CR胸片图像质量的影响与控制

计算机X线摄影（Computer radiography，CR）的发展已有20多年的历史，而在我国应用于临床还不到10年。CR系统可与原有X线摄影设备配套工作，实现了常规X线摄影数字化，具有后处理功能大，图像信息丰富，可以远程传送等优点，现已被各级医院放射科广泛应用，但在实际操作过程中，有诸多因素仍可影响CR图像质量，进而影响X线诊断，因此有必要对如何保证CR图像质量进行探讨，分析其影响的因素及处理措施，从而有效地保证CR图像质量，为临床提供优质的X线诊断。我院自2001年使用AGFACR系统以来，笔者抽取了已打印出的胸片10000张．本文着莺对CR胸片图像质量进行分析，总结经验与教训，进行探讨。     

在CR设备上建立放射科RIS管理系统的应用

我院2002年初购人2套AGFIA-CR设备，使用一年多以来，与传统的屏一胶成像系统相比，CR系统获取图像的信息量更大，通过窗宽／窗位的调节，图像放大等后处理功能，明显提高了图像质量，降低了废片率，提高了诊断质量，但是登记、诊断报告还是采取传统的手写方式，报告的储存及查阅极不方便，另外与其它的大型仪器如数字胃肠机、DSA等设备未能形成网络系统，造成管理工作的不便及资源的浪费。因此我科于2004年初建立了RIS管理系统，提高了放射科办公自动化，增强了内部事务管理的效率，初步完成了放射科RIS的建设。笔者谨就其应用介绍如下。     

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。     

CR的质量控制与质量管理

CR(computed radiography，CR)即计算机X线摄影．是使用荧光物质影像板(imageplat，IP)作为记录载体替代传统的屏／片系统来形成X线影像，再把储存于IP上的X线影像信息用激光扫描装置读出输入计算机进行图像数字化处理，获取高质量的X线图像，最后传输保存到PACS或打印记录于胶片上。我院于2003年初安装了一台美国通用SPl001型CR系统，现将其使用中的质量控制与质量管理经验总结如下：     

CR系统的科学使用与维护保养探讨

计算机X线摄影(computd radiography,CR))实现了X线摄影的数字化，使其图像质量得到明显提高。CR系统作为一套计算机技术与高精密机械技术相结合的设备，其性能的稳定性与日常工作中的科学使用、维护保养有着十分密切的关系。本院于2002年引进AGFACR系统，在工作中探索出一套使用与管理CR设备的程序与方法，经过近2年的实践，取得良好的效果现介绍如下。     

CR技术常见问题的分析和处理

随着计算机X线摄影（computed radiography，CR）技术的广泛应用，我们日常工作中会遇到一些常见问题，如记录错误、图像伪影、图像倒置、图像噪声、重复打片及打印卡片等。正确分析和处理这些问题，对提高影像质量及工作效率有很大帮助，现就我院在使用过程中出现的问题，作以下分析。     

计算机X线摄影在我国的应用价值

随着计算机技术的不断发展，近年来涌现出一大批以数字方式成像的影像成像设备，计算机X线摄影（Computed Radiography CR）自1981年第一台商用CR系统由日本富士公司推出，经历了几十年发展和技术改进，现已成为临床影像检查技术的主力军，它使摄片检查实现了数字化，并扩大了诊断信息量，提高照片的对比度、清晰度，使甲级片率达85％以上。     

CR床旁摄影的临床应用与质量控制

计算机X线摄影（computed radiography，CR）是影像科数字化X线摄影的开端和过渡，其与常规X线摄影设备相兼容，具有良好的成像性能。强大的图像后处理功能以及网络化，使其在国内各级医院均有应用，并不断普及，尤其是在床旁摄影中的应用，显著提高了床旁摄影的成功率和图像质量。床旁摄影的对象主要是危重患者、严重外伤、术后患者及新生儿等。部分患者带有各种导管、心电监护、呼吸机等装置，由于受多种因素的制约影像质量难以保证。CR在床旁摄影中，激光读取器具有较高的灵敏度，能够检出极强与极弱的信号，IP宽容度大，加之计算机强大的图像后处理功能，因而提高了床旁摄影的成功率、病变显示率和诊断准确率。CR床旁摄影的影像质量控制（quality control，QC）是获得优质图像的关键。     

提高CR照片质量的一些体会

计算机X线摄影术（computd．radiography，CR）简称CR。其成像技术使普通X线检查发生了重大变化，CR摄影技术是把传统的X线摄影技术和计算机处理相结合，不仅实现了X线摄影数字化，而且提高了影像质量，同时数字化成像技术为医学图像存档与传输系统（PACS系统）的发展和应用提供了条件。我院自2003年11月装备了KODAKCR800CR系统至今，通过3年多的使用，在实际工作中，我们认为提高CR照片质量，应注重以下几个问题：     

计算机X线摄影图像伪影的处理

计算机X线摄影(CR)系统以其方便、快捷、图像清晰已在各级医院广泛使用。但在实际操作应用中发现CR图像的伪影直接影响图像质量,进而影响临床诊断。因此,有必要对其进行分析探讨,认识其表现形式及其产生的原因,并采取相应的措施加以处理从而有效的避免,以保证CR图像质量,提高影     

One-shot dual-energy subtraction chest imaging with computed radiography: clinical evaluation of film images

A clinical evaluation of one-shot dual-energy subtraction chest imaging by means of computed radiography (CR) with imaging plates was carried out in a comparison with the original plain CR images. In analyses of chest images of 140 patients, new information, not detected on the original plain CR images, was obtained on subtraction images in 21 patients (15%). Receiver operating characteristic curve studies also verified the superiority of CR subtraction over the original plain CR images for the detection of pulmonary nodules, calcification in a nodule, and rib lesions. Subtraction images complemented the original plain images.     

Registration of two-dimensional cardiac images to preprocedural three-dimensional images for interventional applications

PURPOSE: To evaluate the accuracy and efficiency of rigid-body registration of two-dimensional fast cine and real-time cardiac images to high-resolution and SNR three-dimensional preprocedural reference volumes for application during MRI-guided interventional procedures. MATERIALS AND METHODS: Mutual information (MI) and correlation ratio (CR) similarity measures were evaluated. The dependence of registration accuracy and efficiency on different resolution and SNR parameters, and also on cardiac-phase differences was evaluated in a porcine model. Two-dimensional images were initially misoriented at distances (d) of 2-10 mm, and rotations of +/-5 degrees about all axes. Registration error and computation time were evaluated, and performance was also assessed visually. RESULTS: The maximum registration error using MI (<2.7 mm and <3.6 degrees ) occurred for d = 10 mm, misrotation of +/-5 degrees , and relative SNR = 1. The computation time was 15 seconds for MI and 10 seconds for CR. CONCLUSION: Registration accuracy was not highly dependent on the relative timing, within the cycle, between the two-dimensional and three-dimensional images. Registration using CR was faster than that using MI, although accuracy was marginally higher with MI. J.     

Comparison of film, hard copy computed radiography (CR) and soft copy picture archiving and communication (PACS) systems using a contrast detail test object

This paper describes two experiments where a widely available test object (FAXIL TO20) was used to compare film, hard copy computed radiography (CR) and soft copy picture archiving and communication systems (PACS) images. Baseline images were produced with a fixed mAs. All images were scored by four experienced medical physicists. Contrast detail curves for the three types of images were almost identical. A second series of images was produced with the mAs varying from 1 mAs to 250 mAs. The contrast detail curves were plotted for each mAs value and the wider exposure latitude of CR compared with film was demonstrated. Use of PACS provided no further increase in exposure latitude. The density of the film images increased with mAs but the density of the CR hard copy images remained constant. It is of concern that the wider latitude of the CR images extends to exposures that are much higher than those used for film with no noticeable change in CR image density but with better images at higher exposures, because the potential exists for patient doses to increase. Hard copy CR images provide information about the exposure index which relates to the input dose to the plate and hence approximately to the dose to the patient. However, since such information is currently not available on default soft copy images, the authors suggest that all manufacturers of PACS should provide an indication of dose as a mandatory default setting.     

Image display in the operating room: eliminating the barriers in the transition to filmless radiology

As hospitals endeavor to transition from film-based radioloogy to electronic or filmless radiology, one limitation is an effective means for accessing the electronic image archive during surgical procedures. The dependency on using reference images during surgical procedures is a critical function. Scott & White Memorial Hospital in Temple, TX, has been progressively moving toward an electronic paradigm for access to medical information. As the radiology department began to eliminate film as a medium for image presentation and image archiving, it was realized that the hospital needed to provide an electronic solution for the display of images in the operating room (OR) as reference during the surgical procedure. The goals in this project were, therefore, multifold: provide electronic access to images and image files directly within the operating suites, eliminate lost films, and reduced delays caused by lost or unavailable films. The end solution utilized the same Web-based software for all devices, but varied the hardware to meet the individual's or group's needs. The success in this project was not contained to cost savings in radiology, which was realized by reducing film library personnel and eliminating films printed specifically for the surgical environment, but also in greater magnitude for the hospital in improving efficiency of the OR support staff and by directly stimulating a reduction in the average OR time needed for the surgical procedures.     

Effectiveness of flexible noise control image processing for digital portal images using computed radiography

The purpose of this study was to evaluate the clinical efficacy of flexible noise control (FNC) image processing in off-line computed radiography (CR) portal images. An observer study was designed to compare FNC with multiobjective frequency processing (MFP) in images acquired using a CR portal imaging device (CRPID). The image processing of MFP and FNC used the same data and required no additional irradiation of patients, and all images were printed on 10-bit grey-level dry laser film. Four radiation technologists and one oncologist served as observers and evaluated 40 sets of images for three different treatment sites: brain, lung and pelvis. Six to 10 anatomical landmarks were selected from each treatment site. Each observer was asked to rate each landmark in terms of its clinical visibility and rate the ease of making the pertinent verification in the MFP- and FNC-processed images. In the ratings of the visibility of landmarks and for the verification of treatment ports, FNC-processed images were more visible than MFP-processed images except for several landmarks in the anteroposterior (AP) pelvis such as the pubic symphysis. The visibility of landmarks in FNC-processed images was comparable with that in MFP-processed images. The verification of treatment ports using the CRPID with FNC was generally achievable. In conclusion, this study suggests that FNC is effective for image processing of CR portal images.     

A new look at OEM (original equipment manufacturer) service agreements

Next to personnel services, equipment maintenance is the second largest budgetary expense in large radiology departments. Because they are under constant pressure to contain costs, radiology administrators spend considerable time negotiating the best service at the lowest cost. Today, administrators have several options for imaging equipment maintenance: equipment maintenance insurance, in-house engineering, and various arrangements with original equipment manufacturers (OEMs) and independent service organizations (ISOs). In response to increased competition, OEMs have become more price-competitive with ISOs and have expanded their service menu and equipment maintenance insurance programs. OEM service menu options include: full service, tiered pricing, labor only, planned maintenance, full service with deductible, shared maintenance and extended warranty. Any type of service arrangement can be customized according to equipment age and sophistication, redundancy, income-producing potential, criticality of downtime and the strength and depth of the service organization. Even when vendor maintenance contracts are more expensive than purchasing service on a time-and-materials basis, they allow customers to budget accurately for the service of covered equipment. The authors' institution gets the best results for the best price from a judicious mix of maintenance options. Wise customers will explore many options before choosing a service agreement.     

螺旋CT彩色三维图像打印技术探讨

目的 探讨螺旋CT彩色三维(3D)图像打印技术。方法 使用美国Marconi螺旋CT、1台个人计算机、1台彩色喷墨打印机、1台交换机，对136例病人进行了各部位的3D彩图打印。结果 所有病例使用此方法打印出的彩色3D图像都获得了满意的效果。结论 此方法经济、简便又实用，而且能较好的满足临床诊断及手术需求。     

Clinical evaluation of irreversible image compression: analysis of chest imaging with computed radiography

To implement a picture archiving and communication system, clinical evaluation of irreversible image compression with a newly developed modified two-dimensional discrete cosine transform (DCT) and bit-allocation technique was performed for chest images with computed radiography (CR). CR images were observed on a cathode-ray-tube monitor in a 1,024 X 1,536 matrix. One original and five reconstructed versions of the same images with compression ratios of 3:1, 6:1, 13:1, 19:1, and 31:1 were ranked according to quality. Test images with higher spatial frequency were ranked better than those with lower spatial frequency and the acceptable upper limit of the compression ratio was 19:1. In studies of receiver operating characteristics for scoring the presence or absence of nodules and linear shadows, the images with a compression ratio of 25:1 showed a statistical difference as compared with the other images with a compression ratio of 20:1 or less. Both studies show that plain CR chest images with a compression ratio of 10:1 are acceptable and, with use of an improved DCT technique, the upper limit of the compression ratio is 20:1.     

KODAK CR-400PLUS的状态维修

目的总结KODAK CR-400PLUS的状态维修方法,提高设备的可靠度。方法根据状态维修的指导思想,结合实际情况,对KODAK CR-400PLUS制定具体的状态维修计划,保证设备的正常工作。结果使CR的故障率下降,并对关键部件的性能劣化程度达到监测的目的。结论有效地开展状态维修是提高CR可靠度的根本保障。     

高分辨率纸介质打印与干式胶片打印的临床对比研究

目的探讨医用高分辨率纸介质激光打印机的临床应用价值。资料与方法分别采用BELSON纸介质、AGFA干式激光打印机打印CT、DR及MR图像(阳性组91例、阴性组118例)。由三名放射诊断医师分别进行双盲法阅片。通过诊断结果分级及满意度评分评价此两种硬拷贝的诊断效能。阅片结果采用SPSS软件进行卡方检验和受试者操作特征曲线(ROC)分析。结果纸介质打印与胶片打印的ROC曲线下面积无显著性差异(Z=0.97,P>0.05);综合评分中,前者明显优于后者(χ2=14.4,P<0.05),尤其是能够更直观地展现三维重建影像。结论高分辨率纸介质激光打印机能够提供高品质的硬拷贝图像,且不影响诊断效能;具有经济、环保、直观、高效的独特优势。