MIRC Hardware Considerations

This article is intended to assist in selecting hardware configurations for MIRC systems running the RSNA MIRC implementation.

1 Processor

The RSNA MIRC implementation runs on just about any hardware that can be purchased today. It has been tested on systems as small as a 300MHz P2 with 128MB RAM.

The power of the processor and the size of the memory and disk system are driven by the anticipated data volume and the access load. For a personal system, MIRC will run on any laptop or desktop computer. For a departmental system, especially one intended to support multiple storage services, connections to DICOM modalities and PACS, or participate in clinical trials, it is best to buy the fastest processor and the most RAM that can be afforded.

For a high volume departmental system, the following configuration would work very well:

• at least 3GHz P4
• at least 1GB RAM, preferably 2GB or more

Some experienced clinical trial administrators strongly advocate using servers rather than normal desktop systems because servers have much faster internal data busses. The MIRC development team has not run comparison tests of server and non-server configurations. The MIRC development team has also not run comparison tests of single-processor and multi-processor systems. Based only on general rules of thumb, a multi-processor server would be expected to outperform a single processor desktop system in the MIRC application.

2 Network Interface

Just about all computers today come with gigabit ethernet interfaces, and they can make a difference, especially during backups to network attached storage. A gigabit ethernet interface should handle any access load one could imagine a departmental teaching file system encountering.

3 Operating System

MIRC runs on any operating system that fits the hardware: Linux, Solaris, Unix, Mac OSX, or Windows. Judging by the number of problems encountered by administrators setting up their systems, Windows is by far the easiest OS to work with, no matter what anyone tells you. XP Professional is recommended, but XP Home also works well.

Although MIRC has been successfully run on Vista, Tomcat will not run as a service under that operating system. This means that Tomcat must be manually started and stopped, and the server runs in a command window. The MIRC development group is monitoring the Apache project to see when this restriction will be lifted. Because Vista uses more memory than XP, systems running on Vista should have at least 2GB of RAM, preferably more.

4 Storage

The largest MIRC site in a university today contains about 12,000 cases. Most departmental sites contain between 1,000 and 3,000 cases and grow by up to 1,000 cases a year.

The data storage required by a teaching file case strongly depends on how you create the cases. If you send DICOM images from PACS to MIRC, it will store them and reference them in the documents it creates. It will also create JPEG images for all the DICOM ones so a browser will be able to display the case for the user. The latest version of MIRC also has a DICOM viewer, so it is good to have the DICOM images in the document in order to do window width and level, zoom and pan, etc. Having DICOM images in the cases dramatically increases the data storage requirements, but it doesn't affect the performance of the system. Typical teaching file cases contain a few images and some text. Most have been well under 10MB.

With a 10MB estimate of a case size, a system with 1,000 cases, the minimum required by the ACGME for accreditation, would need only 10GB for data storage. A 250GB drive would therefore be more than adequate. Generally, it is best to put the operating system and Java on a different drive than Tomcat and MIRC, so a reasonable configuration would have two drives, with the larger drive being used for Tomcat/MIRC.

If backup is an important consideration, you can add a third drive to mirror the Tomcat/MIRC drive, put everything on a RAID, or add network attached storage and backup periodically on a schedule. The RSNA MIRC site is run on a RAID which is backed up on a schedule by the IT staff. The MIRC development team also has successful experience with the Buffalo Technologies TeraStation, which provides 1.6TB of RAID network attached storage at very low cost.