First, not all U.S. airports have new scanners, many of them not.
In the United States, if you leave an airport with one of these imaging devices, you can choose whether you want to go through the scanner or take a picture.
In that case, you can choose. If you don't want to pass the scanner, you have to be photographed. If you pass the scanner, there is no reason for them to take a shot unless the image's agent sees something they can't identify.
Your grandmother was wrong. They don't force everyone to do it.
The media has greatly distorted this situation. The vast majority of people have no problem with either approach. There are cases that have caught the attention of the media and Internet sites that seem to be standard.
There are two types of imaging devices. One USES radio waves and the other USES x-rays. X-rays are smaller than dental x-rays, which are less than you would receive in flight.
If your aiprort has these machines, you will definitely ask TSA people, if your airport USES one of the X-ray machines, you can use it instead of the scanner.
