CR胸部普通条件摄影与高千伏摄影的临床应用

CR(computed radiography)因其具有较强大的图像后处理功能而得到广泛的临床应用。摄影动态范围广从而提高了摄影条件的选择范围，但在使用中我们发现要想使CR图像达到最佳，细微结构显示清晰，曝光条件起决定性作用。本文通过CR胸部普通条件与高千伏摄影影像质量的比较，探讨两者在胸部摄影的临床应用价值。     

常规数字化X线摄影与组织均衡技术在鼻骨外伤诊断的比较

目的：探讨数字化X线摄影（DR）中组织均衡技术在鼻骨外伤诊断中的应用价值。方法：对94例鼻骨外伤患者分别行常规鼻骨侧位摄片,对直接获得的图像和采用组织均衡技术进行后处理获得的图像进行比较,比较两组影像的图像质量情况。结果：常规摄影技术得到的图像需反复调节不同的窗宽、窗位,才能显示密度、厚度不同的鼻骨与软组织;组织均衡技术可在同一帧图像上清晰显示鼻骨及其邻近软组织。结论：采用组织均衡技术能将密度和厚度不同的鼻骨及其邻近组织在同一帧图像上清晰显示。     

数字摄影DR在小儿胸部的应用体会

直接数字摄影（Direct Digital Radiography）是在CR基础上发展而来，是近几年用于临床的新技术，是常规X规摄影的一大飞跃，由于DR处理器有很强的图像处理功能，调整胶片的分辨力，对比度等，从而使我们的摄影条件的幅度极大放宽，DR对细微病变，组织结构能清晰显示。如：肺的纹理，走行，骨骼的骨小梁的排列，软组织层次，关节的边缘，细小的线性骨折等都能充分显示。     

组织均衡技术在DR胸部影像中的应用优势

目的　探讨胸部直接数字化X线摄影 (DR)中 ,采用组织均衡技术的DR图像与标准DR图像的差别。方法　从我院2 0 0 3 -0 5所摄的DR胸部影像中按顺序抽取 10 0例作为分析材料 ,通过运用组织均衡技术对图像进行处理 ,比较组织均衡图像与标准DR图像的差别。结果　运用组织均衡技术的图像 ,同一幅图像上不同体厚部位的细节均可清晰显示 ;标准DR图像需调节不同的窗宽、窗位才能清晰显示不同体厚部位的细节。结论　在直接数字化X线摄影中 ,运用组织均衡技术能明显改善先前受体厚影响而难于观察部分的可视性 ,而又不牺牲其他部分的细节显示     

多层螺旋CT多平面重建在腰椎小关节损伤中的诊断价值

目的：讨论MSCT多平面重建（MPR）诊断腰椎小关节损伤的临床价值及扫描中的技术探讨。方法：MSCT行腰椎扫描48例，扫描范围L3-S1椎体及椎间盘。所有病例均拍摄腰椎正侧位及双斜位DR片。扫描重建层厚1．25mm，间隔1．0mm，将数据传至工作站行MPR处理：对所得重建图像同X线平片及CT横断面图像进行对比分析。结果：重建后图像可以在不同角度清晰显示腰椎小关节病变，对细小关节面及椎间盘显示清楚。结论：多层螺旋CT多平面重建清晰显示腰椎小关节病变全部细节，对外科制定正确治疗方案有重要价值。     

64层VCT后处理重建对手足关节疾病的评价

目的 探讨多层VCT(MSCT)后处理重建技术在手足关节疾病诊断中的应用价值.方法 对50例手、足关节病变行MSCT扫描.并进行后处理重建,重建技术有多平面重建(MPR)、表面遮盖(SSD)、最大密度投影(MIP)和容积再现(VR),分析病变情况.结果 骨折33例,X线共发现骨折40处,MPR、VR共发现51处.7例涉及关节面的骨折,VR和MPR显示最佳,清晰显示骨折全貌.SSD很好显示骨折脱位周围软组织、皮肤表面血管.4例石膏外固定的病人运用MIP成像,对比平片得到更为清晰的骨的三维图像.结论 64层VCT后处理重建技术在手足关节疾病诊断中具有很高的应用价值.     

CR在双下肢全长投照技术中的应用

目的探讨计算机X线摄影(computed radiology,CR)技术在双下肢全长投照中的应用。方法用普通500mAX线机对双膝关节畸形(如膝关节内外翻)的病人进行投照,视病人身高情况采用2~3个成像板(IP)连接起来同时投照。经过后处理技术,得到双下肢全长(髋关节至踝关节)的完整图像。结果所获得的双下肢全长的图像,不仅是从髋关节到踝关节都能清晰地显示,而且图像完整,并可经过后处理的其它一些功能进行长度测量、角度测量、真实放大等的应用。结论合理应用CR的投照技术和图像后处理技术,就能达到双下肢全长拼接的优质图像。     

16层螺旋CT重建技术与CR在鼻骨骨折诊断中的对照分析

目的：评价16层螺旋CT三维表面遮盖法重建技术（surfsce shaded display．SSD）及多层面重建技术（multiplanar reconstruction，MPR）与CR（computedr．radiography）在诊断鼻骨骨折中的应用价值。方法：分析98例鼻骨骨折的SSD、MPR和CR的表现。结果：98例患者均有经SSD、MPR技术重建的图像及CR鼻骨侧位像。MPR对鼻骨骨折显示良好。98例患者均能清晰显示并能判断骨折类型；SSD在显示骨折类型方面不及MPR，本组仅显示72例，但立体感强。能清晰显示骨折的部位、程度和范围；CR鼻骨侧位像仅显示58例．而且不能清楚显示骨折类型。结论：16层螺旋CTSSD和MPR结合使用对鼻骨骨折的显示明显高于CR鼻骨侧位像，有较高的临床应用价值。     

颞下颌关节的开、闭口位计算机三维重建及测量

目的:探讨计算机三维重建技术在颞下颌关节开闭口运动研究中的应用。方法:利用生物塑化技术制作1.0mm厚的闭口位、大开口位的颞下颌关节的薄层断面标本,在SGI工作站上对关节盘、髁突等结构进行三维重建及相关测量。结果:计算机三维重建图像可显示闭口位、大开口位时颞下颌关节形态、位置变化及其三维解剖结构关系。重建结构均能单独显示、任意搭配显示或整体显示,并可绕任意轴进行旋转,任意径线及角度均可适时测量。结论:计算机三维重建技术对于颞下颌关节运动解剖研究具有重要应用价值。     

数字X线摄影组织均衡技术在鼻骨外伤诊断中的价值

目的:探讨数字X线摄影(DR)组织均衡技术在鼻骨外伤诊断中的价值。方法:回顾性分析100例鼻骨外伤患者的常规条件DR摄影图像和通过组织均衡技术进行处理的图像,比较两组图像的差别,由3位影像学专家采用双盲法对不同方法产生的图像质量进行评价,主观图像质量分3级(优质、标准、可接受)进行评分。结果:100例应用组织均衡技术得到优质图像75例,标准图像17例,可接受图像8例;而常规条件摄影的优质图像为9例,标准图像18例,可接受图像73例。两种方法产生的图像质量差异有统计学意义(P<0.01)。结论:运用组织均衡技术能使鼻骨的图像质量明显提高,将低密度的鼻骨与软组织以及高密度的头颅骨、眼眶同时显示,图像层次丰富,对清晰显示侧位鼻骨极有价值。     

Direct radiographic magnification with computed radiography

Computed radiography was combined with a 0.1-mm microfocus radiographic tube to obtain radiographic magnification of a x3 to x5. Gray-scale image processing compensated for the loss of radiographic contrast associated with the high-kilovoltage, short-exposure technique. The high-pass spatial frequency filtering capability of the computed radiography resulted in enhanced edges and increased displayed latitude. The improved image quality obtained by magnification computed radiography allowed delineation of subtle abnormalities and small anatomic structures not apparent on conventional screen-film contact or magnification radiographs.     

Image enhancement using computed radiography

Computed radiography (CR) is emerging as a digital imaging modality for use in conventional radiography. An advantage of CR over film-screen systems is the separation of image acquisition, processing and display. Selection of many different image display characteristics are possible. The system is also able to alter or enhance image details after the radiographic examination has been completed.     

Digital radiography in an intensive care unit

Mobile chest radiographs obtained in the intensive care unit with a computed radiography system (one of the digital radiography systems) and a conventional screen-film technique were initially compared in 54 pairs. Features such as the air spaces and interstitium of the lungs, the mediastinum, pulmonary vessels, the tracheobronchial tree, and catheters and other devices were compared in both methods. The computed radiography system demonstrated good visualisation of the mediastinum, pulmonary vessels, the tracheobronchial tree, catheters and other devices. Automatic adjustment of the sensitivity and the wide dynamic range of this system were thought to be responsible for the decrease in the number of retakes even in patients with massive fluid collections. The few artefacts created by digital processing were mostly overcome by a routine use of simultaneous display of two different types of image processing.     

数字X线摄影系统中低剂量应用的探讨

目的 通过数字X线摄影系统（DR）在胸部摄影检查中的应用评价DR的低剂量的优越性。方法 利用CDRAD 2.0低对比细节体模评价计算机X线摄影（CR）和DR的影像质量和表面空气吸收剂量（ESD）关系,分别利用两个系统（DR使用ESD约为CR的1/3）得到成人胸部30幅影像。由6位影像科医生来评价以上两者的影像系统对于肩胛骨内侧边缘等胸部结构的清晰程度。结果 CR影像和减少ESD的DR影像在影像诊断质量上差异没有统计学意义（P＞0.05）。结论 DR的较好的分辨率和低噪声特性,以及高DQE有助于减少患者接受的辐射剂量,而不影响诊断质量。     

Combination of multiple pencil-beam imaging to computed storage phosphor radiography: a new method

Computed radiography (CR) with storage phosphors offers a wide dynamic range and improved sensitivity compared to film-screen technology. CR was combined in this study with a prototype multiple pencil-beam (MPB) imaging device which has been shown to be very effective in scatter reduction. The combination was analyzed and compared to the standard technique of grid screening in two ways: a free-response ROC (FROC) analysis was first performed followed by a blinded test arrangement for visual analysis of image quality in a series of computed radiography of the lumbar spine by both the MPB and grid modalities. The results of the FROC study showed a statistically significant (P less than or equal to 0.01) improvement in signal detection. The MPB-CR images of the lumbar spine had more contrast but also a slightly mottled or grainy appearance. Image quality was found good but contrast processing was criticized because it seemed to result in a too steep display of contrast in MPB imaging. This should be avoidable by changing the image processing parameters.     

A comparison of low contrast performance for amorphous Silicon/caesium iodide direct radiography with a computed radiography: A contrast detail phantom study

A range of digital image acquisition devices exists in diagnostic radiology. This study compares contrast performance of two such systems: an amorphous Silicon/caesium iodide (a-Si:CsI) based flat panel (DR) digital chest radiography system and a computed radiography (CR) system. Images of a contrast detail resolution phantom were acquired at a range of radiation doses. Three observers assessed all hardcopy images using a four-alternative forced choice observer perception technique. Contrast detail performance was calculated and low contrast performance quantified.The DR system demonstrated significantly better low contrast performance and potential dose savings of up to 75% compared to the CR system. Threshold levels of contrast detail resolution were defined and levels of under- and over-exposure, compared to the threshold level, were highlighted. Both systems were noise limited at lower exposures and latitude limited at higher exposures. The results demonstrate that the DR system should perform better than the CR system under typical clinical conditions relevant to chest radiography particularly for the detection of low contrast details such as lung metastases or pneumothoraces.     

Artefacts found in computed radiography.

Artefacts on radiographic images are distracting and may compromise accurate diagnosis. Although most artefacts that occur in conventional radiography have become familiar, computed radiography (CR) systems produce artefacts that differ from those found in conventional radiography. We have encountered a variety of artefacts in CR images that were produced from four different models plate reader. These artefacts have been identified and traced to the imaging plate, plate reader, image processing software or laser printer or to operator error. Understanding the potential sources of CR artefacts will aid in identifying and resolving problems quickly and help prevent future occurrences.     

Comparison of traditional methods and digital technics in the study of the biliary and pancreatic systems using endoscopic retrograde cholangiopancreatography (ERCP)

ERCP holds a key role in the diagnosis of pancreatic-biliary disease. In this technical paper the authors report their experience with computed radiography (CR) in ERCP diagnostic imaging. A stimulable phosphor system was employed (Toshiba TCR-201). Fifteen pancreatic-biliary patients were studied with both conventional and CR techniques. With the same diagnostic output and radiological system, CR was superior to conventional technique in: dramatic exposure-time reduction, image post-processing (exposure error amendment, contrast change, spatial filtering, zooming, gray-scale inversion, etc.), patient exposure reduction, and digital archiving.     

Stomach and duodenum: radiographic magnification using computed radiography (CR)

We performed direct radiographic magnification (X3) using a 0.1-mm microfocal tube and computed radiography (CR) in air-barium double-contrast studies of the stomach and duodenum. To eliminate blurring of the image due to motion, we used the maximum kilovolt peak rate possible (102 kVp), the maximum milliampere second rate possible (64 mAs), the shortest possible exposure time (0.1 second), and a horizontal x-ray beam. With the patients in the supine position, CR provided the wide image reproduction range required to obtain satisfactory radiographs. Image processing in the CR system produced radiographs with increased radiographic contrast and enhanced edge definition of anatomic borders or pathologic processes. The duodenal villi were clearly visible in 45% of the cases.     

The scatter-to-primary ratio as a function of varying X-ray absorption measured by computed radiography.

Some scatter studies have previously been conducted using film as a detector. The serious limitations caused by the narrow latitude, the non-linear density response, and the required optical densitometric measurements of film can be avoided by computed radiography (CR) which provides linear numeric data over a wide dynamic range. The imaging plate is used as a large-area detector and the data is analyzed from the computer memory. Variation in the scatter-to-primary ratio within an image caused by absorption differences was simulated in a water-aluminum phantom. The measurement technique showed repeatable results, being comparable to the values expected on the basis of previous studies. A multiple pencil-beam (MPB) imaging device was also compared to a standard 1:12 grid by this technique. The maximal scatter-to-primary ratio in our model was up to 7.9 with no scatter reduction, 1.5 with grid, and 0.4 with the MPB device. The variation caused by the absorption of primary radiation was much less in the MPB modality, and the MPB system was also less sensitive to an increase in the used tube voltage from 60 to 120 kVp. The benefits of multiple pencil-beam imaging in scatter reduction are briefly discussed.