I would like to offer some reading material for folks to perhaps answer their concerns....
Products for Security Screening of People
The TSA Blog
There remains some concern that "leakage" at the top of the scanner surpasses the legal limits. Transparency with regard to current surveys of the equipment posted for public review would be nice.
Some of the info can get technical.
Backscatter technology was evaluated by the Food and Drug Administrationís (FDA) Center for Devices and Radiological Health (CDRH), the National Institute for Standards and Technology (NIST), and the Johns Hopkins University Applied Physics Laboratory (APL).
All results confirmed that the radiation doses for the individuals being screened, operators, and bystanders were well below the dose limits specified by the American National Standards Institute (ANSI).