Integrated implementation revamps information storage

January 20, 2005

As digital management of medical information has extended through the enterprise, so has the need to rethink fundamental approaches to managing this information. The focus is shifting from individual clinical systems such as PACS to what is best termed a healthcare enterprise information system, which encompasses all individual department information systems.

As digital management of medical information has extended through the enterprise, so has the need to rethink fundamental approaches to managing this information. The focus is shifting from individual clinical systems such as PACS to what is best termed a healthcare enterprise information system, which encompasses all individual department information systems.

Future systems will be defined by a storage management system linked by a network to the clinical departments and information system. To be successful, a healthcare enterprise information system must seamlessly integrate and securely archive the information generated by its components. This requirement increases the need for long-term planning and for ensuring the interoperability of systems in a cost-effective storage solution.(1,2)

The healthcare enterprise information system comprises four major components. The infrastructure is the local area and wide area networks and their associated media and electronics. Storage management is the storage infrastructure and related hardware and software. Information management is the component responsible for the acquisition, deployment to storage, and distribution of data and images. Visualization management is the element responsible for the user's ability to efficiently visualize, interact with, and extract information from the data and images (see figure).

The three management components-storage, information, and visualization-deal with data and image files. Data files typically contain variable content that is subject to change. Their size is relatively small, in the kilobyte range or less, and the transaction rate is high. Image files usually consist of fixed content; once an image is created, it is not altered. These files are large, in the megabyte range, and the transaction rate is relatively low.

The information contained in both the fixed- and variable-content files is related to:

- Healthcare enterprise systems, such as the hospital information system, physician portal, computerized physician order entry, and electronic health or medical records. The responsibility for these systems is shared by medical informatics units, clinical departments, and the administration.

- Business systems, such as payroll, accounts receivable, and billing. Responsibility for these systems rests with the administration.

- Clinical department systems, such as radiology information systems, radiology PACS and speech recognition, cardiology hemodynamic systems, cardiology PACS, and structured reporting. Responsibility for these systems falls to each clinical department.


The information technology group in the healthcare enterprise will have an ever-expanding role if the enterprise is to become paperless and filmless and achieve the improvements in patient care and productivity that a digital environment can make possible. IT must provide the leadership, funding, implementation, and support for the enterprise infrastructure, archive, and systems used outside of clinical departments.

Medical informatics units, clinical departments, and the administration must specify performance and storage requirements for the healthcare enterprise information system. Administration should also provide ongoing funding for the infrastructure and enterprise archive. If IT has to compete for funding every year, the process will disrupt the orderly progression of the system's implementation.

In most healthcare institutions, IT has the responsibility for administrative and clinical data systems but not for image systems such as PACS. As the more patient-centric data systems, including electronic health records, are implemented, IT should also take responsibility for their management and support. This will require administration to provide adequate budget and physical facilities for personnel and equipment. IT must be able to meet the performance criteria: availability of information anywhere at any time to any authorized user within seconds of the user's request. When there is a system failure, IT's response time must be measured in minutes, not hours, 24/7.

All parties involved with the healthcare enterprise information system, including the vendors, must work together as a team to achieve the objectives of the digital healthcare environment. Turf battles and departmental ownership of information are unacceptable.


Storage needs in the healthcare enterprise will increase rapidly in the next few years, due to the following factors:

- Additional clinical departments will go digital.

- Imaging modalities will generate more data.

- New developments will occur in imaging technology.

- Hospitals and imaging centers will merge.

- Compliance with regulatory requirements such as the Health Insurance Portability and Accountability Act will be required.

Image files will make up as much as 95% of the increase in storage requirements. Fortunately, the cost and complexity of managing these fixed-content files is less than for managing variable-content files associated with information systems such as the hospital information or computerized order entry system.

Many smaller institutions can eliminate the need for an onsite long-term archive or disaster recovery facility by outsourcing their storage needs to a storage service provider.(3)


In many healthcare institutions, individual departments maintain their own archive for images and sometimes for associated clinical information. This can be costly and can result in poor performance and security failures. Combining all storage resources and management responsibility into one centralized operation makes it possible to optimize performance and security while minimizing cost.

When a healthcare enterprise archive manages all medical data, their integrity is secure and they are universally accessible to authorized personnel. This type of system can eliminate isolated silos of departmental storage, provide integrated storage and storage management, reduce the cost of hardware, software licensing, maintenance fees, and personnel, provide high availability (at least 99.99%) for all information, and cost-effectively satisfy HIPAA requirements.

The environment in which the enterprise archive and its related components reside is critical to ensuring high availability, business continuance, and HIPAA compliance. This environment is expensive to build and maintain and requires redundant power supplies, fire suppression, infrastructure, telecommunication, and physical security for both the data center and disaster recovery center. But this type of system offers several advantages over a departmental solution in which storage is integrated with the clinical application and purchased from the application vendor. A storage vendor can install, support, and monitor the solution in real-time. A clinical information vendor cannot provide an integrated solution for the entire enterprise at an equivalent cost or with the same level of service.

Planning the health enterprise archive involves determining the number of storage tiers and the type of media for each tier. Many experts recommend a spinning magnetic disk solution, but in my opinion this approach is no longer viable, due to new regulatory requirements and growing storage capacity requirements. Hundreds of TB of storage will be required when an entire institution operates in a digital environment, and multi-institutional organizations will have to deal with petabytes.

An institution will typically want three to 24 months of data available on fast magnetic disk to ensure that the first image for at least 99% of the studies queried arrives at the workstation in three seconds or less. The amount of fast disk required depends on the institution's patient population and whether it is an inpatient facility or an imaging center. The balance of the long-term archive can consist of slow disk and/or optical media. The primary storage system at the disaster recovery site must be of a write-once, read-many type to ensure permanence of the information. The most cost-effective medium would be a high-capacity tape such as Super Advanced Intelligent Tape, which has an uncompressed storage capacity of 500 GB. Contrary to conventional wisdom, tape is not dead,(4) but because retrieval from tape is slow, the disaster recovery tape archive should be fronted with slow disk to support one to three months to ensure continuance of clinical and business information systems. Two of the most critical applications for a healthcare institution are payroll and accounts receivable, and they must be implemented on a business continuance basis.


As a result of the HIPAA mandate, outsourcing storage is gaining acceptance. HIPAA requires that all medical information be secure, available, and protected against corruption. But the law also contains the words "reasonable" and "feasible," which could be interpreted to mean that its implementation should not bankrupt an institution or complicate operations to a degree that affects patient care.

Disaster recovery, the long-term archive, and the data center and IT can all be outsourced. The least expensive and most common outsourcing is done for disaster recovery, at a cost of 47 to $1.80 per study, depending on the number of studies and the duration of the contract.(3) Contracts usually range from one year to the statutory life of the study. The price may or may not include telecom costs. All vendors provide onsite spinning media to accommodate up to one year's study volume in order to buffer transmission to the disaster recovery site and provide onsite backup. Outsourcing storage for disaster recovery makes sense for almost all healthcare institutions, excepting those that have adequate IT resources and two or more secure, accessible data centers.

Many small and medium-sized healthcare institutions also outsource the long-term archive. The cost per study can range from $1.40 to $4.(3) Conditions are similar to those for disaster recovery, except that two copies are maintained at two distant secure data centers. Depending on available bandwidth, studies can usually be retrieved from the long-term archive within five minutes; however, the equivalent of one year's study volume is available onsite. Some service providers also store the demographic database.

The third level of outsourcing involves the data center, including hardware and software, and most of the IT support to tier 3 and 4 data centers.(5) (The accompanying table describes the attributes of tier 1 through 4 data centers.) One data center houses servers, information system applications, and storage hardware and management software. A second center manages disaster recovery and business continuance. Redundant telecom connections via different Internet service providers using different switching stations provide the bandwidth between the data centers and healthcare institutions. This level of outsourcing is most appropriate for small, private imaging groups and healthcare institutions where this approach is justified from a risk management and economic perspective.


In this discussion, data migration refers to DICOM objects such as images, structured reports, and waveforms stored in the PACS archive. The files containing these objects are fixed content.

Institutions with existing PACS will probably replace all or part of this system in three to five years. This will require that images in the existing PACS be migrated to a new PACS or storage system, requiring considerable time and, possibly, expense. Depending on the speed of the legacy PACS, 500 to 2000 studies of 30 to 40 MB can be migrated per day, at an estimated cost of 50 per study.

Prior to migrating DICOM files, the files in the legacy PACS must be validated to ensure that the required fields in the DICOM header of each file contain the correct data. The DICOM header will have to be modified in the following cases:

- data were not placed in the correct field, or a critical field was empty in the legacy PACS;

- the new PACS requires data in a different format from the legacy PACS;

- the institution wants the data in a specific field modified.

Migration will not be possible for approximately 10% of the studies, particularly if the legacy PACS, RIS, and modalities did not support modality work list. Another problem in migrating is a file that contains the DICOM header but no image data, as can occur if the study was canceled in the RIS, but the PACS was not notified or ignored the cancellation.

The time required to migrate image files from the legacy PACS to a replacement PACS and the associated cost must be resolved during contract negotiations with vendors. In some cases, the new PACS vendor will perform the migration. The new PACS must be fully DICOM-compliant; if it is not, the migration will have to be customized at a significant increase in cost.


As storage management migrates toward a tightly integrated implementation, careful long-term planning and realistic, dependable funding is mandatory. Enterprise archiving will enable an institution to store the ever-increasing TBs of data in a secure and accessible manner to meet the performance needs of the health enterprise and to satisfy the security, information integrity, and accessibility requirements of HIPAA.

Dr. Smith is a professor of radiology at the University of Rochester School of Medicine and Dentistry in Rochester, NY. He is a member of the advisory boards of InSiteOne and Bycast and was formerly a consultant to Emageon and eRAD/ImageMedical.


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5. Turner WP, Brill KG. Industry standard tier classifications define site infrastructure performance. Available at

6. Slik D, et al. A scalable fault tolerant image communication and storage grid. Proceedings of SPIE 2003;5033:36-47.