GE AMX-4Plus移动X射线机的数字化X射线摄影改造

目的为了提高床旁X射线摄片的图像质量,对现有移动X射线机GEAMX-4Plus进行数字化X射线摄影（DR）改造,由原来影像板（IP）成像再行计算机X射线摄影（CR）扫描获得图像的方式改为DR直接摄片。方法以移动X射线机为基础．配置Pixium3543无线平板系统．设计基于该平板的数字摄影操作平台系统和曝光同步控制系统。结果DR改造后,移动X射线机可以正常使用,性能稳定,图像质量较以前CR模式得到大幅提高,获得临床认可。结论数字化x射线摄影改造既使原有移动X射线机得到充分的利用,也使床旁摄片质量、临床诊断及时性、准确度等方面得到大幅提高。     

颞骨茎突数字化X射线摄影的临床应用价值

目的探讨颞骨茎突数字化X射线摄影（DR）的应用价值。方法 29例有茎突过长综合征的患者,其中男性12例,女性17例;年龄34～63岁,平均年龄42.3岁。采用Kodark Derectview DR7100系统内预设条件,对应于该部位的曝光条件75 kV、320 mAs、0.25 s（张口位）;0.32 s（侧位）,选定模式进入。采取拍摄颞骨茎突1～2颈椎张口位、侧位的方法,来测量双侧茎突的长度、偏角做对比。结果 29例颞骨茎突长度均≥3.20cm,右侧颞骨茎突平均长度3.50cm,左侧3.60cm。23例双侧颞骨茎突长度〉3.30cm;右侧11例、左侧16例颞骨茎突长度≥3.30cm;右侧12例、左侧10例颞骨茎突长度≥3.60cm。最长者达3.74 cm。16例茎突偏曲：右侧7例,左侧9例。29例中2例内倾角大于40°,8例小于20°。结论 DR提供更好的影像,对茎突周边部位亦能够清楚显示,有助于正确诊断,具有较高的临床应用价值。     

大剂量X射线照射后淋巴滤泡的形成

目的：观察用500rad X线全身照射后小鼠胭窝淋巴结淋巴滤泡的形成。方法：本实验用光镜、透射电镜方法及三维重塑技术。结果：X线照射后，淋巴细胞发生凋亡和坏死，淋巴滤泡被破坏。之后，淋巴细胞逐渐增多，从照射后第5天开始，出现淋巴滤泡的再构筑；第10天淋巴滤泡数量增多并且出现生发中心；到照射后第14天，淋巴滤泡的数量正常。此外，滤泡树突状细胞的超微结构没有发生改变。结论：500md的X线可以破坏淋巴滤泡，受破坏的滤泡经过一定时期可以重新再聚集。再构筑的滤泡不是新产生的而是受损滤泡再生形成的。滤泡的再构筑与有无生发中心无关。     

CR静脉肾盂造影图像质量与X射线剂量的探讨

目的探讨计算机X射线摄影（CR）在静脉肾盂造影应用中以满足图像诊断质量和X射线曝光参数（kVp、mAs）的优化组合,使X射线剂量控制在最低,降低被检者的有害X射线辐射量。方法对3组不同体型厚度（18cm、22cm、26cm）的被检者,对每组分别以常规摄影条件,增加kVp、降低mAs进行摄影。以kVp与mAs组合图像质量完全满足诊断要求,剂量最低的参数作为最优参考曝光参数。用体模替代3种被检者体型厚度,用同样摄影曝光参数,分别测量体表、体后及有关被检者器官组织的吸收X射线剂量。结果与常规摄影相比,被检者的X射线吸收剂量平均降低了31.97%,面积乘积剂量平均降低了34.57%,有效剂量降低了33.98%。结论在静脉肾盂造影中用CR成像技术与投照参数优化组合,对降低被检者的X射线吸收剂量是行之有效的,为其他投照部位用CR或数字X射线摄影（DR）数字成像参数优化组合研究提供了指导性的方法,有一定的临床应用价值。     

直接数字化X线摄影及影像后处理对骨折的诊断作用分析

目的探讨直接数字化X线摄影(DDR)及影像后处理在骨折影像上的应用及诊断价值.方法分析45例外伤,放射科首诊可疑骨折的患部DDR图像.由3组医生,分别为DR图像不作处理组、一般处理组和增强处理组,对3组诊断与临床治疗结果及随访结果对比分析,作出ROC曲线.结果 45例中,有骨折30例,无骨折15例.增强处理组敏感度最高,但特异性较低;一般处理组具有较高的敏感度、特异性及准确性.结论①DR图像作适当的后处理可以提高骨折影像诊断的准确性.②DR图像增强处理能提高骨折线细节观察的敏感度,但同时可能会使细节的特异性降低,故不应常规使用.③加强对DR增强影像的适应性和认知力,以提高对细节诊断的特异性和准确性.     

直接数字化X线摄影及影像后处理对骨折的诊断作用分析

目的　探讨直接数字化X线摄影 (DDR)及影像后处理在骨折影像上的应用及诊断价值 .方法　分析 4 5例外伤 ,放射科首诊可疑骨折的患部DDR图像 .由 3组医生 ,分别为DR图像不作处理组、一般处理组和增强处理组 ,对 3组诊断与临床治疗结果及随访结果对比分析 ,作出ROC曲线 .结果　 4 5例中 ,有骨折 30例 ,无骨折 15例 .增强处理组敏感度最高 ,但特异性较低 ;一般处理组具有较高的敏感度、特异性及准确性 .结论　①DR图像作适当的后处理可以提高骨折影像诊断的准确性 .②DR图像增强处理能提高骨折线细节观察的敏感度 ,但同时可能会使细节的特异性降低 ,故不应常规使用 .③加强对DR增强影像的适应性和认知力 ,以提高对细节诊断的特异性和准确性     

数字X射线摄影探测器技术的比较

数字X射线摄影是未来医学影像发展的方向,而探测器是其中关键部件。目前探测器主要分为以下三种：CCD、间接平板式和直接平板式。通过对探测器的构造原理的分析、技术性能的比较,能够正确地评价和认识理解数字图像及数字X射线摄影系统。     

加速器X射线放疗剂量计算系统的建立

为根据治疗条件,快速,准确地计算出达到某靶点治疗剂量所需要的处方剂量,利用卫生部工卫所的ＲＴ－１００放疗剂量仪测量西门子公司ＭＥＶＡＴＲＯＮＫＤ－２型电子直线加速器Ｘ线在水模中特定点的剂量分布,拟合剂量分布函数Ｐ’（ｆ,ｄ）。     

硅胶假体置入及注射丰胸患者全数字化乳腺X射线摄影技术探讨

目的探讨硅胶假体置入及注射丰胸患者全数字化乳腺X射线摄影技术与方法。方法硅胶假体置入患者32例,女性,年龄25~49岁,平均年龄37.94岁。注射丰胸患者21例,女性,年龄30~45岁,平均年龄39.38岁。400例正常乳腺患者作为对照,女性,年龄18~72岁,平均年龄43.58岁。收集数字化乳腺X射线影像资料,对图像质量进行分析,并归纳总结其摄影参数。结果 3组乳腺摄影图像甲级片率分别为84.38%、85.71%及91.00%。假体置入和注射丰胸摄影参数采用的k V值与正常乳腺摄影基本接近,但要得到与正常乳腺摄影相当的影像质量,需要加大m As。在相同的压迫厚度下,假体置入与注射丰胸患者摄影m As约是正常患者的2~3倍。结论掌握假体置入及注射丰胸患者乳腺X射线摄影的方法、技术及摄影参数能够获得高质量的影像,为正确诊断提供可靠的影像学依据。     

自动曝光控制技术在数字化 X 射线胸部摄影中的应用探讨简

目的探讨自动曝光控制（AEC）技术在胸部数字化X射线摄影（DR）中的应用及其对图像质量的影响。方法使用AEC技术和根据经验设置曝光条件法,分别采集50张胸部后前位X射线图像,分为2组。试验组使用AEC技术：其中男性27例,女性23例,年龄9-81岁,平均年龄43．6岁。对照组使用手动选择曝光条件：其中男性24例．女性26例．年龄17-76岁,平均年龄45.3岁。记录每次成像的曝光指数（EU并对两组数据进行统计学分析。结果试验组与对照组图像EI比较,差异无统计学意义（1951．00vs1961．80,P〉0．05）,且绝大多数图像质量都在可诊断范围之内。但AEC技术EI的标准差较小．说明AEC技术能更精确地控制曝光量。结论AEC技术可以减少因曝光量不足引起的图像质量下降．也可以避免因曝光过度而产生不必要的患者辐射．     

Optimization of Dose and Image Quality for Computed Radiography and Digital Radiography

The surface doses to patients during chest, abdomen and pelvis radiography were measured over a period of 3 years, during which time computed radiography (CR) and digital radiography (DR) systems were introduced to replace film–screen systems. For film–screen and CR the surface doses were measured with thermoluminescent dosimeters. For DR the surface doses were calculated from the dose–area product (DAP) meter readings. Measurements were made for each type of examination and detector type on 10 average-size patients. Measurements were made immediately after the new systems were introduced, and subsequently as adjustments were made to optimize dose and image quality. Published diagnostic reference levels were used as target values in this optimization. Initially, CR doses were the same as or higher than for film–screen, and the doses were lower for DR compared to film–screen. Subsequent clinical experience with the systems led to changes in the technique used for chest examinations both for CR and for DR. For CR, it was possible to change the algorithm and decrease the dose to one quarter of the initial value with acceptable image quality. For DR, it was decided to reduce noise by increasing the dose by a factor of two. No changes were made to abdomen or pelvic imaging techniques for either CR or DR. The final patient surface doses using CR were similar to published diagnostic reference doses; for DR, all patient doses were less than published reference levels.     

A Technique for Simulating the Effect of Dose Reduction on Image Quality in Digital Chest Radiography

Purpose: The purpose of this study is to provide a pragmatic tool for studying the relationship between dose and image quality in clinical chest images. To achieve this, we developed a technique for simulating the effect of dose reduction on image quality of digital chest images. Materials and Methods: The technique was developed for a digital charge-coupled-device (CCD) chest unit with slot-scan acquisition. Raw pixel values were scaled to a lower dose level, and a random number representing noise to each specific pixel value was added. After adding noise, raw images were post processed in the standard way. Validation was performed by comparing pixel standard deviation, as a measure of noise, in simulated images with images acquired at actual lower doses. To achieve this, a uniform test object and an anthropomorphic phantom were used. Additionally, noise power spectra of simulated and actual images were compared. Also, detectability of simulated lesions was investigated using a model observer. Results: The mean difference in noise values between simulated and real lower-dose phantom images was smaller than 5% for relevant clinical settings. Noise power spectra appeared to be comparable on average but simulated images showed slightly higher noise levels for higher spatial frequencies and slightly lower noise levels for lower spatial frequencies. Comparable detection performance was shown in simulated and actual images with slightly worse detectability for simulated lower dose images. Conclusion: We have developed and validated a method for simulating dose reduction. Our method seems an acceptable pragmatic tool for studying the relationship between dose and image quality.     

Optimization of Image Quality and Dose in Digital Mammography

Nowadays, the optimization in digital mammography is one of the most important challenges in diagnostic radiology. The new digital technology has introduced additional elements to be considered in this scenario. A major goal of mammography is related to the detection of structures on the order of micrometers (μm) and the need to distinguish the different types of tissues, with very close density values. The diagnosis in mammography faces the difficulty that the breast tissues and pathological findings have very close linear attenuation coefficients within the energy range used in mammography. The aim of this study was to develop a methodology for optimizing exposure parameters of digital mammography based on a new Figure of Merit: FOM?≡?(IQF_inv)²/AGD, considering the image quality and dose. The study was conducted using the digital mammography Senographe DS/GE, and CDMAM and TORMAM phantoms. The characterization of clinical practice, carried out in the mammography system under study, was performed considering different breast thicknesses, the technical parameters of exposure, and processing options of images used by the equipment’s automatic exposure system. The results showed a difference between the values of the optimized parameters and those ones chosen by the automatic system of the mammography unit, specifically for small breast. The optimized exposure parameters showed better results than those obtained by the automatic system of the mammography, for the image quality parameters and its impact on detection of breast structures when analyzed by radiologists.     

DR设备质量保证的初步研究

目的：对数字X线摄影（DR）设备主要性能参数检测进行初步研究。方法：根据设备的性能参数和特点，参考厂家说明和国外文献，对两台DR设备（柯达公司的DirectView DR9000系统，GE公司的RevolutionTMXR／d—XQ／i系统）的主要性能参数进行了质量检测。结果：所测性能参数的结果都在厂家提供的最大允许误差值范围内，表明这些设备可以正常工作，所获得的图像质量可以满足临床诊断的要求。结论：DR设备性能参数的检测是保证设备正常使用的有效措施，也是获取高质量影像的必要手段。     

Artifacts Found During Quality Assurance Testing of Computed Radiography and Digital Radiography Detectors

A series of artifact images, obtained over 5 years of performance testing, of both computed radiography (CR) and integrated digital radiographic X-ray imaging detectors are presented. The images presented are all either flat field or test object images and show artifacts previously either undescribed in the existing literature or meriting further comment. The artifacts described are caused by incorrect flat field corrections, a failing amplifier, damaged detector lines affecting their neighbors, lost information between neighboring detector tiles, image retention, delamination of a detector, poor setup of mechanical movements in CR, suckers damaging a CR plate, inappropriate use of grid suppression software, inappropriate use of a low pass spatial frequency filter, and unsharp masking filters. The causes and significance of the artifacts are explained and categorized as software or hardware related. Actions taken to correct the artifacts are described and explained. This work will help physicists, radiographers, and radiologists identify various image quality problems and shows that quality assurance is useful in identifying artifacts.     

模体大小对CBCT图像剂量计算的影响

目的：锥形束CT（CBCT）使用宽束X-射线,探测板获取的信号受散射线的影响很大。该文对扫描模体大小及散射体积对CBCT重建图像HU值及剂量计算的影响进行研究。方法：在Elekta Synergy-XVICBCT系统中对不同深度及散射体积的均匀水模和非均匀密度参考模体扫描,并测量感兴趣区域的HU值;建立考虑和不考虑散射的两组HU-物理密度曲线应用于水模及头颈部仿真模体CBCT图像进行剂量计算,与常规CT图像（FBCT）计算结果比较。结果：均匀水模CBCT图像的HU值随水模深度增加先增大后略有减少,随纵轴散射长度增加而减少,变化幅度最大均接近10%。随散射长度增加,非均匀密度参考模体CBCT图像的高密度组织的HU值减少而低密度组织HU值增加,对1.609 g/cm3致密度骨最大减少约1422 HU。均匀水模和头颈部仿真模体CBCT图像使用考虑散射的HU-物理密度修正曲线计算与FBCT图像比较结果为：点绝对剂量（cGy/MU）最大偏差小于1.5%,等剂量线偏差小于2 mm~3 mm,2%/2 mm DTA指数的通过率平均大于97%,明显优于不做散射修正的结果。结论：Elekta Synergy-XVI系统获取CBCT图像的HU值受扫描模体的几何大小及散射体积影响很大,应选择与扫描患者近似几何大小及人体组织等效的HU-密度校准模体。考虑模体大小及散射修正的头颈部模体CBCT图像用于剂量计算能满足临床要求。     

Parameters of Digital Detectors and Image Quality

The input dose for an ideal digital detector depends quadratically on the threshold contrast detail detectability (TCDD). The TCDD at the level of image quality sufficiency should be minimized for diagnosis; initial parts of detector amplitude response, as well as pulse fluoroscopy adapted to organ mobility, should be used.     

高千伏胸部摄影在DR系统的应用

目的：探讨DR高千伏胸部摄影的条件，评价DR胸部影像。方法：①选择5种体型人体（特瘦、瘦、中等、胖、特胖）各10人，将KV固定为125KV，按7种不同档次的mAs进行正侧位投照。②选取最佳成像的摄影条件，按此条件对1000例患者进行摄影。③对1000例DR胸部影像进行质量评定。结果：①高千伏投照5种体型最佳成像的mAs范围，正位2．0－6．4mAs，侧位4．0－10．0mAs。②1000例DR胸部影像甲级片占50．6％，乙级片占38．5％，丙级片占10．9％，无废片影像。结论：高千伏DR胸部摄影可代替高千伏屏－胶胸部摄影，并具有更多的优越性。