Airport security X-ray screening of hold baggage: 2D versus 3D imaging and evaluation of an on-screen alarm resolution protocol

Abstract

In airport security screening, passenger baggage that is transported in the hold of an aircraft (hold baggage) is screened using X-ray machines with explosive detection technology. Older systems are based on 2D multi-view imaging whereas newer systems are based on computer tomography (CT) that features 3D rotatable images (3D imaging). Regulators, airport operators and security providers currently discuss whether extensive and specific training is necessary for screeners who are used to 2D multi-view imaging before they start working with 3D imaging. Moreover, to facilitate the decision making of screeners, so called on-screen alarm resolution protocols (OSARP) are available for 3D imaging. However, their effectiveness has not been investigated yet. To address these issues, we compared the visual inspection performance of screeners using state-of-the-art 2D multi-view imaging versus 3D imaging versus 3D imaging following a specific on-screen alarm resolution protocol (OSARP). In a simulated hold baggage screening task, screeners had to decide whether X-ray images contained an improvised explosive device (IED) or not. Results showed that there was no difference in detection performance (d') between 2D and 3D imaging. Visual inspection with 3D imaging following an OSARP resulted in higher detection performance (d') compared to 2D and 3D imaging. In conclusion, screeners currently working with 2D multi-view technology do not need extensive and specific training to achieve comparable detection performance with 3D imaging. The application of an OSARP has the potential to further increase screeners’ detection performance (d') with 3D imaging.