Interplay Effects Research Articles

A novel and clinically useful weight-optimized dynamic conformal arc in stereotactic radiation therapy of non-small cell lung cancer: Dosimetric comparison of treatment plans with volumetric‐modulated arc therapy

PurposeThis study constitutes a feasibility assessment of dynamic conformal arc (DCA) therapy as an alternative to volumetric‐modulated arc therapy (VMAT) for stereotactic body radiation therapy (SBRT) of lung cancer with the free-breathing technique using four-dimensional computed tomography. MethodsA total of 25 patients who received 50 Gy in four fractions treated using VMAT technique having two partial coplanar arcs with 6 MV beams for non-small cell lung cancer (NSCLC) were included. Plans were re‐planned using a novel and clinically technique of weight optimized based on dynamic conformal Arcs with two coplanar partial dynamic conformal arcs (WO-DCA). For the two partial arcs, MLC aperture around the PTV was automatically generated at different margins for both arcs and maintained dynamically around the target during arc rotation. Weight of the two arcs using optimization method was adjusted between the arcs to maximize tumor coverage and protect organs at risk (OAR). The clinical VMAT and WO-DCA plans were compared via the RTOG-0915 protocol for conformity and dose to the organs at risk (OAR). Additionally, delivery efficiency, quality assurance pass rate, monitor unit and beam treatment time were recorded. ResultsThe mean value of quality assurance (QA) pass rate 98.16 ± 1.27 in WO-DCA and 92.87 ± 1.56 in VMAT. The rate was higher in WO-DCA (p < 0.001 and t = 8.75). The values of beam‐on time (BOT) and monitor units (MU) in the VMAT technique were 4.20 (3.45–4.95) and 3155 (2279–4867) and they were 3.10 (2.85–3.35) and 2167 (1702–2948) in WO-DCA. These values were significantly improved with WO-DCA (p < 0.001 and p < 0.001) ConclusionsAs there is, no beam modulation through the target, WO‐DCA plans could potentially minimize small‐field dosimetry error without MLC interplay effects via respiratory motion and provide similar doses to OAR and the tumor while providing faster treatment delivery by significantly reducing MU and BOT in lung cancer for tumors of appropriate localization. Additionally, providing WO‐DCA eliminate patient‐specific VMAT quality assurance; potentially offering cost‐effective, same day SBRT treatments.

Quantifying the coupled monovalent and divalent ions sorption in dense ion-exchange membranes

As a universal phenomenon in solution-membrane systems, the coupled competitive monovalent and divalent ions sorption significantly impacts the transport process in ion-exchange membranes. Often, the quantitative and qualitative relationships between them are unclear. Here, we present a lattice-based molecular model to capture the interplay effect of ion-pairing and electrostatic interaction on the competitive partitioning process. In particular, we utilize statistical mechanics to formulate how the monovalent and divalent counterions competitively pair with the fixed charge group in the membranes. To this end, the model can quantify (a) the counterions sorption and (b) the coion repulsion within the membranes, which, collectively, allow us to quantify the ion partitioning and the pairing site saturation. To showcase the capability of our model, we compare our results with published experiment data, where we achieve a relatively good agreement between them. We demonstrate that the competitive ion partitioning depends highly upon (i) the entropy change generated by the counterions pairing with the fixed charge group, (ii) the binding energy, and (iii) the osmotic pressure, and (iv) the electrostatic interaction. These different factors can explain the favorable sorption of divalent counterions in the cation-exchange membranes but monovalent counterions in the anion ones, as previously reported. Altogether, our theoretical approach provides an insight into the fundamental understanding of coupled competitive monovalent and divalent ions sorption within the dense ion-exchange membranes, further enhancing the knowledge of the competitive ion partitioning process.

Quantitative PCR Effectively Quantifies Triazole-Susceptible and Triazole-Resistant Aspergillus fumigatus in Mixed Infections.

Increasing resistance to triazole antifungals in Aspergillus fumigatus is worrisome because of the associated high mortality of triazole-resistant A. fumigatus (TRAF) infections. While most studies have focused on single triazole-susceptible (WT) or TRAF infections, reports of TRAF cases developing mixed WT and TRAF infections have been described in several studies. However, the prevalence of mixed infections and their responses to current recommended therapies are unknown and could be inappropriate, leading to poor clinical outcomes. To address the urgent need for tools to diagnose, monitor disease development and therapy efficacies in mixed infection settings where quantification of WT versus TRAF is key, this study developed a novel qPCR assay to differentiate WT and TRAF harboring the cyp51A-TR34/L98H mutation. The proposed assay successfully quantified A. fumigatus and discriminated TRAF-TR34 in vitro and in vivo, which was achieved by increasing the yield of extracted DNA through improved homogenization and specific primers targeting the WT-sequence or TR34-insertion and a TaqMan-probe directed to A. fumigatus. The here-developed qPCR assay overcomes sensitivity issues of methodologies such as CFU counts, providing specific, reproducible, and reliable quantitative information to study and follow up the (interplay and individual) effects of mixed A. fumigatus infections on disease development and treatment responses.

Machine-Specific Delivery Sequence Model of Compact Superconducting Synchrocyclotron Proton Therapy Systems – A Multi-Institutional Investigation

<h3>Purpose/Objective(s)</h3> Proton pencil beam scanning delivery sequence varies among institutions due to the vendor, machine type, and configuration. However, having a reliable model of delivery time and sequence is critical to maximizing throughput when proton beam time is limited. In this study, we used an experimental approach to build a precise beam delivery time (BDT) and sequence prediction model for a new compact superconducting synchrocyclotron proton system (PTC#1) and compare it with a different institution using an older version of the same system (PTC#2). We investigated treatment efficiency and the interplay effect for the treatment of mobile tumors. <h3>Materials/Methods</h3> The machine delivery log files from PTC#1 were retrospectively analyzed to model beam delivery parameters. We compared the PTC#1 delivery sequence with PTC#2's published machine-specific model using the same type of proton system. A total of twenty clinical beams from head neck, lung, breast, and esophagus treatment sites were used for model comparison. Also, we used a single clinical treatment day to compare treatment efficiency. The interplay effect is evaluated and compared based on these two different delivery sequence models. A digital thoracic 4DCT phantom image set with a rigid target in the right lung was used for the study. Different delivery techniques such as standard delivery (N_vol=1) and volumetric repainting delivery (N_vol=2-5) were simulated. <h3>Results</h3> The results showed PTC#1 has a much faster spot scanning speed than PTC#2 thanks to a new generation of scanning magnets. The spot switching time (SSWT) is 0s within 11.3mm in x-direction and 8 mm in y-direction. Compared to PTC#2, the average SSWT reduces by 94.37%±3.82% (50.76s±35.10s) in PTC#1. PTC#1 also demonstrated improved burst switching transmission efficiency, which reduced burst switching time (BST) by 39.84%±3.64% (6.00s±2.21s) on average. The energy layer switching time (ELST) dominates the PTC#1 delivery time instead of SSWT for PTC#2 (Table). The total BDT was reduced by 54.61%±12.12% (53.45s±34.47s) on average. Based on the single day patient mix, it was estimated that 67 min irradiation time could be saved by upgrading the scanning magnets in PTC#2 (10% daily patient treatment throughput improvement). The results also indicated the interplay effect would be reduced as volumetric repainting number increased. The system in PTC#2 had better target coverage and homogeneity than PTC#1 for=1-3. Their target coverage converges at=5. <h3>Conclusion</h3> A precise machine-specific delivery sequence model is highly recommended in the interplay effect evaluation and clinical decision. It provided the first quantitative analysis of the impact of the new scanning magnets regarding the improvement in the treatment delivery efficiency.

Improved NO2 gas sensing performance of 2D MoS2/Ti3C2Tx MXene nanocomposite

In this study, novel MoS2/Ti3C2Tx heterostructures were prepared from Ti3C2Tx MXene via a hydrothermal strategy. The well-bonded interface developed between the MoS2 nanostructure and the conductive Ti3C2Tx MXene played a crucial role in improving the sensing abilities of the prepared heterostructures compared to their pristine counterparts. Owing to the synergistic interplay effect, the optimal MoS2/Ti3C2Tx heterostructure exhibited room-temperature NO2 sensing activity with a rapid response and full recovery at low gas concentrations. To understand the high sensitivity, density functional theory calculations were used to observe stable configurations and adsorption behaviors. The proposed concept may provide an archetype for understanding the sensing characteristics of materials for NO2 detection at room temperatures.

Statistical breathing curve sampling to quantify interplay effects of moving lung tumors in a 4D Monte Carlo dose calculation framework

PurposeThe interplay between respiratory tumor motion and dose application by intensity modulated radiotherapy (IMRT) techniques can potentially lead to undesirable and non-intuitive deviations from the planned dose distribution. We developed a 4D Monte Carlo (MC) dose recalculation framework featuring statistical breathing curve sampling, to precisely simulate the dose distribution for moving target volumes aiming at a comprehensive assessment of interplay effects. MethodsWe implemented a dose accumulation tool that enables dose recalculations of arbitrary breathing curves including the actual breathing curve of the patient. This MC dose recalculation framework is based on linac log-files, facilitating a high temporal resolution up to 0.1 s. By statistical analysis of 128 different breathing curves, interplay susceptibility of different treatment parameters was evaluated for an exemplary patient case. To facilitate prospective clinical application in the treatment planning stage, in which patient breathing curves or linac log-files are not available, we derived a log-file free version with breathing curves generated by a random walk approach. Interplay was quantified by standard deviations σ in D5%, D50% and D95%. ResultsInterplay induced dose deviations for single fractions were observed and evaluated for IMRT and volumetric arc therapy (σD95% up to 1.3 %) showing a decrease with higher fraction doses and an increase with higher MU rates. Interplay effects for conformal treatment techniques were negligible (σ<0.1%). The log-file free version and the random walk generated breathing curves yielded similar results (deviations in σ< 0.1 %) and can be used as substitutes for interplay assessment. ConclusionIt is feasible to combine statistically sampled breathing curves with MC dose calculations. The universality of the presented framework allows comprehensive assessment of interplay effects in retrospective and prospective clinically relevant scenarios.

Cyclotron quantization and mirror-time transition on nonreciprocal lattices

Unidirectional transport and localized cyclotron motion are two opposite physical phenomena. Here, we study the interplay effects between them on nonreciprocal lattices subject to a magnetic field. We show that, in the long-wavelength limit, the trajectories of the wave packets always form closed orbits in four-dimensional (4D) complex space. Therefore, the semiclassical quantization rules persist despite the nonreciprocity, which preserves real Landau levels. We predict a different type of non-Hermitian spectral transition induced by the spontaneous breaking of the combined mirror-time reversal ($\mathcal{MT}$) symmetry, which generally exists in such systems. An order parameter is proposed to describe the $\mathcal{MT}$ phase transition, not only to determine the $\mathcal{MT}$ phase boundary but also to quantify the degree of $\mathcal{MT}$-symmetry breaking. Such an order parameter can be generally applied to all types of non-Hermitian phase transitions.

Synergetic one-step synthesis of SiC/SiOC/TiO2 composites for visible-light-driven hydrogen generation from methanol reforming

The photocatalysts area aims for feasible clean-renewable energy generation, targeting new low-cost and straightforward manufacturing of visible light-responsive materials by developing organic and inorganic novel composites. This work shows a novel approach, exploring three widely used commercially available powders (SiC, SiOC, and TiO2) to build a ternary-component system based on the polymer-derived ceramic (PDC) pathway. Furthermore, the results disclose the phases' interplay and synergetic effects that improve the composites' catalytic activity. The interaction between Si and Ti atoms in the composite system decreases the bandgap from 3.2 eV to 2.89 eV, increasing the ceramic yield from 51% to 86% while hindering the TiO2 anatase-to-rutile transformation. The SiC–SiOC–TiO2 interplay boosts the visible-light-driven hydrogen generation through photoreforming for hydrogen generation up to approximately 5-fold compared to pristine TiO2. In addition, the synthesis reported herein provides a straightforward and practical approach by increasing existing catalysts’ activity toward visible-light-driven hydrogen generation systems and facilitates further filtration processes.

A DFT theoretical investigation on the interplay effects between cation-π and intramolecular hydrogen bond interactions in the mesalazine⋯Fe2+ binary complex

A DFT theoretical investigation on the interplay effects between cation-π and intramolecular hydrogen bond interactions in the mesalazine⋯Fe2+ binary complex

Crashworthiness reinforcements of multi-cell thin-walled tubes through topology optimized lattice structures under axial and lateral loadings

Thin-walled tubes have been predominantly utilized in passive vehicle safety systems as crash energy absorbers. With the increasing popularity of additive manufacturing technique, it is feasible to fabricate novel internal reinforcement structures to further reinforce the crashworthy performances of thin-walled tubes. In the present work, a novel nonuniform Lattice-reinforced multi-cell tube based on topology optimization was put forward to explore the crashworthy performances under axial loading and lateral bending. Numeric models validated against the experiments were established to reveal the crashworthy performances of lattice material infilled multi-cell tubes (MCTs). It is observed that the optimized nonuniform lattice structure absorbs more energy than the uniform counterpart. In addition, the hybrid multi-cell filled tubes exhibit remarkable improvements in terms of energy absorption and crushing force efficiency in contrast to the corresponding empty tubes. Furthermore, the specific energy absorption of the three-layer hybrid multi-cell tube is improved by 38.2% and 20.0% under two loading conditions respectively relative to the sum of individual components on account of interplay effect. Collectively, the hybrid nonuniform lattice reinforcement tube provides a promising method for the crashworthy design of MCTs, which can be recommended as an underlying candidate for passive safety protection applications.

Developing an accurate model of spot-scanning treatment delivery time and sequence for a compact superconducting synchrocyclotron proton therapy system

BackgroundA new compact superconducting synchrocyclotron single-room proton solution delivers pulsed proton beams to each spot through several irradiation bursts calculated by an iterative layer delivery algorithm. Such a mechanism results in a new beam parameter, burst switching time (BST) in the total beam delivery time (BDT) which has never been studied before. In this study, we propose an experimental approach to build an accurate BDT and sequence prediction model for this new proton solution.MethodsTest fields and clinical treatment plans were used to investigate each beam delivery parameter that impacted BDT. The machine delivery log files were retrospectively analyzed to quantitatively model energy layer switching time (ELST), spot switching time (SSWT), spot spill time (SSPT), and BST. A total of 102 clinical IMPT treatment fields’ log files were processed to validate the accuracy of the BDT prediction model in comparison with the result from the current commercial system. Interplay effect is also investigated as a clinical application by comparing this new delivery system model with a conventional cyclotron accelerator model.ResultsThe study finds that BST depends on the amount of data to be transmitted between two sequential radiation bursts, including a machine irradiation log file of the previous burst and a command file to instruct the proton system to deliver the next burst. The 102 clinical treatment fields showed that the accuracy of each component of the BDT matches well between machine log files and BDT prediction model. More specifically, the difference of ELST, SSWT, SSPT, and BST were (− 3.1 ± 5.7)%, (5.9 ± 3.9)%, (2.6 ± 8.7)%, and (− 2.3 ± 5.3)%, respectively. The average total BDT was about (2.1 ± 3.0)% difference compared to the treatment log files, which was significantly improved from the current commercial proton system prediction (58 ± 15)%. Compared to the conventional cyclotron system, the burst technique from synchrocyclotron effectively reduced the interplay effect in mobile tumor treatment.ConclusionAn accurate BDT and sequence prediction model was established for this new clinical compact superconducting synchrocyclotron single-room proton solution. Its application could help users of similar facilities better assess the interplay effect and estimate daily patient treatment throughput.

Effect of plan complexity on the dosimetry, delivery accuracy, and interplay effect in lung VMAT SBRT with 6MV FFF beam.

The purpose of this study is to investigate the effect of plan complexity on the dosimetry, delivery accuracy, and interplay effect in lung stereotactic body radiation therapy (SBRT) using volumetric modulated arc therapy (VMAT) with 6MV flattening-filter-free (FFF) beam. Twenty patients with early stage non-small cell lung cancer were included. For each patient, high-complexity (HC) and low-complexity (LC) three-partial-arc VMAT plans were optimized by adjusting the normal tissue objectives and the maximum monitoring units (MUs) for a Varian TrueBeam linear accelerator (Varian Medical Systems, Palo Alto, CA, USA) using 6MV FFF beam. The effect of plan complexity was comprehensively evaluated in three aspects: (1)The dosimetric parameters, including CI, D2cm, R50, and dose-volume parameters of organs at risk were compared. (2)The delivery accuracy was assessed by pretreatment quality assurance for two groups of plans. (3)The motion-induced dose deviation was evaluated based on point dose measurements near the tumor center by using aprogrammable phantom. The standard deviation (SD) and maximum dose difference of five measurements were used to quantify the interplay effect. The dosimetry of HC and LC plans were similar except the CI (1.003 ± 0.032 and 1.026 ± 0.043, p = 0.030) and Dmax to the spinal cord (10.6 ± 3.2 and 9.9 ± 3.0, p = 0.012). The gamma passing rates were significantly higher in LC plans for all arcs (p < 0.001). The SDs of HC and LC plans ranged from 0.5-16.6% and 0.03-2.9%, respectively, under the conditions of one-field, two-field, and three-field delivery for each plan with 0.5, 1, 2, and 3 cm motion amplitudes. The maximum dose differences of HC and LC plans were 34.5% and 9.1%, respectively. For lung VMAT SBRT, LC plans have ahigher delivery accuracy and alower motion-induced dose deviation with similar dosimetry compared with HC plans.

The interplay of active energy harvesting and wastewater organic loading regulates fermentation products and microbiomes in microbial fuel cells

Fruit juice wastewater (FJW) contains high strength and acidic organics that are difficult to remove. We developed microbial fuel cells (MFCs) to treat FJW and employed new energy harvesting methods to investigate how different operation conditions influence system performance and microbial community assembly. Specifically, we found both energy harvesting regime and organic loading affected current production, organic matter decomposition, product distribution, and microbial community. The power output under maximum power harvesting (MFC-MPP) condition showed the most stable output of 300 mW/m2 under different organic loadings. The MFC reactors maintained good organic removal (82.10–94.65%) at low loading of 1500–3000 mg/L, but the removal decreased with high loadings (7500–15,000 mg/L), presumably due to insufficient retention time, acid accumulation, and reduced degradability. Accordingly, higher VFA concentrations were observed in high loading reactors with the dominant products, formic acid and acetic acid. Electrofermentation coefficients (0.02–23.85%) of MFCs suggested that microaerobic electrofermentation (MEF) occurred in all reactors. MFCs under active harvesting demonstrated lower community diversity of anode biofilms at high organic loadings. The majority of dominant populations in the anode biofilm was affiliated with Lactococcus, Veillonella, and Bacteroides. This work demonstrates active energy harvesting and organic loading had interplay effects on system performance and microbiome, and system operation should consider such impacts to improve performance. AEH also provides a new alternative to a poised potential strategy for electrofermentation controlling.

Bell nonlocality, entanglement, and entropic uncertainty in a Heisenberg model under intrinsic decoherence: DM and KSEA interplay effects

Bell nonlocality, entanglement, and entropic uncertainty in a Heisenberg model under intrinsic decoherence: DM and KSEA interplay effects

The complex interplay of firm innovation, internationalization and learning capability in driving firm performance: a configurational analysis

PurposeThis study examines how the complex interplay of innovation, internationalization and learning capability is associated with firm performance.Design/methodology/approachThis study employs a qualitative comparative analysis (QCA) over a sample of 2,844 manufacturing firms over the period of 2008–2014.FindingsThis study finds a general complementarity between high process innovation, export breadth and high organizational learning capability, and a substitution between R&D and employee training as sources of learning capability. The analyses by firm size suggest that, contrary to SMEs, large firms do not require high export breadth to achieve profitability, which is likely because they enjoy sufficient economies of scale and scope through their strong domestic presence and multiple business units.Research limitations/implicationsThis study examines specific facets of the three constructs, and the effect of firm size. Future research could consider other facets and contextual factors, such as managers' competencies, family firm governance or network memberships, which have potential effects on the relationships studied here.Practical implicationsFirms may benefit from the various interplay effects of strategic factors to improve competitiveness. For example, leveraging the knowledge and resources stemming from their presence in multiple countries may significantly increase the efficiency and efficacy of innovation activities, eventually enhancing firm performance.Originality/valueThis study is the first to employ a large sample to test the complementarity of the three activities in achieving superior profitability. The paper also provides a more nuanced view of these relationships by considering the interplay of different facets of internationalization (export breadth and intensity), innovation (product and process) and learning capability (R&D and employee training).

Menthol Flavor in E-Cigarette Vapor Modulates Social Behavior Correlated With Central and Peripheral Changes of Immunometabolic Signalings.

The use of electronic cigarette (e-cigarette) has been increasing dramatically worldwide. More than 8,000 flavors of e-cigarettes are currently marketed and menthol is one of the most popular flavor additives in the electronic nicotine delivery systems (ENDS). There is a controversy over the roles of e-cigarettes in social behavior, and little is known about the potential impacts of flavorings in the ENDS. In our study, we aimed to investigate the effects of menthol flavor in ENDS on the social behavior of long-term vapor-exposed mice with a daily intake limit, and the underlying immunometabolic changes in the central and peripheral systems. We found that the addition of menthol flavor in nicotine vapor enhanced the social activity compared with the nicotine alone. The dramatically reduced activation of cellular energy measured by adenosine 5′ monophosphate-activated protein kinase (AMPK) signaling in the hippocampus were observed after the chronic exposure of menthol-flavored ENDS. Multiple sera cytokines including C5, TIMP-1, and CXCL13 were decreased accordingly as per their peripheral immunometabolic responses to menthol flavor in the nicotine vapor. The serum level of C5 was positively correlated with the alteration activity of the AMPK-ERK signaling in the hippocampus. Our current findings provide evidence for the enhancement of menthol flavor in ENDS on social functioning, which is correlated with the central and peripheral immunometabolic disruptions; this raises the vigilance of the cautious addition of various flavorings in e-cigarettes and the urgency of further investigations on the complex interplay and health effects of flavoring additives with nicotine in e-cigarettes.

Dosimetric effect of respiratory motion on planned dose in whole-breast volumetric modulated arc therapy using moderate and ultra-hypofractionation

Background and purposeThe interplay effect of respiratory motion on the planned dose in free-breathing right-sided whole-breast irradiation (WBI) were studied by simulating hypofractionated VMAT treatment courses.Materials and methodsTen patients with phase-triggered 4D-CT images were included in the study. VMAT plans targeting the right breast were created retrospectively with moderately hypofractionated (40.05 Gy in 15 fractions of 2.67 Gy) and ultra-hypofractionated (26 Gy 5 fractions of 5.2 Gy) schemes. 3D-CRT plans were generated as a reference. All plans were divided into respiratory phase-specific plans and calculated in the corresponding phase images. Fraction-specific dose was formed by deforming and summing the phase-specific doses in the planning image for each fraction. The fraction-specific dose distributions were deformed and superimposed onto the planning image, forming the course-specific respiratory motion perturbed dose distribution. Planned and respiratory motion perturbed doses were compared and changes due to respiratory motion and choice of fractionation were evaluated.ResultsThe respiratory motion perturbed PTV coverage (V95%) decreased by 1.7% and the homogeneity index increased by 0.02 for VMAT techniques, compared to the planned values. Highest decrease in CTV coverage was 0.7%. The largest dose differences were located in the areas of steep dose gradients parallel to respiratory motion. The largest difference in DVH parameters between fractionation schemes was 0.4% of the prescribed dose. Clinically relevant changes to the doses of organs at risk were not observed. One patient was excluded from the analysis due to large respiratory amplitude.ConclusionRespiratory motion of less than 5 mm in magnitude did not result in clinically significant changes in the planned free-breathing WBI dose. The 5 mm margins were sufficient to account for the respiratory motion in terms of CTV dose homogeneity and coverage for VMAT techniques. Steep dose gradients near the PTV edges might decrease the CTV coverage. No clinical significance was found due to the choice of fractionation.

The role of origin products and networking on agritourism performance: The case of Tuscany

Recently agritourism has been strongly argued as a tool for rural development and investigating determinants that boost its performance is of paramount importance for policy design. This study examined the impact on agritourism performance of origin products (i.e. products whose specific quality is essentially attributable to geographical origin) and of participation in networks.Quantitative data from a sample of 292 agritourism farms in Tuscany, Italy, together with qualitative information gathered from personal interviews, are considered. To analyse quantitative data, the structural equation modeling methodology is implemented.The core contribution of this study is an empirical examination of the interplay effects of origin products, networking and agritourism performance. The expected positive effects of origin products on agritourism performance are significantly supported by our analysis. Results highlight that those agritourism farms that participates in networks will experience a positive performance. Networking mediates the relationship between origin products and performance. Research and policy implications from these findings are discussed.

Quantum fluctuations on top of a PT -symmetric Bose-Einstein condensate

We investigate the effects of quantum fluctuations in a parity-time($\mathcal{PT}$) symmetric two-species Bose-Einstein Condensate(BEC). It is found that the $\mathcal{PT}$-symmetry, though preserved by the macroscopic condensate, can be spontaneously broken by its Bogoliubov quasi-particles under quantum fluctuations. The associated $\mathcal{PT}$-breaking transitions in the Bogoliubov spectrum can be conveniently tuned by the interaction anisotropy in spin channels and the strength of $\mathcal{PT}$ potential. In the $\mathcal{PT}$-unbroken regime, the real Bogoliubov modes are generally gapped, in contrast to the gapless phonon mode in Hermitian case. Moreover, the presence of $\mathcal{PT}$ potential is found to enhance the mean-field collapse and thereby intrigue the droplet formation after incorporating the repulsive force from quantum fluctuations. These remarkable interplay effects of $\mathcal{PT}$-symmetry and interaction can be directly probed in cold atoms experiments, which shed light on related quantum phenomena in general $\mathcal{PT}$-symmetric systems.

Small spot size versus large spot size: Effect on plan quality for lung cancer in pencil beam scanning proton therapy.

PurposeThe purpose of the current study was to evaluate the impact of spot size on the interplay effect, plan robustness, and dose to the organs at risk for lung cancer plans in pencil beam scanning (PBS) proton therapyMethodsThe current retrospective study included 13 lung cancer patients. For each patient, small spot (∼3 mm) plans and large spot (∼8 mm) plans were generated. The Monte Carlo algorithm was used for both robust plan optimization and final dose calculations. Each plan was normalized, such that 99% of the clinical target volume (CTV) received 99% of the prescription dose. Interplay effect was evaluated for treatment delivery starting in two different breathing phases (T0 and T50). Plan robustness was investigated for 12 perturbed scenarios, which combined the isocenter shift and range uncertainty. The nominal and worst‐case scenario (WCS) results were recorded for each treatment plan. Equivalent uniform dose (EUD) and normal tissue complication probability (NTCP) were evaluated for the total lung, heart, and esophagus.ResultsIn comparison to large spot plans, the WCS values of small spot plans at CTV D95%, D96%, D97%, D98%, and D99% were higher with the average differences of 2.2% (range, 0.3%–3.7%), 2.3% (range, 0.5%–4.0%), 2.6% (range, 0.6%–4.4%), 2.7% (range, 0.9%–5.2%), and 2.7% (range, 0.3%–6.0%), respectively. The nominal and WCS mean dose and EUD for the esophagus, heart, and total lung were higher in large spot plans. The difference in NTCP between large spot and small spot plans was up to 1.9% for the total lung, up to 0.3% for the heart, and up to 32.8% for the esophagus. For robustness acceptance criteria of CTV D95% ≥ 98% of the prescription dose, seven small spot plans had all 12 perturbed scenarios meeting the criteria, whereas, for 13 large spot plans, there were ≥2 scenarios failing to meet the criteria. Interplay results showed that, on average, the target coverage in large spot plans was higher by 1.5% and 0.4% in non‐volumetric and volumetric repainting plans, respectively.ConclusionFor robustly optimized PBS lung cancer plans in our study, a small spot machine resulted in a more robust CTV against the setup and range errors when compared to a large spot machine. In the absence of volumetric repainting, large spot PBS lung plans were more robust against the interplay effect. The use of a volumetric repainting technique in both small and large spot PBS lung plans led to comparable interplay target coverage.