In an attempt to appease the public, TSA placed the people viewing the scans in a closed off room where they would have no contact or line of sight with the person being scanned. However, this failed to quell the complaints that continued to flood the airport screeners.
Another concern that has been raised with the backscatter x-ray scanners was a health issue, especially for travelers who flew frequently. Were frequent flyers being exposed to harmful amounts of radiation? The question remains unresolved which is why TSA officials recently contracted the National Academy of Sciences to study the scanners and their effects on the human body.
At the moment, the backscatter x-ray machines are being used in 30 airports in the US. They had plans to expand their use, until the company that provides the scanners and software said that they could not meet the congressionally ordered deadline to provide privacy software for the 174 scanners used at the 30 airports.
Rapiscan, notified TSA that they will not be able to meet the deadline, so TSA has cancelled its contract with Rapiscan and has announced plans to pull all of the backscatter x-ray scanners out of the airports. They will be replaced with the millimeter wave scanners that are currently being used in 170 airports. These scanners have privacy software that prevents the person from viewing the scans of being able to see a clearly defined nude image of the passengers.
The removal of the backscatter x-ray scanners should alleviate the concerns over privacy and over the harmful effects of frequent scans. The millimeter wave scanners, at least for now seem to be the answer to both concerns.