Digital archive solution offers low-cost storage

A combination of advances in scanner technology and greater emphasis on radiological diagnosis in healthcare has produced a steady increase in imaging data in hospitals across Europe. Imagers, in turn, are faced with the challenge of finding affordable storage that not only copes with the growing load but allows for fast retrieval of past examinations. Researchers from Germany believe they have found a solution to this problem, with a system based entirely on OpenSource software.

The Marvin digital archive is a low-cost, user-friendly system that allows rapid access to image data, according to Alexander Haderer, a researcher in the radiology department at Charite Hospital in Berlin. The system stores all imaging information online and allows access via Web browsers, avoiding the need for tapes or other recordable media that can be costly and may become obsolete.

Haderer outlined the Marvin setup at the EuroPACS 2002 meeting in Oulu, Finland, in September (CIS) (Figure 1). A central image server receives radiological images via DICOM and stores patient data. Separate servers keep the image data on a soft-RAID and deliver images either by HTTP or DICOM. As space in the archive fills up, additional storage capacity is added.

The OpenSource archive has been operational at the Berlin hospital since the last quarter of 2000. By September 2002, it had expanded to include 12 storage servers and 300 registered users. The system contained 6.3 million images (390,000 separate series) of 60,000 patients, taking up 3.6 TB of the available 4.8 TB.

"We have a reliable and robust image archive. It has high user acceptance and high performance through its multiple server concept," Haderer said. "Our flat architecture results in simple administration, and storing everything online guarantees direct image access at any time."

The radiology department at Charite produced an average 9.6 GB of new image data per day in August, the bulk of it from multidetector CT examinations, Haderer said.

"We have a four-slice CT, an eight-slice, and a 16-slice system that produce a lot of data," he said.

Hardware costs for the Marvin archive to date are Euro 70,000, while the system's OpenSource software was free of charge. This compares favorably with the projected cost of the alternative image storage solutions shown in Figure 2.

Marvin storage servers have an estimated three-year lifetime, at which point all data must be copied to a new storage server. The continued increase in hard disk capacity, however, means that fewer storage servers are required for the renewal, Haderer said. The price per GB of hard disk capacity is also falling.