Rapiscan technicians in the field are required to test radiation levels 10 times in a row, and divide by 10 to produce an average radiation measurement. Often, the testers failed to divide results by 10, Horowitz said.

“Certainly, the errors are not acceptable. It’s not every report. We believe the technology is safe,” she said. ”We’ve done extensive, independent testing. It doesn’t raise alarms in terms of safety.”

Rapiscan, in a letter to the TSA, admitted the mistake and is “redesigning the form” used by its “field service engineers” when surveying the Rapiscan Secure 1000 that is deployed to 38 airports.