Data clustering and other archive retrieval strategies for teleradiology and picture archiving and communication systems

A key advantage in the conversion from film-based to digital radiology is the possibility of a long-term on line electronic archival of patient studies. The popular approach based on optical disk jukeboxes for the long-term archive and magnetic disk storage for data caching is not economically attractive because of the cost of both the jukebox and the medium. Strategies for extending the archival system design with a tape jukebox have been studied. The proposed strategy calls for the use of high-ratio lossy compression together with low-cost tape storage to make long-term on line archiving more affordable. An intelligent prefetching algorithm based on hospital information system and radiologic information system triggers, which in turn are augmented by manual case preparation, can effectively overcome the longer latency of ad hoc retrievals. This longer latency is caused by both system-level bottlenecks and the sequential access constraint of the tape drive. Strategies for image clustering and tape allocation by patient classification also enhance retrieval efficiency. This archival design using image compression, prefetching, and clustering could be implemented in many of the existing teleradiology and picture archiving and communication systems.     

The picture exchange communication system

The Picture Exchange Communication System (PECS) was developed as a means to teach children with autism and related developmental disabilities a rapidly acquired, self-initiating, functional communication system. Its theoretical roots combine principles from applied behavior analysis and guidelines established within the field of alternative and augmentative communication. This approach has several potential advantages relative to imitation-based strategies (both vocal and gestural) and symbol selection strategies. The system begins with the exchange of simple icons but rapidly builds "sentence" structure. The system also emphasizes developing the request function prior to developing responding to simple questions and commenting. The development of requesting with a sentence structure also permits the rapid development of attributes more traditionally taught within a receptive mode. The relationship between the introduction of PECS and various other behavioral issues (i.e., social approach and behavior management) as well as its relationship to the codevelopment of speech are reviewed.     

Improvement of signal-to-noise and contrast-to-noise ratios in dual-screen computed radiography

A dual-screen computed radiography (CR) technique has been developed to improve and optimize the overall image signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). With this technique, two CR screens are exposed together and separately scanned to form a front and a back image. These two images are then superimposed to form an image of improved SNR and CNR. A mathematical model has been derived to describe the improvement and optimization of the SNR and CNR. Based on this model, the front and back images should be weighted in proportion to their SNR squared to optimize the SNR of the composite image. Imaging experiments have been conducted to verify the theoretical model under mammographic and chest imaging conditions. The results largely agree with the theoretical predictions. It has also been found that optimization of the SNR results in nearly optimal CNR and vice versa. For mammographic imaging, a 14%-22% improvement in the SNR and a 13%-19% improvement in the CNR have been demonstrated. For chest imaging, a 31%-36% improvement in the SNR and a 28%-30% improvement in the CNR has been demonstrated.     

Single-exposure conventional and computed radiography. The hybrid cassette revisited

RATIONALE AND OBJECTIVES: The authors constructed and evaluated a hybrid cassette for single-exposure extremity imaging with storage-phosphor plates and conventional radiographic film. METHODS: A hybrid cassette was constructed using a fine radiographic screen and a storage-phosphor plate. Exposures of a Lucite step wedge and a line pair gauge were made with the hybrid cassette, a conventional radiographic cassette, and a storage-phosphor cassette. The spatial resolution and imaging speeds of the hybrid and standard systems were compared. RESULTS: Spatial resolution loss was less than 0.5 line pairs per mm with the hybrid cassette. Speed loss was characteristic of the hybrid cassette, requiring approximately 40% greater exposure to produce the same film density as standard cassettes. CONCLUSIONS: The speed difference between this and a previous study is probably due to differences in film-screen choice, kilovolt peak, and storage-phosphor plate generations. The sensitivity spectrum of our film and the emission spectrum of our screens were more closely matched than were the spectra in the previous study; we used lower kilovolt peak, and our storage-phosphor plates were a later, more efficient, generation. Despite slight speed losses, the hybrid cassette appears to be a better choice for obtaining matched images for clinical trials than the alternative of two separate exposures.     

Use of computed radiography in the study of an historic painting

The authors demonstrate the use of radiography in the investigation of an historic painting and describe the potential benefits of computed radiography compared with conventional screen-film radiography. The subject for the comparison was a 16 x 19-foot oil-on-canvas painting, Scipio Africanus Freeing Massiva, by Giovanni Battista Tiepolo. Radiographs of the painting were obtained by using a portable, industrial radiographic unit and both conventional screen-film and photostimulable phosphor plate cassettes. For this investigation, computed radiography had a number of advantages over screen-film radiography, largely due to its wider dynamic range and its capabilities for enhancing the digital images with image processing tools such as magnification, edge enhancement, colorization, and airbrushing. The ability to electronically combine images from the large painting into a single composite image file was extremely valuable, as this technique was much less cumbersome and resulted in much higher quality composite images than could be achieved with conventional radiography. An additional advantage of computed radiography includes the capability to easily archive and transmit these images in a digital format for subsequent review.     

Design, construction, implementation, and cost of a hospital pharmacy cleanroom

The authors sought to clarify in a cross-sectional study the possible associations between homeostatic regulators of calcium and occupational exposure to lead. Subjects were 146 industrial male employees, 56 with and 90 without occupational lead exposure. The main outcome measures were serum concentration of parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D (calcitriol). The median values of blood lead were 40.5 microg/dl in the exposed group and 4.0 microg/dl in the controls. There were no differences between groups in dietary history and serum calcium levels. PTH and calcitriol levels were significantly higher in the exposed than in the nonexposed subjects (42.0+/-24.2 vs. 33.6+/-14.9 pg/ml, p <0.05; and 83.8+/-27.0 vs. 67.9+/-17.6 pmol/liter, p <0.001, respectively). Multivariate analyses showed that after controlling for possible confounders, occupational lead exposure (no/yes) was independently associated with PTH level (pg/ml) (beta = 7.81, 95% confidence interval (CI) 3.7-11.5) and with calcitriol (pmol/liter) (beta = 12.3, 95% CI 3.84-20.8). It is concluded that subjects occupationally exposed to lead show a substantial compensatory increase in PTH and calcitriol activities which keep serum calcium levels within normal range. This may be of clinical significance since a sustained increase in calcitropic hormones in susceptible subjects may eventually increase the risk of bone disorders.     

一个具有四翼吸引子的超混沌系统设计与实现

为提高超混沌吸引子的拓扑结构的复杂性,构造了一个新的超混沌系统,对新的系统进行了理论分析和计算机仿真,并设计了一个模拟电路对系统进行实验,实验所得相图与数值仿真一致,是具有四翼吸引子的超混沌系统,从而证明了理论分析和数值仿真的正确性.     

Evaluation of an automatic-mode image processing method in chest computed radiography

RATIONALE AND OBJECTIVES: The automatic image processing mode of the storage phosphor computed radiography system was evaluated. MATERIALS AND METHODS: A dedicated chest unit designed for erect view was used to examine a chest phantom. Lucite plates 1, 2, and 3 cm thick that conformed to the shape of the lung were attached to the phantom, and images were obtained in automatic and manual image processing modes. The changes in the optical density of the lung, rib, and heart and the changes in contrast were measured. The degree of diffuse opacity due to the plates and the visibility of superimposed simulated nodular and honeycomb opacities were evaluated. RESULTS: The decrease in optical density and contrast caused by increasing thickness of the Lucite plates was less pronounced in the automatic mode compared with the manual mode. When plates were placed only on the right lung, the optical density and the contrast on the contralateral side either increased or remained unchanged with the automatic mode. The degree of diffuse opacity was rated higher in the manual mode, and the visibility of superimposed simulated opacities was considered relatively constant in the automatic mode. CONCLUSION: The automatic image reading mode used in the computed radiography chest system may mask the detection of abnormalities such as diffuse homogeneous lung opacity.     

Automatic background recognition and removal (ABRR) in computed radiography images

A novel method to automatically recognize and remove background signals in computed radiography (CR) images caused by X-ray collimation during projection radiographic examinations is presented. There are three major steps in this method. In the first step, a statistical curve is derived based on many hierarchical CR sample images as a first approximation to loosely separate image and background pixels. Second, signal processing methods, including specific sampling, filtering, and angle recognition, are used to determine edges between image and background pixels. Third, adaptive parameter adjustments and consistent and reliable estimation rules are used to finalize the location of edges and remove the background. In addition, this step also evaluates the reliability of the complete background removal operation. With this novel method implemented in a clinical picture archiving and communication system (PACS) at the University of California at San Francisco, we achieved 99% correct recognition of CR image background, and 91% full background removal without removing any valid image information.     

Mucoepidermoid carcinoma in the mandible: findings of panoramic radiography and computed tomography

The Health Physics Department of the Korea Atomic Energy Research Institute and the Human Monitoring Laboratory have collaborated to compare the LLNL and JAERI torso phantoms. The counting efficiencies of the phantoms at 17.7 keV, 59.5 keV, 121.8 keV, and 344 keV were measured with KAERI's germanium lung counting system. The data were made comparable by converting the chest wall thicknesses and adipose mass fractions of the phantoms to muscle equivalent chest wall thicknesses. The counting efficiencies of the two phantoms are within 12% to 17% of each other at 17.7 keV, 15% to 22% at 59.5 keV, 10% to 15% at 121.8 keV, and 7% to 10% at 344 keV. This joint study has shown that the LLNL and JAERI phantom are essentially equivalent for the purposes of calibrating a lung counting system that consists of two ACTII germanium detectors.     

Simultaneous multilayer arthrotomography of the temporomandibular joint using photostimulable phosphor computed radiography

OBJECTIVE: To compare the image quality of photostimulable phosphor computed radiography (CR) with that of a conventional screen-film system for simultaneous multilayer arthrotomography of the temporomandibular joint (TMJ). METHODS: X-ray attenuation, resolution and granularity was compared. Simultaneous multilayer tomography of TMJ was performed using a skull phantom and diagnostic quality of bone structures estimated. The clinical outcome is demonstrated in two typical cases. RESULTS: X-ray attenuation was larger with CR. Granularity was more prominent in edge-enhanced CR images and was associated with inferior diagnostic quality. However, it was improved by using a higher tube voltage. Clinical CR without edge enhancement showed a similar resolution to the conventional system but this decreased with enhancement. In an enhanced arthrotomogram, the boundary between contrast medium, bone and soft tissue were clearly defined and a fibrous adhesion also easily seen. CONCLUSION: Photostimulable phosphor CR is an acceptable alternative for simultaneous multilayer arthrotomography of the TMJ.     

Missed lung cancer on chest radiography and computed tomography: imaging and medicolegal issues

The solvent and temperature dependence of the rate constant for spin echo dephasing, 1/Tm, for 0.2 to 1.2 mM glassy solutions of chromyl bis(1-hydroxy-cyclohexanecarboxylic acid), CrO(HCA)-2; aquo vanadyl ion, VO2+ (aq), and vanadyl bis(trifluoroacetylacetonate), VO(tfac)2 were examined. At low temperatures where 1/T1 < 1/Tm, 1/Tm in 1:1 H2O:glycerol is dominated by solvent protons. At low temperature 1/Tm increases in the order 1:1 H2O:glycerol or 9:1 CF3CH2OH:ethyleneglycol (no methyl groups) < 9:1 i-PrOH:MeOH (hindered methyl groups) < 9:1 n-PrOH:MeOH (less hindered methyl groups). This solvent dependence of 1/Tm is similar to that observed for nitroxyl radicals, which indicates that the effect of solvent methyl groups on spin-echo dephasing at low temperature is quite general. At higher temperatures the echo dephasing is dominated by spin-lattice relaxation and is concentration dependent. As the glass softens, echo dephasing is dominated by the onset of molecular tumbling.     

烧结过程决策支持系统的设计与实现

针对某大型钢铁企业烧结生产过程的质量管理问题,提出一种基于控制图分析的烧结过程决策支持系统设计方案.首先,应用主成分分析、灰色关联分析方法,对烧结过程信息进行提取,确定影响质量的主要参数.然后,对烧结矿质量数据进行控制图分析,得到质量异常信息,并分析异常原因,为指导生产提供判断依据.实际运行结果表明该系统能够帮助决策者指导生产调整,提高烧结矿质量.     

The effects of operator implementation cost on planfulness of problem solving and learning

This paper explores the idea that problem solving search strategies are chosen so as to optimize performance within the constraints of a particular situation. Four experiments are reported that examine the hypothesis that the cost of performing an operation affects "planfulness"--the level of planning during problem solving. The first experiment investigated problem solving with the 8-puzzle and compared strategies adopted when there was a high versus a low cost of making a move, manipulating cost in terms of command length. The second experiment used protocol analysis to provide more direct evidence for increased planning. The third and fourth experiments looked at the effects of these different strategies on learning: the third examined how problem solving performance on a direct manipulation interface is affected by prior problem solving experience in the same domain with either a high cost or low cost command-driven interface, demonstrating improved performance as a result of training on an interface with high cost operations; the fourth experiment, like the third, examined the effects of prior problem solving experience with either a high cost or low cost interface on subsequent problem solving performance in a different domain using a direct manipulation interface showing no effect to training interface on subsequent performance.     

包装车间控制系统改造的设计与实现

冀东1^#水泥生产线水泥包装子系统改造,采用了A－B PLC5系列控制器,本文着重介绍该系统的硬件配置和功能,以及改造需解决的问题和软件功能的实现。     

Ganglion cysts of the knee: articular communication revealed by delayed radiography and CT after arthrography

OBJECTIVE: The diagnosis of ganglion cysts of articular origin may sometimes be uncertain when communication with the joint is not evident. Because we have observed that opacification of ganglion cysts revealed by arthrography can be significantly delayed, the purpose of this study was to determine retrospectively in 20 cases the time delay needed to show with arthrography a communication between the articular cavity and ganglion cysts of the knee. CONCLUSION: Arthrographic evidence of a communication between the articular cavity of the knee and communicating ganglion cysts requires delayed radiography performed at least 1 hr after intraarticular injection of contrast material. The best results are obtained with additional CT performed 1-2 hr after injection.     

基于零知识证明的智能合约投票系统设计与实现

作为一种具有法律约束力的程序,智能合约为电子投票系统提供了可信执行平台．然而,由于合约部署在公开透明的区块链上,这将为投票内容的有效性与隐私性带来巨大威胁．为了解决上述问题,基于交互式零知识证明技术设计了智能合约投票系统．首先,提出了一个新的交互式零知识集合成员关系证明协议,使得投票者在不泄露投票内容的前提下,完成对投票内容有效性的验证,从而避免无效选票对投票系统的影响．其次,本文通过智能合约规范语言SPESC对投票合约进行描述并对投票各个阶段的触发条件进行限定,通过将合约以JAR包形式上传至区块链,实现智能合约投票系统的部署和自动化执行．最后,对智能合约投票系统的性能进行分析,实验结果表明该系统投票和计票阶段均可高效实施,为密码协议构造技术与智能合约投票系统的有效结合提供参考．     

Comparison of radiography, computed tomography and magnetic resonance imaging in the detection of sacroiliitis accompanying ankylosing spondylitis

OBJECTIVE: To compare magnetic resonance (MR) imaging, computed tomography (CT), and radiography in the detection of sacroiliitis accompanying ankylosing spondylitis (AS). DESIGN AND SUBJECTS: Nine volunteers and 24 patients were recruited. Radiography, CT, and MR imaging were completed within a 1-week period in 24 patients with AS. In precontrast MR examination, spin-echo T1, fast spin-echo T2, and gradient echo with rephasing T2* images were obtained without fat saturation using a 0.3-T imager for all volunteers and patients. Postcontrast MR examination was performed using the same precontrast SE T1 sequence for patients with AS. RESULTS AND CONCLUSIONS: MR imaging directly showed the normal cartilage in all 16 sacroiliac joints of the 8 volunteers. In the 24 patients with AS, cartilage abnormalities were observed in 42 sacroiliac joints. More diagnoses of sacroiliitis were made using MR and CT imaging than using radiography (P < 0.001). Therefore, low-field-strength MR can be useful in detecting early sacroiliitis in patients with AS. MR imaging was able to reveal early cartilage changes and bone marrow edema, which could not be found by either CT or radiography.