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Why a remote relay?

With many studies it is necessary to collect data from multiple sites.  With a single XNAT instance this can mean manual uploads from every site, with significant human overhead and increased risk of errors.

XNAT can receive DICOM from the network, however, DICOM is not a secure protocol and should not be used on unsecured networks.    This meant that scanner technicians would have to log into XNAT via HTTPS and upload DICOM.

The solution is remote relay on the same network as the scanner. 

What is a remote relay?

A remote relay is managed XNAT server that will receive DICOM from one or more scanners and push sessions to another XNAT using Xsync to securely push the DICOM to an upstream XNAT system.   However, this XNAT server is very light weight and usually on very small foot print hardware such as an Intel NUC


DICOM only Relay

Very little compute power is needed, however, reliability is essential.   We have had very good results from the Intel NUC computing platform with SSD storage.   Here is a typical build we have used in 2016/2017:

  • Intel NUC Kit NUC6i3SYK
  • 16 GB RAM 
  • 250 - 500 GB SSD 
    Chose base on the volume of data that will pass through.   Typically we use the Samsung 850 EVO line and expect them to last about 5-7 years.  For higher volume use the 850 PRO line.

DICOM and Raw k-space Data

Raw k-space data can be rather data high volume and requires more storage.   While the NUC with an SSD could potentially store 4TB of data if using all SSD, the cost becomes very high.  In this case we build a mini-server.

  • Supermicro 5028A-TN4
  • 16 GB RAM
  • Two 120 GB SSDs
    Used for mirrored boot/OS and SSD cache for disk pool
  • Two 1 ft. SATA cables for SSDs to be mounted internally.
  • Four 4-8 TB enterprise grade SATA disks 

Network / Security Requirements

Network Requirements


  • A single 1 Gb/s ethernet connection on a network that can be reached by the scanner and has access to the internet.

Raw k-space 

In order to collect raw data the data relay must be connected directly to the scanner's back end network.

  • A scanner network tap at either the host computer or MARS computer
  • A 1 Gb/s Ethernet connection on a network that can be reached by the scanner and has access to the internet
  • An Ethernet connection on a network that administrators can access

Security Requirements

  • Must be reachable by the scanner(s) that will send DICOM
  • HTTP/HTTPS access to the the Internet
  • Internal users must be able to reach the relay via HTTP/HTTPS
  • SMTP must be allowed to either a local relay or directly to the NRG mail relay.
  • Administrator access via SSH 
  • Firewall should restrict access to only required users and administrators

Additional Information

  • NRG / HCP Built Data Relay
  • Prebuilt DICOM and Raw data relay image



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