探讨DR颈椎斜位影像中应用组织均衡技术的优势

目的探讨颈椎斜位直接数字化X线摄影（direct digital radiography，DR）中，采用组织均衡技术的DR图像与标准DR图像的差别。方法利用中国医科大学附属第一医院引进的GE—Revolution XQ／Ⅰ型DR机对所摄的颈椎斜位影像中随机抽取100例作为分析资料。应用组织均衡技术对图像进行处理，同时与标准DR图像进行比较。结果应用组织均衡技术的图像，同一幅图像上不同部位的细节均可清晰显示；标准DR图像需调节不同的窗宽、窗位才能清晰显示或不能显示不同体厚部位的细节。结论在直接数字化X线摄影中，应用组织均衡技术能明显改善因受体厚度影响而难于观察部分的可视性，同时又不牺牲其他部分的细节显示，使DR的应用更完美。     

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。     

数字X线摄影组织均衡技术在胸腰段椎体病变的应用价值

目的探讨数字X线摄影（DR）组织均衡技术在胸腰段椎体病变诊断中的应用价值。方法80例骨折病人，其中男性66例，女性14例，年龄20～82岁，平均年龄52．5岁。用碘化铯非晶硅阵列数字平板探测器采集图像，行胸腰段椎体正侧位摄影，所有病人的侧位影像均行DR组织均衡技术后处理。由3位高级影像专家采用双盲法评价图像，并行统计学处理。结果胸腰段椎体病变32例，正常48例。胸腰段椎体侧位的常规DR与运用组织均衡技术处理的影像质量区别较大。差异有统计学意义。结论DR组织均衡技术对显示胸腰段椎体的侧位影像有较大的临床价值。     

数字X线摄影技术在子宫输卵管造影中的应用

目的通过数字X线摄影（DR）系统在子宫输卵管造影检查中的应用,探讨DR机的优越性。方法分别使用DR和计算机X线摄影（CR）对40例患者进行子宫输卵管造影检查,每组20人。再将所得图像随机分为2组,由2名放射科医师和2名技师采用单独影像观察和比较影像观察的方法,分析CR和DR的影像质量,评价CR和DR摄像系统对图像显示的清晰程度。结果结果显示对DR的影像判断结果评分高于CR;DR具有较好的分辨率和低噪声特性,且通过摄片条件的调整,降低了kV和mA值,可减少患者接受辐射剂量,同时不影响诊断。     

直接数字X射线摄影组织均衡技术在颈胸段摄影中的应用

背景:由于颈胸段侧位摄影时,成像区域的组织厚薄相差大,且重叠多,即使数字X射线摄影具有曝光动态范围大,图像能进行多种后处理的功能,但数字X射线摄影的常规摄影也难以显示颈胸段的解剖结构来了解病情,颈胸段正侧位数字X射线摄影影像质量需要进一步提高。目的:比较应用直接数字X射线摄影组织均衡技术产生的颈胸段图像和直接数字X射线摄影产生的标准数字X射线摄影图像的差别,在颈胸段摄影中探究最佳图像质量。方法:从解放军总医院放射科2005-04/2009-08所摄的数字X射线摄影颈胸段影像中按随机数字表法抽取200例作为分析资料,应用直接数字X射线摄影组织均衡技术对标准数字X射线摄影图像进行处理,比较组织均衡图像与标准数字X射线摄影图像的差别。结果与结论:应用直接数字X射线摄影组织均衡技术产生的新的图像,在同一幅图像上下颈上胸段的细节均可清晰显示;标准数字X射线摄影图像需要反复调节不同的窗宽、窗位才能清晰显示下颈上胸段的细节。提示在直接数字X射线摄影中,应用组织均衡技术能明显改善被检体受厚度影响而不容易观察的细节,同时,又不影响其他部位的细节显示。操作简便,可提高诊断率,减少误诊率,减少成本。     

婴幼儿胸部DR摄影源像距与辐射剂量和图像质量的相关性研究

目的 探讨婴幼儿胸部数字X射线摄影(DR)的源像距(SID)与图像质量及辐射剂量的相关性.方法 先进行仿真胸部体模(成都剂量体模)实验性曝光,采用同一管电压(65 kVp)和不同SID进行曝光组合,记录每次曝光的毫安秒(mAs)、单位面积剂量:在实验的基础上进行婴幼儿胸部DR,收集2008年5月～2010年5月初次人院的50例婴幼儿行胸部DR(其中男性28例,女性22例;年龄5个月～2岁,平均年龄10个月),住院期间复查1次作为对照,初检组均使用110cmSID,复检组均使用90cmSID进行DR胸部摄影.由3名资深影像学专家对获取的100幅图像质最进行评判,评判结果运用统计学软件SPSS 13.0进行分析,使用接受者操作特征曲线(ROC)分析和t检验.结果 100例初检及复查婴幼儿的图像质量均符合诊断要求(P>0.05);而不同的SID曝光的面积剂量差异有统计学意义(P<0.05).结论 婴幼儿胸部DR的不同SID,其辐射剂量差异具有统计学意义,且图像质量均能满足诊断要求,90cmSID在婴幼儿胸部DR中值得提倡.     

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.     

多层螺旋CT低剂量扫描在小儿胸部的应用探讨

目的:评价小儿胸部多层螺旋CT低剂量与常规剂量扫描的图像质量,探讨低剂量扫描在小儿胸部应用的可行性.材料与方法:(1)随机选择肺部感染的患儿30例,先常规剂量(150mAs)扫描,再在感染灶局部加作低剂量扫描,剂量为50,35及15mAs.其他参数为:120kV,床进28.8mm/圈,0.5s/圈,16×1.5mm准直,重建层厚及间隔均为3mm.分别记录不同剂量扫描时的CT权重剂量指数(CTDIw)及剂量长度乘积(DLP).(2)由2位高年资医师按优、良、合格及不合格的等级盲法评价不同剂量的图像质量,结果进行统计学处理.结果:(1)小儿胸部35mAs和15mAs的CTDIw与常规剂量150mAs的比值分别为23.0%及10.0%,其DLP与常规剂量比值为23.3%和10.0%.(2)图像质量评价结果:150,50,35,15mAs的可诊断图像χ2检验,肺窗P>0.05 ,纵膈窗P<0.05,提示上述剂量肺窗图像差异无显著性意义,纵膈窗图像差异有显著性意义.用150,50,35mAs的可诊断图像进行χ2检验, P>0.05,提示其差异亦无显著性意义.结论:多层螺旋CT低剂量扫描适用于小儿胸部检查,在保证图像质量的前提下,采用35mAs左右的扫描条件较为适宜.     

浅谈规范放射科DR的操作技术

数字X线摄影DR具有影像清晰度高,曝光量少,图像空间分辨率、密度分辨率、时间分辨率高,成像环节少等优势,以及安装除噪设备减少了噪声,可以根据个人的视觉效果来调节图像,使其达到最佳诊断效果,但由于检查患者数量的增加,DR操作技师的不规范操作和不必要的人为操作错误,增加了球管的损耗和被检者的辐射,使图像质量不尽人意,直接影响诊断的准确性。     

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。     

Simultaneous presentation of soft tissue and bone tissue in computed tomography with combined window

OBJECTIVES: To examine whether in computed tomography (CT) soft tissue and bone tissue can be simultaneously presented with a combined window without loss of diagnostic information compared to the separate presentations with soft tissue and bone tissue windows. MATERIALS AND METHODS: Forty-seven CT examinations from different patients with pathological changes at the soft tissue or bone tissue after an accident or due to malignant tumour were evaluated. The CT data were transformed into grey level data with three different windows: (1) soft tissue window; (2) bone tissue window to show spongiosa and bone cortex; and (3) special window to show ethmoidal sinus and mastoidal cells. The images were then weighted with a weighting factor of 2, 3 and 1, respectively, resulting in one image with combined window. This image was compared with the conventional soft tissue and bone tissue images. RESULTS: All diagnostic information could be obtained and anatomical details be recognized on the image with combined window. In some cases soft tissue structures could be delineated from each other or from adjacent bone better on this image than on the soft tissue image. CONCLUSIONS: Combined window could enable a reduction of film consumption or digital storage because soft tissue and bone tissue are presented on the same image and not separately. The risk for overlooking important pathological changes might be reduced as both tissues are always presented.     

数字化摄影流程中常见的问题与质量控制

目的分析全数字化摄影流程中常见的问题及原因,总结和改进数字化摄影条件下技术组质量控制方法。方法将数字化摄影流程的质量控制细分为影像输入、处理、输出、阅读4个质量控制过程,仅就技术方面逐项分析解决质量控制问题。依据不同时间段抽取对照组和试验组各2000份影像资料进行比较。结果依据质量管理机制,在摄影技术工作范畴内,分析总结了数字化摄影流程中最容易出现问题的几个关键点。对照组2 000份网络存储胸部摄影资料,存在各类影像缺陷689份,占34.45%。施行质量控制评价机制,尤其是全程陪伴检查并现场纠正操作错误后,抽取试验组2 000份胸部资料,缺陷项由6项降低为3项,为106份,占总数的5.3%,图像质量较前有明显改善。结论通过规范登记流程、摄影摆位,改善摄影条件,规范化后处理软件的应用,减少人为因素造成的失误,使数字摄影工作质量得到显著提高。     

X射线摄影效应测定尺的研发与应用

目的探讨X射线摄影测量出现误差的原因,提高X射线测量的准确性。方法自行研制X射线摄影效应尺,由底尺、高度尺和活动尺三大部分构成,分别刻以灌注铅胶的刻度,用于实际测量。检测焦片距100cm、物片距20cm时显示图像尺寸与实际尺寸的大小。结果各公司平板显示范围未能达到所标识的43 cm×43 cm,Kodak 7500、GE、佳能、西门子4家公司实际显示范围分别为41.5 cm、40.5 cm、42.5 cm、41.0 cm。而焦片距100 cm、物体厚度20 cm进行曝光时,底尺显示43.0 cm时,实际物体尺寸仅有36.0 cm,7.0 cm的物体盲区未被显示。结论为避免图像放大引起的失真,摄影时使用X射线摄影效应测定尺即可进行准确测量,减少误差。     

肩关节结核的CT、MRI诊断

目的:探讨肩关节结核的CT、MR影像表现,旨在提高其诊断的准确性.方法:回顾性分析6例经手术后病理证实为肩关节结核的CT及MR影像表现特点.结果:1例骨型肩关节结核伴滑膜结核,CT表现为肩关节间隙变窄,肱骨头变形及骨质破坏并累及肩胛盂,破坏边缘伴骨质硬化,肩关节周围及腋窝软组织肿胀、密度减低,伴散在死骨形成;其MRI表现为肩关节间隙变窄,肱骨头变形,其内骨质破坏异常信号,周围软组织肿胀及信号异常,关节囊积液.5例滑膜型肩关节结核,CT表现为肩关节周围软组织肿胀,伴单个或多个囊性低密度影,可相互沟通;MRI表现为肩关节周围软组织内单发或多发囊性长T1长T2信号.结论:CT、MRI检查可提高肩关节结核诊断的准确率,在诊断肩关节结核方面具有重要价值.     

Removal of bone in CT angiography of the cervical arteries by piecewise matched mask bone elimination

In maximum intensity projection (MIP) images of CT angiography (CTA) scans, the arteries are often obscured by bone. A bone removal method is presented that uses an additional, nonenhanced scan to create a mask of the bone by thresholding and dilation. After registration of the CTA scan and the additional scan, the bone in the CTA scan is masked. As the cervical area contains bones that can move with respect to each other, these bones are separated first using a watershed algorithm, and then registered individually. A phantom study was performed to evaluate and quantify the tradeoff between the removal of the bone and the preservation of the arteries contiguous to the bone. The influence of algorithm parameters and scan parameters was studied. The method was clinically evaluated with data sets of 35 patients. Best results were obtained with a threshold of 150 HU and a dilation of 8 in-plane voxels and two out-of-plane voxels. The mean width of the soft tissue layer, which is also masked, was approximately 1 mm. The mAs value of the nonenhanced scan could be reduced from 250 mAs to 65 mAs without a loss of quality. In 32 cases the bones were registered correctly and removed completely. In three cases the bone separation was not completely successful, and consequently the bone was not completely removed. The piecewise matched mask bone elimination method proved to be able to obtain MIP images of the cervical arteries free from overprojecting bone in a fully automatic way and with only a slight increase of radiation dose.     

多排螺旋CT低剂量扫描高分辨率重建在新型冠状病毒肺炎筛查中的应用

目的:探讨多排螺旋CT（MDCT）低剂量扫描高分辨率重建在新型冠状病毒肺炎（COVID-19）筛查中的应用价值。方法:选取2020年2月1日~3月1日间就诊的66例疑似COVID-19肺炎患者作为研究对象,将66例患者随机平均分为2组,分别实施胸部常规剂量CT扫描（n=33, 120 kV, 300 mAs）和胸部低剂量CT扫描（n=33,100 kV,70 mAs）,其中常规剂量组采用512×512矩阵,低剂量组采用1 024×1 024矩阵。同时对胸部低剂量组用4种不同权重的迭代算法进行处理（30%、50%、70%、90%）,对比两种检查模式的辐射剂量和图像质量。结果:低剂量组的有效辐射剂量为（1.81±0.14） mSV,与常规剂量组（6.83±0.68） mSV相比降低73.5%（P<0.05）;采用1 024大矩阵、90%权重迭代算法的低剂量组图像的CNR、SNR均略低于采用512常规矩阵、90%权重迭代算法的常规剂量组,但差异无统计学意义（SNR:5.11±0.75 vs 5.38±0.41,CNR:5.37±0.33 vs 5.44±0.51, P>0.05）;低剂量组患者的肺窗、纵膈窗图像质量主观评分低于常规剂量组,但差异无统计学意义（肺窗:3.30±0.72 vs 3.39±0.78;纵膈窗:3.15±0.90 vs 3.36±0.82, P>0.05）。结论:使用MDCT进行胸部低剂量扫描,同时采用高分辨率重建技术及90%权重迭代算法可用于COVID-19肺炎筛查,可在保证图像质量的前提下显著降低患者所受辐射剂量。     

Computed Tomography is Diagnostic in the Cervical Imaging of Helmeted Football Players With Shoulder Pads

OBJECTIVE: Prospective, observational case series evaluating the value of cervical spine computed tomography (CT) scans in the initial evaluation of a helmeted football player with suspected cervical spine injury. SUBJECTS: Five asymptomatic male football players, fully equipped and immobilized on a backboard. DESIGN: Multiple 3.0-mm, helically acquired, axially displayed CT images of the cervical spine were obtained from the skull base inferiorly through T1, with images filmed at soft tissue and bone windows. Sagittal and coronal reformatted images were performed. Software was used to minimize metallic artifact. MEASUREMENTS: All series were reviewed by a Board-certified neuroradiologist for image clarity and diagnostic capability. RESULTS: Lateral scout films demonstrated mild segmental degradation, depending on the location of the metallic snaps overlying the spine. Anteroposterior scout films and bone window images were of diagnostic quality. The soft tissue windows showed minimal localized artifact occurring at the same levels as in the lateral scout views. This minimal beam-hardening streak artifact did not affect the diagnostic quality of the soft tissue windows. Reconstructed images were uniformly of clinical diagnostic quality. DISCUSSION: When CT scans were reviewed as a unit, sufficient information was available to allow reliable clinical decisions about the helmeted football player. In light of recent publications demonstrating the difficulty of obtaining adequate radiographs to evaluate cervical spine injury in equipped football players, helmeted athletes may undergo CT scanning without any significant diagnostic limitations.     

Comparison of Image Enhancement Methods for the Effective Diagnosis in Successive Whole-Body Bone Scans

Whole-body bone scan is one of the most frequent diagnostic procedures in nuclear medicine. Especially, it plays a significant role in important procedures such as the diagnosis of osseous metastasis and evaluation of osseous tumor response to chemotherapy and radiation therapy. It can also be used to monitor the possibility of any recurrence of the tumor. However, it is a very time-consuming effort for radiologists to quantify subtle interval changes between successive whole-body bone scans because of many variations such as intensity, geometry, and morphology. In this paper, we present the most effective method of image enhancement based on histograms, which may assist radiologists in interpreting successive whole-body bone scans effectively. Forty-eight successive whole-body bone scans from 10 patients were obtained and evaluated using six methods of image enhancement based on histograms: histogram equalization, brightness-preserving bi-histogram equalization, contrast-limited adaptive histogram equalization, end-in search, histogram matching, and exact histogram matching (EHM). Comparison of the results of the different methods was made using three similarity measures peak signal-to-noise ratio, histogram intersection, and structural similarity. Image enhancement of successive bone scans using EHM showed the best results out of the six methods measured for all similarity measures. EHM is the best method of image enhancement based on histograms for diagnosing successive whole-body bone scans. The method for successive whole-body bone scans has the potential to greatly assist radiologists quantify interval changes more accurately and quickly by compensating for the variable nature of intensity information. Consequently, it can improve radiologists’ diagnostic accuracy as well as reduce reading time for detecting interval changes.     

MOSFET dosimeter depth-dose measurements in heterogeneous tissue-equivalent phantoms at diagnostic x-ray energies

The objective of the present study was to explore the use of the TN-1002RD metal-oxide-semiconductor field effect transistor (MOSFET) dosimeter for measuring tissue depth dose at diagnostic photon energies in both homogeneous and heterogeneous tissue-equivalent materials. Three cylindrical phantoms were constructed and utilized as a prelude to more complex measurements within tomographic physical phantoms of pediatric patients. Each cylindrical phantom was constructed as a stack of seven 5-cm-diameter and 1-cm-thick discs of materials radiographically representative of either soft tissue (S), bone (B), or lung tissue (L) at diagnostic photon energies. In addition to a homogeneous phantom of soft tissue (SSSSSSS), two heterogeneous phantoms were constructed: SSBBSSS and SBLLBSS. MOSFET dosimeters were then positioned at the interface of each disc, and the phantoms were then irradiated at 66 kVp and 200 mAs. Measured values of absorbed dose at depth were then compared to predicated values of point tissue dose as determined via Monte Carlo radiation transport modeling. At depths exceeding 2 cm, experimental results matched the computed values of dose with high accuracy regardless of the dosimeter orientation (epoxy bubble facing toward or away from the x-ray beam). Discrepancies were noted, however, between measured and calculated point doses near the surface of the phantom (surface to 2 cm depth) when the dosimeters were oriented with the epoxy bubble facing the x-ray beam. These discrepancies were largely eliminated when the dosimeters were placed with the flat side facing the x-ray beam. It is therefore recommended that the MOSFET dosimeters be oriented with their flat sides facing the beam when they are used at shallow depths or on the surface of either phantoms or patients.     

CT图像质量和辐射剂量的影响因素研究

目的对自动曝光技术性能进行定量评价。方法①在自动曝光方式下,检测肩部体模偏离扫描野中心时,噪声和有效mAs的变化。②在自动曝光和手动固定曝光方式下,对圆锥体模用头部和腹部方案分别进行螺旋扫描,比较2种曝光方式噪声和有效mAs随体模直径的变化。结果体模偏离扫描野中心25mm及以上时,图像的噪声在统计学上有显著差异．辐射剂量降低幅度依赖体模直径,体模位置明显影响图像质量和辐射剂量。结论在自动曝光方式下,体模位置明显影响图像质量和辐射剂量,辐射剂量降低幅度与体模的结构和大小有关。