The walk-through and carry on scanners are nothing compared to the cargo and baggage scanners.
As a matter of course, I always remove my DEVICES from my photo pack: Laptop, camera body, light meter and external hard drives (I may be taking it a bit far, but I want the TSA goons to see what they're looking at before they nuke it) and put them in a tub.
I also insist upon the scanner operator waiting until I'm on the exiting side of the scanner before he/she runs it through. Since I usually fly red-eyes and am very early (meaning a short, if any line), it's never been a problem for them to do that.
Also, if you have a pack, you may need to open it anyway so that they can scan through the multiple levels "properly."