Phantom-based evaluations of two binning algorithms for four-dimensional CT reconstruction in lung cancer radiation therapy

Objective: The purpose of this study was to evaluate the performance of the phase-binning algorithm and amplitude-binning algorithm for four-dimensional computed tomography(4DCT) reconstruction in lung cancer radiation therapy. Methods: Quasar phantom data were used for evaluation. A phantom of known geometry was mounted on a four-dimensional(4D) motion platform programmed with twelve respiratory waves(twelve lung patients trajectories) and scanned with a Philips Brilliance Big bore 16-slice CT simulator. The 4DCT images were reconstructed using both phase- and amplitude-binning algorithms. Internal target volumes(ITVs) of the phase- and amplitude-binned image sets were compared by evaluation of shape and volume distortions. Results: The phantom experiments illustrated that, as expected, maximum inhalation occurred at the 0% amplitude and maximum exhalation occurred at the 50% amplitude of the amplitude-binned 4DCT image sets. The amplitude-binned algorithm rendered smaller ITV than the phase-binning algorithm. Conclusion: The amplitude-binning algorithm for 4DCT reconstruction may have a potential advantage in reducing the margin and protecting normal lung tissue from unnecessary irradiation.

基于CT影像儿童枢椎正常发育与变异的解剖特征

背景:枢椎发育演变过程复杂,研究报道较少。CT成像可以显示枢椎的正常发育过程、解剖结构、发育变异与畸形,明确枢椎骨化中心出现与骺板闭合时间及其演变过程和规律具有重要的临床价值。目的:基于CT影像展示儿童枢椎正常发育与变异的解剖结构。方法:回顾性分析2016年6月至2019年11月行颈部扫描的732例0-15岁儿童CT图像。观察指标包括枢椎齿状突、双侧椎弓、椎体骨化中心,齿突尖部二次骨化中心,椎弓、齿突基底部及后正中骺板,以及枢椎发育变异或畸形。分析与比较各项指标在不同年龄下的变化情况,并利用SPSS 17.0统计学软件包进行数据分类处理及统计学分析。结果与结论:(1)732例研究对象包括枢椎正常发育718例(98.1%),畸形或发育异常14例(1.9%);(2)枢椎5个骨化中心,其中双侧椎弓及齿突、椎体骨化中心在出生时已出现;齿突尖部二次骨化中心出现的中位年龄是5.7岁,年龄四分位差(IQR)是4.1-7岁,最早出现的为8个月22 d,最迟未出现的为12岁10个月;(3)齿突尖骺板融合的中位年龄是6岁,IQR是5-8岁,未融合最大年龄是8岁9个月,融合的最小年龄是4岁3个月;(4)双侧椎弓骺板闭合的中位年龄约3.8岁,IQR约2.9-4.6岁,闭合的最小年龄是2岁3个月,未闭合的最大年龄是6岁;(5)齿突基底部骺板闭合的中位数5.2岁,IQR为3.5-6.8岁,闭合最小年龄是2岁6个月,最晚未闭合年龄是9岁6个月;(6)后正中骺板闭合年龄中位数为1.5岁,IQR为1.0-2.1岁,最晚未闭合2例分别为2岁5个月、14岁,最早闭合为6个月20 d;(7)枢椎畸形或发育异常,包括出现副骨化中心及副骺板7例、枢椎游离骨化小骨3例、后正中骺板不闭合2例、无齿突尖部二次骨化中心2例及枢椎齿突骨化中心未出现1例;(8)提示多层螺旋CT扫描、结合多平面重组技术可以完整显示枢椎的解剖结构,评估其正常发育变异及畸形。

Testing a Four-Dimensional Variational Data Assimilation Method Using an Improved Intermediate Coupled Model for ENSO Analysis and Prediction

A four-dimensional variational （4D-Var） data assimilation method is implemented in an improved intermediate coupled model （ICM） of the tropical Pacific. A twin experiment is designed to evaluate the impact of the 4D-Var data assimilation algorithm on ENSO analysis and prediction based on the ICM. The model error is assumed to arise only from the parameter uncertainty. The ＂observation＂ of the SST anomaly, which is sampled from a ＂truth＂ model simulation that takes default parameter values and has Gaussian noise added, is directly assimilated into the assimilation model with its parameters set erroneously. Results show that 4D-Var effectively reduces the error of ENSO analysis and therefore improves the prediction skill of ENSO events compared with the non-assimilation case. These results provide a promising way for the ICM to achieve better real-time ENSO prediction.

CT衍生的血流储备分数对梗阻性冠状动脉疾病患者主要不良心血管事件的预测价值研究

背景目前,血流储备分数(FFR)是评估冠状动脉血流的功能和生理学的金标准,与之相比,CT衍生的血流储备分数(CT-FFR)反映冠状动脉病变处血流动力学改变,以及在区分病变特异性缺血方面,均有较高的诊断性能和鉴别能力。目的评价CT-FFR对冠状动脉梗阻性稳定性胸痛患者发生MACE的预测价值。方法本研究纳入2017年1月—2021年6月在宁夏医科大学总医院因稳定性胸痛行冠状动脉CT血管造影(CCTA)检查的患者116例为研究对象,中位随访时间2(0,25)个月。按照随访期内是否发生主要不良心血管事件(MACE)将研究对象分为MACE组(55例)和非MACE组(61例)。比较两组间冠状动脉管腔狭窄程度和CT-FFR之间差异性;再分别根据狭窄程度及CT-FFR中位数将患者分类,比较不同分类患者MACE总发生率和随访<3个月、3~6个月、>6个月MACE的发生率。采用Spearman秩相关分析探讨冠状动脉管腔狭窄程度与CT-FFR之间的相关性;采用多因素Logistic回归分析探讨患者发生MACE的影响因素;绘制狭窄程度、CT-FFR及二者结合后预测冠状动脉梗阻性稳定性胸痛患者发生MACE的受试者工作特征(ROC)曲线,并依据ROC曲线下面积(AUC)比较不同指标的预测性能。结果116例患者冠状动脉管腔狭窄程度中位数为70%(60%,80%),中位CT-FFR为0.79(0.74,0.85)。MACE组患者冠状动脉管腔狭窄程度高于非MACE组(Z=-4.41,P<0.001),CT-FFR低于非MACE组(Z=-5.54,P<0.001)。冠状动脉管腔狭窄程度70%~90%患者MACE发生率高于50%~69%患者(χ^(2)=19.221,P<0.001);CTFFR≤0.8患者MACE发生率高于CT-FFR>0.8患者(χ^(2)=30.025,P<0.001);不同冠状动脉管腔狭窄程度联合不同CT-FFR患者MACE发生率比较,差异有统计学意义(χ^(2)=37.789,P<0.001)。冠状动脉管腔狭窄程度70%~90%患者随访时间<3个月MACE发生率高于50%~69%患者,CT-FFR≤0.8患者随访时间<3个月MACE发生率高于CT-FFR>0.8患者,狭窄程度70%~90%+CT-FFR≤0.8的患者随访时间<3个月MACE发生率高于其他分类(P<0.05)。Spearman秩相关分析结果显示,冠状动脉管腔狭窄程度与CT-FFR呈负相关(rs=-0.5326,P<0.001)。多因素Logistic回归分析结果显示,冠状动脉管腔狭窄程度70%~90%(OR=3.085,95%CI=1.147~8.298,P=0.026)、CT-FFR≤0.8(OR=6.527,95%CI=2.560~16.641,P<0.001)是患者发生MACE的危险因素。冠状动脉管腔狭窄程度联合CT-FFR预测患者发生MACE的价值更高(AUC=0.812,95%CI=0.731~0.892,P<0.001)。结论冠状动脉管腔狭窄程度70%~90%、CT-FFR≤0.8可能是患者发生MACE的危险因素。与狭窄程度相比,CT-FFR对预测冠状动脉阻塞性稳定性胸痛患者发生MACE具有增益价值,狭窄程度与CT-FFR结合后的预测性能更佳。

Real-Time Four-Dimensional Trajectory Generation Based on Gain-Scheduling Control and a High-Fidelity Aircraft Model

Aircraft ground movement plays a key role in improving airport efficiency,as it acts as a link to all other ground operations.Finding novel approaches to coordinate the movements of a fleet of aircraft at an airport in order to improve system resilience to disruptions with increasing autonomy is at the center of many key studies for airport airside operations.Moreover,autonomous taxiing is envisioned as a key component in future digitalized airports.However,state-of-the-art routing and scheduling algorithms for airport ground movements do not consider high-fidelity aircraft models at both the proactive and reactive planning phases.The majority of such algorithms do not actively seek to optimize fuel efficiency and reduce harmful greenhouse gas emissions.This paper proposes a new approach for generating efficient four-dimensional trajectories(4DTs)on the basis of a high-fidelity aircraft model and gainscheduling control strategy.Working in conjunction with a routing and scheduling algorithm that determines the taxi route,waypoints,and time deadlines,the proposed approach generates fuel-efficient 4DTs in real time,while respecting operational constraints.The proposed approach can be used in two contexts:①as a reactive decision support tool to generate new trajectories that can resolve unprecedented events;and②as an autopilot system for both partial and fully autonomous taxiing.The proposed methodology is realistic and simple to implement.Moreover,simulation studies show that the proposed approach is capable of providing an up to 11%reduction in the fuel consumed during the taxiing of a large Boeing 747-100 jumbo jet.

Density of excess modes below the first phonon mode in four-dimensional glasses

Glasses are known to possess low-frequency excess modes beyond the Debye prediction.For decades,it has been assumed that evolution of low-frequency density of excess modes D(ω) with frequency ω follows a power-law scaling:D(ω)~ω~γ.However,it remains debated on the value of γ at low frequencies below the first phonon-like mode in finitesize glasses.Early simulation studies reported γ=4 at low frequencies in two-(2D),three-(3D),and four-dimensional(4D)glasses,whereas recent observations in 2D and 3D glasses suggested γ=3.5 in a lower-frequency regime.It is uncertain whether the low-frequency scaling of D(ω)~ω^(3.5) could be generalized to 4D glasses.Here,we conduct numerical simulation studies of excess modes at frequencies below the first phonon-like mode in 4D model glasses.It is found that the system size dependence of D(ω) below the first phonon-like mode varies with spatial dimensions:D(ω) increases in2D glasses but decreases in 3D and 4D glasses as the system size increases.Furthermore,we demonstrate that the ω^(3.5)scaling,rather than the ω~4 scaling,works in the lowest-frequency regime accessed in 4D glasses,regardless of interaction potentials and system sizes examined.Therefore,our findings in 4D glasses,combined with previous results in 2D and 3D glasses,suggest a common low-frequency scaling of D(ω)~ ω^3.5) below the first phonon-like mode across different spatial dimensions,which would inspire further theoretical studies.

Generating one-,two-,three-and four-scroll attractors from a novel four-dimensional smooth autonomous chaotic system

A new four-dimensional quadratic smooth autonomous chaotic system is presented in this paper, which can exhibit periodic orbit and chaos under the conditions on the system parameters. Importantly, the system can generate one-, two-, three- and four-scroll chaotic attractors with appropriate choices of parameters. Interestingly, all the attractors are generated only by changing a single parameter. The dynamic analysis approach in the paper involves time series, phase portraits, Poincare maps, a bifurcation diagram, and Lyapunov exponents, to investigate some basic dynamical behaviours of the proposed four-dimensional system.

Evaluation of mitral chordae tendineae length using four-dimensional computed

BACKGROUND Mitral valvuloplasty using artificial chordae tendineae represents an effective surgical approach for treating mitral regurgitation.Achieving precise measurements of artificial chordae tendineae length(CL)is an important factor in the procedure;however,no objective index currently exists to facilitate this measurement.Therefore,preoperative assessment of CL is critical for surgical planning and support.Four-dimensional x-ray micro-computed tomography(4D-CT)may be useful for accurate CL measurement considering that it allows for dynamic three-dimensional(3D)evaluation compared to that with transthoracic echocardiography,a conventional inspection method.AIM To investigate the behavior and length of mitral chordae tendineae during systole using 4D-CT.METHODS Eleven adults aged>70 years without mitral valve disease were evaluated.A 64-slice CT scanner was used to capture 20 phases in the cardiac cycle in electrocardiographic synchronization.The length of the primary chordae tendineae was measured from early systole to early diastole using the 3D image.The primary chordae tendineae originating from the anterior papillary muscle and attached to the A1-2 region and those from the posterior papillary muscle and attached to the A2-3 region were designated as cA and cP,respectively.The behavior and maximum lengths[cA(ma),cP(max)]were compared,and the correlation with body surface area(BSA)was evaluated.RESULTS In all cases,the mitral anterior leaflet chordae tendineae could be measured.In most cases,the cA and cP chordae tendineae could be measured visually.The mean cA(max)and cP(max)were 20.2 mm±1.95 mm and 23.5 mm±4.06 mm,respectively.cP(max)was significantly longer.The correlation coefficients(r)with BSA were 0.60 and 0.78 for cA(max)and cP(max),respectively.Both cA and cP exhibited constant variation in CL during systole,with a maximum 1.16-fold increase in cA and a 1.23-fold increase in cP from early to mid-systole.For cP,CL reached a plateau at 15%and remained elongated until end-systole,whereas for cA,after peaking at 15%,CL shortened slightly and then moved toward its peak again as end-systole approached.CONCLUSION The study suggests that 4D-CT is a valuable tool for accurate measurement of both the length and behavior of chordae tendineae within the anterior leaflet of the mitral valve.

Novel four-dimensional autonomous chaotic system generating one-,two-,three- and four-wing attractors

In this paper, we propose a novel four-dimensional autonomous chaotic system. Of particular interest is that this novel system can generate one-, two, three- and four-wing chaotic attractors with the variation of a single parameter, and the multi-wing type of the chaotic attractors can be displayed in all directions. The system is simple with a large positive Lyapunov exponent and can exhibit some interesting and complicated dynamical behaviours. Basic dynamical properties of the four-dimensional chaotic system, such as equilibrium points, the Poincare map, the bifurcation diagram and the Lyapunov exponents are investigated by using either theoretical analysis or numerical method. Finally, a circuit is designed for the implementation of the multi-wing chaotic attractors. The electronic workbench observations axe in good agreement with the numerical simulation results.

Four-Dimensional Computerized Tomography (4D-CT) Reconstruction Based on the Similarity Measure of Spatial Adjacent Images

Objective:To investigate the feasibility of a 4D-CT reconstruction method based on the similarity principle of spatial adjacent images and mutual information measure. Methods:A motor driven sinusoidal motion platform made in house was used to create one-dimensional periodical motion that was along the longitudinal axis of the CT couch. The amplitude of sinusoidal motion was set to an amplitude of ±1 cm. The period of the motion was adjustable and set to 3.5 s. Phantom objects of two eggs were placed in a Styrofoam block, which in turn were placed on the motion platform. These objects were used to simulate volumes of interest undergoing ideal periodic motion. CT data of static phantom were acquired using a multi-slice general electric (GE) LightSpeed 16-slice CT scanner in an axial mode. And the CT data of periodical motion phantom were acquired in an axial and cine-mode scan. A software program was developed by using VC++ and VTK software tools to resort the CT data and reconstruct the 4D-CT. Then all of the CT data with same phase were sorted by the program into the same series based on the similarity principle of spatial adjacent images and mutual information measure among them, and 3D reconstruction of different phase CT data were completed by using the software. Results:All of the CT data were sorted accurately into different series based on the similarity principle of spatial adjacent images and mutual information measures among them. Compared with the unsorted CT data, the motion artifacts in the 3D reconstruction of sorted CT data were reduced significantly, and all of the sorted CT series result in a 4D-CT that reflected the characteristic of the periodical motion phantom. Conclusion:Time-resolved 4D-CT reconstruction can be implemented with any general multi-slice CT scanners based on the similarity principle of spatial adjacent images and mutual information measure.The process of the 4D-CT data acquisition and reconstruction were not restricted to the hardware or software of the CT scanner and has the feasibility ,which extensive applicability.

锥形术CT测量分析下颌第一磨牙拟种植区剩余牙槽嵴的骨量

背景:随着口腔领域的发展与进步,口腔种植技术逐渐成为替代传统义齿的主流选择。近年来,多种骨增量技术的成熟以及口腔数字化领域的不断发展,使种植适应证不断扩大,种植手术的成功率也越来越高。但是种植手术前使用锥形术CT对剩余牙槽嵴骨量进行准确测量并且个性化制定合适的种植方案,成为一部分临床医师的难题。目的:采用锥形束CT对下颌第一磨牙拟种植区剩余牙槽嵴骨量进行测量分析,为优化下颌第一磨牙区种植方案的设计提供参考。方法:采用回顾性研究设计,纳入205例下颌第一磨牙缺失患者的锥形术CT影像,测量下颌第一磨牙拟种植区剩余牙槽嵴高度及宽度,并将剩余牙槽嵴形态分为Ⅰ、Ⅱ、Ⅲ、Ⅳ4类(Ⅱ、Ⅲ、Ⅳ类剩余牙槽嵴为骨量不足),统计分析下颌第一磨牙剩余牙槽嵴高度、宽度、形态频数分布,不同性别患者下颌第一磨牙剩余牙槽嵴高度和牙槽嵴顶宽度的差异,剩余牙槽嵴高度与剩余牙槽嵴顶宽度、剩余牙槽嵴底宽度的相关性,年龄与剩余牙槽嵴顶宽度、高度的相关性。结果与结论:①下颌第一磨牙拟种植区剩余牙槽嵴高度平均为(12.14±2.96)mm,其中<12 mm者占43.41%(89/205),下颌第一磨牙拟种植区牙槽嵴顶宽度平均为(6.80±1.65)mm,其中<6 mm者占26.34%(54/205);②男性下颌第一磨牙剩余牙槽嵴高度高于女性,但差异无显著性意义(P>0.05),男性下颌第一磨牙剩余牙槽嵴顶宽度宽于女性,差异有显著性意义(P<0.01);③剩余牙槽嵴高度与剩余牙槽嵴顶宽度和剩余牙槽嵴底宽度呈负相关(P<0.05);年龄与剩余牙槽嵴顶宽度呈正相关(P<0.05),与剩余牙槽嵴高度无明显相关性(P>0.05);④剩余牙槽嵴形态Ⅰ类占58.05%(119/205),Ⅱ类占9.27%(19/205),Ⅲ类占20.49%(42/205),Ⅳ类占12.19%(25/205),其中多数为Ⅲ类剩余牙槽嵴骨量不足,临床医生需要根据剩余牙槽嵴类型个性化设计最佳的种植方案。

The Role of Cultural Compatibility in Effective Management The Application of Cultural Four-dimensional Model in Transnational Corporations

Cross-cultural management is often regarded as a discipline of international management focusing on cultural encounters between the organization and the nation-state, and providing tools to tackle cultural difl＇erences seen as sources of conflict, friction or misunderstanding. Based on Greet Hofstede＇ s Cultural Model, this paper attempts to shed some light on effective corporation management through cultural analysis of the difl＇erences between China and western countries. The paper puts more emphasis on the impact of cultural compatibility on effective corporation man- agement through the case study of China, Japan, Germany and America. The author argues that managers and employ- ees involved in companies with diverse cultural backgrounds should be integrated and developed into a specific local context through interlocking their cultural identifications and the organizational practices.

A Four-Dimensional Variational System for Skillful Operational Prediction of Convective Storms

Forecasting convective storms using NWP models is an important goal and a highly active area of ongoing research. Skillful and reliable NWP of convective storms could allow for severe weather warnings with longer lead times, as opera- tional forecasters begin to incorporate convective-scale fore- casts into severe weather forecast operations （Stensrud et al., 2009, 2013）. This would then provide vulnerable individuals and industries with more time to seek shelter and/or mitigate the impact of severe weather hazards.

Clinical effect of four-dimensional therapy on patients with cervical hypertension

Objective:To research the effect of four-dimensional therapy on the clinical effect (symptoms, blood pressure, and pain degree), the changes of blood rheology and arterial (left vertebral artery (LVA), right vertebral artery (RVA), and basal artery (BA)) hemodynamics (average cerebral blood flow (Vm), resistance index (RI), pulsatility index (PI)) on patients with cervical hypertension. Method: Selecting 120 patients (Department of Orthopaedics, the second Affiliated Hospital to Liaoning University of Chinese Medicine, 2012.6-2018.10) with cervical hypertension, then they were divided into observation group (n=60) and control group (n=60). The control group were given enalapril meleate (amlodipine besylate) +conventional therapy (acupuncture treatment and massage), the observation group were given four-dimensional therapy on the basic of control group, they were treated 3 weeks. The primary endpoints were the changes from baseline to week 3 in the symptoms and function were scored using the Evaluation Scale for Cervical Vertigo, the secondary endpoints were changes from baseline to month 3 in the artery hemodynamics (Vm, RI, and PI) in the BA, LVA, blood rheology, and RVA. At last, assessing the pain degree through visual analog scale (VAS), measuring the blood pressure, and accessing the clinical effect.Results:The score of vertigo in the two groups had no statistical significance before treatment, the score of vertigo in the two groups were higher than pretherapy, and had statistical significance, and the score in the observation group were higher than control group, and had statistical significance. The hemodynamics (Vm, RI, and PI) in the artery (BA, LVA, and RVA) had no statistical significance in the two groups before treatment, and the hemodynamics (Vm) in the artery (BA, LVA, and RVA) were higher than pretherapy, and had statistical significance, the hemodynamics (Vm) in the artery (BA, LVA, and RVA) of observation group were higher than control group, and had statistical significance. The hemodynamics (RI and PI) in the artery (BA, LVA, and RVA) were lower than pretherapy, and had statistical significance, the the hemodynamics (Vm) in the artery (BA, LVA, and RVA) of observation group were lower than control group, and had statistical significance. The blood rheology had no statistical significance in the two groups before treatment, the blood rheology were lower than pretherapy, and had statistical significance, the blood rheology of observation group were lower than control group, and had statistical significance. The degree of VAS had no statistical significance in the two groups before treatment, the degree of VAS was lower than pretherapy, and had statistical significance, the degree of VAS of observation group were lower than control group, and had statistical significance. The blood pressure (systolic pressure and diastolic pressure) had no statistical significance in the two groups before treatment, the blood pressure (systolic pressure and diastolic pressure) were lower than pretherapy, and had statistical significance, the blood pressure (systolic pressure and diastolic pressure) of observation group were lower than control group, and had statistical significance, the clinical effect in the observation group were higher than control group, and had statistical significance.Conclusions:Giving four-dimensional therapy can improve the blood pressure and relieve the pain through improving blood rheology and hemodynamics in the artery in the patients with cervical hypertension.

优化双下肢动脉能谱CT血管造影成像方案

目的优化双下肢动脉能谱CT血管造影(CTA)成像方案。方法回顾性分析30例疑诊双下肢动脉硬化性闭塞症(ASO)患者双下肢动脉能谱CTA资料,经重建获得40~80 keV(间隔5 keV)单能量(共9种)及100 kVp混合能量图像,对比双下肢动脉在不同图像中的CT值、噪声(SD)值、信噪比(SNR)及对比度噪声比(CNR);针对50、60 keV单能量和100 kVp混合能量图像质量及血管节段的可诊断性进行主观评估,观察40、45、50、60 keV单能量和100 kVp混合能量图像的自动去骨能力。结果40~80 keV范围内,随keV升高,各动脉在图像中的CT值、SD值、SNR及CNR均逐渐降低。相比100 kVp,腘动脉(PA)及其近端动脉的CT值、CNR及SNR均在40~55 keV图像中升高(P均<0.05);50~55 keV图像中SD值升高(P均<0.05),而60 keV图像中差异无统计学意义(P>0.05)。50及60 keV图像质量主观评分及可诊断动脉节段数与100 kVp差异均无统计学意义(P均>0.05)。PA以远节段的SNR及CNR在各单能量图像及100 kVp图像中差异均无统计学意义,其CT值在40~45 keV图像中、SD在40 keV图像中均高于100 kVp(P均<0.05),但SD在45 keV与100 kVp图像中差异无统计学意义(P>0.05);50 keV图像中,PA以远节段图像质量主观评分及可诊断节段数均高于60 keV及100 kVp(P均<0.05)。40 keV图像对9例(9/30,30.00%)、45 keV图像对6例(6/30,20.00%)不能自动去骨,50及60 keV、100 kVp对30例(30/30,100%)均可自动去骨。结论行双下肢动脉能谱CTA时,对PA及其近端节段以60 keV单能量成像较佳,对其以远或双下肢全程则以50 keV单能量成像较佳。

基于CT技术的黄原胶加固土干湿循环条件下力学性能和微观结构劣化机制研究

干湿循环对岩土体的工程特性具有重要影响。采用CT扫描技术和力学测试,对加入不同含量黄原胶(0%,0.5%,1.5%)加固的黏土在经历不同次数(0,1,4,8,12次)干湿循环作用下的力学性能和微观结构劣化机制进行了研究,得到结论:(1)黄原胶能够有效提高土体的抗压强度和耐干湿循环效果。随着黄原胶含量的增加,干湿循环作用后的强度损失逐渐减小,当循环次数从0次增加到4次时,对于加入黄原胶含量分别为0%,0.5%,1.5%的试样,抗压强度分别损失了42.75%,17.2%,14.04%。(2)加固土的抗压强度与干湿循环次数之间保持指数下降的关系,当循环次数达到4次后,随着循环次数的进一步增加,抗压强度和弹性模量均在较小的变化范围内波动。(3)随着干湿循环次数的增加,黄原胶加固土的孔隙率表现出先增加后减小的趋势,连通孔隙不断扩展,而孤立孔隙表现出先增加后减小的趋势。(4)随着试样的干燥,黄原胶在土颗粒间形成网状基质,提高土体的强度和耐干湿循环能力。

基于岩石CT扫描的冻融作用对花岗岩细观结构及力学强度影响研究

近年来随着西部地区的基础工程建设数量及规模不断增加,西部高原地区的季节性冻融循环效应的影响也随之增强,开展冻融循环作用下岩石细观特性及强度劣化性质研究对指导西部寒区基础工程建设至关重要。首先在偏光显微镜下对岩石薄片进行观察,获取岩石的矿物成分和微结构;接着利用CT扫描技术,对冻融后的花岗岩进行扫描,对扫描图层利用阈值分割进行二值化处理,堆叠得到样品内外结构的高分辨3D数据及影像;结合分形理论计算图像计盒维数并由此对图像复杂度做出量化判断,由此对冻融循环对花岗岩内部结构演化分布特点进行分析;进而揭示其强度演化规律,探究结构演化与强度之间的关系。偏光显微镜下,岩石呈块状构造,具有似斑状粗粒不等粒花岗结构,局部见交代蠕虫结构。似斑晶矿物主要为碱性长石;其他矿物粒径0.25~4.0 mm为主,矿物成分主要为石英、斜长石、碱性长石,次要矿物为黑云母、绿帘石,副矿物有磷灰石、锆石、黄铁矿等,镜下鉴定为似斑状粗粒不等粒黑云二长花岗岩。CT扫描显示,冻融循环效应在影响花岗岩细观结构时,会导致花岗岩内部孔隙率的整体上升,但岩石渗透性变化不大,岩石渗透率仅上升0.003×10^(-3)μm^(2);内部孔隙发育不均匀,试样整体结构改变以萌生较多新的微孔隙为主。冻融循环后岩石内部结构复杂度有所下降,但岩石整体完整性仍然较好,分形维数仍保持在较高水平。分形研究显示,20次冻融循环并未导致花岗岩的结构复杂度发生较大变化,同时试样整体力学特性出现下降,黏性增加以及长期强度出现较大幅度的衰减,进入蠕变试验阶段的应变阈值提高。在评价此类原生结构较致密的岩石的安全性时,仅从结构上进行考量与实际情况往往会出现偏差,应结合必要的强度指标综合评估。岩石在经历冻融循环后,在强度更低的同时会发生更大的变形。该研究可为分形理论在岩石细观结构演化方面的应用及岩石细观结构与强度演化相关研究提供借鉴,并对高寒地区工程施工有指导意义。

乳腺癌患者腋窝淋巴结转移的危险因素及行X线摄影与CT检查的诊断效能分析

目的:探讨乳腺癌患者腋窝淋巴结转移的危险因素及X线与CT检查的诊断效能比较。方法:选取2021年1月至2023年5月在我院治疗的乳腺癌患者112例,分析发生和未发生腋窝淋巴结转移患者临床资料差异;同时分析X线、CT检查诊断腋窝淋巴结转移的价值。结果:112例患者中,腋窝淋巴结转移患者32例,腋窝淋巴结转移率为28.57%;发生腋窝淋巴结转移患者组织低分化比例、组织类型为浸润性癌比例、有脉管浸润比例、肿瘤直径≥5cm比例、组织Ki-67表达≥14%比例分别为68.75%、90.63%、28.13%、31.25%和84.38%,明显高于未发生腋窝淋巴结转移患者(P<0.05);Logistic回归分析显示:分化程度、病灶组织类型、脉管浸润、Ki-67表达是乳腺癌患者发生腋窝淋巴结转移的影响因素(P<0.05);X线诊断腋窝淋巴结转移与病理结果一致性Kappa值为0.500,P<0.05,一致性较差;CT诊断腋窝淋巴结转移与病理结果一致性Kappa值为0.825,P<0.05,一致性较好;CT诊断腋窝淋巴结转移的准确性、灵敏性和阴性预测值分别为92.86%、87.50%和95.00%,明显高于X线检查(P<0.05)。结论:乳腺癌患者腋窝淋巴结转移受分化程度、病灶组织类型、脉管浸润、Ki-67表达的影响;相较于X线,CT诊断腋窝淋巴结转移的价值较高。

急性颅脑损伤患者CT评分变化及血清乳酸、NSE、CRP的相关性分析

目的探讨急性颅脑损伤(ACI)患者计算机断层扫描(CT)评分变化与血清乳酸(LA)、神经元特异性烯醇化酶(NSE)及C-反应蛋白(CRP)水平的关系及其对预后的预测价值。方法选取2020年1月—2022年1月东台市人民医院收治的50例急性颅脑损伤患者作为疾病组,根据患者治疗后格拉斯哥预后评分(GOS)分为预后良好组(32例)和预后不良组(18例);选取50例行健康体检受试者作为健康组。受试者工作特征曲线(ROC)评估血清乳酸、NSE、CRP水平与CT评分对急性颅脑损伤患者预后的评估价值。结果疾病组血清乳酸、NSE、CRP水平均高于健康组(P<0.05);预后不良组乳酸、NSE、CRP水平和CT评分均高于预后良好组;经Spearman相关分析,急性颅内损伤患者血清中乳酸、NSE、CRP水平与CT评分呈正相关(r=0.431、r=0.345、r=0.226,均P<0.05);ROC曲线分析显示,血清乳酸、NSE、CRP水平、CT评分联合预测急性颅内感染预后的曲线下面积(AUC)高于单一指标检测(P<0.05)。结论急性颅脑损伤患者CT评分与患者入院血清乳酸、NSE、CRP水平呈正相关,联合诊断对患者预后评估有一定价值。

多期CT血管成像对急性缺血性卒中血管内治疗短期预后的价值

目的:探讨多期CT血管成像对急性缺血性卒中(AIS)血管内治疗短期预后的价值。方法:回顾性分析183例接受血管内治疗的AIS患者,按随访90 d改良Rankin量表(mRS)评分分为预后良好(mRS评分≤2)组和预后不良(mRS评分>2)组。通过改良Tan评分评估多期CT血管成像显示的侧支循环情况,侧支循环不良为闭塞大脑中动脉区域的侧支循环小于对侧1/2,侧支循环良好为闭塞大脑中动脉区域的侧支循环大于对侧1/2。采用多变量logistic回归,曲线下面积(AUC)评价模型性能,DeLong检验比较AUC间的差异。结果:Logistic回归显示,较低入院NIHSS评分和动脉晚期侧支循环良好是AIS患者短期预后良好的独立预测因素,AUC分别为0.72(0.65~0.79)和0.75(0.68~0.81)。两者联合时AUC可达0.79,显著高于单一预测因素(DeLong检验,均P<0.05)。结论:动脉晚期侧支循环良好和较低入院NIHSS评分是血管内治疗短期预后良好的独立预测因素。联合预测模型具有较高的诊断效能,可为临床治疗方案选择提供参考。