RE:Perception is everything To pick up a bit further on Leo's post, those that wish to do evil will find a way to do so and other than dealing with their motivations or living in a police state. You can never make anywhere 100% safe, even if our schools were operated out of high security prisons people have to come and go and that is an opportunity to strike. What PAT offers is a passive system that only detects threats allowing the 99.9999% of people to go about their lives unimpeded.
Turning back to perception, PATSCAN offers the opportunity for due dilligence to occur (insurance companies love it when clients applie due dilligence) Like taking all efforts to avoid slips and falls, when it happens, there is less opportunity for a negligence arguement to happen if someone does slip and fall.
When we look at PATs future business, it was mentioned earlier that an element of the business will be training, this is smart. Train those who will be using the tool, not just the set up and operation but the tactics, techniques and proceedures around establishing and maintaining security in target areas. The creation of security zones typically include a layered approach and take many shapes depending on the environment. Example https://www.rcmp-grc.gc.ca/physec-secmat/pubs/g1-026-eng.htm
In the case of an active shooter at a school, the closer they are the more risk they are. If you employ PAT as a standoff sensor, you trade space for time. Say at access points to the school yard 100m from the closest access, if someone with a gun passes it will raise an alarm and potentially lock down the school, if the shooter passes they hit the doors of the building itself, onther opportunity to alert officials and lock another set of doors. If linked to a camera system, now a photo is available to officials to ID the shooter, if the system has facial recognition it can follow the suspect in realtime, leading law enforcement to the shooter.
The other thing you will find is often shooters will do dry runs or dress rehersal to see how close they can get, ie they could carry a gun into school every day without being detected. PAT would potentially help law enforcement stop them during a dress rehersal.
Training on how to integrate PAT into existing security protocols for both institutional security and law enforcement is a wise move for PAT as an additional line of operation. As much as I hate to live in a world where this tech is required, my money is on PAT for the long haul.