[Worldwide comment from BridgeHead Solutions Consultant, Tim Kaschinske – @TimKaschinske]

Two weeks ago at RSNA 2012, BridgeHead Software introduced a new white paper which identifies three often overlooked threats to the availability of PACS images. Leading healthcare consultant Joe Marion, a founder of Healthcare Informatics (HCI) and principal of Healthcare Integration Strategies LLC, validated the threat in remarks made by Marion at a press conference held at the RSNA 2012 last Tuesday, Nov 27.

Marion was also quoted in the press announcement made by BridgeHead on the same day, as saying: “Many administrators remain unaware that a standard VNA is insufficient for ensuring image availability as DICOM-level archive technologies are not designed to preserve multiple file copies, on multiple types of storage, with embedded signature validation. As a result, patient care is put at risk by these organizations because their images are not adequately protected.”

Marion went on to say: “What is needed to ensure image availability is an approach to VNA that is based upon a solid foundation of data protection. I applaud BridgeHead’s efforts to educate healthcare organizations on the risks present, and how to overcome the problem by taking an approach to VNA which is built on a solid data management foundation.”

What is Needed to Overcome the Threat: More Details on the File Layer Archive
To ensure the availability of PACS images, a multi-layered archive approach is required. The details of the four levels of archive which are required (Storage Layer, Abstraction Layer, File Layer and Content Layer), and how they work together to ensure image availability, are described in our recent white paper on VNA image availability. In this blog entry, I provide some added detail on the critical capabilities required in the file layer.
Data protection is provided by the file layer working with the abstraction layer.  DICOM images, scanned documents, reports, video and results from many different studies are stored as files. The basic file format provides the lowest common denominator for providing archive functionality that is application independent.

The file format as lowest common denominator, combined with functionality from the abstraction layer, provides the basis for data protection.  Digital signatures, from the abstraction layer, when applied to files, provide the ability to ensure that those files are archived correctly, free from corruption when retrieved. When files are archived to multiple storage media, the digital signatures are used to detect and correct files that have been identified as corrupt on a particular storage medium. Digital signatures can also be used to detect duplicate files and reduce the storage allocated to them.

The process of file archiving allows multiple versions of a file to be stored e.g., keeping versions of a file after it has been modified. This can provide support for regulatory requirements that need the ability to keep prior versions of a file. It can also be used to protect against the day-to-day disasters such as when a file is incorrectly modified (whereby a prior version of the file can be restored to correct the inadvertent modification).
Because data protection requires multiple copies of files, including multiple versions, policy rules can be used to manage the costs of storing these multiple copies. Policy rules can be designed to keep older, less used, copies of files on less expensive storage such as nearline disk or tape. Policy rules can also be based upon the file name, extension, creation date, modification date, or any other file attribute. Policy rules include retention dates to indicate how long to keep files, and can vary for different media types. An example would be to keep files in onsite disk storage for 2 years, offsite disk storage for 4 years, and on tape indefinitely.

Policy rules can also be used to manage the primary storage used for the production copy of a file. There are several policy rules that can be used, but the two most common are:
• Archive and Keep: This rule maintains the copy of the file on primary storage while making archive copies of the file. This is the basic archive protection rule.
• Archive and Stub: This rule replaces the copy of the file on primary storage with a ‘stub’ file that takes up less space than the original file. If the stub is accessed, the file is automatically restored from the fastest archive location, usually onsite nearline disk. File attributes such as creation or modification date can be used to determine which files to stub, such that primary production storage is maintained for the files that are most commonly used.

Finally, encryption is used to protect archived copies of data from unauthorized access. Where device encryption is available it is used. However, software encryption is also available for protection on devices that do not provide device encryption.

File archiving functionality provides a powerful method to protect data stored in files. A VNA that is not built upon a strong foundation of file archiving leaves its data at great risk of loss or corruption.