Designing an in-field system for illicit drug detection using X-ray diffraction

One way of smuggling drugs into a country is via the postal and courier services. Automated systems are necessary to scan incoming parcels and make quick decisions on whether they contain drugs or not. Few false positive and negative results are an important requirement for the end users of such a system, as neither parcels containing drugs should be lost nor parcels without drugs should stop the workflow. According to previous studies, x-ray diffraction has demonstrated the potential to meet this requirement, as it has shown high ability in identifying drugs, compared to other methods. This is mainly due to the crystalline pattern of the drugs and their unique diffraction signature. The same technique has also been applied in explosives and calculi identification in the past with great success. In this study, a simulation model was developed simulating energy dispersive x-ray diffraction from the powder diffraction profiles of several materials that could be found in a common parcel. A database containing thousands of such materials has been collected. The aim of this study was to test several possible infield systems for drug identification and decide on the optimum that will be developed in the lab. To this direction, several geometries (including distances, collimation, scattering angles etc.), x-ray spectrum energies and detector energy resolutions (HPGe, CZT, Si and NaI) were tested. A variety of parcel sizes and compositions were designed and simulated and the results were analyzed using Multivariate Analysis (MVA). Results showed that several geometries and detectors can lead to a system with high sensitivity and specificity. The next step of this study is the development of these systems in the lab.