© Archiving ©

As digital storage becomes the norm, what is to prevent the community from requiring all information be stored permanently?

There are not many manual systems that meet the above criteria to a high degree of satisfaction. There is always one area that is functionally corrupt. Manual systems have enough problems just storing and monitoring patient film jackets. The following breakdown of the problems associated with the three major archive functions makes it easier to understand the complexities the digital archive faces.

• IDENTIFICATION - Identification and retrieval of a patient file relatively easy because of color coding and numeric identification. All films are placed in a folder unique to the patient. The exam History and other relevant data such as patient, NAME, DOB, and ID are printed on the outside of the folder enabling easy retrieval. A fair number of institutions separate patient folders into sub-folders sorted by modality utilizing folder inserts with the same patient information relevant to that specific modality.
• The problems associated with identifying individual films is the way the information is embedded upon each film.
• The print type is very small allowing for a misread ID.
• With diagnostic film the patient information is sometimes blurred.
• Diagnostic film is occasionally mis-marked.



• STORAGE - Storage in most cases is done by putting folders in numeric order utilizing a unique patient identifier. Storage space is usually determined in linear feet. The files are placed onto racks designed to hold the largest film size. Increasingly storage requirements have become problematic. As technology has progressed, the amount of required space has increased due to the influx of information being recorded. Traditionally space was annexed from within the facility for storage solutions. Lately, with space becoming a premium, this has evolved to utilizing outside storage. This is accomplished by either leasing warehouse space or paying an outside source to handle those films that are considered excess.
• Both methods of outside storage have created additional problems or exacerbated previous issues.
• Films are no longer easily accessible.
• Retrieval times have increased.
• Duplicate film folders are created for the purpose of temporarily storing films while they are being read and awaiting the original folder delivery. These folders sometime become the original by default.
• Imaging centers are now held hostage to delivery schedules.
• The storage facility does not duplicate the climate controlled atmosphere normally associated with a proper archive.



• PROTECTION - Protection consists not only of a physically secure environment but also ensuring access limited to those that are authorized. Even with the best security and access limitations negative incidents occur. Most file storage areas are not manned 24 hours and films are not traditionally treated as a patient record by hospital staff.
• Most problems arise when the file is released outside of the archive area.
• The most problematic area is the confidence of image location because film file systems are not set up to monitor individual films.
• Films are occasionally unavailable, lost, marred or destroyed and sometimes films are never returned by patients and doctors.
• Films are unavailable if someone else is reviewing them at that time yet to the requestor they may as well be lost.

DIGITAL ARCHIVES , MEDIA TYPES and ARCHIVE DESIGN

A digital archive must perform, electronically, the same functions that are currently performed manually and it must perform them faster and better with no breakdowns. A digital archive is not functional if there is any physical intervention other than maintenance. No person should be required to load, track or store media., this defeats the purpose of electronics.

Knowing how the archive must function is as critical as the configuration of the archive relative to the type of storage media and how much data must be stored. Archive size is determined by the same retention statutes and annual volumes as the film archive. The storage media is determined by archive size and speed requirements. Size and speed determine the type of media needed as well as cost.

Currently archive needs can be placed into four categories, live, short term, intermediary and long term or permanent.

• Live - immediately available.
• Information is located at the point of interaction, on the workstation being utilized.
• The information available is constantly changing or volatile.
• Intermediary(Secondary) - immediately accessible.
• Information is located on the network as an accessible on line archive.
• The storage capacity is large enough to not significantly hinder information retrieval for daily operations. The information is stored for the purpose of providing an intermediary point before permanent storage, hence its name.
• Permanent (Tertiary)- accessible.
• Information is still available for retrieval.
• The capacity is configured to store enough information to fit the business needs of the client. This could range from one year to 10 or more years depending upon the industry standards.
• This could also incorporate data back up and disaster recovery solutions.

TYPES of MEDIA

Archive media plays the most important role in PACS. As much as the PACS/RIS/MODALITY interface is a significant part of PACS, the archive is what makes it all happen. Without storage media, who knows what information is available. When any information is produced how is it transferred to another for use. Currently archive media falls into three categories, disk, optical and tape.

• DISK - Exactly the same as what is on a PC - can be constructed as a Hard Drive or a Redundant Array of Inexpensive Disks (RAID) Drive.
• Hard Drive usually holds operating system and serves as short term storage.
• Configured up to 3 Giga Bytes probably more in the near future.
• Very fast data transfer with access times in milliseconds.
• Inexpensive.
• Should be considered as live storage.
• RAID Drive is usually for information storage. Depending on the configuration, it can be used as system backup. In this case it is used expressly for speed.
• Configured in excess of 10 Giga Bytes.
• Very fast data transfer with access times still in the millisecond range.
• Relatively inexpensive depending on size.
• Should be considered live.



• OPTICAL - Two technology types - Optical Disk (OD) or Compact Disk ROM (CD). I do not know the difference between OD and CD other than I must assume it is different writing technology. CD currently does not have the capacity of OD. OD technology has two types Write Once Read Many, meaning single use, (WORM) and Re-Writeable usually meaning magneto-optical.
• WORM
• Storage capacity varies with disk size. Some disks are 12 inches or greater.
• Single use only.
• Provides longer image life, no degradation, than magnetic tape.
• Easy to use and fairly inexpensive.
• Storage of multiple disks can become a problem.
• Re-Writeable OD
• Each disk holds approximately 2.4 Giga Bytes.
• Gives tremendous storage capacity when set up in a Juke Box configuration; greater than 100 disks on-line.
• Data access and transfer and rate is relatively fast but slower than Disk. You won't have time to get coffee.
• Relatively expensive and can be very expensive if it is used as permanent storage.
• Should be utilized as intermediary storage.

• TAPE - many types - tape media is changing, not only are access times decreasing but capacity and longevity are also increasing. Tape comes a variety of sizes and recording methods, 8 mm Cartridge, DAT and Optical Tape. All tape storage should be considered a long term or permanent archive solution.
• 8 mm cartridge - 8 mm tape in a cartridge similar to the cam corder.
• Large capacity in some cases more than 30 Giga Bytes per tape.
• Can be set up in Juke Box configuration allowing storage capacity in the Tera byte range.
• Access time is long because data is stored sequentially although the file method is changing. Time should not be considered a minus because data transfer is still faster than the manual method. Additionally this becomes seamless with IS integration.
• Offers an economical storage. Inexpensive less than $20.00 per cartridge or cents per image.
• Best utilized as permanent storage.

ARCHIVE DESIGN

The price and capacity of archive media changes almost as quickly as the time of day. The archive design should obviously incorporate your current as well as future needs. I recommend the following:

• Build your live archive to accommodate your currently needed files and size your full archive for the future, then divide it into separate archives by function.
• The live archive should only have capacity for a maximum of six months ( most patient follow-up care occurs within the first six months of treatment) and then should be offloaded to a secondary or tertiary structured archive.
• Investigate offsite digital archives for backup and disaster recovery, most disaster recovery plans require an offsite location for backup data.
• Consider utilizing a third party for the offsite archive, this could help you alleviate absorbing the cost of a large archive by sharing it with others through the vendor.
• This puts the burden on the vendor to keep up with the following:
• Changes in technology,
• Changes in the DICOM standard,
• Equipment investment,
• Maintenance,
• Providing a true disaster plan for the facility.