Injection Location Research Articles

Transarterial drug delivery for liver cancer: numerical simulations and experimental validation of particle distribution in patient-specific livers

ABSTRACT Background: Transarterial therapies are routinely used for the locoregional treatment of unresectable hepatocellular carcinoma (HCC). However, the impact of clinical parameters (i.e. injection location, particle size, particle density etc.) and patient-specific conditions (i.e. hepatic geometry, cancer burden) on the intrahepatic particle distribution (PD) after transarterial injection of embolizing microparticles is still unclear. Computational fluid dynamics (CFD) may help to better understand this impact. Methods: Using CFD, both the blood flow and microparticle mass transport were modeled throughout the 3D-reconstructed arterial vasculature of a patient-specific healthy and cirrhotic liver. An experimental feasibility study was performed to simulate the PD in a 3D-printed phantom of the cirrhotic arterial network. Results: Axial and in-plane injection locations were shown to be effective parameters to steer particles toward tumor tissue in both geometries. Increasing particle size or density made it more difficult for particles to exit the domain. As cancer burden increased, the catheter tip location mattered less. The in vitro study and numerical results confirmed that PD largely mimics flow distribution, but that significant differences are still possible. Conclusions: Our findings highlight that optimal parameter choice can lead to selective targeting of tumor tissue, but that targeting potential highly depends on patient-specific conditions.

Керування вектором тяги ракетного двигуна вдувом продуктів детонації в надзвукову частину сопла

For solving non-traditional problems of rocket flight control, in particular, for the conditions of impact of a nuclear explosion, non-traditional approaches to the organization of the thrust vector control of a rocket engine are required. Various schemes of gas-dynamic thrust vector control systems that counteract impact actions on the rocket were studied. It was found that the dynamic characteristics of traditional gas-dynamic thrust vector control systems do not allow one to solve the problem of counteracting impact actions on the rocket. Appropriate dynamic characteristics can provide a perturbation of the supersonic flow by injecting into the nozzle the detonation products with the main shock wave propagating in the supersonic flow. This way to perturb the supersonic flow in a rocket engine nozzle is investigated in this paper. In order to identify the principles of producing control forces and provide a perturbation of the supersonic flow by injecting into the nozzle the detonation products with the main shock wave propagating in the supersonic flow, a computer simulation of the nozzle flow was performed. The nozzle of the 11D25 engine developed by Yuzhnoye State Design Office and used in the third stage of the Cyclone-3 launch vehicle was taken as a basis. The thrust vector control scheme relies on the use of the main fuel component detonation. The evolution of the detonation wave in the supersonic flow of the combustion chamber nozzle was simulated numerically. According to the nature of the perturbation propagation in the nozzle, the lateral force from the perturbation has an alternating character with the perturbation stabilization in sign and magnitude when approaching the critical nozzle section. The value of the relative lateral force is sufficient for counteracting large disturbing moments of short duration. Thus, the force factors that can be used to control the rocket engine thrust vector are identified. Further research should focus on finding the optimal location of the detonation product injection in order to prevent mutual compensation of force factors.

Effect of transverse fuel injection system on combustion efficiency in scramjet combustor

Supersonic mixing layer behind the hydrogen fueled wedge shaped strut has been demonstrated by means of combined fuel injection strategy. Numerical investigation on the Effect of wall transverse fuel injection system in addition with parallel fuel injection approach have been found suitable for stable flame and combustion performance. The experimental supersonic combustor observation was performed by Waidmann et al. in German Aerospace Centre (DLR), which has been utilised in validation section to examine the accuracy and applicability of present computational work. Non-reacting and reacting both types of flow field characteristics are analysed to complete the validation. Good agreement was found in the contour plots towards oblique shock incident location moreover expansion fan behaviour at the end tip of the strut was observed. Pressure graph near the combustor walls and mid plane of the combustor were well matched with numerical observation however velocity graph was best suitable for near wake region instead of far-field region. Thus Ansys 14.0 fluent software has been chosen to compare the experimental data from the literature with numerical analysis. Two-dimensional computational combustor geometry has been taken with involving steady state, SST k-ω two equation based turbulence model analysis. Finite rate-eddy dissipation chemistry based combustion model is used to analyse the combustion process. Parallel fuel injection location is engaged at the same point and the change of wall transverse fuel injection port position have been analysed. Variations can be visualised in the numerical analysis outcome of combustion and mixing performance. The combustion efficiency plot is divided in to two section i.e. rapid change in chemical reaction in all four cases and second is gradual consumption of fuel. The outcome shows that the abrupt change in 68 mm transverse fuel injector model with 96% combustion efficiency.

Numerical Study of the Effects of Twin-Fluid Atomization on the Suspension Plasma Spraying Process

Suspension plasma spraying (SPS) is an effective technique to enhance the quality of the thermal barrier, wear-resistant, corrosion-resistant, and superhydrophobic coatings. To create the suspension in the SPS technique, nano and sub-micron solid particles are added to a base liquid (typically water or ethanol). Subsequently, by using either a mechanical injection system with a plain orifice or a twin-fluid atomizer (e.g., air-blast or effervescent), the suspension is injected into the high-velocity high-temperature plasma flow. In the present work, we simulate the interactions between the air-blast suspension spray and the plasma crossflow by using a three-dimensional two-way coupled Eulerian–Lagrangian model. Here, the suspension consists of ethanol (85 wt.%) and nickel (15 wt.%). Furthermore, at the standoff distance of 40 mm, a flat substrate is placed. To model the turbulence and the droplet breakup, Reynolds Stress Model (RSM) and Kelvin-Helmholtz Rayleigh-Taylor breakup model are used, respectively. Tracking of the fine particles is continued after suspension’s fragmentation and evaporation, until their deposition on the substrate. In addition, the effects of several parameters such as suspension mass flow rate, spray angle, and injector location on the in-flight behavior of droplets/particles as well as the particle velocity and temperature upon impact are investigated. It is shown that the injector location and the spray angle have a significant influence on the droplet/particle in-flight behavior. If the injector is far from the plasma or the spray angle is too wide, the particle temperature and velocity upon impact decrease considerably.

Corticosteroid and Local Anesthetic Use Trends for Large Joint and Bursa Injections: Results of a Survey of Sports Medicine Physicians.

Physician decision-making surrounding choices for large joint and bursa injections is poorly defined, yet influences patient safety and treatment effectiveness. To identify practice patterns and rationale related to injectate choices for large joint and bursal injections performed by physician members of the American Medical Society for Sports Medicine (AMSSM). An electronic survey was sent to 3400 members of the AMSSM. Demographic variables were collected: primary specialty (residency), training location, practice location, years of clinical experience, current practice type, and rationale for choosing an injectate. A total of 674 physicians responded (minimum response rate of 20%). Not applicable. Outcomes of interest included corticosteroid type and dose, local anesthetic type, and total injectate volume for each large joint or bursa (hip, knee, and shoulder). Most respondents used triamcinolone (50% to 56% of physicians, depending on injection location) or methylprednisolone (25% to 29% of physicians), 21 to 40 mg (53% to 60% of physicians), diluted with lidocaine (79% to 87%) for all large joint or bursa injections. It was noted that 36.2% (244/674) of respondents reported using >40 mg for at least one injection type. Most (90.5%, 610/674) reported using an anesthetic other than ropivacaine for at least one type of joint or bursa injection. Physicians who reported lidocaine use were less likely to report that their injectate choice was based on the literature that they reviewed (odds ratio [OR]0.41 [0.27-0.62], P < .001). Respondents predominantly used 5 to 7mL of total injectate for all large joints or bursae (45% to 54% of respondents), except for the pes anserine bursa, where 3-4mL was more common (51% of physicians). It appears that triamcinolone and methylprednisolone are the most commonly used corticosteroids for sports medicine physicians; most physicians use 21 to 40 mg of corticosteroid for all injections, and lidocaine is the most-often used local anesthetic; very few use ropivacaine. Over one-third of respondents used high-dose (>40 mg triamcinolone or methylprednisolone) for at least one joint or bursa.

Identifying Contaminant Intrusion in Water Distribution Networks under Water Flow and Sensor Report Time Uncertainties

Contamination events in water distribution networks (WDNs) could have severe health and economic consequences. Contaminants can be deliberately or accidentally introduced into the WDN. Quick identification of the injection location and time is important in devising a mitigation plan to prevent further spread of the contaminant in the network. A method of identifying the possible intrusion point in a given network and reporting data is to use an inverse calculation by backtracking the potential path of the contaminant in the network. However, there is an element of uncertainty in the data used for calculation, particularly in water flow and sensor report time. Given the uncertainties, a method was developed in this study for fast and accurate contaminant source identification. This paper proposes a comparison filter of results by first identifying potential contaminant locations through backtracking, followed by a forward calculation to determine the injection time range, thereby reducing the potential suspects and providing likeliness comparison among the suspects. The effectiveness of the proposed method was examined by applying it to a benchmark WDN. By simulating uncertainties and filtering through the results, several possible contaminant intrusion locations and times were identified.

Vaso-Occlusive Events Precipitated By Intraarticular Steroid Injections in Patients with Sickle Cell Disease

Introduction: Sickle cell disease (SCD) is a group of inherited hemoglobin diseases (Hb), caused by a point mutation in the b-globin gene, that affects more than 100,00 people in the US and millions worldwide. No organ system is left unaffected by SCD, including the musculoskeletal system; complications which can greatly decrease quality of life and contribute to significant burden for these patients. Orthopedic complications include bone pain, dactylitis, growth retardation and atypical skeletal development, osteomyelitis and septic arthritis, bone demineralization, motor/mobility impairment, osteonecrosis and other causes of arthritis and rheumatologic disease. While surgical repair by arthroplasty is often a definitive solution to joint pain, conservative, non-operative treatments are first-line, including physical therapy and intraarticular corticosteroid injections. Corticosteroid injections can be used as a convenient outpatient solution to reduce inflammation and relieve pain without undergoing surgical measures. The use of steroids for non-orthopedic complications of SCD is not benign for many patients, and may be associated with the development of rebound vaso-occlusive pain events, requiring hospitalization, as well as hemorrhagic stroke. A review of the literature revealed two cases of patients with SCD who received intraarticular steroid injections for rheumatoid arthritis in whom the injections precipitated an acute vaso-occlusive episode that required admission. In view of these findings, we are interested in determining if any adults in our adult SCD clinic who had an intraarticular injection of a steroid developed worsening of pain. Methods: After approval by the UIC IRB, a retrospective chart review was conducted for subjects enrolled in the UIC Adult Sickle Cell Center treated with an intraarticular steroid injection. Data collected included: type of medication used, injection location, indication, pain complication and timeline of symptoms, admission, age, sex, genotype and BMI. Vaso-occlusive events described were unusually severe compared to the pre-corticosteroid clinical course and not reported with other triggers for SCD vaso-occlusive events. Results: Four patients were identified. Characteristics of these patients and injections are listed in table 1. Patients received one or more injections of knees, hips, wrists and fingers before recognizing the associated pain with the injection. Indications for injections included primary osteoarthritis, osteoarthritis secondary to avascular necrosis, tendonitis and tenosynovitis. All injections were a combination of local anesthetic and glucocorticoid. The majority of injections were 2 cc lidocaine 1%, 1 cc triamcinolone acetonide-40mg. Other local anesthetics used were xylocaine and bupivacaine. Discussion: With improvements in medical care, more people with SCD are surviving into adulthood and developing orthopedic complications of SCD, as well as aging, such as osteoarthritis. While the development of acute pain after treatment of the acute chest syndrome with steroids is known, there were only 2 reported cases of SCD patients who developed severe pain associated with intraarticular injections. We report here four additional cases of adults with SCD who received an injection and developed worsening of their pain, often requiring admission. While these numbers are small, we believe that this may be a much more common complication of steroid injections and providers should discuss this with their patients. The observations that are made in this study raise into question the idea that while temporary pain relief is the intended outcome, this is not the result in all patients- the fact of which should be a consideration made by all clinicians when offering steroid injections as opposed to non-steroid joint injections to patients with SCD. The pathophysiology behind this effect of steroid injections is unclear. In the event that a patient with SCD presents with pain symptoms, either worsening pain or pain uncharacteristic of their usual symptoms, a consideration for potential causes should be recent steroid injection for joint pain. These considerations may help guide clinical decision making. Disclosures No relevant conflicts of interest to declare.

A DBD-Integrated Discharge Device for Low-Voltage Atmospheric Plasma Generation

A dielectric barrier discharge (DBD)-integrated plasma device for low-voltage atmospheric plasma generation is presented. By utilizing DBD afterglows as initiation carriers, a significant reduction in the breakdown voltage across a gap of 1 mm was achieved. The use of integrated DBD offers a precise control of initiation carrier injection and suppresses sputtering-induced electrode wear. The proposed integration scheme enables a highly reliable atmospheric plasma generation on a substrate at a very low voltage. This study also reveals that the injection location and the amount of initiation carriers play a key role in triggering avalanche breakdown process in the discharge. An optimized device structure has demonstrated atmospheric plasma across a gap of 1 mm at 700 V, which is only one-third of the breakdown voltage using a conventional two-electrode structure.

Performance Evaluation of Diesel Engine Using Novel Variable Compression Ratio Mechanism

Increasingly stringent emission and fuel economy standards brings opportunities and research in automobile engine technology development to make it more efficient and less polluting. There are various performance improvement strategies adopted by different researchers in order to get maximum power from the minimum quantity of fuel alongside substantial reduction in exhaust gas emission. The techniques such as CRDI (Common Rail Direct Injection), VVT (Variable valve timing) and such more are commercially viable and successfully incorporated in vehicles. Along the similar track, this paper highlights the importance of variable compression ratio diesel engine, method of achieving the variable compression ratio (VCR) as per load and speed conditions. Variable compression ratio (VCR) technology is one of the method for improving the automobile engine performance, efficiency, fuel economy with reduced emission for range of fuels. The basis of the VCR engine is to operate at different compression ratio, by altering the combustion chamber volume, as per need of most suitable operating conditions. Apart from this, the fuel injection location needs to be varied as per load and speed conditions. The synchronization of both VCR and variable fuel injector location (VFIL) becomes important. Knowing this fact, the study for the diesel Comet engine (3.7 kW@2100 RPM) is undertaken for variable clearance volume accompanied with VIPL. The work consists of design and development of mechanism consisting of auxiliary cylinder and auxiliary piston which will operate in and out of combustion chamber as per load and speed conditions. The detailed drawings and complete experimentation will be carried out to judge the improvement of performance of diesel engine with modification of variable clearance volume concept. The performance parameters consist of brake power, brake thermal efficiency and brake specific fuel consumption under various load conditions.

Effects of fuel injection angle on mixing performance of scramjet pylon-cavity flameholder

A numerical investigation on the effects of fuel injection angle on various mixing parameters within a pylon-cavity aided supersonic combustor flameholder under non-reactive flow conditions is performed. The computational model based on Reynolds-averaged Navier–Stokes equations for compressed real gas is solved by a coupled, implicit, second-order upwind solver with a two-equation Menter’s shear stress transport turbulence model. The steady simulations are experimentally validated using wall pressure data, two-dimensional (2D) velocity field, and fuel mass fraction. Three distinct fuel injection locations at the cavity floor are used for sonic hydrogen fuel injection at 90° and 45° injection angles, with a crossflow Mach number of 2.2. The results show deeper fuel jet penetration capability for the transverse injection when compared to an angled injection, whereas better mixing capability is observed for the latter. The fuel jet vortex pairs formed due to the interaction of the surrounding cavity flow with the barrel shock play a vital role in the mixing mechanisms. The lower pressure regions due to the barrel shock result in the formation of a secondary fuel jet vortex pair. The Kelvin–Helmholtz instability observed between the counter-rotating vortex pairs results in the formation of smaller eddies, which enhance the fuel dispersion and transport.

Experimental Study of Direct Water Injection Effect on NOx Reduction from The Gas Fuel

Direct Water Injection (DWI) is commonly used in many nitrogen oxides (NOx) emissions control applications due to its effect to reduce the adiabatic flame temperature. In this paper an experimental test rig is designed to study the effect of water injection spray inside a simulated gas turbine combustor from the gas fuel. The practical work introduced by the chemical reaction methodology followed by the experiment which was presented and discussed carefully. Results are obtained in term of the exhaust gas temperature and different injection parameters including position, direction and fuel mass flow rate on the nitrogen oxide emission value in PPM (Parts per Million) at different conditions. The results showed that the best water injection effect was obtained at 45° degree inside the primary air zone. Injection location has a major effect on the NOx reduction as the best injected location is the Primary air zone compared with the direct fuel nozzle tip due to the increase of the water droplets residence time inside the combustor and perform a vortex that will affect the reduction of exhaust gas temperature and NOx emission respectively. The huge impact was observed at LPG (Liquefied Petroleum gas) flowrate 2.7L/min and water to fuel ratio about 0.4 as the NOx value was decreased about 73% from almost 381 PPM to 73 PPM. The chemical reaction arrangement order methodology presented good agreement with the experimental results at different fuel flow rate and equivalence ratio. The chemical Reaction equations were implemented to calculate the different adiabatic flame temperatures which is experimentally known as the exhaust gas temperature and impacted directly the NOx emission results.

Effect of in-cylinder air-water interaction on water evaporation and performance characteristics of a direct water injected GDI engine

Water injection is one of the promising strategies for modern downsized GDI engines to meet performance and emission requirements under wide operating conditions. However, the benefits of water injection strongly depend upon water evaporation and distribution of water vapours inside the combustion chamber. In this regard, water injector location and orientation are two significant geometrical parameters which decide the in-cylinder positioning of the water spray, evaporation, and vapour distribution. Therefore, this CFD study presents the effects of water injector location, and orientation on the in-cylinder air-water interaction, water evaporation, vapour distribution, performance and emission characteristics of a wall-guided GDI engine. It also presents the effects of water injector location and orientations on water evaporation rate, water droplet distribution, heat release rate, IMEP, and exhaust emissions. In this study, the spark-plug is considered as located in the middle of the cylinder head, and the water injector is mounted in between the exhaust valves. Four locations of the water injector (21 mm, 25 mm, 29 mm, and 33 mm from the spark-plug) are considered for the investigation. Also, the injector orientation is varied from 12° to 28°, in the step of 4°. The engine is operated under naturally aspirated and full-load conditions at an engine speed of 2000 rev/min. Analysis of results shows that the water evaporation rate increases when more amount of water is sprayed in the region where the velocities of water droplets are in the opposite direction of that of the in-cylinder air. It is found that the water injector located at 29 mm with the orientation of 24° is found to be optimum configuration, where the IMEP improved by about 9.2%, while NOx and soot emissions reduced by about 48.2% and 22.6% respectively compared to those of the case of no_water.

Disruption mitigation efficiency and scaling with thermal energy fraction on ASDEX Upgrade

Disruption mitigation remains a critical and unresolved issue for ITER. Measurement uncertainties preventing quantification of a system’s efficacy remains a significant hurdle in producing and validating a viable disruption mitigation system. This study addresses this issue through the creation of a dataset on the ASDEX Upgrade tokamak targeted at developing analysis techniques to quantify mitigation that are applicable irrespective of the disruption mitigation system being studied. These experiments used a range of thermal energy fractions to address concerns for ITER from JET massive gas injection (MGI) experiments showing a decrease in efficacy with increasing thermal energy fraction. The dataset produced in this study used MGI valves in two toroidal locations. The high resolution foil bolometers and AXUV diode arrays were used to infer radiation emission profiles at varying toroidal distances from the injection location. The fueling efficiency of the two systems was found to be comparable and toroidal asymmetries over the entire disruption were found to be negligible. The AXUV diodes were cross-calibrated with the foil bolometers and used to estimate the thermal energy radiated and magnetic energy coupled to the vessel structure and coils. It was estimated that 75–95% of the thermal energy was radiated and an almost constant 60% of the total magnetic energy was coupled. Radiated energy fractions of 0.8–1.0 were calculated and no decrease as a function of thermal energy fraction was found. A ± 20% variation in the coupled magnetic energy was explored and it did not alter this trend.

Anatomic surface landmarks to guide injection for posterior interosseous nerve block

Proper injection of the posterior interosseous nerve (PIN) is important for both the therapeutic and diagnostic management of wrist pain. However, no anatomical study exists describing the site of injection based on individual wrist width. We sought to develop a reproducible anthropometric ratio utilizing external wrist surface anatomy to predict a safe and accurate injection site for the PIN. Fresh frozen cadaver forearms were dissected at the University of Louisville tissue lab. Several anthropometric measurements were obtained in order to develop a reproducible ratio to calculate location of injection. A total of 16 cadaver forearms of equal male to female ratio were obtained. On average, the male forearm had a greater mean wrist circumference obtained at the level of Lister’s tubercle compared to female forearms, 17.1 cm vs. 13.5 cm. An injection given ulnar to proximal edge of Lister’s tubercle at a length of one-fourth the distance between Lister’s tubercle and radial aspect of ulnar styloid resulted in 100% accurate perineural injection without intraneural injection. An anthropometric ratio of one-fourth the distance from Lister’s tubercle to the ulnar styloid was able to predict accurate injection sites for the distal PIN in cadaveric specimens of varying anatomical proportions.

Control of emergent magnetic monopole currents in artificial spin ice

The control of emergent magnetic monopoles for the generation of monopole currents in artificial spin ice is essential for their use in nanomagnet-based device applications. Here we present a scheme to inject monopole currents into an artificial square ice at specific locations, which provides a means to control the propagation of the generated emergent monopole currents. Specifically, we modify an artificial square ice by populating two of its edges with different vertex configurations consisting of two, three, and four nanomagnets meeting at a common point. After setting an initial state with a global magnetic field, injection of monopoles occurs at one of the edges where the vertices have higher switching probability. We experimentally observe this vertex-specific nucleation of emergent magnetic monopoles using x-ray photoemission electron microscopy. Additionally, we demonstrate that a lateral shift in the reversal of the magnets, leading to the formation of large domains, is consistent with theoretical simulations incorporating higher-order contributions in the magnetic Hamiltonian. Finally, we find a strong correlation between the location of emergent monopole injection and the film thickness, which is a result of the switching probability associated with the different vertex configurations.

Numerical simulation and optimization of injection rates and wells placement for carbon dioxide enhanced gas recovery using a genetic algorithm

The aim of CO2 enhanced gas recovery (CO2-EGR) is to extract more natural gas from depleted gas reservoirs and simultaneously sequestrate large amount of CO2. To achieve these dual objectives, the optimization of CO2 injection strategy in CO2-EGR is proposed to achieve maximum benefit. Thus, the focus of this work is to study CO2-EGR by numerical simulation and optimization. For this purpose, a 3D reservoir model with ‘five-spot’ well pattern (an injection well and four production wells) is established for simulations using the multiphase simulator TOUGH2, and the main focus is on optimization of CO2 injection rate and well placements by coupling the genetic algorithm (GA) with TOUGH2. Simulations are performed to determine the optimal injection rate for both two types of injection wells placements, one vertical injection well with number of perforations at various depth and orthogonal horizontal wells on top of the reservoir. The results show that multipoint perforations in the vertical injection well and the horizontal injection wells with appropriate length show improvement in natural gas recovery and CO2 storage compared to the injection location at the reservoir bottom. More importantly, the optimized injection rate determined by GA-TOUGH2 can substantially improve the natural gas recovery factor for both vertical and horizontal well injection. After computing a number of optimized cases, it’s shown that the case employing the horizontal injection wells with optimized injection rate of 0.0778 kg/s achieves the maximum recovery of 67.21% and maximum CO2 storage efficiency of 69.54%, equal to 23.88 × 106 kg of natural gas exploited from the depleted reservoir and 74.52 × 106 kg of CO2 stored in pore volume of 1.81 × 106 m3 of the reservoir. This case also has minimum injection pressure jump of 0.08 MPa thereby reducing the risk of formation fracture and CO2 leakage. However, by conducting a simple cost/benefit analysis, it is determined that this optimally performing case is not the best economically because of higher drilling cost of horizontal well compared to a vertical well. It is found that a vertical well with two suitably placed perforations with optimized injection rate of 0.1025 kg/s is economically superior since the previously used production wells can be reused for CO2 injection, which can therefore reduce both the equipment and the drilling costs. It is hoped that the findings of this work should provide some insights into the optimization of CO2-EGR with maximum economic benefit for implementation in industrial practice.

Configuration analysis of the injection position and shape of the gel spacer in gynecologic brachytherapy

PurposeIn this single-institution retrospective study, configuration analysis was performed to determine the optimal location and volume of hyaluronic acid gel spacer injection into the rectovaginal or vesicovaginal septum for effective dose reduction (DR) to the organs at risk (OARs), the rectum and bladder. Methods and materials70 and 50 intracavitary brachytherapy treatment plans used only vaginal cylinders with gel spacers for the rectal and bladder sides, respectively, whereas 28 did not use spacers. Correlation analysis was performed between the geometrical parameters and injection position of the gel spacers and the 2-cm3 covering doses of the OARs for each treatment. ResultsA higher DR was predicted for hyaluronic acid gel spacer injection within ±5 mm and ±2.5 mm in the lateral-medial direction from the midpoint on the rectal and bladder sides, and ±10 mm in the cranial–caudal direction from the midpoint on the rectal side. There were correlations between 2-cm3 covering doses and the gel spacer parameters: the volume on the rectal (p = 0.02) and bladder (p = 0.04) sides; the craniocaudal length on the rectal side (p << 0.05); and ventrodorsad thickness on each OAR (p << 0.05) sides. There was no significant difference in the DR between a volume of ∼10 cm3 and that of a higher volume (p >> 0.05). ConclusionsA gel spacer volume of ∼10 cm3 provides sufficient OAR DR if its gravity point is on the midpoint between the cylinder applicator and OAR, and its craniocaudal length covers the active length of the cylinder applicator.

Postintravitreal Injection Endophthalmitis: An Infection Control Investigation and Case–Control Analysis of Risk Factors

Background: Intravitreal injection of vascular endothelial growth factor inhibitors with or without steroids is a well-established, effective therapy for several ocular disorders. The expected rate of complications from these injections is low, with meta-analyses reporting 5–6 occurrences of infectious endophthalmitis per 10,000 injections. Through October 2019, our health system observed 8 cases of endophthalmitis among 7,693 injections (10.4 per 10,000 injections), compared to 1 case in 2018. This unusually high rate prompted an infection control investigation and a case control study to examine risk factors for the development of postintravitreal injection endophthalmitis. Methods: Infection control providers performed direct observation of several ophthalmologists performing intravitreal injections on 3 separate occasions to determine points of intervention to prevent infection. To define risk factors for postintravitreal injection endophthalmitis, we conducted a retrospective case-control study of the 8 affected patients. Four control patients were selected per case, matched by clinic location, drug injected, and date of injection (total subjects, N = 40). We extracted patient-level risk factors from medical records; documentation was not sufficient to compare procedure-level factors. We conducted unadjusted univariate Poisson regression and Mantel–Cox method rate ratios to identify significant risk predictors of endophthalmitis. Results: Direct observation yielded variable practice in use of masks, gloves, sterile lid speculum, and the duration of povidone-iodine contact on the ocular surface prior to injection. The location of alcohol hand gel relative to the procedure field was suboptimal. Due to patient volume, there were significant delays between procedure and patient prep and injection time. The mean age was 76 years among cases and 74.1 years among controls; 35% of patients were men. Age-related macular degeneration was the most common indication for injection (55%). Only 10% of injections were bilateral. Although not statistically significant, patients with coronary artery disease had a higher rate of infection than those without coronary artery disease (165.3 vs 16.3 per 10,000 person years; IRR = 3.0; 95% CI, 0.60–14.8; P = .18); current smokers were also at higher risk (86.9 per 10,000; IRR, 3.2; 95% CI, 0.33–30.4; P = .32). Conclusions: Coronary artery disease and smoking were risk factors for the development of postintravitreal injection endophthalmitis in a 2019 cluster of cases in our organization. We are continuing to work with our ophthalmologists to optimize infection prevention in the injection environment, including strict use of gloves, appropriate use of povidone-iodine, and routinely wearing a mask and encouraging a no-talking policy during injections.Funding: NoneDisclosures: None

Multiscale Computational Fluid Dynamics Modeling for Personalized Liver Cancer Radioembolization Dosimetry.

Yttrium-90 (90Y) radioembolization is a minimally invasive procedure increasingly used for advanced liver cancer treatment. In this method, radioactive microspheres are injected into the hepatic arterial bloodstream to target, irradiate, and kill cancer cells. Accurate and precise treatment planning can lead to more efficient and safer treatment by delivering a higher radiation dose to the tumor while minimizing the exposure of the surrounding liver parenchyma. Treatment planning primarily relies on the estimated radiation dose delivered to tissue. However, current methods used to estimate the dose are based on simplified assumptions that make the dosimetry results unreliable. In this work, we present a computational model to predict the radiation dose from the 90Y activity in different liver segments to provide a more realistic and personalized dosimetry. Computational fluid dynamics (CFD) simulations were performed in a 3D hepatic arterial tree model segmented from cone-beam CT angiographic data obtained from a patient with hepatocellular carcinoma (HCC). The microsphere trajectories were predicted from the velocity field. 90Y dose distribution was then calculated from the volumetric distribution of the microspheres. Two injection locations were considered for the microsphere administration, a lobar and a selective injection. Results showed that 22% and 82% of the microspheres were delivered to the tumor, after each injection, respectively, and the combination of both injections ultimately delivered 49% of the total administered 90Y microspheres to the tumor. Results also illustrated the nonhomogeneous distribution of microspheres between liver segments, indicating the importance of developing patient-specific dosimetry methods for effective radioembolization treatment.

New interactive agent based reinforcement learning approach towards smart generator bidding in electricity market with micro grid integration

In order to suit the needs of the dynamically changing electricity market, software developers have developed various tools taking in to account the need of artificial intelligence for the electricity market entities. Algorithms in artificial intelligence are often divided into either supervised, unsupervised and reinforcement learning approach. A reinforcement learning when compared to supervised and unsupervised learning makes use of agent to learn from interaction with an environment and receives rewards based on the action it takes. It either exploits or explores in finding a solution. In the deregulated power market, the GenCos are modeled as agent by which the GenCo learns the market environment as agent and explores to get profited The Multi-agent based simulation is an effective method to incorporate this sort of intelligence and for providing efficient communication among the market entities. Using Multi-agent system, the problem existing in electricity market can be reduced since each entity problem can be solved by an individual agent. Multi-agent based reinforcement learning algorithm is used to handle the electricity market data. Here an agent based computational framework named Agent Based Modeling of Electricity Systems (AMES) under Java platform is developed for the design of electricity market. Market Agents balances the supply and demand through Market Clearing Price (no congestion) and Locational Marginal Price (congestion management) by performing optimal power flow. The agent also maximizes the profit of the Generator Companies (GenCo’s) through new learning strategy proposed using Variant Roth–Erev (VRE) interactive reinforcement learning method towards smart bidding among GenCo’s. The congestion relieving action in the transmission line and its effects on GenCo learning is discussed in this paper. The analysis is carried out on the electricity whole sale market functioning on a day-ahead basis developed by means of location and timing of injection of power. IEEE-3 bus system and IEEE-30 bus system with microgrid considered as non-dispatchable load is considered using agent based analysis. This technique helps the GenCo’s to attain possible high net earnings even with microgrid integration thus helps to relieve the congestion in the transmission lines.