X 线平片与三维 CT 检查在胫骨平台骨折评估中的应用价值?

目的：通过比较 X 线平片与三维 CT 检查对胫骨平台骨折损伤评价的信度和效度,探讨 X线平片与 CT 检查的应用价值。方法：回顾性分析2015年1月至2016年1月间收治的32例胫骨平台骨折损伤的病例,分别使用 X 线平片和三维 CT 检查对骨折损伤程度及部位做出判断,对骨折特征进行分析,对结果的效度进行判断（金标准为手术记录所描述）,并用 McNemar 检验比较 X 线平片和三维 CT 判断结果。结果：胫骨平台骨折三维 CT 重建在外柱诊断优于 X 线平片（P =0.031）,对骨折分型具有更高临床价值。结论：使用三维 CT 检查能够提高对胫骨平台骨折损伤评价的可靠性和准确性,可更好指导诊断及治疗方案的制订。     

Timing and occurrence rate of X-ray plasma ejections

We examined 126 limb flares formed between October 1991 and August 1998. X-ray plasma ejections were found in 54 flares. All the X-ray plasmoids were detected in images taken before the maximum peak of hard X-ray (HXR) emission or in each of the first image after the HXR peak. In our choice of 57 flares which Yohkoh started to observe before the HXR peak, with the soft X-ray telescope aboard, X-ray plasma ejections were found in ∼63–70% of these flares. We found X-ray plasma ejections in 100% of X-class flares and 74–82% of M-class flares, whereas only 31–38% of C-class flares have X-ray plasma ejections. It is difficult to detect X-ray plasma ejections in C-class flares, because the scale size and lifetime of ejections are short. We propose that solar flares including microflares occur through magnetic reconnection and that X-ray plasma ejections are general phenomena associated with solar flares.     

新型冠状病毒肺炎的X线及CT表现

目的:总结新型冠状病毒肺炎(2019-nCoV)的X线、CT表现,为临床提供影像学诊断依据。材料与方法:收集2020年1月21日至2月25日我院发热门诊的1028例患者,均进行X线检查,其中18例核酸检测确诊为2019-nCoV,6例同日行CT检查,9例于1周内进行影像学复查。结果:18例确诊的2019-nCoV患者,4例X线表现为肺纹理增重,14例X线表现为肺内单发或多发病灶。好发部位为肺下叶,单侧肺下叶病灶9例,双肺下叶病灶3例,双下肺合并双肺上叶病灶2例。6例同日进行CT检查,1例CT正常,3例发现X线胸片未显示的小片状磨玻璃影,2例CT显示的病灶较X线片多,CT表现以双肺胸膜下分布为主,可伴空气支气管征且小叶间隔增厚。6例患者1周内复查X线片,3例复查CT,其中1例CT显示磨玻璃影吸收,8例显示病变进展,范围较前增大和病灶增多,以双下肺外带为著。结论:新冠肺炎胸部X线及CT表现具有一定的特征性,结合临床病史和实验室检查可作出明确诊断。      

士兵胫骨应力性骨折的影像评分与临床表现相关分析

目的:明确士兵胫骨应力性骨折患者不同影像学评分与临床表现之间的相互关系,增强对士兵胫骨应力性骨折的认识。方法:本研究共纳入34例参加军事训练出现胫骨应力性骨折的士兵患者,所有对象平均年龄为19.1岁。所有患者分别由骨科医生及影像科医生采用X线、MRI扫描及CT扫描来评价胫骨应力性骨折的严重程度。同时由骨科医生对临床严重程度评分进行评价。统计学分析不同影像学检查评分与临床严重程度之间的相互关系,影像学检查评分与治愈时间之间的关系以及评价不同医生采用不同影像学设备评价患者的可靠性。结果:临床严重程度与患者的X线(r=-0.529,P=0.029)、MRI扫描(r=-0.641,P=0.006)及CT (r=-0.573,P=0.016)影像学评分存在负相关。治愈时间与患者的X线及CT影像学评分无相关性,与MRI扫描的影像学评分虽无相关性,但有相关的趋势(P=0.09)。MRI扫描的可靠性最佳(α=0.849),CT次之(α=0.779),X线第三(α=0.623)。结论:胫骨应力性骨折临床严重程度与X线、磁共振及CT扫描影像学评分存在负相关。X线、磁共振及CT扫描影像学评分与治愈时间无相关性。      

CT机器、图像后处理技术的新进展

1）CT机的进展：CT机器自问世以来，随着计算机技术、探测器技术、X线技术的不断及发展以及新的微电子和显微技术不断的应用于CT机，从而提高了CT机的性能，标志着CT扫描从层面扫描到螺旋扫描的换代。2）图象后处理技术：螺旋CT的出现及计算机软件的开发，利用导航技术做出具有3D仿真内窥镜的图象，既（VE），这种新的影像学方法，引起了广泛的关注。     

三维CT与X线片检查跟骨骨折中的应用价值分析

目的:研究三维CT检查和X线片对跟骨骨折损伤评价的准确度及效用,同时探讨其应用价值。方法:选择2017年1月至2018年1月我院收治的32例跟骨骨折病例。分别使用三维CT和X线片检查,并对跟骨损伤程度及部位进行分析,对结果的准确度进行判断（依据为手术术中所见）,并用McNemar检验比较其结果的准确度。结果:跟骨骨折三维CT重建在诊断准确率方面优于X线片,对骨折部位及特征描述具有更高临床应用价值。结论:应用三维CT重建跟骨骨折检查可以有效提高对骨折损伤评价的准确度和效用性,对于临床诊断及治疗均有明确的意义。      

Variations in the natural X-ray background in the polar atmosphere

X-ray intensity variations in the surface layer of the atmosphere during precipitation in Apatity and Spitsbergen were analyzed. Based on a comprehensive system of monitoring over the radiation background, X-ray radiation variations were detected. These variations were found to be associated with meteorological processes in the lower atmosphere. X-ray energy spectra were obtained under good weather and precipitation conditions. These spectra have no characteristic lines inherent to radionuclides. Additional studies make it possible to suggest that the growth in X-ray radiation during precipitation is mainly caused by braking radiation of energetic electrons additionally accelerated by electric fields in rain clouds.     

风云二号C/D卫星与GOES卫星太阳X射线探测数据交叉比对

风云二号卫星是我国研制的第一代静止业务气象卫星.本文针对风云二号C星/D星(FY-2C/D)太阳X射线探测数据与美国GOES系列卫星太阳X射线探测数据开展交叉比对,以检验FY-2C/D卫星数据的有效性.研究结果表明在X射线通量变化的时间特性以及通量大小等方面,FY-2C/D卫星探测结果与GOES系列卫星探测结果具有较好的一致性.对2004年11月—2010年6月期间85次耀斑事件X射线峰值流量的比对结果表明,FY-2C卫星与GOES系列卫星的探测结果在1~8 Å波段的相关系数为0.795,FY-2D卫星与GOES系列卫星的探测结果在0.5~3 Å和1~8 Å波段的相关系数分别为0.921和0.989,说明FY-2C/D卫星太阳X射线探测结果可信度较高,能够用于太阳X射线耀斑的监测、预警以及研究工作.     

MSCT和X线平片在诊断腰椎滑脱症中的临床价值比较

目的:比较X线平片和多排螺旋CT诊断腰椎滑脱的准确性,并评价临床价值。方法:搜集40例经X线平片、MSCT检查诊断并手术治疗的腰椎滑脱患者,X线平片和MSCT判定腰椎滑脱程度、部位、类型的结果与手术对照。结果:40例患者,27例手术证实为真性滑脱,13例为假性滑脱。以手术为对照,X线平片、MSCT诊断腰椎滑脱程度和部位准确率为100%;X线平片判定腰椎滑脱类型的敏感性、特异性、阳性和阴性预测值为分别为59.3%、100%、100%和54.2%;MSCT判定滑脱类型的敏感性、特异性、阳性和阴性预测值均为100%;X线平片和MSCT对滑脱类型判定具有明显统计学差异(P0.01)。结论:X线平片、MSCT判定腰椎滑脱程度和部位均具有较高的准确性;判定腰椎滑脱类型,MSCT比X线平片好,X线平片目前仍是基本的筛查方法,MSCT进一步明确腰椎滑脱类型诊断,为临床提供更多的影像信息和治疗方案。     

9 MeV工业CT系统下一种简单的 线衰减系数测定方法

在考虑选择射线源能量、计算射线源的穿透能力或研究材料屏蔽性能时,被检测材料的线衰减系数是一个重要参数。本文基于9 MeV工业CT系统,提出一种简单的线衰减系数测定方法,对CT检测工作中常见的铝（Al）、钨（W）和钢（Fe）材料进行线衰减系数的测定。首先,选取不同厚度的金属材料,分别放置于探测器与射线源之间,使中心射束垂直透过金属材料;然后分别读取不同厚度金属材料下探测器通道的示数,通过线性拟合计算出被检测材料的线衰减系数;最后将测定结果与文献和NIST数据库中的结果进行比较。结果表明,通过实验测定的三种材料的线衰减系数比较准确,实验结果可用于相同材料的CT检测中,也可采用本文方法计算其他材料的线衰减系数。      

腰腿痛病例临床影像学分析

目的：分析腰腿痛的病因,探讨影像学检查对腰腿痛病因诊断的作用。方法：对198例腰腿痛病例的影像学资料进行回顾性分析。结果：X线平片显示腰腿痛病因阳性率为89．4％;CT诊断阳性率为96．7％,其中腰椎间盘突出症144例;在X线及CT诊断阴性结果25例中,MRI诊断椎管内肿瘤2例,转移瘤3例,早期强直性脊柱炎8例。结论：腰腿痛病因复杂,腰椎间盘突出为最常见的病因,X线平片可以作为必不可少的筛选方法,MRI应作为首选的方法,特别是对椎管肿瘤的病例,在条件不许可情况下,CT可以替代MRI进行检查,CT扫描对腰椎间盘突出症有较高的诊断价值。     

CTX射线能谱滤过器的优化设计

采用蒙特卡罗方法对CTX射线能谱滤过器的优化设计进行了研究。使用EGSnrc软件对电子打靶产生X光子的物理过程和X光子穿过不同滤过器的物理过程进行了模拟,从信噪比的角度给出了优化设计的依据和计算公式。结果表明,滤过器设计存在最优化的设计参数,但是在不同的成像条件和成像要求下,其最优化参数是不同的,需要根据具体的条件来确...     

小型移动CT扫描仪的焦皮距问题研究

最小焦皮距是国标中限制CT扫描仪小型化的一个关键参数。本文介绍焦皮距的物理意义,分析X射线透视成像和X射线计算机断层成像的异同,以及滤过器在X射线计算机断层成像中对扫描孔内吸收剂量分布的重要影响。实验证明,由于滤过器的作用,大、小CT扫描仪扫描孔内的吸收剂量分布都是中心区域高、内壁区域低。源自X射线透视成像的最小焦皮距概念,在断层成像中不能发挥同样的作用,但是会限制CT扫描仪小型化的发展。      

基于风云二号X射线监测数据的短波通讯可用频率预报

介绍了风云二号气象卫星空间环境探测资料的处理、显示技术。研究了如何利用风云二号X射线探测数据计算短波通讯最低可用频率及电离层D层的电波吸收,并设计了一个基于风云二号X射线探测数据的短波通讯最低可用频率经验预报模式。     

X射线断层扫描投影图像背景不一致的校准

在X射线断层扫描(X-ray CT)成像过程中,经常会出现射线源、样品和探测器三者之间的相对移动,导致采集的投影图像(Projection image)以及亮场图像(flat field image)的空间位置配准关系出现偏差。这直接影响了投影图像背景的正常扣除,以及后续的CT图像重建。本文利用互相关方法,求出各投影图像背景与探测器原始采集位置之间的不一致量。然后将投影图像和亮场图像作相应变换,最后扣除背景得到校准后的图像。由于该方法对图像灰度较为敏感,所以在对实际样品校准之前,本文先对该样品投影图像及亮场图像进行了照度归一化。实验结果表明,该方法能够有效校正由射线源、样品和探测器之间相对移动造成的CT投影图像背景不一致,获得较好的CT投影图像和重建切片。      

Global X-ray emission during an isolated substorm — a case study

The polar ionospheric X-ray imaging experiment (PIXIE) and the UV imager (UVI) onboard the Polar satellite have provided the first simultaneous global scale views of the patterns of electron precipitation through imaging of the atmospheric X-ray bremsstrahlung and the auroral UV emissions. While the UV images in the Lyman–Birge–Hopfield-long band used in this study respond to the total electron energy flux which is usually dominated by low-energy electrons (<10 keV), the PIXIE images of X-ray bremsstrahlung above ∼2.7 keV respond to electrons of energy above ∼3 keV. Comparison of precipitation features seen by UVI and PIXIE provides information on essentially complementary energy ranges of the precipitating electrons. In this study an isolated substorm is examined using data from PIXIE, UVI, ground-based measurements, and in situ measurements from high- and low-altitude satellites to obtain information about the global characteristics during the event. Results from a statistical study of isolated substorms, which has reported a significant difference in the patterns of energetic electron precipitation compared to the less energetic precipitation are confirmed. A localized maximum of electron precipitation in the morning sector delayed with respect to substorm onset is clearly seen in the X-ray aurora, and the time delay of this morning precipitation relative to substorm onset strongly indicates that this intensification is caused by electrons injected in the midnight sector drifting into a region in the dawnside magnetosphere where some mechanism effectively scatter the electrons into the loss cone. In this study, we also present the results from two low-altitude satellite passes through the region of the localized maximum of X-ray emission in the morning sector. Measured X rays are compared with X-ray fluxes calculated from the electron spectral measurements. By fitting the electron spectra by a sum of two exponentials we obtain fairly good agreement between calculated and directly measured X-ray flux profiles.     

软骨母细胞型骨肉瘤的影像诊断

目的:探究软骨母细胞型骨肉瘤的X线平片、CT及MRI表现和诊断要点.方法:回顾性分析2010年1月至2020年6月我院经病理证实的软骨母细胞型骨肉瘤18例患者的病历资料,分析其X线平片、CT及MRI表现.结果:X线平片和CT显示肿瘤骨(棉絮样瘤骨12例,象牙质样瘤骨3例,针样瘤骨3例)、瘤软骨钙化(沙粒状、斑点状钙化8...     

胸腔积液的X线与CT的对照研究

目的：探讨诊断胸腔积液的价值。方法：通过对照分析了280例胸腔积液X线和CT表现。结果：发现其有特异性表现；结论：对鉴别胸腔积液与炎性病变及良恶性肿瘤等亦起到重要作用。     

Time structure of the X-ray emission of thermal solar flares

Based on observations of electromagnetic radiation, a concept of thermal solar flares has been proposed. The absence of hard X-ray emission implies no accelerated electrons. This fact is the basis of the proposed concept of thermal flares. Since the acceleration rate should not exceed the electron energy loss rate, plasma density in the acceleration range must be at least 10¹¹ cm^?3. The temperature of plasma emitting in the soft X-ray range is of the order of 10⁷ K. In the simplified problem of heated plasma hydrodynamics, we calculated the temperature profiles and their changes over time and by coordinate. The emission measure values determined from observations of the soft X-ray emission of flares is of the order of 10⁴⁵ cm^?3. The geometry of the source is an axial symmetric straight cylinder with a section of 10¹⁶ cm² and an axial coordinate determined by the depth of plasma heating. Time profiles of soft X-ray emission were calculated for different sources of plasma heating, which were simulated using the Gaussian distribution law with respect to the coordinate and time. We have considered two modes of plasma heating: single (in time) and multipulse modes with different pulse intervals. The dynamics of plasma heating and cooling was shown to control the experimentally observed time profiles of soft X-ray emission. A comparison of numerical results with observational data allows us to confirm the implications of the proposed concept of thermal flares and, in addition, to perform diagnostics of plasma parameters in the emission source.     

导线线圈的射线层析检测

本文选用不同的方法对两个导线线圈进行了射线检测,主要采用透射式工业CT检测和康普顿背散射成像检测两种射线层析检测方法,有效检测了导线线圈内部的缺陷隋况,并指出射线层析检测作为一项新技术和新手段,可充分应用在航天产品的无损检测中。