计算机X线摄影与屏-片成像系统的ROC曲线特性比较研究

目的研究计算机X线摄影(computed radiography，CR)、屏-片系统的ROC曲线特性并对它们进行比较。方法在中速屏．片系统特性曲线与CR系统总特性曲线基本一致的前提下，获得CR系统和中速屏．片系统ROC实验标准体模影像，然后变化后处理参数旋转量(GA)、密度变换(GS)、频率增强(RN)和频率等级(RE)，分别获得CR系统照片。请临床医师用5值判别法识别所有影像信号，并对结果进行ROC解析。结果(1)获得CR系统和中速屏-片系统影像的ROC曲线下面积(Az)分别为0．87556和0．93958，屏．片系统明显优于CR系统(t=2．526，P=0．0355)。(2)层次调节结果：①其他参数不变，调节GA=0．6、1．0,2．0、3．0、4．0时，CR系统影像的ROC曲线下Az分别为0．80024、0．87556、0．88184、0．88928和0．85944，调节GA，CR系统的ROC曲线下Az有所变换，但并不能达到或接近中速屏片系统。②其他参数不变，调节GS=0．3、0．4、0．5、0．6、0．7、0．8时，CR系统影像的ROC曲线下Az分别为0．77254、0．87556、0．92720、0．93356、0．94266和0．93512，调节GS，CR系统的ROC曲线下Az变换明显，可以达到或超过中速屏-片系统。(3)空间频率调节结果：①其他参数不变，调节RE=0．5、5．0、10．0、15．0时，CR系统影像的ROC曲线下Az分别为0．87556、0．92524、0．94084和0．94148，调节RE，CR系统的ROC曲线下Az可以达到或超过中速屏一片系统。②先调节RE=10，其他参数不变，调节RN=0、3、5、8时，CR系统影像的ROC曲线下Az分别为0．91438、0．94084、0．89518和0．86030，调节RN，CR系统的ROC曲线下Az可以达到或超过中速屏．片系统。结论(1)在CR系统总特性曲线与中速屏-片系统特性曲线一致并使用同样摄影条件时，CR系统影像上信息量明显小于中速屏-片系统。(2)只有恰当地选择CR的后处理参数获得的信息量才能超过屏-片系统。     

应用CR系统提高胸部摄影技术

计算机摄影术(Computed Rediongraphy．CR)的出现．使传统放射技术发生了很大变化，CR摄影是将透过人体X线影像信息记录于影像板(image plate．IP)上，而不是记录在胶片上，记录在IP板上影像经过读取、处理和显示步骤，显示出数字化图像。本文通过临床胸部平片及床边胸部     

CR与屏-片系统在乳腺摄影中的应用比较

随着计算机技术和图像处理技术的飞速发展，医学影像设备的更新换代，乳腺疾病影像学检查技术逐步得到改进。本院已由钼靶乳腺机的屏．片系统摄影改为CR（computedradiographv，CR）摄影，并配有专用乳腺处理软件，其曝光条件的宽容度、密度分辨力、X线量子检出率等几项指标均高于屏一片系统。现对一组应用CR系统和屏一片系统摄影的乳腺疾病病例进行对比分析。     

床边CR摄影与传统床边摄影的对比研究

目的：评价计算机X线摄影术(CR)在床边照片的应用。方法：抽取我院CR床边按照影像和传统床过照片备1000例，由2位放射学医师及1位主管技师对影像进行分析，分别统计甲、乙、丙及废片率，同时也对条件进行分析评价。结果：(1)CR影像：甲级片率32．1％，乙级片率44.5％，丙级片率23．4％，废片率0％。(2)传统床造影像：甲级片率20．3％，乙级片率53．5％，丙片率16．8％，废片率9．4％。结论：CR床边照片质量明显比传统床边投照优秀，CR床边照片有利于放射诊断。     

计算机X射线摄影系统与屏-片系统能量响应的对照研究

目的探讨计算机X射线摄影(CR)影像像素值与曝光因子(kVp和mAs)、被照体厚度的关系，传统屏-片系统照片密度与曝光因子、被照体厚度的关系，并对两种能量响应的关系进行比较，为使用CR影像像素值和成像板(IP)平均入射照射量的测量值作为自动曝光控制系统的设定参数提供依据。方法厚度为10、15、20cm的丙烯树脂板分别在50～90、70～120、90～140kVp和密度档为-2时成像，对照屏-片系统与CR系统在不同管电压、相同被照体和密度档时的自动曝光响应。以上测试都使用滤线栅，用电离室测量IP的入射照射量。结果在获得满足临床诊断要求的情况下，CR所需曝光量大约是高速屏-片系统的2倍。CR系统的管电压像素值关系曲线与管电压照射量曲线相同。10cm被照体时，50～90kVp间的照片密度差值为1．21，像素差值为270；而20cm被照体时，90～130kVp间的密度差值为0．30，像素差值为100；15cm被照体时密度和像素差值居于两者之间，分别为0．62和160。结论Kodak CR900系统的感度值与中速屏-片系统的感度比较接近。均匀野影像的曝光指示器值EI和IP照射量测量值可以用来设定自动曝光控制系统的光电计时器。屏-片系统照片密度和CR影像像素值随kVp变化的规律以及两者的差异，对自动曝光控制系统的校准起参照作用。     

CR系统在乳腺钼靶摄影中的临床应用

目的：探讨计算机X线成像系统（CR系统）在乳腺钼靶X线摄影中的应用价值。方法：随机抽查屏／片乳腺片、CR钼靶乳腺图像各100份，比较两组照片的满意率、废片率、检出率和投照剂量。结果：普通钼靶摄影组的满意率、废片率、检出率分别为78％、2．8％和76％；数字化乳腺摄影组的满意率、废片率、检出率分别为99．7％、0和85％。CR系统仅用常规摄影剂量的1／5—1／10。结论：利用CR成像系统与钼靶摄影机的结合可以实现乳腺数字化摄影，效果优于普通屏／片摄影，在提高乳腺疾病的检出率方面更具优势，为临床早发现早治疗乳腺疾病提供了可靠依据。     

DR、CR和屏-片系统的IVP摄影效果比较

目的：比较DR、CR和屏-片系统IVP（静脉尿路造影）摄影效果。材料和方法：IVP用美国友通公司E—Corn2000DR检查70例，用Kodak CR400 plus行CR检查59例，用F78-ⅢAmA屏-片检查48例，相应影像设备。比较DR、CR和屏-片系统IVP尿路显示情况、检查时间、用片数量及影像质量、辐射剂量等项指标。结果：DR、CR和屏-片系统IVP综合效果，DR最优，CR其次，屏-片系统第三。结论：IVP综合摄影效果比较，DR是最理想、效果最好的检查方法，CR其次，屏-片系统第三。     

全脊柱DR与CR成像质量的对比分析

目的 探讨直接数字X线摄影(DR)在立位脊柱全长摄片中的应用.方法 177例患者按就诊时间先后分2组分别使用CR和DR技术拍摄全脊柱正侧位片,由放射科经验丰富的医师技师各2名对所有全脊柱影像进行评析.结果 (1)DR摄影成像的密度对比优于CR.(2)DR图像的拼接成功率低于CR.结论 使用DR进行全脊柱摄片,图像质量优于CR摄片.     

计算机X线摄影与屏片系统摄影对比分析

目的:评价计算机X线摄影(CR)的应用价值。方法:抽取我院CR照片和常规X线摄影照片各1200 例,由2位主管技师和1位副主任技师对照片进行分析,统计出甲、乙、丙及废片率。并对乙、丙级片及废片产生的 原因进行了分析。结果:①照片影像质量:CR照片甲级片率51.6%,乙级片率35.5%,丙级片率12.2%,废片率 0.7%。常规X线摄影照片甲级片率40.6%,乙级片率42.5%,丙级片率15.2%,废片率1.7%。②摄影条件:数字 比模拟摄影电压高1～5kV,曝光量高20%左右。结论:CR摄影影像质量好于模拟摄影(即甲级片率高,废片率 小),可为临床提供可靠诊断。但曝光条件比屏 片系统高,增加了病人的X线接受剂量。     

计算机X线摄影与传统摄片影像质量对比分析

目的：探讨计算机X线摄影(computed radiography,CR)的影像质量及其主要影响因素。材料和方法：参照卫生部“三甲”医院检查采用的标准,评定甲、乙、丙级和废片。对1000份不同部位CR影像片和1000份与前者部位相同的传统片影像的质量进行评定,分析造成非甲级片的成因,对两组影像质量及影响因素进行统计学分析。结果：CR片的甲片率为53．6％,明显高于传统片42．5％的甲片率,造成CR非甲级片主要成因是体位及铅字号码放置缺陷、摄影体部有异物和摄影前患者准备不佳(98．92％),传统片为76．7％;摄影条件不佳、影像处理技术不良(暗室技术)对CR影像质量影响不大(1．08％),而对传统片影像质量的影响为23．3％。CR片的废片率为0．0％(不包括机器故障造成的废片),低于传统片的2．0％废片率。结论：CR片影像质量明显优于传统片的影像质量,可广泛应用于除动态影像检查外的临床影像学检查。     

Musculoskeletal system

Diagnostic imaging has played a major role in the evaluation of patients with cancers of the bone and soft tissue. The imaging modalities have included radiography, computed tomography, magnetic resonance imaging, and bone scintigraphy. Current experience suggests that functional imaging with positron emission tomography (PET) and [F-18]fluorodeoxyglucose (FDG) may also have an important role in the imaging evaluation of patients with bone and soft tissue sarcoma, including guiding biopsy, detecting local recurrence in amputation stumps, detecting metastatic disease, predicting and monitoring response to therapy, and assessing for prognosis. Prospective studies with large patient groups will be essential to define the exact diagnostic role of FDG PET in this clinical setting, which should also include an evaluation of the cost-effectiveness and the short-term and long-term benefits in clinical decision making and management. In this article, we review the diagnostic utility of dedicated PET and PET combined with computed tomography imaging system in the evaluation of patients with bone and soft tissue malignancies.     

Dedicated MR system and acute trauma of the musculo-skeletal system

MRI diffusion in the osteoarticular field is limited by the high costs of whole-body systems. Recent technological advances have allowed the development of cost-effective and easy-to-install dedicated MRI systems. One such system, which can only be employed for the study of limbs, is based on a 0.2-T permanent magnet. Acute trauma of the musculo-skeletal system represents an important area of application. Over a period of 2 years, 1258 patients with acute trauma of the joints (64%) and the periarticular bones (36%) have been studied. Satisfactory results, comparable to those from whole-body scanners operating at higher magnetic fields, were obtained. Acute painful syndromes did not represent an obstacle to the performance of the examination. Only in 2% of patients was it not possible to carry out the examination due to oversized limbs or complete articular blocks. On the basis of these considerations, it may be predicted that in the near future dedicated MR systems will find increasingly wide application in the field of musculo-skeletal traumatology.     

Biteblock-head immobilizer system

To accurately deliver high doses of radiation to the head and neck region one must be able to achieve three primary goals: reproduce the patient set-up or position, immobilize the patient, and most importantly, position the treatment field on the patient in the same exact location on a daily basis. Many patient positioning devices are available commercially but none address the concept of positioning the treatment field on the patient. The system presented in this paper accomplishes all 3 goals. Using a biteblock and a coordinate system, it has decreased the daily set-up time and improved the accuracy of the treatment field placement on the patient. Five hundred port films were reviewed retrospectively from previously treated patients who were treated without this new system (66% of those films were approved, and 34% needed some sort of adjustment). Using the new system the accuracy of 107 port films was determined (91% were approved, while only 9% needed any type of adjustment). This newly developed system provides the extra step, treatment accuracy, that no other device has done.     

Assessing system performance

Measuring system performance during image-guided procedures is difficult but necessary if the safety, quality, and efficiency of interventional radiology are to be improved. Because overall performance during these procedures is directly related to the operator's skill, this article will focus on how observable manifestations of skill can be elicited and analyzed. The discussion includes issues encountered when the results of "high-stakes" tests such as board certification are used to predict future system performance. The underlying theme is that process improvement uses the scientific method to gain knowledge of a system. The successive cycles of "predict-test-analyze-decide" found in any training program generate an expanding knowledge base that leads to measurable improvements in system performance.