Originally Posted by TSORon

For the TSA, the decision on which system to install at each individual airport comes down to logistics. Not which is better or worse, which is more or less invasive, but which one will fit in the space provided.

MMW consists of a large tubular type system that is also quite tall. Airports that can accommodate this type of system are fewer and further between than those that can accommodate the Backscatter system and its requirement for more floor space. Most airports were designed and built long before either of these technologies was even thought of, and the space for them was not allocated to the screening process by the varying airport authorities, nor was it thought of to provide the screening areas with exceptionally high ceilings. WTMD does not require anywhere near the space that either of the AIT systems do, and that was the standard screening device when most airports were designed.

On the theory of what the systems do or do not detect, what I can tell you is that they do detect anomalies. Not guns, not paper, not implants, not scars, not explosives, not hair gel, not just about anything. They only detect anomalies. Pre-ATR it was up to the TSO in the imaging booth to do the detecting. Now, can a human detect all of the above? Normally yes. They may not be able to tell the search officer what the anomaly is, but they can certainly tell the officer if it is there or not.

On the theory of which is safer, well since you have gotten more ionizing radiation from your computer monitor (or cell phone) reading this post than you got from your last 2 runs through either AIT system, I guess it’s a matter of “acceptable risk”, and only you can make that choice for yourself.