In contrast to the traditional X-ray machine, which detects hard and soft materials by the variation in transmission through the target, backscatter X-ray is a newer imaging system which detects the radiation which comes back from the target.

The resolution of the resulting images is quite high. Some backscatter X-ray scanners are able to penetrate up to 12" (30cm) of solid steel. As such, the technology is in use to search containers and trucks much more quickly, and potentially allow a larger percentage of shipping to be checked for smuggled items or weapons.

The technology has been proposed as an alternative to personal searches at airport and other security checkpoints, since it can easily penetrate clothing and reveal concealed weapons and other items. Privacy advocates are opposed to this use of the technology, since it appears to screeners essentially as a nude picture of the subject.

External links

• American Science and Engineering - pioneers in the field.
• University of Florida Reseach - High Resolution Scatter X-ray Imaging

X-rays