Storage Architecture

Evorad RIS-PACS supports multiple alternative architectures for medical images, ranging from small servers with built-in storage to multi-terabyte multi-tier deployments solutions that include Storage Area Network (SAN) and tape library solutions.

All images are stored in original unmodified DICOM format as they are received from the modalities. However, they are compressed using fast lossless technology to a ratio of 1:2 to 1:3. This technology leaves the original DICOM files intact. Compression saves both storage space and network bandwidth when the images are transferred.

Multi-tier deployment

In the case of a large deployment the following storage tiers are proposed:

  • Online short-term storage. Stores the patient and examination database, the diagnosis voice recordings and images of current examinations. This tier is implemented using very fast hard disks using Storage Area Network (SAN) technologies. The administrator will typically set the retention period for examinations at this tier to be equal to the average time spent between performing the examination and recording the diagnosis.
  • Online medium-term storage. Stores images of all recent examinations. This tier is implemented using fast hard disks using Storage Area Network (SAN) technologies. The administrator will typically set the retention period for examinations at this tier to be equal to the average return period for a patient requiring a second examination for reevaluation.
  • Long-term storage and backup. Stores images of all examinations within the retention period required by electronic archiving policies (e.g. 3 years). This tier is implemented using Tape Library technologies with short response times.
  • Disaster recovery site. To ensure maximum operational continuity a separate RIS±PACS system deployment is suggested, which should be located in a different geographic location to compensate for physical disasters (e.g. fire). In the case that such a location is not available, Evorad RIS±PACS support data-center outsourcing to appropriate service providers, offering full data encryption during network transfer and while the data is stored.