Originally Posted by red456

The goal is to scan everyone (except those who can't stand in the scanner and those poor souls will probably get the full monty of being felt up). At some airports there are terminals/concourses that cannot be accessed except by going through a scanner. At others, it's the luck of the draw.

That said, to scan everyone who flies would require thousands of scanners and that won't happen, at least not for a long time.