Terrorism has become the most prominent security issue of the 21st century and fighting terrorism is a top priority. Our society has been the target of a series of deadly terror attacks in recent years. A total of 11,072 terrorist attacks occurred worldwide in 2016, resulting in more than 25,600 total deaths and more than 33,800 people injured . In Europe, 142 attacks with 379 injuries and 142 deaths were reported in 2016 . Explosives were used in 54% of the attacks. Explosives or bombs can be made easily at home and hidden simply in a suit or under clothes, making it impossible to notice without specialised equipment. Moreover, the explosives are getting increasingly ‘explosive’: critical quantities as required to cause serious damage are getting smaller, which complicates detection. Recent terrorist attacks clearly demonstrate that there is a gap in detecting explosive threats in public areas: the September 2017 terrorist bombing in a crowded London subway station injured at least 30 passengers; the March 2016 bombings at Brussels Zaventem Airport - 32 killed and 170 injured; the June 2016 bomb attack at Istanbul Ataturk Airport - 41 killed and more than 230 injured. Any public area is a potential terrorism target, including airport, metro, train station, museum, shopping mall, etc.