suitcase screening device (web picture)
People and their luggage get scanned at airports, major bus terminals / train stations, malls, courthouses, and other public facilities (at least this is the case in Israel) - the purpose of that being to detect concealed metallic or non-metallic security threats (knives,weapons,explosives, certain liquids/ gels/ powders/ plastics).
body screening (web picture)
handheld scanner (web picture)
As for success, well, we invest millions in things that we know in advance that there will be very little success about them, and yet we do it, we have to do it. For example, all those reabilitation centers for drug and alcohol addicts, or for released jail prisoners. Most of these people return to their old habits and pose a risk both to themselves and to society. Nobody will dare suggest to give in and close the above mentioned centers.