Apparently "determination of risk" is not a criteria for how/where these are deployed. Clear evidence that the machines are unnecessary and primarily intended for propaganda and budget padding:
According to DHS, locations for the new units were chosen based on their "readiness, checkpoint infrastructure, and capacity to ensure privacy protections - including a separate, remotely located room for viewing images-are carefully considered before AIT units are deployed to selected airports."
http://www.federalnewsradio.com/?nid=35&sid=2007029