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。     

乳腺癌的钼靶X线摄影与计算机后处理

本文报告使用ASR-3000钼靶乳腺X线机乳腺摄影时的投照条件、体位与冲洗条件。结果：除病灶为致密增生的致密影遮盖的4例由超声检查检出外，各例乳癌的结节影或细小钙化影都得以清晰显示。乳腺X线机与CR设备结合，应用IP板代替胶片记载影像信息，经读取装置读出再转换为数字信息经计算机处理与图像重建，能增强病灶信息。抑制致密增生腺体的信息而增高病灶的检出率，故明显提高诊断的准确率与扩大诊断范围。     

优化组合CR系统自动曝光控制成像参数

目的:优化组合CR系统自动曝光控制成像参数.材料和方法:采用两种规格的成像(IP)板,用不同组合的成像参数对胸部拟人水模摄影,检测电离室密度补偿与曝光参数的变化.以所得成像数据和两种规格的IP板,对A、B、C三组患者(每组各180例),不同部位摄影,检测不同曝光剂量组合摄影的影像质量和影像的密度值.结果:A组以两种规格的IP板、125kV摄胸部,图像对比度差;病灶细微结构显示不清.以73～85kV摄胸部,其图像明显好于125kV;B组与C组的小规格IP板(20.5cm×25.6cm)优于大规格IP板的(35cm×35cm)图像质量;影像密度值均在0.8～1.30范围内.结论:CR系统不宜采用高kV摄影;应使用合适规格的成像板.     

CR与普通摄影曝光剂量和剂量当量的比较

目的比较CR与普通摄影曝光剂量和受照剂量当量大小。方法通过热释光测量计、线对卡等工具,对中速屏-片、感绿屏-片及IP板3种影像载体的曝光剂量和剂量当量均值进行检测与比较。结果显示2.0L.P/mm时,IP板曝光剂量只有中速屏-片的5%、感绿屏-片的33%,剂量当量均值是中速屏-片的3%、感绿屏-片的35%。而显示4.0L.P/mm时,IP板曝光剂量接近中速屏-片的200%、感绿屏-片的950%,剂量当量均值是中速屏-片的180%、感绿屏-片的1110%。在2.5~3.2L.P/mm范围内,IP板的曝光剂量分别是中速屏-片的50%~75%、感绿屏-片的220%~290%,剂量当量均值又分别是中速屏-片的37%~66%、感绿屏-片的190%~270%。结论在2.5~3.2L.P/mm内,CR的曝光剂量和剂量当量均值比中速屏-片低约1/2~3/4倍mAs、1/3~2/3倍mSv,但比感绿屏-片高约2~3倍mAs、2~3倍mSv。在这一范围内投照,均可获得优质的影像。     

CR系统在头颈部的应用

计算机X线摄影(computedradiography ,CR)由于其强大的后处理功能,一次曝光即可通过对兴趣区调整窗宽、窗位,克服常规X线摄影一次曝光后难以同时显示骨与软组织,从而使X线诊断更趋于全面、完整。本文就CR系统在头颈部应用的优势进行阐述。材料与方法本院于2 0 0 1年7月一次性安装了3台ACR 2 0 0 0i成像板读出装置,通过它获得直接数字投照X线照片影像。用10in×12in( 2 5cm×3 0cm )和8in×10in( 2 0cm×2 5cm )ST V型成像板,把用常规X线摄影条件进行头颈部投照过的成像板从暗盒中取出,并放入扫描仪,5 0s后一张2k×2 .5k×12bit的国际…     

乳腺钼靶X线摄影在CR系统中的应用

乳腺钼靶X线摄影是使用乳腺专用IP板，利用CR成像系统，将IP板上记录的信息经过激光扫描和计算机处理，最终将图像显示在荧光屏上，从而得到一张层次分明，清晰度优良的X线照片，达到诊断乳腺疾病的目的。     

乳腺计算机X射线摄影自动曝光模式的校正

目的 通过参照乳腺屏一片系统摄影自动曝光控制模式,对乳腺CR摄影自动曝光进行校正,从而实现影像质量与辐射剂量的最优化.方法 应用屏-片组合,28 kV条件下,对40 mm厚的有机玻璃进行自动曝光,以此所得曝光量(mAs)为基准,分10档分别采用±10 mAs的曝光量用CR进行曝光,选取LgM=2.0的曝光量作为基准,对CR的自动曝光模式进行校正.采用经校正后的CR自动曝光模式,分别采用26、28和30 kV对Fluke NA 18-220乳腺模体进行摄影,模体采用自动曝光控制(AEC)模式进行摄影,记录曝光量数值(mAs),对CR影像进行处理.同时CR采用相同的kV和照射野及不同的曝光量对模体进行摄影.CR影像经后处理后请4位放射医师进行双盲阅片,按照美国放射学会(ACR)的评分标准评价打分.结果 采用稍高于传统屏-片组合的曝光量作为cR自动曝光校正基准值,可实现乳腺CR摄影自动曝光模式的校正,经校正后模体测试影像的评分均高于ACR的评分标准.结论 乳腺CR摄影自动曝光模式可根据CR特点进行校正,经校正后的乳腺CR摄影的自动曝光控制模式应用于临床既町明显降低病人辐射剂量,又可得到满足临床诊断需求的优质乳腺影像.     

乳腺计算机X射线摄影自动曝光模式的校正

目的 通过参照乳腺屏一片系统摄影自动曝光控制模式,对乳腺CR摄影自动曝光进行校正,从而实现影像质量与辐射剂量的最优化.方法 应用屏-片组合,28 kV条件下,对40 mm厚的有机玻璃进行自动曝光,以此所得曝光量(mAs)为基准,分10档分别采用±10 mAs的曝光量用CR进行曝光,选取LgM=2.0的曝光量作为基准,对CR的自动曝光模式进行校正.采用经校正后的CR自动曝光模式,分别采用26、28和30 kV对Fluke NA 18-220乳腺模体进行摄影,模体采用自动曝光控制(AEC)模式进行摄影,记录曝光量数值(mAs),对CR影像进行处理.同时CR采用相同的kV和照射野及不同的曝光量对模体进行摄影.CR影像经后处理后请4位放射医师进行双盲阅片,按照美国放射学会(ACR)的评分标准评价打分.结果 采用稍高于传统屏-片组合的曝光量作为cR自动曝光校正基准值,可实现乳腺CR摄影自动曝光模式的校正,经校正后模体测试影像的评分均高于ACR的评分标准.结论 乳腺CR摄影自动曝光模式可根据CR特点进行校正,经校正后的乳腺CR摄影的自动曝光控制模式应用于临床既町明显降低病人辐射剂量,又可得到满足临床诊断需求的优质乳腺影像.     

乳腺钼靶X线摄影在CR成像中的应用

高质量乳腺X线摄影是医生正确诊断乳腺疾病的基础。由于普通乳腺钼靶摄影受到暗室条件、机器性能、曝光条件、技术参数等多方面因素的影响，所以通过普通乳腺摄影获得高质量的乳腺图像比较困难。而我院通过使用乳腺专用IP板，利用现有的CR处理系统，实现了由普通钼靶X线摄影技术向半数字化成像技术的转化。通过适当调节机器的技术参数和图像的后处理，使乳腺摄影过程更加简单、     

CR与DR在下肢全长摄影中的应用比较

目的：探讨数字化摄影中,下肢全长CR1次成像和DR多次成像方法的实际应用。方法：40例被检者下肢全长CR1次曝光成像,在CR系统内合成下肢全长;40例DR系统进行多次曝光成像,在DR图像处理系统中合成下肢全长,对投照方法和图像的合成进行比较。结果：1次曝光CR组40例,多次曝光DR组32例,所合成双下肢全长图像清晰,能满足临床应力线的测量,下肢全长1次曝光CR成像操作简便,图像视觉连贯性和密度均匀性优于多次曝光DR成像。结论：下肢全长CR1次曝光更具有推广价值。     

Noise properties in the fading of the imaging plate on a computed radiography system

Fading of the imaging plate (IP) in computed radiography (CR) systems with photostimulable phosphors is known well. The relation between noise properties and the fading of the IP in a CR system was investigated. Uniform exposure for the IP with various times between exposure and readout for the same exposure was used for this study. The relative intensity of photostimulated emission and the digital Wiener spectra were calculated. The relative intensity of photostimulated emission decreased with increasing time, whereas Wiener spectral values showed no difference with increasing time. We concluded that noise properties were not affected by the fading of the IP in the CR system.     

Measurement of focal spot in X-ray tube using imaging plate

Comparisons of focal-spot size measurements with a direct-exposure X-ray film, screen-film (S/F) system, and imaging plate (IP) were carried out for slit and star resolution pattern camera techniques. The focal-spot measurements of X-ray units with the nominal size of 0.1-1 mm were performed, and measurement using the computed radiography (CR) system was investigated. Compared with the direct-exposure X-ray film method, the measurements of focal-spot size by the S/F system were slightly small for all focal spots. The measurements obtained with IP were slightly large for large and small focal spots, although the measurement of micro focal-spot size was overestimated, extending the tolerance level owing to the sampling. With the star pattern camera technique, differences between the three kinds of detectors were minimal. Therefore, it was thought that measurement of focal-spot size using the CR system would be practical for both large and small focal spots if this method were used for quality control in medical facilities.     

Effects of collimator size of a dental X-ray unit on image contrast.

OBJECTIVES: To examine the effect of collimator size on image contrast in dental radiography. METHODS: Two conventional collimators, one circular (53 mm in diameter) and one rectangular (35x45 mm2), were compared with a small rectangular collimator (26x39 mm2). Low-contrast and high-contrast resolution was assessed with the aid of contrast-detail and line-pair phantoms. RESULTS: Shallower holes were observed with the small rectangular collimator. Two-thirds of 17 observers assessing high-contrast resolution considered the small collimator to result in a clearer image than the conventional collimators. The same effect was demonstrated with the line-pair phantom and by microdensitometry. With the small collimator the energy imparted is estimated to be reduced by 54 and 36% compared with the conventional circular and rectangular collimators respectively. CONCLUSIONS: Decrease of the collimator size to fit the film size used for children will result in improved low-contrast and, under some conditions, improved high-contrast resolution. This improvement might have implications for caries diagnosis and monitoring.     

Clinical experiences with computed radiography

Computed radiography (CR) based on photostimulable phosphor is currently the only feasible way for a radiological department to digitize the bulk of radiological data: the lung and skeletal examinations. Regarding the quality of images for diagnostic purposes, CR imaging is never inferior to a screen/film system (SF) and for several clinical entities CR is superior. Of the many processing possibilities of the image plate (IP) image, the unsharp masking or edge enhancement should be used at a minimum. Dose reduction with CR ranges from 15% to 95%; at our institution it is 37%. Softcopy reading of CR images is advantageous due to the many postprocessing and improved display facilities. Currently there is little use for a 4000 × 4000 (4 K) pixel imaging and display. All images (including mammograghy) can be read in 2 K without any loss of clinically important information. To include CR in a picture archive and communication system (PACS) is demanding because of the load of data that each CR image represents. Networks for image distribution are essential if digital imaging is to have any impact on patient treatment and hospital organization.     

数字X线照片影像质量相关因素初步分析

目的：探讨影响数字X线照片影像质量的相关因素，提高数字X线照片影像质量。方法：通过分析计算机X线摄影(CR)与直接数字X线摄影(DR)所产生的数字X线照片影像质量相关因素：曝光量与自动曝光控制(AEC)的使用；DR、CR主机(扫描仪)及图像读取工作站；影像板(IP)因素；图像后处理工作站功能；激光打印机等。针对数字X线照片成像的各个环节加以控制。结果：获得优质数字X线照片影像必需做到：选择合适的曝光条件并合理使用AEC；掌握DR主机、CR扫描仪及图像读取工作站的性能特点；保证IP质量及定期清洗保养IP；充分了解并利用好图像后处理工作站的功能；正确设置配套激光打印机参数。结论：了解影响数字X线照片影像影像质量的相关因素，充分发挥数字X线照片影像图像的后处理优势，可以明显提高数字X线照片影像图像的质控水平。     

Evaluation of metal artifact in computed radiography

We know that computed radiography (CR) has many factors to generate artifacts, such as the over / under shoot, aliasing and more. Recently, we encountered an artifact, we call a metal artifact, not attributable to any known factors in clinical images. To elucidate the cause of this artifact, we did some experiments with an in-house phantom. The experiments showed that the metal artifact was seen only when we put an object that absorbs X-rays parallel to the scanning line on imaging plate (IP). From these results, we speculated that the factor causing the afterglow is associated with photo-stimulated luminescence from IP.     

Low contrast detectability of a new CR system with two-sided reading

A new imaging plate (IP) with a transparent support and reading system that can detect emissions from both sides of the IP has been developed and has already been introduced in some facilities. In this study, low contrast threshold detectability was investigated experimentally for a CR system with a two-sided reading system (new CR) and for a conventional CR system. Images of a Contrast-Detail phantom were obtained with the new and conventional CR systems at dose levels corresponding to 26%, 49%, 82%, 103%, and 164% of the dose used for the screen-film system. Using an observer performance study of Contrast-Detail phantom images, the threshold contrast of disk-shaped objects ranging from 0.3 mm to 4.0 mm in diameter was determined. We also calculated image quality figure (IQF) from the results of observation. The new CR system showed significantly better contrast detectability than the conventional CR system. The use of a new CR system provided a reduction of approximately 25% in radiographic dose while providing comparable IQF.     

曝光条件、IP尺寸等与CR照片影像的空间分辨力

目的：探讨曝光条件、IP尺寸等与CR照片影像空间分辨力的关系。方法：依据Siemens点数法曝光条件表，在点数不变的情况下换算出摄影部位手的数组曝光条件，选用四种不同尺寸的IP及大小焦点，分别对矩形波测试卡进行摄影。采用无放大和放大2倍的后处理技术，视读并记录CR照片影像的空间分辨力数值，分析其影响CR照片影像空间分辨力的条件。结果：①摄影部位、曝光条件相同，CR照片影像的空间分辨力，小焦点大于大焦点；②摄影部位、曝光条件及焦点大小相同，CR照片影像的空间分辨力随IP尺寸的增加而减小；③CR照片影像的空间分辨力，放大2倍的照片影像明显高于无放大处理的照片影像；④适宜的曝光条件可提高CR照片影像的空间分辨力。结论：影响CR照片影像空间分辨力的条件：小尺寸IP大于大尺寸IP；小焦点大于大焦点；适宜的后处理放大倍数大于无放大处理；适宜的曝光条件组合大于其它组合。     

Preliminary experience of the study of the hand using digital radiology with photo-excitable phosphors and direct magnification. Comparison with the traditional high resolution technique

Photostimulable phosphor computed radiography (CR) is a new technique. The authors applied direct magnification CR to hand study (IP matrix: 1770 x 2370), and compared the results with conventional radiography ones (high MTF industrial type film, without screens, 5 x optic enlargement reading). In both cases, a mammographic unit was employed for acquiring the images. Thirty patients affected with renal osteodystrophy, psoriatic arthropathy or rheumatoid arthritis, and 20 normal subjects were examined. Digital images were processed by a particular sensitometry curve and spatial filtering with unlinear unsharp masking: we obtained good visualization of small lesions (subperiosteal resorption, cortical bone tunnelling, minute periosteal necrosis), not inferior to that obtained with conventional techniques. CR has further advantages, such as low economic and biological cost, wide exposure and recording range, image processing, easy archiving and networking.     

动态范围压缩技术在CR足部影像中的应用

目的探讨动态范围压缩技术在体厚差别较大的足部CR图像处理中的应用价值。方法回顾性分析成人足部CR图像50例,采用动态范围压缩技术处理用以观察趾周软组织、第1趾甲沟、第5趾骨远侧节、距骨小粱、跟骰关节间隙的清晰显示率,并与常规CR处理图像进行比较。结果经动态范围压缩技术处理后,显示全足组织结构更加清晰,与常规CR图像相比,两者在统计学上存在显著差异(t=7.732,P<0.05)。结论对体厚差别较大的足部CR图像,应用动态范围压缩技术使大量有用信息得以充分利用,能在同一幅图像上同时显示软组织、骨骼及关节结构,具有较大的临床应用价值。