I know this issue was posted and discussed back in Sept., then archived so I'd like to bring it up again:
There are now mobile backscatter x-ray carrying trucks that can drive down a highway or park by the side of the road and x-ray the contents of vehicles. They can also drive by a structure and x-ray the insides of it.
The company that makes these things:
http://www.as-e.com/zbv/From their website:
A breakthrough in X-ray detection technology, AS&E's Z Backscatter Van™ (ZBV) is a low-cost, extremely maneuverable screening system built into a commercially available delivery van. The ZBV allows for immediate deployment in response to security threats, and its high throughput capability facilitates rapid inspections. The system's unique "drive-by" capability allows one or two operators to conduct X-ray imaging of suspect vehicles and objects while the ZBV drives past.
The ZBV can also be operated in stationary mode* by parking the system and producing X-ray images of vehicles as they pass by. Screening can also be accomplished remotely while the system is parked. Remote operation allows scanning to be done safely, even in dangerous environments, while maintaining low-profile operation. The system is unobtrusive, as it maintains the outward appearance of an ordinary van.
The ZBV employs AS&E's patented Z Backscatter technology, which reveals contraband that transmission X-rays miss - such as explosives and plastic weapons - and provides photo-like imaging for rapid analysis. The ZBV is also capable of identifying low levels of radioactivity from both gamma rays and neutrons with optional Radioactive Threat Detection (RTD) technology. The ZBV is ideal for counterterrorism applications, as it can detect dirty bombs and nuclear WMD, in addition to conventional explosives.