Heterogeneity induced strain localization in block-in-matrix-soils subjected to uniaxial loading using real-time CT scanning

Block-in-matrix-soils(bimsoils)are geological mixtures that have distinct structures consisting of relatively strong rock blocks and weak matrix soils.It is still a challenge to evaluate the mechanical behaviors of bimsoils because of the heterogeneity,chaotic structure,and lithological variability.As a result,only very limited laboratory studies have been reported on the evolution of their internal deformation.In this study,the deformation evolution of bimsoils under uniaxial loading is investigated using real-time X-ray computed tomography(CT)and image correlation algorithm(with a rock block percentage(RBP)of 40%).Three parameters,i.e.heterogeneity coefficient(K),correlation coefficient(CC),and standard deviation(STD)of displacement fields,are proposed to quantify the heterogeneity of the motion of the rock blocks and the progressive deformation of the bimsoils.Experimental results show that the rock blocks in bimsoils are prone to forming clusters with increasing loading,and the sliding surface goes around only one side of a cluster.Based on the movement of the rock blocks recorded by STD and CC,the progressive deformation of the bimsoils is quantitatively divided into three stages:initialization of the rotation of rock blocks,formation of rock block clusters,and formation of a shear band by rock blocks with significant rotation.Moreover,the experimental results demonstrate that the meso-motion of rock blocks controls the macroscopic mechanical properties of the samples.

Real-time Quantitative RT-PCR for CT9 Level in Human Cancer

CT9 is a recently cloned cancer-testis antigen, which is a member of the bromodomain and extraterminal family. Each member of this protein family contains two N-terminal bromodomain motifs. We investigated the distribution of CT9 in different tissues and the possibility for it to be used as a potential therapeutic target in cancer treament. By using the real-time RT-PCR method and 18SrRNA as an internal standard, we analyzed the CT9 expression in several normal human tissues and in the tissues of patients suffering from cancer. The result of this study shows that the highest level of mRNA is only present in testis tissue because the CT9 expression has not been detected in other normal tissues. In 6 of 10 cases of gastric adenocarcinoma, in 3 of 10 cases of esophageal squamous cell carcinoma, in 2 of 9 cases of endometrial carcinoma and only in 1 of 12 cases of brain cancer, the low level expression of CT9 was detected. In none of the 12 cases of cervical squamous cell carcinoma, the expression of CT9 was detected. Since the high level expression of CT9 is only found in the normal testis tissue, but the low expression in cancer tissues, for example tissues of cervical squamous cell carcinoma, brain cancer, endometfial adenocarcinoma, esophageal squamous cell carcinoma, we conclude that CT9 cannot be used as a cancer therapeutic target molecule for cervical squamous cell carcinoma, brain cancer, endometrial adenocarcinoma, esophageal squamous cell carcinoma.

Static superconducting gantry‑based proton CT combined with X‑ray CT as prior image for FLASH proton therapy

Proton FLASH therapy with an ultra-high dose rate is in urgent need of more accurate treatment plan system(TPS)to promote the development of proton computed tomography(CT)without intrinsic error compared with the transformation from X-ray CT.This paper presents an imaging mode of proton CT based on static superconducting gantry different from the conventional rotational gantry.The beam energy for proton CT is fixed at 350 MeV,which is boosted by a compact proton linac from 230 MeV,and then delivered by the gantry to scan the patient’s body for proton imaging.This study demonstrates that the static superconducting gantry-based proton CT is effective in clinical applications.In particular,the imaging mode,which combines the relative stopping power(RSP)map from X-ray CT as prior knowledge,can produce much a higher accuracy RSP map for TPSs and positioning and achieve ultra-fast image for real-time image-guided radiotherapy.This paper presents the conceptual design of a boosting linac,static superconducting gantry and proton CT imaging equipment.The feasibility of energy enhancement is verified by simulation,and results from Geant4 simulations and reconstruction algorithms are presented,including the simulation verification of the advantage of the imaging mode.

A new imaging mode based on X-ray CT as prior image and sparsely sampled projections for rapid clinical proton CT

Proton computed tomography(CT)has a distinct practical significance in clinical applications.It eliminates 3–5%errors caused by the transformation of Hounsfield unit(HU)to relative stopping power(RSP)values when using X-ray CT for positioning and treatment planning systems(TPSs).Following the development of FLASH proton therapy,there are increased requirements for accurate and rapid positioning in TPSs.Thus,a new rapid proton CT imaging mode is proposed based on sparsely sampled projections.The proton beam was boosted to 350 MeV by a compact proton linear accelerator(LINAC).In this study,the comparisons of the proton scattering with the energy of 350 MeV and 230 MeV are conducted based on GEANT4 simulations.As the sparsely sampled information associated with beam acquisitions at 12 angles is not enough for reconstruction,X-ray CT is used as a prior image.The RSP map generated by converting the X-ray CT was constructed based on Monte Carlo simulations.Considering the estimation of the most likely path(MLP),the prior image-constrained compressed sensing(PICCS)algorithm is used to reconstruct images from two different phantoms using sparse proton projections of 350 MeV parallel proton beam.The results show that it is feasible to realize the proton image reconstruction with the rapid proton CT imaging proposed in this paper.It can produce RSP maps with much higher accuracy for TPSs and fast positioning to achieve ultra-fast imaging for real-time image-guided radiotherapy(IGRT)in clinical proton therapy applications.

Research on Automatic Elimination of Laptop Computer in Security CT Images Based on Projection Algorithm and YOLOv7-Seg

In civil aviation security screening, laptops, with their intricate structural composition, provide the potential for criminals to conceal dangerous items. Presently, the security process necessitates passengers to individually present their laptops for inspection. The paper introduced a method for laptop removal. By combining projection algorithms with the YOLOv7-Seg model, a laptop’s three views were generated through projection, and instance segmentation of these views was achieved using YOLOv7-Seg. The resulting 2D masks from instance segmentation at different angles were employed to reconstruct a 3D mask through angle restoration. Ultimately, the intersection of this 3D mask with the original 3D data enabled the successful extraction of the laptop’s 3D information. Experimental results demonstrated that the fusion of projection and instance segmentation facilitated the automatic removal of laptops from CT data. Moreover, higher instance segmentation model accuracy leads to more precise removal outcomes. By implementing the laptop removal functionality, the civil aviation security screening process becomes more efficient and convenient. Passengers will no longer be required to individually handle their laptops, effectively enhancing the efficiency and accuracy of security screening.

岩石疲劳损伤扩展规律CT细观分析初探

利用笔者研制的CT(ComputerizedTomography)机专用三轴加载试验设备 ,进行了实时的岩石疲劳损伤演化CT细观试验。从细观尺度证实了岩石疲劳破坏存在门槛值 ,研究了循环荷载最大应力值的变化对岩石疲劳破坏的影响机理 ,得到了岩石细观疲劳损伤扩展的初步规律。

纵隔型肺癌的X线及CT表现分析

目的旨在分析纵隔型肺癌的X线及CT表现特点,提高对纵隔型肺癌影像学表现的认识。方法回顾性分析23例经过手术、穿刺、支纤镜和病理证实纵隔型肺癌的X线及CT资料。患者均行胸部正侧位DR照片,CT平扫、增强扫描检查。对病变进行影像学分类及对其影像学表现进行观察。结果纵隔型肺癌影像学分为中央型(14例)、周围型(6例)、隐匿型(3例)。中央型肺癌表现为单侧性中上纵隔增宽,肺门区结节状、团块状肿块,肺段支气管狭窄、闭塞,肿块内缘见脂肪线影。周围型肺癌表现为表现为中、上纵隔增宽,纵隔旁肿块病灶内缘紧贴纵隔。肿块与肺组织分界不清。隐匿型表现为纵隔内广泛淋巴结肿大,调窗见支气管粘膜面小结节。结论纵隔型肺癌易被误诊为纵隔原发肿瘤或纵隔转移瘤,通过仔细观察、分析病变表现,结合临床症状可作出明确诊断。

70例脑梗死临床和CT分析

目的通过分析70例脑梗死的临床表现和脑CT来反应脑梗死的发病规律和相关因素。方法分析70例不同性别、年龄、位置和基础疾病患者的临床资料。结果脑梗死的多发人群为61～80岁人群,58例,所占比例为82.86%,患有腔隙性脑梗死为40例,其中有高血压的31例,所占比例为77.50%,好发位置是基底节区和半卵圆中心区。结论 61～80岁的老年人应成为脑CT诊断梗塞关注的人群,高血压为主要的发病原因。

CT高压增强对比剂渗漏防范措施的效果观察

目的探讨CT高压增强渗漏防范措施的效果,减少渗漏事件的发生。方法将CT增强的患者分为实验组与对照组,每组内按可能导致渗漏发生的疾病进行分类,分为高血压动脉硬化、糖尿病、恶液质、配合不良和无特殊等。试验组采取使用留置针、评估渗漏风险及报警器等措施。对照组未采取上述措施。结果实验组,发生渗漏22人,占0.35%。其中轻、中、重度占渗漏分别为59.1%、27.3%、13.6%。对照组发生渗漏217人,占3.54%。其中轻、中、重度占渗漏分别为80.1%、13.4%、6.5%。试验组渗漏人数明显低于对照组(p<0.01)。结论在CT高压增强采取系列防范措施对减少渗漏具有显著效果。

改良2-^(△△CT)法分析RNASET2基因在卵巢癌卡铂耐药中的表达

目的:建立改良的相对定量2^(-△△CT)法并应用其分析RNASET2基因在卵巢癌卡铂耐药细胞系中的差异表达。方法:分别提取卵巢癌卡铂耐药SKOV3细胞系与其亲本SKOV3细胞系的总RNA,将等量的mRNA逆转录为cDNA,应用实时荧光定量PCR(real-time RT-PCR)技术检测核糖核酸酶T2(RNASET2)基因在卵巢癌卡铂耐药中的差异表达,参照2^(-△△CT)公式的推导步骤,对其改良演化出一个新的公式即改良2^(-△△CT)公式。以绝对定量法为对照,应用该公式分析real-time RT-PCR技术检测结果并比较两种方法的差异。结果:改良2^(-△△CT)公式与绝对定量法分析实验结果差异无统计学意义(P>0.05)。卵巢癌卡铂耐药SKOV3细胞系RNASET2基因的表达相对于卵巢癌非耐药SKOV3细胞系的表达降低。结论:改良2^(-△△CT)公式分析real-time RT-PCR反应数据是一种简便可行的相对定量方法,RNASET2表达下调与卵巢癌卡铂耐药相关。

2型糖尿病骨关节病患者的X线及CT分析

目的分析2型糖尿病骨关节病患者的X线及CT表现。方法本文所选55例2型糖尿病骨关节病患者均为我院2013年3月—2017年1月所收治,全部患者均给予X线检查和CT检查,对X线和CT影像表现进行分析。结果全部50例患者均存在骨质疏松,44例患者存在骨干对称性变细和骨质萎缩,30例患者存皮质骨缺损,18例患者存在骨性关节炎,3例患者存在第二跖趾关节夏科关节病,35例接受CT检查的患者存在局部软组织肿胀。结论骨性关节炎、骨质疏松、周围软组织肿胀为2型糖尿病骨关节病患者的主要影像学表现,在实际的临床诊断中应和临床密切结合。

岩石疲劳破坏的变形控制律、岩土力学试验的实时X射线CT扫描和边坡坝基抗滑稳定分析的新方法

介绍了近年来在岩土力学领域方面取得的一些进展:①关于岩石疲劳破坏试验方面的实验结果。大量的试验清楚表明岩石发生疲劳破坏时的变形量受岩石应力-应变全过程曲线控制的规律,介绍了这方面的试验技术及新型的岩石力学试验机——RMT机的特性,对岩石的I型和Ⅱ型分类作了评述。岩石疲劳试验结果也提示我们在研究岩石的强度理论时要特别重视从变形角度去探讨。②简要介绍了岩土力学室内试验方面的一项新的实验技术——实时X射线CT扫描的试验方法和原理。重点给出了南桥砂岩三轴试验的结果,并与典型的全过程曲线作了对比分析。这一新技术为岩土力学界提供了一种新手段,使宏观的力学性能与细观层次上的结构演变和裂纹萌生、扩展直到破坏有机地联系起来,为损伤研究提供了一种新的实验手段。③论述了采用强度储备概念求抗滑稳定安全系数方面的不足之处。基于力是矢量这一基本概念,提出了计算抗滑稳定安全系数的新方法——矢量和分析方法,并与传统分析方法作了对比,指出了这种新方法的优点。除了平面问题外,还论述了三维问题的计算方法和算式。

肝脏转移瘤的CT表现与病理分析

目的:探讨肝脏转移瘤的CT表现与病理特点,提高临床诊断水平。方法:收治肝脏转移瘤患者28例,均行全肝平扫加动脉期(HAP)和门脉期(PVP)增强扫描,并取活检或手术病理进行分析。结果:肝脏转移瘤CT平扫以结节或(和)巨块出现,结节可以低密度、等密度、高密度、钙化及囊肿等多种形式出现。就肝脏病变分布而言,发生于右叶20例,发生于左叶8例。病变的形态:圆形或类圆形24例,不规则形4例。本组有10例见到"牛眼征"。病灶边缘清楚26例(92.9%),边缘不清2例(7.1%)。病灶大小1.4cm×1.1cm～10.1cm×7.5cm,平均5.3cm×4.2cm。病理镜检:24例以梭形细胞为主,2例以上皮细胞为主,2例是混合型。结论:CT表现和病理对诊断肝脏转移瘤有着重要的临床意义。

Characteristics of viral specimens collected from asymptomatic and fatal cases of COVID-19

We sought to determine the characteristics of viral specimens associated with fatal cases,asymptomatic cases and non-fatal symptomatic cases of COVID-19.This included the analysis of 1264 specimens found reactive for at least two SARS-CoV-2 specific loci from people screened for infection in Northern Nevada in March-May of 2020.Of these,30 were specimens from fatal cases,while 23 were from positive,asymptomatic cases.We assessed the relative amounts of SARS-CoV-2 RNA from sample swabs by real-time PCR and use of the threshold crossing value(Ct).Moreover,we compared the amount of human RNase P found on the same swabs.A considerably higher viral load was found to be associated with swabs from cases involving fatality and the difference was found to be strongly statistically significant.Noting this difference,we sought to assess whether any genetic correlation could be found in association with virus from fatal cases using whole genome sequencing.While no common genetic elements were discerned,one branch of epidemiologically linked fatal cases did have two point mutations,which no other of 156 sequenced cases from northern Nevada had.The mutations caused amino acid changes in the 3′-5′exonuclease protein,and the product of the gene,orf8.

Fracture evolution analysis of soil-rock mixture in contrast with soil by CT scanning under uniaxial compressive conditions

Soil-rock mixture(SRM),as a type of extremely heterogeneous geomaterial,is very common in nature and engineering.The fracture and damage of SRM often induce severe geological disasters.Hence,it is important to analyze the fracture evolution process of this material.In the present research,real-time computed tomography(CT)scanning was conducted on SRM and pure soil samples under uniaxial compressive experiments to investigate the influence of rocks on fracture evolution in SRM.The initiation of cracks,the original values of,and variations in,average density and heterogeneity in the soil matrix,the crack width evolution during loading,and the final failure modes were all studied.Cracks with a width greater than 0.1 mm will not arise until over 90%of ultimate stress is reached.In general,in SRM,areas where the initial average density of the soil matrix is smaller and the initial heterogeneity is greater,are much easier to crack,but the results for pure soil show the opposite effect.According to fracturing conditions shown in CT slices,fracturing and non-fracturing areas in the soil matrix were investigated.The average density of the soil matrix decreases in all areas under loading,except non-fracturing areas in SRM.For the whole sample,the increase in heterogeneity in the soil matrix of SRM is greater than that of pure soil;but for the fracturing areas,this increase in pure soil is greater.Besides,the average and standard deviations of crack width both follow logarithmic distributions with high correlation coefficients.

股骨头缺血坏死CT和MRI诊断的Meta分析

目的应用循证医学Meta分析来评价CT和MRI对股骨头缺血坏死（ avascular necrosis of the femoral head, ANFH）诊断的应用价值。方法检索cochrane图书馆（2011年第1期）、PubMed（1966～2011）、Embase（1989～2011）、中国生物医学文献数据库（1982～2011）、万方数据库（1982—2011），纳入国内外公开发表的关于股骨头缺血坏死的CT和MRI诊断的文献，按照纳入标准进行筛选，两名调查员独立对文献质量进行严格评价和资料提取，对符合标准的8篇文献在诊断ANFH方面使用软件Review mangager5．0进行Meta分析。结果共纳入8篇研究，共515例患者。Meta分析及其偏倚分歧提示MRI对股骨头缺血坏死阳性率的诊断价值高于CT，两者差别有显著统计学意义[OR=0．12（95％CI，0．04～0．33），P〈0．0001]。MRI对股骨头缺血坏死早期阳性率的诊断价值高于CT，两者差别有统计学意义[OR=0．45（95％CI，0．26～0．78），P=0．005]。结论MRI是首选的股骨头缺血坏死诊断手段，但仍需大样本随机对照试验来验证。

18氟-脱氧葡萄糖-正电子发射计算机断层扫描对大动脉炎疾病活动性诊断和评估的Meta分析

目的评估正电子发射计算机断层扫描（PET）在大动脉炎疾病活动性诊断中的作用。方法文献检索基于PubMed/Medline、中国知网等数据库，纳入2016年12月前与大动脉炎和PET有关的文献。文献质量评价采用QUADAS-2，数据分析采用Meta-Disc统计软件。结果通过检索共获得文献70篇，最终纳入9篇英文文献进行Meta分析。患者疾病诊断均采用美国风湿病学会诊断分类方法。活动度评估标准多依据美国国立卫生研究院（NIH）评分，少数为临床评分。PET的结果评价采用了视觉分级或半定量方法。9项研究合并诊断比值比（DOR）为17.54，合并的敏感度和特异度分别为84%和73%，但特异度合并时具有异质性（I2=81.4%）。9项研究中有2项的结果纳入了同一患者的多次PET结果，1项研究有较多疑似活动患者最终纳入非活动组，可能影响Meta分析结果。分别通过敏感性分析去除以上研究，得到的统计结果一致性较好。去除以上研究后研究合并的DOR为30.32，敏感度为86%，特异度为85%（I2=23%）。结论PET在大动脉炎的活动性诊断和评估中具有稳定的敏感度，但特异度差异较大，可作为临床上评估方法之一。