双倾斜角度CT扫描在肺部结节性病变中的诊断价值

目的 探讨肺末梢结节不同角度CT扫描的影像学表现，并评价其应用价值。方法 选择12例原发性肺癌作为研究对象，分别行常规横轴位CT扫描及双倾斜角度CT扫描。从毛刺征、切迹征、棘状突起征、胸膜凹陷征、血管关联征、空气支气管征像等方面，观测肺末梢型结节在双倾斜角度CT扫描上的显示率，并与常规横轴位CT扫描作比较。结果 毛刺征、切迹征、棘状突起征、血管关联征在双倾斜角度CT扫描上的显示率达100％，空气支气管征66．66％，胸膜凹陷征83．33％；而常规横轴位CT扫描空气支气管征显示仅1例，显示率为8，34％；胸膜凹陷征显示率亦低，显示不清楚达5／12(41．66％)。结论 双倾斜角度CT扫描与常规横轴位CT扫描比较，影像学特征表现显示更明显，特别是胸膜凹陷、空气支气管征的显示更优。     

多层螺旋CT对创伤性膈损伤的诊断价值

目的 探讨创伤性膈损伤的多层螺旋CT(MSCT)表现特征及诊断价值.方法 回顾性分析笔者医院创伤性膈损伤患者33例,其中男性28例,女性5例,患者年龄1～76岁,33例均行MSCT检查且行冠、矢状位多平面重建(MPR)处理,分析患者临床资料与MSCT表现特征及诊断价值,影像学表现包括膈肌连续性中断征、膈肌增厚征、项圈征、面包征及膈疝部位及内容物等.结果 33例中,2例为单纯挫伤,31例为钝性损伤(左侧26例,右侧5例),膈疝内容物分别为胃或含液气肠袢(左侧25例,右侧1例)、肝脏(仅右侧3例)及腹腔脂肪(左侧16例,右侧2例);MSCT提示膈肌异常的敏感度为100％,21例(67.7％)可见膈肌连续性中断征,10例(32.2％)可见膈肌增厚征,项圈征与面包征各5例(16.1％).与横断面相比,MPR能更好地显示膈肌连续性中断征(P＜0.05).结论 MSCT检查对诊断创伤性膈损伤有重要价值,尤其是MPR技术对诊断有很大帮助.     

CBCT/CT与普通X线片在上颌前牙区埋伏多生牙定位的比较

目的探讨锥形束CT(CBCT)/CT与普通X线片在上颌前牙区埋伏多生牙定位检查的应用价值。方法结合临床病例,对上颌前牙区完全埋伏多生牙采用CBCT/CT与多种普通X线片定位方法进行比较和分析。结果普通X线片对埋伏多生牙的定位有一定帮助,视差定位法是比较经济和实用的定位方法。CBCT/CT检查能准确展示多生牙的三维结构,并进行相应的测量与辅助手术设计,与普通X线片比具有显著优势。结论上颌前牙区埋伏多生牙可根据医疗条件选择适合的定位检查方法,而CBCT检查将是发展的趋势。     

Fatigue Analysis and Defect Size Evaluation of Filled NBR including Temperature Influence

The fatigue behavior of a filled non-crystallizing elastomer was investigated on axisymmetric dumbbell specimens. By plotting relevant Wöhler curves, a power law behavior was found. In addition, temperature increases due to heat build-up were monitored. In order to distinguish between initiation and crack growth regimes, hysteresis curves, secant and dynamic moduli, dissipated and stored energies, and normalized minimum and maximum forces were analyzed. Even though indications related to material damaging were observed, a clear trend to recognize the initiation was not evident. Further details were revealed by considering a fracture mechanics. The analysis of the fracture surfaces evidenced the presence of three regions, associated to initiation, fatigue striation, and catastrophic failure. Additional fatigue tests were performed with samples in which a radial notch was introduced. This resulted in a reduction in lifetime by four orders of magnitude; nevertheless, the fracture surfaces revealed similar failure mechanisms. A fracture mechanics approach, which considered the effect of temperature, was adopted to calculate the critical defect size for fatigue, which was found to be approximately 9 μm. This value was then compared with the particle size distribution obtained through X-ray microcomputed tomography (μ-CT) of undamaged samples and it was found that the majority of the initial defects were indeed smaller than the calculated one. Finally, the evaluation of J-integral for both unnotched and notched dumbbells enabled the assessment of a geometry-independent correlation with fatigue life.     

X线、MSCT和MRI对主动脉夹层的临床运用对比研究

目的对比分析X线、MSCT及MRI在主动脉夹层（AD）中影像学特征,并评价其临床运用价值。方法 30例经手术或行DSA造影证实的AD患者,对其X线、MSCT及MRI检查影像资料进行分析,总结归纳其影像特点。结果 X线仅见AD的间接征象,而MSCT和MRI均能不同程度地显示真假两腔、内膜破口、内膜片及附壁血栓。结论 X线对AD只能提示诊断,而MSCT和MRI可作特异性诊断,并且MRI在显示AD的破口位置、无钙化的内膜片及附壁血栓时均优于MSCT,但对内膜及主动脉壁钙化和急危重者的检查MSCT优于MRI。     

Formation and Thermal Stability of the ω-Phase in Ti–Nb and Ti–Mo Alloys Subjected to HPT

This paper discusses the features of ω-phase formation and its thermal stability depending on the phase composition, alloying element and the grain size of the initial microstructure of Ti–Nb and Ti–Mo alloys subjected to high-pressure torsion (HPT) deformation. In the case of two-phase Ti–3wt.% Nb and Ti–20wt.% Nb alloys with different volume fractions of α- and β-phases, a complete β→ω phase transformation and partial α→ω transformation were found. The dependence of the α→ω transformation on the concentration of the alloying element was determined: the greater content of Nb in the α-phase, the lower the amount of ω-phase that was formed from it. In the case of single-phase Ti–Mo alloys, it was found that the amount of ω-phase formed from the coarse-grained β-phase of the Ti–18wt.% Mo alloy was less than the amount of the ω-phase formed from the fine α′-martensite of the Ti–2wt.% Mo alloy. This was despite the fact that the ω-phase is easier to form from the β-phase than from the α- or α′-phase. It is possible that the grain size of the microstructure also affected the phase transformation, namely, the fine martensitic plates more easily gain deformation and overcome the critical shear stresses necessary for the phase transformation. It was also found that the thermal stability of the ω-phase in the Ti–Nb and Ti–Mo alloys increased with the increasing concentration of Nb or Mo.     

Initial Abdominal CT and Laboratory Findings Prior to Diagnosis of Crohn’s Disease in Children

PurposeTo identify initial abdominal computed tomography (CT) and laboratory findings prior to a diagnosis of Crohn’s disease (CD) in children.Materials and MethodsIn this retrospective study, patients (≤18 year-old) who were diagnosed with CD from 2004 to 2019 and had abdominal CT just prior to being diagnosed with CD were included in the CD group. Patients (≤18 years old) who were diagnosed with infectious enterocolitis from 2018 to 2019 and had undergone CT prior to being diagnosed with enterocolitis were included as a control group. We assessed the diagnostic performances of initial CT and laboratory findings for the diagnosis of CD using logistic regression and the area under the curve (AUC).ResultsIn total, 107 patients (50 CD patients, 57 control patients) were included, without an age difference between groups (median 13 years old vs. 11 years old, p=0.119). On univariate logistic regression analysis, multisegmental bowel involvement, mesenteric vessel engorgement, higher portal vein/aorta diameter ratio, longer liver longitudinal diameter, lower hemoglobin (≤12.5 g/dL), lower albumin (≤4 g/dL), and higher platelet (>320×10³/µL) levels were significant factors for CD. On multivariate analysis, multisegmental bowel involvement [odds ratio (OR) 111.6, 95% confidence interval (CI) 4.778–2605.925] and lower albumin levels (OR 0.9, 95% CI 0.891–0.993) were significant factors. When these two features were combined, the AUC value was 0.985 with a sensitivity of 96% and specificity of 100% for differentiating CD.ConclusionMultisegmental bowel involvement on CT and decreased albumin levels can help differentiate CD from infectious enterocolitis in children prior to a definite diagnosis of CD.     

Quasi-Static Compression Response of Carbon Fiber Reinforced 2.5D Woven Composites at Different Loading Directions

2.5D woven composites have been increasingly used in aerospace and military applications due to their excellent mechanical properties. In this research, 2.5D woven composites were produced, and their compression responses were investigated in different directions by compression experiments. XR-CT (X-ray computed tomography) technology was used to observe the microstructural damage profiles, and to analyze the failure mechanism of the material. The results show that when subjected to compression loads, the maximum load-bearing capacity of the material in the thickness direction was better than the maximum load-bearing capacity in the warp and weft directions. The compressive strength of the material in the warp and weft directions was lower than that in the thickness direction, and compression damage patterns in each direction also differed.     

X-ray Fluorescence Analysis of Pigments in Gothic Frescoes,Coats of Arms,and Polychromy on Sculptures on the Triforium in St. Vitus Cathedral on the Territory of the Czech Kingdom in the 14th Century

Pigments in the paints used for the coats of arms, polychromy on sculptures, and pigments in frescoes characterize not only the epoch but also individual creators or groups of artists involved in their creation. X-ray fluorescence analysis is a non-destructive method suitable for determining the chemical composition of these artifacts. This article covers the results of measurements of selected objects, and compares them with similar objects from the territory of the Czech Kingdom in the 14th century.     

Position-Sensitive Bulk and Surface Element Analysis of Decorated Porcelain Artifacts

Non-destructive characterization of decorated porcelain artifacts requires the joint use of surface-analytical methods for the decorative surface pattern and methods of high penetration depth for bulk-representative chemical composition. In this research, we used position-sensitive X-ray Fluorescence Spectrometry (XRF) and Prompt-gamma activation analysis (PGAA) for these purposes, assisted by 3D structured-light optical scanning and dual-energy X-ray radiography. The proper combination of the near-surface and bulk element composition data can shed light on raw material use and manufacturing technology of ceramics.