size range; 54–63 nm for the materials annealed at 500, 600 and 800 °C, respectively. Antibacterial activities of the materials were investigated and compared against E. Coli and MRSA via disc diffusion method with respect to the surface O2− and particle size. DFT studies were carried out for structural and geometric analysis of Mg 1-x Ni x O slab using Generalized Gradient Approximation (GGA). Energetic behavior of the compound was determined by band gap and density of state (DOS) at the same level of theory. Molecular docking studies of the material with bacterial DNA revealed spontaneity of the reaction depicting highest binding strength with DNA in case of MgNiO dimer. Graphical abstract Image Highlights • Synthesis and characterization of Mg 1-x Ni x O (x = 0.5) nano-solid solution. • Experimental antibacterial studies in relation to surface O2− and particle size. • Computational studies showed strongest binding between MgNiO dimer & bacterial DNA. • Results of experimental studies matched well with the computational findings. [ABSTRACT FROM AUTHOR]

To develop an analytic risk management method that uses mathematical models in Failure Modes and Effects Analysis (FMEA) to design mitigation efforts to control pandemic infection, while ensuring safe delivery of radiotherapy. A two-stage FMEA approach is proposed to modify radiotherapy workflow during a pandemic. In stage 1, an Infection Control FMEA (IC-FMEA) is conducted, where risks are evaluated based on environmental parameters, clinical interactions, and modeling of the pandemic infection risk. Occupancy' Risk Index (ORI) is defined as a metric of infection risk probability in each room, based on the degree of occupancy during clinical operations. ORI, in combination with ventilation rate per person (R p), is used to provide a broad infection risk assessment of workspaces. For detailed IC-FMEA of clinical processes, Infection containment failure mode (ICFM) is defined to be any instance of disease transmission within the clinic. Infection risk priority number (IRPN) has been formulated as a function of time, distance, and degree of protective measures. Infection control measures are then systematically integrated into the workflow. In stage 2, a conventional radiotherapy FMEA (RT-FMEA) can be performed on the adjusted workflow. A number of different clinical processes within radiotherapy workflow have been evaluated with this approach. The COVID-19 pandemic was used to illustrate stage 1 IC-FMEA. ORI and R p values were calculated for various workspaces within a radiotherapy clinic. A deep inspiration breath hold (DIBH) CT simulation was used as an example to demonstrate detailed IC-FMEA with ICFM identification and IRPN evaluation. A total of 90 ICFMs were identified in the DIBH process. For minimal protective measures the IRPN values ranged from 2 – 1200, while for increasing degrees of infection control the values decreased to 2-530 and 1-189 corresponding to moderate and enhanced measures respectively. The framework developed in this work provides tools for radiotherapy clinics to analytically assess risks and adjust workflows during a pandemic. [ABSTRACT FROM AUTHOR]

Purpose: To provide a rapid method to reduce the radiofrequency (RF) E-field coupling and consequent heating in long conductors in an interventional MRI (iMRI) setup. Methods: A driving function for device heating (W) was defined as the integration of the E-field along the direction of the wire and calculated through a quasistatic approximation. Based on this function, the phases of four independently controlled transmit channels were dynamically changed in a 1.5 T MRI scanner. During the different excitation configurations, the RF induced heating in a nitinol wire immersed in a saline phantom was measured by fiber-optic temperature sensing. Additionally, a minimization of W as a function of phase and amplitude values of the different channels and constrained by the homogeneity of the RF excitation field (B1) over a region of interest was proposed and its results tested on the benchtop. To analyze the validity of the proposed method, using a model of the array and phantom setup tested in the scanner, RF fields and SAR maps were calculated through finite-difference time-domain (FDTD) simulations. In addition to phantom experiments, RF induced heating of an active guidewire inserted in a swine was also evaluated. Results: In the phantom experiment, heating at the tip of the device was reduced by 92% when replacing the body coil by an optimized parallel transmit excitation with same nominal flip angle. In the benchtop, up to 90% heating reduction was measured when implementing the constrained minimization algorithm with the additional degree of freedom given by independent amplitude control. The computation of the optimum phase and amplitude values was executed in just 12 s using a standard CPU. The results of the FDTD simulations showed similar trend of the local SAR at the tip of the wire and measured temperature as well as to a quadratic function of W, confirming the validity of the quasistatic approach for the presented problem at 64 MHz. Imaging and heating reduction of the guidewire were successfully performed in vivo with the proposed hardware and phase control. Conclusions: Phantom and in vivo data demonstrated that additional degrees of freedom in a parallel transmission system can be used to control RF induced heating in long conductors. A novel constrained optimization approach to reduce device heating was also presented that can be run in just few seconds and therefore could be added to an iMRI protocol to improve RF safety. [ABSTRACT FROM AUTHOR]

Contamination caused by heavy metals as well as their toxic effects on the environment and mankind is well known. However, it has been observed that some native plants have survived within areas polluted with heavy metals. This has been the case with the woody subshrub Solanum elaeagnifolium. It is possible to take advantage of this singular feature by using its inactivated tissues as a biofiltration system. In this work we characterized the mechanism of the binding between the biomass tissues with heavy metals by using chemical modification techniques. These techniques included chemical esterification and hydrolyzation of carboxylic groups and methyl esters, respectively. These studies have shown an overall decrease in metal binding for the esterified biomass, and an overall increase in metal binding for the hydrolyzed biomass as compared with the unmodified biomass. These experiments were performed with Cu(II), Pb(II), Cr(III), Zn(II) and Ni(II). In addition, experiments conducted with modified biomass at different pH conditions were done in order to corroborate the biomass modification results. Also, we used X-ray absorption spectroscopy techniques (XANES and EXAFS) to elucidate the mechanism(s) of metal ion binding. [Copyright &y& Elsevier]