Digital image management: networking, display, and archiving

The requirements for implementing a radiology imaging network are similar to those for local area networks now being designed for other purposes to manage large data films. A radiology department serving a 500-bed hospital generates about 927 megabytes of digitally formatted data per working day. These data are expected to be on line for the patient's hospitalization period. The retrieval rate of these data among the interactive diagnosis display stations requires data throughput rates of between 2 and 5 megabits per second. This throughput rate requires signaling rates of between 20 and 50 megabits per second. Analog hard-copy generation of the images on the network is required by the referring physician for selected images that support the consultation report. Digital laser recorders using paper may be quite satisfactory. Long-term archiving must be low in cost and requires a database scheme capable of managing more than a terabyte of image data. Radiology networks must be required to bridge with other hospital information systems.     

Medical image management

Medical image management is becoming increasingly complex as additional data are produced by equipment using digital techniques. As the requirements to store and display these images increase, the following questions become important: (a) What methods can be used to ensure that information given to the physician represents the originally acquired data? (b) What technology and methods are needed to guarantee that information is presented in a timely fashion when requested? (c) How can an image archiving and transmission system be designed to protect the patient's rights of confidentiality? The authors discuss the legal implications of digital archiving of image information and propose some approaches to designing systems that provide the most information to the physician and yet attempt to minimize infringement of the patient's rights.     

Digital image archiving: challenges and choices

In the last five years, imaging exam volume has grown rapidly. In addition to increased image acquisition, there is more patient information per study. RIS-PACS integration and information-rich DICOM headers now provide us with more patient information relative to each study. The volume of archived digital images is increasing and will continue to rise at a steeper incline than film-based storage of the past. Many filmless facilities have been caught off guard by this increase, which has been stimulated by many factors. The most significant factor is investment in new digital and DICOM-compliant modalities. A huge volume driver is the increase in images per study from multi-slice technology. Storage requirements also are affected by disaster recovery initiatives and state retention mandates. This burgeoning rate of imaging data volume presents many challenges: cost of ownership, data accessibility, storage media obsolescence, database considerations, physical limitations, reliability and redundancy. There are two basic approaches to archiving--single tier and multi-tier. Each has benefits. With a single-tier approach, all the data is stored on a single media that can be accessed very quickly. A redundant copy of the data is then stored onto another less expensive media. This is usually a removable media. In this approach, the on-line storage is increased incrementally as volume grows. In a multi-tier approach, storage levels are set up based on access speed and cost. In other words, all images are stored at the deepest archiving level, which is also the least expensive. Images are stored on or moved back to the intermediate and on-line levels if they will need to be accessed more quickly. It can be difficult to decide what the best approach is for your organization. The options include RAIDs (redundant array of independent disks), direct attached RAID storage (DAS), network storage using RAIDs (NAS and SAN), removable media such as different types of tape, compact disks (CDs and DVDs) and magneto-optical disks (MODs). As you evaluate the various options for storage, it is important to consider both performance and cost. For most imaging enterprises, a single-tier archiving approach is the best solution. With the cost of hard drives declining, NAS is a very feasible solution today. It is highly reliable, offers immediate access to all exams, and easily scales as imaging volume grows. Best of all, media obsolescence challenges need not be of concern. For back-up storage, removable media can be implemented, with a smaller investment needed as it will only be used for a redundant copy of the data. There is no need to keep it online and available. If further system redundancy is desired, multiple servers should be considered. The multi-tier approach still has its merits for smaller enterprises, but with a detailed long-term cost of ownership analysis, NAS will probably still come out on top as the solution of choice for many imaging facilities.     

Software suite for image archiving and retrieval.

The efficient operation of a clinical picture archiving and communication system (PACS) requires a fully functional image archive. The archive should not only be able to store and retrieve images reliably but should also work in concert with software that optimizes the flow of image-related information throughout the PACS. The authors devised a software suite that serves to improve the flow and content of information and the integrity of the data. The software was developed by translating the functions performed by a conventional film library. Types of transactions possible with this system include scheduling, canceling, rescheduling, and prestaging examinations; changing demographic information; merging patient information; and generating reports. The authors believe such a software suite is essential for a clinically useful PACS.     

Information preserving image compression for archiving NMR images

This paper presents a result on information preserving compression of NMR images for the archiving purpose. Both Lynch-Davisson coding and linear predictive coding have been studied. For NMR images of 256 x 256 x 12 resolution, the Lynch-Davisson coding with a block size of 64 as applied to prediction error sequences in the Gray code bit planes of each image gave an average compression ratio of 2.3:1 for 14 testing images. The predictive coding with a third order linear predictor and the Huffman encoding of the prediction error gave an average compression ratio of 3.1:1 for 54 images under test, while the maximum compression ratio achieved was 3.8:1. This result is one step further toward the improvement, albeit small, of the information preserving image compression for medical applications.     

Introduction to digital medical image management: departmental concerns

OBJECTIVE: The objective of this article is to provide an overview of the considerations that are faced when a film-based imaging department transitions to a filmless practice. Both departmental and enterprise issues will be discussed in the context of a single geographically confined campus. CONCLUSION: A successful transition to a filmless practice results from applying imaging informatics principles and using established standard, appropriate change management practices, all coordinated by a team of representative stakeholders.     

医学影像信息管理人才的培养

在当今高科技发展的年代里，档案信息化管理人才的培养颇为重要。因为现代化信息的处理和利用不再是那些传统的方式方法，而是通过计算机、网络、声像、影像等现代化的途径传播，笔者就此问题谈几点粗浅看法。     

Review of optical storage technology for archiving digital medical images

Digital optical recording (DOR) is a data-acquisition and storage technology important to the development of picture archiving and communication systems (PACS). DOR offers attractive advantages in high-density, low-cost archival storage of images and other information. At present, film is used as the storage medium for archiving images generated by both conventional equipment and digital technologies such as computed tomography, digital subtraction angiography, magnetic resonance imaging, and nuclear medicine. The basic methods of DOR data storage are discussed together with requirements essential for making DOR an acceptable alternative to film archiving. The impact of DOR technology on the operation of an imaging department is projected.     

Clinical evaluation of a medical image management system for chest images

The clinical efficacy and physicians' assessment of a medical image management system (MIMS) for chest images that involved the medical intensive care unit (MICU) and the radiology department were evaluated. A token-passing fiber-optic network was implemented to connect display stations in the MICU and in the chest reading area in the radiology department with a laser film digitizer and an archiving system. To study the clinical efficacy of this system, blocks of 8 weeks during which portable chest images were digitized and immediately made available in the MICU were alternated with blocks of 8 weeks during which film images only were available. Approximately 3000 portable chest examinations were tracked; patients were entered into the study at a rate of 65 per month. Data on time intervals associated with the examination process were collected from MICU physicians, radiologists, radiographers, and film librarians. The time from the completion of an examination to the time an action was taken that was based on radiographic findings showed significant reductions during the digital periods for certain actions. For example, the time to begin drug therapy decreased from a mean of 4.7 hr when films were viewed to a mean of 3.3 hr when digital images were viewed. In conclusion, if prompt action by the MICU physician improves a patient's outcome, a positive effect on patient care will result from the immediate availability of radiographic images.     

Fast image accessing based on an analysis of the picture archiving and communications system in Kochi Medical School

A large-scale picture archiving and communication system was developed by Kochi Medical School. Using JPEG to achieve 90% compression, this system was capable of storing several years worth of CT and MR examination records and eliminated the bottleneck in conventional systems caused by slow data access in the filing system. Under the new system, access of image files from client PCs was checked for bottlenecks. The image file retrieval from the image database on the server was found to require the longest time. Two methods were considered to eliminate this bottleneck. One was a multiimages filing into a file. Another was an image transmission with multiparallel transmission sessions, which is proposed in this article. By adopting the latter method, the system can transmit 50 CT images from the image database server to a client PC in about 10 s.     

Description of an acquisition, management and archiving system for digital images

The authors present a digitalizing and archiving system, for radiologic pictures. This system is composed by a camera, a microcomputer (MacIntosh II) with a digitalizing card and a great capacity optical disk (WORM) for storage. Acquiring and archiving are automatically driven by a special soft. The principal qualities of this system are simplicity for the user, speed and low cost.     

实施个体医学影像编码统一,提高医学信息管理水平

随着局域网(包括picture archiving communication system，PACS)在医院内的建立，个体的医学影像存储或检索取得了很大进步，为了推动其顺利发展，促进个体医学影像更方便、更快捷地存储或检索，我们对北京、济南的九家医院的个体医学影像编号的现状、问题做一分析，提出一种将患者个体医学影像编码统一的方法。     

医学图像融合

医学图像融合是医学图像后处理的研究热点,它充分利用多模式图像,获得互补信息,使临床的诊断和治疗更加准确完善。本文介绍了融合的三大关键技术,即转换、对位和信息提取,对常用的各类对位方法,尤其是内部特征法的多种算法进行了介绍和对比分析,并且展望了融合的发展趋势。     

HVS-based medical image compression

INTRODUCTION: With the promotion and application of digital imaging technology in the medical domain, the amount of medical images has grown rapidly. However, the commonly used compression methods cannot acquire satisfying results. METHODS: In this paper, according to the existed and stated experiments and conclusions, the lifting step approach is used for wavelet decomposition. The physical and anatomic structure of human vision is combined and the contrast sensitivity function (CSF) is introduced as the main research issue in human vision system (HVS), and then the main designing points of HVS model are presented. On the basis of multi-resolution analyses of wavelet transform, the paper applies HVS including the CSF characteristics to the inner correlation-removed transform and quantization in image and proposes a new HVS-based medical image compression model. RESULTS: The experiments are done on the medical images including computed tomography (CT) and magnetic resonance imaging (MRI). At the same bit rate, the performance of SPIHT, with respect to the PSNR metric, is significantly higher than that of our algorithm. But the visual quality of the SPIHT-compressed image is roughly the same as that of the image compressed with our approach. Our algorithm obtains the same visual quality at lower bit rates and the coding/decoding time is less than that of SPIHT. CONCLUSIONS: The results show that under common objective conditions, our compression algorithm can achieve better subjective visual quality, and performs better than that of SPIHT in the aspects of compression ratios and coding/decoding time.     

医学影像存档与通讯系统在影像诊断教学中的初步应用

目的 评价医学影像存档与通讯系统(picture archiving and communication systems，PACS)在医学影像诊断教学中的应用价值。方法 利用GE PACS和天助公司的放射信息管理系统(radiology information system，RIS)、终端图文工作站等硬件、软件配置，构建大屏幕多媒体阅片室，设置典型影像教学片库，开辟电子学习室，直接从PACS调取图像制作多媒体幻灯教学课件和制备考试题库。结果 成功完成了各项构建，在PACS设置的教学分类片库中积累了有价值的影像资料近5000例，改变了传统的影像教学方法，实现了影像教学的实时化、多样化，在影像诊断教学和实习中获得一致好评，提高了教学质量。结论 PACS有利于提高医学影像诊断学的教学质量，值得完善和推广。