改善CT扫描技术在提高鼻骨骨折诊断率中的应用

目的:探讨分析改善CT扫描技术在提高鼻骨骨折诊断率中的应用效果。方法:选取我院2013年4月-2014年4月收治的70例鼻骨骨折患者,将其分成观察组和对照组,每组各35例,给予观察组患者实施冠状及横断位HRCT扫描检查,给予对照组患者常规X线片。对比分析两组患者不同扫描技术的诊断率。结果:观察组35例患者均发现鼻骨骨折,占100%,其中双侧骨折3例,额骨骨折2例,上颌窦骨折3例,粉碎性骨折6例,单侧骨折5例,眼眶壁骨折2例,线性骨折5例,鼻中隔骨折4例。对照组35例患者仅有15例发现鼻骨骨折,占42.8%,其中双侧骨折3例,额骨骨折3例,上颌窦骨折1例,粉碎性骨折2例,单侧骨折2例,鼻中隔骨折1例,眼眶壁骨折2例,线性骨折3例。两组诊断率对比差异具有明显统计学意义(P0.05)。结论:改善CT扫描技术(冠状和X线及横断位HRCT扫描)诊断率高,能全面、清晰的显示鼻骨骨质细微改变,有利于临床对鼻骨骨折治疗,如结合横断位效果更佳,可作为鼻骨骨折首选和常规检查方法。     

薄层螺旋CT诊断眼眶内侧壁骨折的应用价值

目的：探讨薄层螺旋CT诊断眶内侧壁骨折的应用价值。方法：对53例患者或志愿者行常规轴位及薄层轴位、冠位扫描。分别将常规轴位扫描图像与薄层轴位扫描图像及薄层冠位扫描图像与轴位薄层扫描MPR冠状位重建图像进行比较。结果：前组图像对病变显示率二者有明显差异（P〈0．001），后组无明显差异。结论：仅薄层CT扫描即可精确诊断眶内侧壁骨折，尤以轴位图像显示为佳。     

鼻骨骨折DR与64层螺旋CT扫描结果对比分析

目的:探讨鼻骨骨折DR与64层螺旋CT扫描结果的差异,以进一步提高影像学诊断符合率。方法:收集我院2012年2月-2013年7月诊治的80例鼻骨骨折患者,均进行常规DR双侧位拍片和64排CT扫描。结果:本组80例鼻骨骨折患者DR检查出鼻骨骨折59例,可疑鼻骨骨折9例,未见骨折12例,64层CT检查均诊断鼻骨骨折,两组比较有显著性差异(P<0.05),DR诊断为粉碎性骨折20,单纯线性骨折39例,可疑骨折9例,64层CT检查诊断为复合性骨折21例,粉碎性骨折22例,单纯线性骨折37例。结论:DR线平片对于鼻骨骨折的诊断有一定辅助意义,操作简单,费用低廉,适宜基层医院,64层CT检查费时,费用高,但诊断符合率高。     

16层螺旋CT对诊断隐匿性骨折的应用价值

目的：探讨16层螺旋CT对诊断隐匿性骨折的应用价值。方法：58例经X线平片（DR）检查阴性但临床高度怀疑骨折的急性外伤患者于伤后2h-7d行16层螺旋CT检查,薄层重建后行多平面重组（MPR）、曲面重建和三维重建。结果：58例患者经16层螺旋CT扫描后处理确诊鼻骨骨折19例,眼眶骨折10例,肋骨骨折20例,胸腰椎横突骨折2例,股骨颈骨折4例,髋臼骨折2例,胫骨平台骨折1例。结论：16层螺旋CT后处理技术,尤其是MPR成像显著提高了细微骨折的检出率,是诊断隐匿性骨折有效而可靠的检查方法。     

薄层螺旋CT诊断眼眶内侧壁骨折的应用价值

目的:探讨薄层螺旋CT诊断眶内侧壁骨折的应用价值。方法:对53例患者或志愿者行常规轴位及薄层轴位、冠位扫描。分别将常规轴位扫描图像与薄层轴位扫描图像及薄层冠位扫描图像与轴位薄层扫描MPR冠状位重建图像进行比较。结果:前组图像对病变显示率二者有明显差异(P<0．001),后组无明显差异。结论:仅薄层CT扫描即可精确诊断眶内侧壁骨折,尤以轴位图像显示为佳。     

薄层螺旋CT诊断眼眶内侧壁骨折的应用价值

目的:探讨薄层螺旋CT诊断眶内侧壁骨折的应用价值.方法:对53例患者或志愿者行常规轴位及薄层轴位、冠位扫描.分别将常规轴位扫描图像与薄层轴位扫描图像及薄层冠位扫描图像与轴位薄层扫描MPR冠状位重建图像进行比较.结果:前组图像对病变显示率二者有明显差异(P＜0.001),后组无明显差异.结论:仅薄层CT扫描即可精确诊断眶内侧壁骨折,尤以轴位图像显示为佳.     

单排螺旋CT扫描技术在腕关节外伤中的应用分析

目的：探讨腕关节外伤患者应用单排螺旋CT扫描的临床诊断价值。方法：选取我院2012年3月－2014年3月收治的腕关节外伤患者94例,分别开展单排螺旋CT扫描与腕部X线检查,观察不同检查方法的确诊率、敏感度与特异度。结果：本组患者共117处骨折,不稳定或脱位共11处,X线对骨折的确诊率为84.6%,不稳定或脱位情况的确诊率为72.7%,明显低于CT扫描,具有统计学意义（P＜0.05）。CT准矢状位扫描对骨折与不稳定或脱位的确诊率明显高于CT轴位扫描,具有统计学意义（P＜0.05）,而CT准矢状位扫描的敏感度与特异度最高。结论：针对腕关节外伤患者,开展单排螺旋CT具有更佳的诊断效果,在具体开展过程中可依据患者的实际情况选择更适合的扫描方式,能够提高临床诊断的准确程度。     

X线与CT诊断鼻骨骨折的价值分析

目的:分析X线与CT诊断鼻骨骨折价值。方法:回顾性分析2014年3月-2015年3月本院收治鼻骨骨折96例患者临床资料,所有患者均进行X线、CT线检查,比较两种检查方式的诊断阳性率及各类型骨折阳性率。结果:经X线检查确诊为鼻骨骨折45(46.88%)例,疑似鼻骨骨折有20(20.83%)例,非鼻骨骨折有29(30.21%)例,CT检查确诊为鼻骨骨折96(100.00%)例,X线诊断为单纯型鼻骨骨折10(43.48%)例,鼻中隔型骨折26(27.08%)例,复合型鼻骨骨折15(100.00)例,CT诊断结果分别为23(100.00%)例、58(100.00%)例、15(100.00%)例,两种检查方法的准确度、阳性率均比较差异具统计意义(P0.05)。结论:与X线比较,CT诊断鼻骨骨折的阳性率及准确率较高,可以作为鼻骨骨折的首选影像学诊断方法,具有一定临床应用与研究价值。     

多层螺旋CT各向同性冠状位重组图像在成人不典型急性阑尾炎诊断及分型中的应用价值

目的:探讨多层螺旋CT各向同性冠状位重组图像在成人不典型急性阑尾炎诊断及分型中的应用价值。方法:回顾性分析2017年1月至2019年12月间本院收治的75例疑似不典型急性阑尾炎患者的临床资料,所有患者均给予64层螺旋CT平扫与增强扫描,由3位资历不同的放射科医生独立观察CT成像的横断位图像以及横断位+冠状位图像。探讨多层螺旋CT在不典型急性阑尾炎诊断和分型中的应用价值。结果:工作资历5年者、10年者和15年者在横断位+冠状位扫描对不典型急性阑尾炎方面的诊断灵敏性和特异性虽均略高于横断位扫描结果,但两者对比均不具有统计学意义(P0.05)。36例确诊患者在参考CT分型和手术病理结果的情况下最终诊断为阑尾结构完整可辨型15例、阑尾结构难辨型10例、阑尾结构不清型7例和团块型4例。从横断位图像读片发现,其与病理检查结果在不典型急性阑尾炎分型的Kappa值为0.377 5,一致性较差;从横断位+冠状位图像读片发现,其与病理检查结果在不典型急性阑尾炎分型的Kappa值为0.723 4,一致性良好。结论:无论是多层螺旋CT横断位还是横断位+冠状位对成人不典型急性阑尾的诊断均具有较高的应用价值,但在判断患者疾病分型方面横断位+冠状位的读片结果更能获得与手术病理结果高度一致的答案,临床应用价值更高。     

螺旋CT容积扫描方法诊断胸廓骨及肋骨骨折的临床价值

目的:研究探讨螺旋CT容积扫描法对胸廓股骨折及肋骨骨折的临床诊治效果。方法:以我院2014年5月-2014年6月收治的90例胸廓股骨折及肋骨骨折患者作为研究对象,所有患者均进行X线,3D图像,CT轴位扫描,并分析患者的X线图像,3D图像,CT轴位扫描图像的诊断结果。结果:以CT轴位扫描图像的结果为标准,其中X线诊断的灵敏度为61.55%,X线诊断的特异度为66.68%,3D图像容积重建(VR)诊断的灵敏度为98.55%,3D图像容积重建(VR)诊断的特异度为87.52%。结论 :螺旋CT容积扫描法对胸廓股骨折及肋骨骨折的临床诊治效果明显,可以明显显示出骨折位置,适合于临床推广使用。     

X线平片与C盼断21例跖骨跗骨骨折研究

将X线平片与CT对跖骨跗骨骨折患者的诊断优势进行对比分析。方法：对我院收治的跖骨跗骨骨折患者中选取21例患者先进行X线平片诊断,后进行CT扫描,将两组的诊断结果进行对比分析。结果：X线平片诊断出32个跖骨、跗骨骨折,CT扫描诊断出38个跖骨、跗骨骨折,两组差异具有统计学意义（P〈0．05）。结论：CT扫描通过多平面重建（MPR）以及表面遮盖显示（SSD）技术可以更全面的显示出患者足部跖骨附骨骨折的具体病况,让医生能够制定更加科学的治疗方案,提高患者的康复率。     

Failure Analysis of a Diesel Engine Connecting Rod

A failure investigation has been conducted on a diesel engine connecting rod. The fracture occurred at the small head of the connecting rod. Visual and scanning electron microscopy observations show that a lot of axial grooves appear on the internal surface close to the fracture and the fatigue cracks initiated from the axial grooves. Fractography indicates that the multiple-origin fatigue fracture is the dominant failure mechanism. The machining or assembling process was responsible for the formation of the axial grooves.     

Axial compression fracture in carbon fibres

Axial compression fracture of carbon fibres was studied by embedding single fibres in epoxy resin and compressing the specimens parallel to the fibre axis. By careful optical monitoring of the fibre surface the earliest stages of fracture were identified leading to estimates of the fibre axial compression failure strengths. Compression strength decreases markedly from about 2.2 GN m^?2 for moderately oriented fibres to <1 GN m^?2 for highest modulus filaments. The trend towards decreasing compression strength with increasing anisotropy is explained on the basis of an increasing fibre microfibrillar nature. However fracture morphology studies show that the unduly rapid strength decrease results from an increasing degree of fibre outer layer ordering which accompanies increasing axial anisotropy in carbon fibres since cracking occurs first on the more highly aligned filament surfaces. It is suggested that fibre compression fracture changes from a shear to a microbuckling or kinking mode with increasing fibre anisotropy, where the latter initiates in individual, well-aligned but uncoupled microfibrils. The similarity of fine axial compression fractures in oriented carbon fibres to those found in elastica loop experiments is noted as are the possible implications which the low strain-to-failure in compression of very high modulus fibres might have for practical composites.     

Effects of repeated loading on the fracture behavior of notched TiAl specimens

Notched specimens of a fully lamellar TiAl alloy and a duplex TiAl alloy were in situ tensile tested with repeated loading-unloading-reloading processes in a scanning electron microscope (SEM). The step-by-step processes of initiation and extension of the main crack were captured by SEM. The fracture surfaces were observed and one-sector-to-one-sector related to the crack extension. Effects of loading-unloading damage on the fracture behavior were evaluated by combining the pictures of propagating crack configurations, corresponding fracture surfaces and the load locus. The results revealed the following events: (1) at the elastic regime, the loading-unloading process had negligible effect on the fracture behavior produced by subsequent reloading; (2) at the plastic regime, even at a value much lower than that of the preload, the reload extended further the existing main crack; (3) after a heavy loading-unloading process, the main crack extended and resulted in final fracture at a value of the reload, which was lower than that of the preload and (4) microcracks produced in the loading-unloading process had minor effects on the fracture behavior.     

An investigation on the effects of equal channel angular pressing on the mixed‐mode fracture toughness and mechanical properties of 6063 aluminium alloy

In this study, effects of equal channel angular pressing (ECAP) on the mixed‐mode fracture toughness of Al‐6063 were investigated. The ECAP process continued up to 5 passes without failure. Grain refinement was obvious after 5 passes of the ECAP process. The average grain size reduced from 45μm to less than 1μm, and textural studies shows aligning the grains in known directions. After 4 passes, yield and ultimate strengths increase respectively from 100 and 209 MPa to 300 and 375 MPa and reduction in elongation was also observed. The microhardness improved after the process. The fracture toughness for different orientations was measured. For pure mode I (opening mode), its value decreased after the first pass from 18.4 to 15.71  ; however, it increased to about 18.8  after the fifth pass. For mixed‐mode loading condition, different orientations were investigated. The results revealed different fracture toughness reductions after the first passes of the process for specimens with different orientations. The fracture surfaces were studied by using scanning electron microscope, and refined equiaxed dimples were observed after the ECAP process.     

纤维增强铅基复合材料单轴拉伸试验的动态观察

在扫描电镜下对单向拉伸应力状态下的铅基复合材料的断裂过程进行观察;找出了铅基复合材料在拉伸状态下裂纹萌生及扩展的规律;结合拉伸断口形貌分析,讨论影响铅基复合材料拉伸断裂过程的主要因素。      

Effect of thermal ageing of CF8M on multi‐axial ductility and application to fracture toughness prediction

This paper proposes a method to predict the thermal ageing effect on fracture toughness of CF8M cast stainless steel. The proposed method is based on multi‐axial fracture strain combined with finite element damage analysis to simulate ductile tearing. Multi‐axial fracture strain loci of un‐aged and aged CF8M are determined by analyzing notched bar tensile test. It is shown that the thermal ageing effect on multi‐axial fracture strain loci can be characterized by one constant. It is further shown that J‐resistance curves of un‐aged and aged CF8M can be predicted well from finite element damage analysis using multi‐axial fracture strain loci. Implication of present results to practical application of crack assessment of aged cast stainless steels is discussed.     

Comparison of transmission and scanning electron fractography

The transmission electron microscope, with suitable replication techniques, was used extensively during the 1950s and 1960s to study the surfaces of metal fractures, both to understand the mechanism of fracture and for practical failure analysis. When the scanning electron microscope was introduced in the 1960s, these studies were greatly simplified by the lack of necessity for replication. The appearance of the fracture surfaces, however, was different in some cases from the appearance the fractographer was accustomed to seeing from his or her negative replica. This work was done to help translate from one technique to another.