Effects of dry-wet cycles on three-dimensional pore structure and permeability characteristics of granite residual soil using X-ray micro computed tomography

Due to seasonal climate alterations,the microstructure and permeability of granite residual soil are easily affected by multiple dry-wet cycles.The X-ray micro computed tomography(micro-CT)acted as a nondestructive tool for characterizing the microstructure of soil samples exposed to a range of damage levels induced by dry-wet cycles.Subsequently,the variations of pore distribution and permeability due to drywet cycling effects were revealed based on three-dimensional(3D)pore distribution analysis and seepage simulations.According to the results,granite residual soils could be separated into four different components,namely,pores,clay,quartz,and hematite,from micro-CT images.The reconstructed 3D pore models dynamically demonstrated the expanding and connecting patterns of pore structures during drywet cycles.The values of porosity and connectivity are positively correlated with the number of dry-wet cycles,which were expressed by exponential and linear functions,respectively.The pore volume probability distribution curves of granite residual soil coincide with the χ^(2)distribution curve,which verifies the effectiveness of the assumption of χ^(2)distribution probability.The pore volume distribution curves suggest that the pores in soils were divided into four types based on their volumes,i.e.micropores,mesopores,macropores,and cracks.From a quantitative and visual perspective,considerable small pores are gradually transformed into cracks with a large volume and a high connectivity.Under the action of dry-wet cycles,the number of seepage flow streamlines which contribute to water permeation in seepage simulation increases distinctly,as well as the permeability and hydraulic conductivity.The calculated hydraulic conductivity is comparable with measured ones with an acceptable error margin in general,verifying the accuracy of seepage simulations based on micro-CT results.

Phase II Clinical Study of Three-Dimensional Printed Coplanar Template Combined with CT-Guided Percutaneous Core Needle Biopsy of Pulmonary Nodules in Elderly Patients

Background: As the population age structure gradually ages, more and more elderly people were found to have pulmonary nodules during physical examinations. Most elderly people had underlying diseases such as heart, lung, brain and blood vessels and cannot tolerate surgery. Computed tomography (CT)-guided percutaneous core needle biopsy (CNB) was the first choice for pathological diagnosis and subsequent targeted drugs, immune drugs or ablation treatment. CT-guided percutaneous CNB requires clinicians with rich CNB experience to ensure high CNB accuracy, but it was easy to cause complications such as pneumothorax and hemorrhage. Three-dimensional (3D) printing coplanar template (PCT) combined with CT-guided percutaneous pulmonary CNB biopsy has been used in clinical practice, but there was no prospective, randomized controlled study. Methods: Elderly patients with lung nodules admitted to the Department of Oncology of our hospital from January 2019 to January 2023 were selected. A total of 225 elderly patients were screened, and 30 patients were included after screening. They were randomly divided into experimental group (Group A: 30 cases) and control group (Group B: 30 cases). Group A was given 3D-PCT combined with CT-guided percutaneous pulmonary CNB biopsy, Group B underwent CT-guided percutaneous pulmonary CNB. The primary outcome measure of this study was the accuracy of diagnostic CNB, and the secondary outcome measures were CNB time, number of CNB needles, number of pathological tissues and complications. Results: The diagnostic accuracy of group A and group B was 96.67% and 76.67%, respectively (P = 0.026). There were statistical differences between group A and group B in average CNB time (P = 0.001), number of CNB (1 vs more than 1, P = 0.029), and pathological tissue obtained by CNB (3 vs 1, P = 0.040). There was no statistical difference in the incidence of pneumothorax and hemorrhage between the two groups (P > 0.05). Conclusions: 3D-PCT combined with CT-guided percutaneous CNB can improve the puncture accuracy of elderly patients, shorten the puncture time, reduce the number of punctures, and increase the amount of puncture pathological tissue, without increasing pneumothorax and hemorrhage complications. We look forward to verifying this in a phase III randomized controlled clinical study. .

Numerical analysis of the failure process of soil-rock mixtures through computed tomography and PFC3D models

Soil-rock mixture （SRM） is a unique type of geomaterial characterized by a heterogeneous composition and a complicated structure. It is intractable for the continuum-based soil and rock mechanics theories to accurately characterize and predict the SRM＇s mechanical properties. This study reports a novel numerical method incorporating microfocus computed tomography and PFC3D codes to probe the deformation and failure processes of SRM. The three-dimensional （3D） PFC models that represent the SRM＇s complex structures were built. By simulating the entire failure process in PFC3D, the SRM＇s strength, elastic modulus and crack growth were obtained. The influence of rock ratios on the SRM＇s strength, deformation and failure processes, as well as its internal mesoscale mechanism, were analyzed. By comparing simulation results with experimental data, it was verified that the 3D PFC models were in good agreement with SRM＇s real structure and the SRM＇s compression process, deformation and failure patterns; its intrinsic mesomechanism can be effectively analyzed based on such 3D PFC models.

Influences of Motion Artifacts on Three-Dimensional Reconstruction Volume and Conformal Radiotherapy Planning

Objective ：To investigate the influences of motion artifacts on three-dimensional （3D） reconstruction volume and conformal radiotherapy planning. Methods： A phantom which can mimic the clip motion of lung tumor along the cranial-caudal direction is constructed by step motor, small ball of polyethylene and potato. Ten different scan protocols were set and CT data of the phantom were acquired by using a commercial GE LightSpeedl6 CT scanner. The 3D reconstruction of the CT data was implemented by adopting volume-rendering technology of GE AdvantageSim 6.0 system. The reconstructed volumes of each target in different scan protocols were measured through 3D measuring tools. Thus, relative deviations of the reconstruction volumes between moving targets and static ones were determined. The three-dimensional conformal radiation therapy （3D- CRT） plans and conformal fields were created and compared for a static/moving target with the WiMRT treatment planning system （TPS）. Results：For a static target, there was no obvious difference among the 3D reconstruction volumes when the CT data were acquired with different pitches and slices. The appearance of 3D reconstruction volume and 3D conformal field of a moving target was quite different from that of static one. The maximum relative deviation is nearly 90% for a moving target scanned with different scan protocols. The relative deviations are variable among the different targets, about from -39.8% to 89.5% for a smaller target and from - 18.4% to 20.5% for a larger one. Conclusion ：The motion artifacts have great effects on 3 D-CRT planning and reconstruction volume, which will greatly induce distorted conformal radiation fields and false DVHs for a moving target.

Visualization of Three-dimensional Human Data Based on CT Image

Three-dimensional medical image visualization becomes an essential part for medical field, including computer aided diagnosis, surgery planning and simulation, artificial limb surgery, radiotherapy planning, and teaching etc. In this paper, marching cubes algorithm is adopted to reconstruct the 3-D images for the CT image sequence in DICOM format under theVC＋＋6.0 and the visual package VTK platform. The relatively simple interactive operations such as rotation and transfer can be realized on the platform. Moreover, the normal vector and interior point are calculated to form the virtual clipping plane, which is then used to incise the 3-D object. Information of the virtual slice can be obtained, in the mean while the virtual slice images are displayed on the screen. The technique can realize the real time interaction extraction of virtual slice on 3-D CT image. The cuboids structured can be zoomed, moved and eircumrotated by operating mouse to incise the 3-D reconstruction object. Real time interaction can be realized by clipping the reconstruction object. The coordinates can be acquired by the mouse clicking in the 3D space, to realize the point mouse pick-up as well angle and distance interactive measurement. We can get quantitative information about 3-D images through measurement.

Permeability differences based on three-dimensional geometrical information of void spaces

In this study,the permeabilities of Berea and Otway sandstones were measured under different confining pressures,and porosity was investigated through mercury intrusion porosimetry(MIP).The total porosities of the Berea and Otway sandstones were approximately 17.4%and 25%,respectively.Pore size distributions of each sandstone were almost the same,but the pores in the Otway sandstone were slightly narrower.However,the permeability of the Otway sandstone was smaller than that of the Berea sandstone by one order of magnitude.Three-dimensional(3D)void geometry and geometrical properties of the void spaces relevant to flow were compared to obtain the relation between the permeability differences and porosities of the two sandstones.The 3D geometrical analysis using microfocus X-ray computed tomography(CT)was performed,and the pore geometries of both sandstones were compared using the 3D medial axis(3DMA)method.Pore and throat radii,pore coordination number,tortuosity,number of connecting paths,connecting path volume,and other factors were determined using 3DMA.The Otway sandstone was characterized by a small effective throat/pore radius ratio.Based on the fluid flow mechanism,the lower effective throat/pore radius ratio results in a lower permeability induced by the fluid energy loss,which means that the 3D geometrical shape of void spaces affects the permeability value.

血清CA15-3和超声、CT、MRI检查对乳腺癌诊断价值的比较

目的:探讨了三种非创伤性影像检查方法,超声(US)、X线计算机断层摄影技术(CT)和磁共振成像(MRI)及血清CA15-3水平在乳腺癌诊断中的敏感性和准确性,以提高对乳腺癌早期诊断的方法。方法:回顾分析,比较38例乳腺癌患者的US、CT和MRI及CA15-3的优缺点。结果:乳腺癌的确诊率US为76.3%,CT为84.2%,MRI为93.8%,CA15-3为68.4%。US对乳腺癌的早期检出率较高,但确诊率较低。CT和MRI对乳腺癌的确诊率较高,血清CA15-3的确诊率较低。结论:US、CT、MRI和血清CA15-3各有其优点,合理的综合应用可提高对乳腺癌的早期诊断。

CT灌注成像参数与血清CTRP-3、LDL-C及MMP-9对急性脑梗死后出血转化的评价

目的:探讨CT灌注成像参数与血清补体C1q/肿瘤坏死因子相关蛋白-3(CTRP-3)、低密度脂蛋白胆固醇(LDL-C)及基质金属蛋白酶-9(MMP-9)对急性脑梗死(ACI)后出血转化(HT)的评价。方法:选取2019年8月至2022年7月于简阳市人民医院诊治的206例ACI患者,根据患者静脉溶栓后是否发生HT分为HT组(45例)和非HT组(161例),对比两组CT灌注成像参数[血流量(BF)、血容量(BV)、平均通过时间(MTT)、表面通透性(PS)]、CTRP-3、LDL-C及MMP-9;采用受试者工作特征曲线(ROC)模型分析CT灌注成像参数、CTRP-3、LDL-C及MMP-9诊断HT的曲线下面积(AUC)值、灵敏度及特异度。结果:HT组的BF、BV低于非HT组,而MTT、PS高于非HT组,差异均有统计学意义(t=-5.941,t=-5.777,t=5.863,t=6.954;P<005)。HT组的CTRP-3、LDL-C均低于非HT组,而MMP-9高于非HT组,差异均有统计学意义(t=-3.788,t=-5.835,t=6.935;P<0.05)。ROC曲线分析显示,BF、BV、MTT、PS、CT综合参数、CTRP-3、LDL-C及MMP-9诊断HT的AUC值分别为0.790、0.779、0.738、0.775、0.949、0.692、0.777和0.785;灵敏度分别为88.90%、100.00%、53.30%、66.70%、100.00%、88.90%、66.70%和78.60%;特异度分别为64.60%、51.60%、91.30%、77.60%、81.40%、47.80%、78.90%和75.80%;CT灌注图像参数与CTRP-3、LDL-C和MMP-9的AUC比较,差异均有统计学意义(Z=6.202,Z=4.563,Z=3.704;P<0.05)。结论:CT灌注成像参数及血清CTRP-3、LDL-C及MMP-9水平与ACI后HT具有密切关联,监测其变化程度有助于为预测ACI患者溶栓后发生HT提供重要参考依据。

Experimental investigation of junction growth of rough contacts using X-ray computed tomography

The real contact area(RCA)of randomly rough contacts has received a great deal of attention because it correlates strongly with friction,lubrication,sealing,and conductivity.Simulations have revealed that the RCA associated with deterministic normal squeezing loads increases when tangential loads are also applied,in a phenomenon called junction growth.However,experimental investigations of the junction growth of randomly rough contacts are rare.Here,we used X-ray computed tomography(CT)to measure junction growth when two aluminum alloy surfaces were in contact.A high-resolution experimental setup was used to apply loads and observe contact behaviors at a resolution of 4μm.The RCA and average contact gaps were computed using a three-dimensional(3D)geometric model constructed from gray CT images using the Otsu thresholding method.The results showed that the RCA increased as the normal load increased.The RCA increased by 22.67%after a tangential load was applied(junction growth),and the average gap decreased by 14.01%after a tangential load was applied.Thus,X-ray CT accurately measured the junction growth as a novel quantitative method.

三维高分辨工业X-CT系统

介绍了采用高分辨CCD面阵列探测器的微焦点三维CT系统的基本结构 ,应用基于Feldkamp的近似三维重建算法获得了令人满意的图像质量。与以往用线阵列探测器的CT系统比较 ,该系统具有采集数据快 ,成像速度快 ,检测周期短的特点 ,可实现对被检测陶瓷样品 10 0 %的检测。给出了使用该系统检测陶瓷轴承球的DR(数字照相 )

多层螺旋CT血管成像在颈内动脉起始部狭窄介入治疗中的应用价值

目的探讨多层螺旋CT血管成像(MSCTA)在颈内动脉起始部狭窄的血管内介入治疗的应用。方法回顾性分析42例颈内动脉起始部狭窄行血管内介入诊疗的MSCTA影像资料,总结这些资料在该病治疗中的应用价值。结果MSCTA检查均能获得明确诊断。通过多平面重建测量42例84侧颈内动脉起始部的面积狭窄百分率,其中面积狭窄百分比≤50%者15支,狭窄程度在50%～70%者17支,>70%者30支,闭塞者4支,单侧正常者18例。MSCT重建技术能显示斑块及狭窄管腔内部形态。结论MSCTA可直观地显示颈内动脉起始部狭窄程度及斑块性质,在颈内动脉起始部支架内再狭窄的评价中起着重要作用。

下肢动脉硬化闭塞症的MSCTA的诊断价值

目的探讨下肢动脉硬化闭塞症的多排螺旋CT血管成像(MSCTA)的诊断价值。方法对48例临床诊断为下肢动脉硬化闭塞症患者行MSCTA检查,同时行DSA检查和/或手术治疗。MSCTA检查包括MIP、VR、MPR和CTVE重建。结果48例下肢动脉硬化闭塞症的MSCTA均能获得准确的诊断,与DSA和手术结果比较,其敏感性、特异性和准确性均为100%。通过多平面重建测量其面积狭窄百分比,以狭窄程度最严重处为准,表现为轻度狭窄者3例,中度狭窄8例,重度狭窄16例,闭塞21例。MSCT重建技术能显示斑块及狭窄管腔内部形态。结论MSCTA可直观地显示下肢动脉硬化闭塞症的狭窄程度,有利于术前评价。

143例地震伤的影像诊断特点

回顾性分析143例地震伤的影像学及临床资料,以探讨地震伤的影像诊断特点。143例患者均行X线平片检查,78例行CT检查,19例行MRI检查。四肢骨折81例,单发骨折34例,多发骨折47例,开放性骨折6例,闭合性骨折75例。关节脱位14例,软组织内异物5例,膝关节半月板损伤1例,气性坏疽1例。脑硬膜外血肿4例,颅内血肿2例,脑挫裂伤9例,肾挫伤2例、肝挫伤1例。22例脊椎地震伤患者中,脊椎压缩骨折20例,爆裂性骨折2例。单发椎体骨折12例,多发椎体骨折10例,共累及31个椎体。31个椎体骨折中,颈椎3个,胸椎12个,腰椎14个,骶椎2个。30例胸部地震伤均为复合伤,其中肋骨骨折18例,胸椎骨折8例,肩胛骨骨折3例,锁骨骨折3例,胸骨骨折1例,胸壁软组织伤5例,肺挫裂伤5例,肺内血肿1例,肺部感染4例,气胸及液气胸6例,双侧胸腔积液1例。

腭部肿瘤的多排螺旋CT诊断

目的探讨腭部恶性肿瘤的多排螺旋CT(multi-slice spiral CT,MSCT)的检查方法和诊断价值。方法通过调整舌和口腔的位置对28例研究对象进行常规法、伸舌法、抵舌法和发音法MSCT扫描,并进行容积再现、多平面重建、最大密度投影及CT仿真内窥镜重建。结果合理选择常规法、伸舌法、抵舌法和发音法MSCT扫描检查可获得符合诊断的影像图像,18例腭部病变者经MSCT检查发现病变位于软腭10例,硬腭7例,软腭及硬腭交界处1例,MSCT的定位诊断与临床符合率为100%。15例恶性腭部肿瘤的MSCT表现为腭部局限性肿块者15例,腭骨质破坏6例,邻近结构受累及者5例,颈部淋巴结转移4例。3例腭部良性病变者MSCT表现为腭部软组织弥漫性增厚。结论 MSCT有利于显示腭部肿瘤的形态特征以及侵犯途径,并有利于临床治疗和预后评估。

下肢动脉狭窄闭塞性病变的多排螺旋CT血管成像

目的探讨下肢动脉狭窄闭塞性病变的多排螺旋CT血管成像(MSCTA)的诊断价值。方法48例临床怀疑下肢动脉狭窄闭塞性病变患者行MSCTA检查,同时行DSA检查和/或手术治疗,所有MSCTA检查均行MIP、VR、MPR和CTVE重建。结果48例下肢动脉狭窄闭塞性病变的MSCTA均能获得准确的诊断,与DSA和手术结果比较,其敏感性、特异性和准确性均为100%。通过多平面重建测量其面积狭窄百分率,以狭窄程度最严重处为准,表现为轻度狭窄者3例,中度狭窄8例,重度狭窄16例,闭塞21例。MSCT重建技术能显示斑块及狭窄管腔内部形态。结论MSCT血管成像可直观地显示下肢动脉狭窄闭塞性病变的狭窄程度,有利于术前评价。

发育性髋脱位术后再脱位的三维CT分析

目的利用3D-CT影像,来探讨发育性髋脱位术后再脱位的髋臼及股骨近段的骨性病理形态改变,以分析术后再脱位的原因,从而指导和改进发育性髓脱位的治疗。方法对28例(28侧)发育性髋脱位术后再脱位患者的3D-CT影像资料进行分析,测量各参数指标,并与38例(51侧)手术成功患者术后值以及正常组对比分析,来探讨术后再脱位的原因。结果术后再脱位组患者的颈干角与正常组和手术成功组比较,均有高度显著性差异,其数值明显增大;术后再脱位组患者髋臼外上缘重型缺损者所占比例,与手术成功组比较有高度显著性差异;术后再脱位组股骨颈前倾角与正常组比较差异有显著性,而与手术成功组比较差异则无显著性。结论术后再脱位原因与股骨颈干角的角度、髋臼外上缘形态、股骨头与髋臼是否恢复同心圆复位关系等密切相关;股骨颈前倾角值比正常组偏大并非导致术后再脱位的必然因素,其术中矫正范围不能完全以正常组为标准,而应当以健侧为标准,纠正到一个比正常组略大的范围。

多层螺旋CT三维重建技术在脊柱退行性病变中的诊断价值

目的 :探讨多层螺旋 CT(MSCT)三维重建技术对脊柱退行性病变的诊断价值。材料与方法 :12 0例颈、腰椎退行性病变患者 ,其中颈椎病变 78例 ,腰椎病变 4 2例。所有患者经 MSCT扫描 ,分别行 MPR、MIP、VRT、SSD三维重建图像 ,分析不同重建方法的应用价值。结果 :MPR使用简便 ,可从轴位、冠状位、矢状位及任意角度的斜位重建同样高质量的优秀图像 ,较好地显示颈椎钩突增生、椎间盘病变、椎管狭窄、椎管内改变及椎体边缘性骨质增生 ,对颈椎间孔的显示亦有一定价值 ;VRT及 MIP可从不同角度观察颈椎间孔变窄及腰椎弓峡部骨质状况、椎体边缘骨质增生 ,效果类似大体标本 ;SSD在显示脊椎椎体边缘骨质增生方面效果好 ,与 VRT效果相当 ;MIP、VRT及 SSD均无法评价椎间盘病变及椎管内改变。结论 :MSCT各种三维重建技术在脊柱退行性病变检查中各有优势 ,综合应用以上各种重建方法有利于全面、准确地评价脊柱退行性病变。

Research on CT characteristics reconstruction technology

The traditional computed tomography(CT)reconstruction methods are noisy,low resolution,poor contrast,and generally not suitable to detect the smaller flaws.Besides,the filter design is also difficult.The CT characteristics reconstruction technology was brought forward to improve in these aspects,which is defined to directly reconstruct the characteristics of the projection for the best requirements not the overall image quality.The two-dimension(2D)and three-dimension(3D)CT characteristics reconstruction algorithm were firstly introduced,then by detailed analysis,experimental results and comparsion of parameters calculated,its advantages in keeping better high-frequency feature,better noise immunity,short time-consuming and easier design are verified.

^(18)F-脱氧葡萄糖PET/CT诊断恶性孤立性肺结节的Meta分析

目的孤立性肺结节(solitary pulmonary nodule,SPN)的定性诊断十分困难,PET/CT是目前评价良、恶性病变最具优势的影像学手段之一。文中用Meta分析方法综合评价18F-脱氧葡萄糖(18Fluorodexglucose,FDG)PET/CT显像诊断恶性孤立性肺结节的价值。方法以孤立性肺结节、FDG、PET/CT等为检索词,检索1994年1月至2009年7月的Medline数据库、西文生物医学期刊文献服务系统、外文生物医学期刊全文数据库、中国学术期刊网全文数据库等相关中英文文献。对符合标准的研究进行质量评估,用MetaDisc1.4软件进行异质性检验,综合敏感性、特异性和诊断优势比,绘制汇总受试者工作特征(summary receiver operating characteristic,SROC)曲线和计算曲线下面积(the area under the curve,AUC),并进行敏感性分析。结果共检索相关文献29篇,其中11篇符合标准纳入分析,A级1篇,B级10篇,各研究之间存在异质性,按照随机效应模型合并敏感性、特异性、诊断优势比(diagnostic odds ratio,DOR)及其95%可信区间分别为91%(87%~93%)、83%(78%~87%)和51.04(23.33~111.66),AUC为0.9383,Q值为0.875 3,纳入文献稳定性较好。结论 18F-FDG PET/CT显像能灵敏、准确地诊断恶性孤立性肺结节,具有较高的临床应用价值。

螺旋CT在胸腰椎骨折中的应用

目的:探讨螺旋CT对胸腰椎骨折的诊断价值。方法:分析36例胸腰椎骨折的X线和螺旋CT扫描资料。结果:螺旋CT能清晰显示胸腰椎脊柱骨折、椎管狭窄和脊髓损伤的程度。结论:螺旋CT能明确创伤病变的部位、性质、程度,而且敏感性和特异性高。与X线相比能为临床的诊断及制定治疗方案提供更多信息及可靠依据,是目前脊柱损伤重要的检查方法之一。