CR与DR系统胸部摄影参数对比的实验研究

目的：比较CR、DR在胸部摄影中的最优化摄影参数。方法：CR、DR系统分别对胸部等效衰减模体行不同参数曝光成像,记录每次曝光的模体表面剂量,并计算模体影像图像质量因子反数值IQFinv。应用统计学软件分析获取CR组、DR组最佳图像的IQFinv值,并换算成摄影参数。结果：CR组、DR组摄影剂量和图像质量IQFinv值之间的线性回归方程为DR：IQFinv=0.005D＋3.359,CR：IQFinv=0.005D＋1.651,D为辐射剂量。ROC曲线分析（曲线下面积AUC=0.893,P〈0.001）,最佳IQFinv值为3.55,获得DR、CR最佳图像摄影参数分别为125 kV、1.6 mAs,125 kV、16 mAs。结论：要得到满足诊断要求且一致的图像质量,CR的摄影剂量大致是DR的4倍。     

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。     

CR系统曲面断层X线摄影在上颌窦检查中的临床应用

目的：探讨上颌窦曲断与直线断层在上颌窦检查中的应用价值和优势。方法：应用曲断行上颌窦平片X线扫描病变定位，行直线断层扫描额面、侧位、斜位的检查。结果：应用上颌窦全景曲断摄影、上颌窦直线摄影优于传统瓦氏位摄影，对观察病变形态结构准确诊断提供依据。结论：应用上颌窦全景曲断摄影、上颌窦直线断层摄影对窦腔结构可做到多角度、多方位地清晰显示。     

CR影像系统在传统曲面断层设备中的应用

目的 介绍一种简便实用的儿童数字牙片摄影装置.方法 利用现有的panouraULTRA曲面断层牙片机设备,将曲面断层牙片机的成像载体支架轴承杆和胶片盒手柄位置进行改进,使其支持把传统增感屏-胶片,改为装载数字X线成像IP板进行摄片,用FCR5000R读取器对IP板进行读取,再经终端处理器对所获图像进行计算机后处理,最后用FUJIFILM DRY PIX7000激光相机打印,从而得到1张高清晰、高质量的数字牙片.结果 利用改进后的曲面断层牙片机的成像载体支架,随机对200例适龄患儿进行曲面断层摄影,甲片196张,甲片率达98%以上.结论 改进后的曲面断层牙片机具有多种优点,在口腔临床及科研教学方面有良好应用前景.     

CR在临床应用中的体会

计算机X线成像(CR)的应用改变了传统X线成像的方法，适应了图像处理、存档及传输等过程。我院于2001年7月份引进了德国AGFA公司的ADC compact CR系统，经过几年的临床应用，已经深受临床医生及广大患者的欢迎，我们对ADC compact CR系统的应用有如下体会：     

CT灌注和X线摄影在乳腺疾病诊断中的价值

目的：探讨CT灌注和X线摄影对乳腺疾病的诊断价值。方法：45例乳腺病变均行X线摄影和CT灌注检查,并与病理结果进行对比分析。结果：X线摄影、CT灌注诊断符合率分别为77.28%和88.89%,综合X线摄影和CT灌注诊断符合率为95.56%,三者之间差异有统计学意义（P〈0.05）。在CT灌注中,乳腺恶性病变的血流量（BF）、血容量（BV）和表面通透性（PS）的均值均明显高于良性病变（P〈0.05）。CT灌注对病变范围、乳腺癌坏死灶的判别优于X线摄影（P〈0.05）。X线摄影对钙化灶的定性诊断优于CT灌注（P〈0.05）。结论：X线摄影和CT灌注具有互补性,两者结合可提高乳腺癌诊断符合率。     

颞下颌关节计算机曲面断层与胶片摄影技术对比研究

目的对颞下颌关节（TMJ）开闭口位计算机曲面断层摄影（COPT）与薛氏位（sR）、胶片曲面断层摄影（FOPT）进行对比研究，探讨COPT的优势。方法对98例患者分组并分别采用双侧TMJ开闭口位COPT、FOPT、SR等3种摄影技术进行摄影检查，对图像所显示的各解剖结构满意率采用Pearson卡方检验，对各组满意率两两比较采用q检验进行统计学分析。结果144幅COPT、128幅FOPT和120幅sR摄取的TMJ开闭口位图像显示的下颌支满意幅数分别为144、128、6，满意率分别为100％、100％、5％（P〈0．01）；冠突显示满意幅数分别为144、128、12，满意率分别为100％、100％、10％（P〈0．01）；切迹显示满意幅数分别为144、128、66，满意率分别为100％、100％、55％（P〈0．01）；关节间隙显示满意幅数分别为96、89、120，满意率分别为75％、62％、100％（P〈0、01）；对髁突、关节结节显示满意幅数分别为144、128、120，满意率均为100％。下颌支、冠突、切迹、关节间隙显示满意率3种摄影方法两两比较，SR与FOPT间比较，差异有统计学意义（P值均〈0．01）；sR与COPT问比较（P值均〈0.01），差异有统计学意义；FOPT与COPT间比较，差异无统计学意义（P值均〉0．05）。双侧TMJ开闭口位3种摄影技术曝光量分别为COPT99—113mAs、FOPT210～225mAs、SR210—500mAs。因此，COPT、FOPT对下颌支、冠突、切迹的显示质量优于sR，对关节间隙的显示不及SR，对髁突、关节结节显示三者相同，SR曝光量大于COPT和FOPT，FOPT大于COPT。结论COPT检查颞下颌关节开闭口位，优于FOPT及SR摄影技术，应该在临床中推广应用。     

数字断层融合摄影在肺转移结节诊断和随访中的价值

目的探讨胸部数字断层融合(DTS)检查对恶性肿瘤肺转移结节的诊断和随访价值。资料与方法对257例恶性肿瘤患者进行胸部DTS检查和数字X线摄影(DR)检查,以多层螺旋CT作为参照,比较DTS和DR对肺转移结节的检出情况,评估DTS对肺转移结节的诊断效能。结果 257例患者中,34例发生肺转移,共确认187个转移结节。DR检出16例共计65个结节,DTS检出31例共计164个结节。DR和DTS对恶性肿瘤肺转移的诊断敏感性、特异性、阳性预测值、阴性预测值分别为47.1%、87.9%、37.2%、91.6%和91.2%、99.6%、96.9%、98.7%。DTS对直径<5mm和5～10mm的肺转移结节的检出率明显高于DR(P<0.01)。结论 DTS较DR对肺转移结节具有更高的敏感性,可用于转移性肺癌的诊断和随访。     

X线管倾斜摄影时CR、DR成像质量对比研究

目的:探讨计算机X线摄影(computedradiography ,CR)和数字X线摄影(digitalradiography ,DR)在X线管倾斜摄影时是否存在X线斜射效应。方法:对于屏-片组合、CR、a Si型DR和a Se型DR四种X线成像方式,分别在X线管倾斜0°、15°、30°、4 5°时对矩形波测试卡摄影。结果:在X线管倾斜0°～4 5°角范围内摄影时,CR影像分辨力无变化;a SiDR和a SeDR影像分辨力略下降;屏-片组合影像分辨力下降明显。结论:在X线摄影常用的倾斜角度范围内,屏-片组合存在X线斜射效应,CR基本上不存在X线斜射效应,a-Si型DR和a-Se型DR存在轻微的X线斜射效应     

女性盆腔CT增强扫描的方法研究

目的：研究提高妇科盆腔CT增强效果的方法。方法：搜集我院临床诊断盆腔占位病变的女性患者资料75例,随机分为三组,行盆腔增强CT螺旋扫描。甲组和乙组均采用一次性团注法;丙组采用2次间隔团注法。使用PhilipsBrilliance6螺旋CT,Medrad高压注射器,依病人公斤体重计算,按2ml/kg给予碘比乐370对比剂,最大剂量不超过120ml;扫描参数三组均采用5mm层厚和层间隔,6×1．5mm准直器,P=0．9。最后三组原始数据全部选用2mm层厚、1mm层间隔行离线重叠重建。由两位医师分别在金盘GDPACS诊断工作站盲法分析75例观测对象的CT图像资料,对增强效果进行分级评分;最后对所得三纽对应数据进行组间t检验。结果：丙组评分最高且评优图像最多。三组数据兴趣点CT值平均值统计结果,丙组CT值最高;乙纽相对于甲纽仅髂内动脉的CT值变化有统计学意义;丙组相对于甲组髂内动脉、髂总静脉和子宫肌壁的CT值变化均有统计学意义;丙组相对于乙组,除子宫肌壁外,双侧髂内动脉和髂总静脉的CT值变化均有统计学意义。结论：采用2次间隔静脉快速团注法行妇科盆腔增强CT扫描,能大大提高盆腔动、静脉的强化水平,提高病灶与正常组织和血管之间的对比显示情况,更有利于病灶的检出和显示。     

全景片切牙根部模糊的原因及解决方法

目的 研究全景片切牙根部模糊的原因及解决方法。方法 (1)回顾分析400份成人全景片，求出切牙根部模糊的全景片所占的比例；(2)用实验方法测出全景摄影图像层面各点厚度及P12(Pmgram12)切牙小区域摄影的图像层面厚度；(3)使用4mm直径的钢珠间隔5mm镶嵌在一塑料直尺上模拟切牙进行不同倾斜角度全景摄影，检测切牙倾角对全景摄影时图像清晰度的影响；(4)对40例成年志愿者进行常规全景摄影及P12切牙小区域摄影，常规全景摄影有切牙根部模糊者进行调整角度后全景摄影。结果 (1)400份成人全景片中，318份存在切牙根部模糊，占79．5％。(2)全景摄影图像层面各点的厚度是不同的，切牙区最薄，为0．7cm，P12切牙小区域摄影的图像层面厚度为2．4cm。(3)直尺上钢珠的清晰度与直尺的倾斜角度有关，倾角过大即可产生模糊。(4)40例志愿者的常规全景摄影中32例有切牙根部模糊，调整头颅倾斜角度后可使牙根显示清晰，P12切牙小区域摄影全部清晰。结论 全景片上切牙根部产生模糊的主要原因是图像层面未能包含切牙全长。调整头颅倾斜角度而改变切牙倾斜角度，或改变断层扫描轨迹增加图像层面厚度使切牙全长均位于图像层面内，即可避免切牙根部的模糊。     

Perception of anatomical structures in digitally filtered and conventional panoramic radiographs: a clinical evaluation

Objectives

The aims of the study were to compare subjective image quality of clinical images obtained with a storage phosphor plate (SPP)-based digital and conventional film-based panoramic system for the visualization of various anatomical structures and to evaluate the effect of various processing algorithms on image interpretation.

Methods

Panoramic radiographs were taken in 42 patients both with film and with a SPP system. SPP images were treated with shadow, sharpen, negative, greyscale sigma and greyscale exponential filters. Four observers subjectively evaluated films and unfiltered and filtered SPP images for the visibility of anatomical structures with various radiodensities as well as for overall image quality on a three-point rating scale. The statistical methods used were Kruskal–Wallis, odds ratio analysis and Cohen''s kappa.

Results

No statistically significant difference was found between film and unfiltered digital images except for low-contrast structures (P > 0.05). Film images were preferred for the visibility of low-contrast structures (P < 0.05). Best overall image quality was obtained with sharpened images (P < 0.05) followed by films and unfiltered digital images. Among all filtered images, sharpened ones received the highest ratings for the visibility of all anatomical structures (P < 0.05). The intra- and interobserver agreement ranged between moderate and substantial and between fair and moderate, respectively.

Conclusions

Film and unfiltered SPP-based panoramic images performed equally well in terms of overall quality; however, films were best for the perception of low-contrast structures. The sharpening filter may be recommended for enhancing SPP panoramic images to improve the visual perception of most of the anatomical structures as well as overall quality.     

Developments in digital radiography: an equipment update

Digital X-ray imaging technology has advanced rapidly over the past few years. This review, particularly aimed at those involved in using and purchasing such technology, is an attempt to unravel some of the complexities of this potentially confusing subject. The main groups of X-ray imaging devices that are considered are digitisers of conventional radiographs, image-intensifier-based fluorography systems, photostimulable phosphor computed radiography, amorphous selenium-based technology for thorax imaging and flat-panel systems. As well as describing these different systems, we look at ways of objectively assessing their image quality. Concepts that are used and explained include spatial resolution, grey-scale bit resolution, signal-to-noise ratio and detective quantum efficiency. An understanding of these basic parameters is vital in making a scientific assessment of a system's performance. Image processing and techniques are also briefly discussed, particularly with reference to their potential effects on image quality. This review aims to provide a basic understanding of digital X-ray imaging technology and enables the reader to make an independent and educated assessment of the relative merits of each system.     

不同部位放大像与普通X线平片对照分析(附210例分析)

目的：探讨放大像与普通Ｘ线平片对同一部位骨质病变的诊断效果。材料与方法：对２１０例（男１２０例、女９０例）既有Ｘ线平片又有放大像的病例所摄照片进行分析、对比。结果：放大像发现病变的阳性率为７２％；Ｘ线平片发现病变的阳性率为５９％。结论：当临床高度怀疑有骨质病变，常规Ｘ线平片表现为正常或怀疑异常时，应摄放大像以减少漏诊。     

Assessment of using digital manipulation tools for diagnosing mandibular radiolucent lesions

Objective

The purpose of this study was to analyse the use of digital tools for image enhancement of mandibular radiolucent lesions and the effects of this manipulation on the percentage of correct radiographic diagnoses.

Methods

24 panoramic radiographs exhibiting radiolucent lesions were selected, digitized and evaluated by non-experts (undergraduate and newly graduated practitioners) and by professional experts in oral diagnosis. The percentages of correct and incorrect diagnoses, according to the use of brightness/contrast, sharpness, inversion, highlight and zoom tools, were compared. All dental professionals made their evaluations without (T₁) and with (T₂) a list of radiographic diagnostic parameters.

Results

Digital tools were used with low frequency mainly in T₂. The most preferred tool was sharpness (45.2%). In the expert group, the percentage of correct diagnoses did not change when any of the digital tools were used. For the non-expert group, there was an increase in the frequency of correct diagnoses when brightness/contrast was used in T₂ (p=0.008) and when brightness/contrast and sharpness were not used in T₁ (p=0.027). The use or non-use of brightness/contrast, zoom and sharpness showed moderate agreement in the group of experts [kappa agreement coefficient (κ)=0.514, 0.425 and 0.335, respectively]. For the non-expert group there was slight agreement for all the tools used (κ≤0.237).

Conclusions

Consulting the list of radiographic parameters before image manipulation reduced the frequency of tool use in both groups of examiners. Consulting the radiographic parameters with the use of some digital tools was important for improving correct diagnosis only in the group of non-expert examiners.     

Length of endodontic files measured in digital radiographs with and without noise-suppression filters: an ex-vivo study

Objectives

The aim of this study is to evaluate if theoretically possible edge shifts induced by noise-suppression filters potentially occur on objects found in digital radiographs. Most manufacturers carry out noise-suppression filtering of their images before they are displayed to the user. It is not usually possible for the user to disrupt the function of the filters. The use of these filters can lead to deletion of small image structures.

Methods

K-files (ISO size 06, 08, 10 and 15) were placed in the root canals of 6 human teeth located in cadaver jaw segments. File tip positions were measured on original and filtered digital images by three observers. The file position was marked on each filtered image and compared with the unfiltered ones.

Results

The 5 × 5 pixel-sized median and mean filters caused the largest underestimation of measured lengths between −7.87 pixels and −10.8 pixels (−306.93 μm and −421.2 μm). Maximum standard deviation for length differences was found for the calculated position ( = gold standard) and the original unfiltered images with 13.31 pixels. The standard deviation found for the 5 × 5 mean and median filter was 7.62 pixels and 8.68 pixels.

Conclusion

Different studies showed that noise-suppression filters can induce edge shifts in diagnostic radiographs. The high standard deviations found for length differences between the defined gold-standard and the original images indicate that theoretical edge shifts may not be clinically relevant for length measurements of endodontic files.     

Relationship between radiation dose reduction and image quality change in photostimulable phosphor luminescence X-ray imaging systems

Objectives

The aim of the study was to clarify the change in image quality upon X-ray dose reduction and to re-analyse the possibility of X-ray dose reduction in photostimulable phosphor luminescence (PSPL) X-ray imaging systems. In addition, the study attempted to verify the usefulness of multiobjective frequency processing (MFP) and flexible noise control (FNC) for X-ray dose reduction.

Methods

Three PSPL X-ray imaging systems were used in this study. Modulation transfer function (MTF), noise equivalent number of quanta (NEQ) and detective quantum efficiency (DQE) were evaluated to compare the basic physical performance of each system. Subjective visual evaluation of diagnostic ability for normal anatomical structures was performed. The NEQ, DQE and diagnostic ability were evaluated at base X-ray dose, and 1/3, 1/10 and 1/20 of the base X-ray dose.

Results

The MTF of the systems did not differ significantly. The NEQ and DQE did not necessarily depend on the pixel size of the system. The images from all three systems had a higher diagnostic utility compared with conventional film images at the base and 1/3 X-ray doses. The subjective image quality was better at the base X-ray dose than at 1/3 of the base dose in all systems. The MFP and FNC-processed images had a higher diagnostic utility than the images without MFP and FNC.

Conclusions

The use of PSPL imaging systems may allow a reduction in the X-ray dose to one-third of that required for conventional film. It is suggested that MFP and FNC are useful for radiation dose reduction.     

Hand radiographs: a comparative study of digital luminescent radiography (DLR) and conventional screen-film system combinations

A total of 102 matched hand radiographs were taken by digital luminescent radiography (DLR) and conventional) screen film system combinations. In DLR two differently postprocessed images were obtained from each data set: A display with low-spatial frequency enhancement filtered to took like a conventional radiograph was placed opposite a display with high-edge enhancement. Conventional and digital images were evaluated rank only and separately by four radiologists, using a questionnaire. Using DLR proved diagnostically equivalent to the conventional technique except for a diminished visibility of subtle erosions and fissures. High-frequency enhancement did not provide additional diagnostic information and led to artifacts at the edges of metal prostheses. Densitometry confirmed an optimized density of digital radiographs. The main argument for the employment of digital techniques is the availability of data for picture archiving and communications systems.     

Object position and image magnification in dental panoramic radiography: a theoretical analysis

Objectives

The purpose of our study was to investigate how image magnification and distortion in dental panoramic radiography are influenced by object size and position for a small round object such as a ball bearing used for calibration.

Methods

Two ball bearings (2.5 mm and 6 mm in diameter) were placed at approximately the same position between the teeth of a plastic skull and radiographed 21 times. The skull was replaced each time. Their images were measured by software using edge detection and ellipse-fitting algorithms. Using a standard definition of magnification, equations were derived to enable an object''s magnification to be determined from its position and vice versa knowing the diameter and machine parameters.

Results

The average magnification of the 2.5 mm ball bearing was 1.292 (0.0445) horizontally and 1.257 (0.0067) vertically with a mean ratio of 1.028 (0.0322); standard deviations are in parentheses. The figures for the 6 mm ball bearing were 1.286 (0.0068), 1.255 (0.0018) and 1.025 (0.0061), respectively. Derived positions of each ball bearing from magnification were more consistent horizontally than vertically. There was less variation in either direction for the 6 mm ball bearing than the 2.5 mm one.

Conclusions

Automatic measurement of image size resulted in less variation in vertical magnification values than horizontal. There are only certain positions in the focal trough that achieve zero distortion. Object location can be determined from its diameter, measured magnification and machine parameters. The 6 mm diameter ball bearing is preferable to the 2.5 mm one for more reliable magnification measurement and position determination.