Most collections of on The Cancer Imaging Archive can be accessed without logging in. Logging in offers certain advantages over accessing the archive as a guest user, since a registered user who logs in can:

• Access query history and save queries for future use,
• Share query results,
• Request access to private collections.

Access to some collections is limited to registered users who have been given permission to access that collection. This allows The Cancer Imaging Archive to:

• Support data collection for private or internal projects,
• Protect data while investigators are publishing results,
• Limit access to just those individuals directly involved in a project.