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Selection and training of x-ray image analysts at the Nonintrusive Inspection Technology Testbed

The Non-intrusive Inspection Technology Testbed is a high-energy radiographic imaging system for the detection of contraband in intermodal containers. X-ray images are analyzed with a complement of computer-based enhancement tools so that a decision can be made whether to pass the container into the stream of commerce or recommend that it be opened and searched. This paper applies signal detection theory to the analyst's task and reports on a study that explored the relationship between the Embedded Figure Test (EFT) and performance in detecting contraband. It was found that the EFT score and the performance measure were correlated (r equals -0.58, p equals 0.023). A replication of this study using airport X-ray screeners and X-ray proficiency ratings by their supervisors also showed a correlation (r equals 0.44, p < 0.04). It was concluded that the EFT predicts the ability of an operator to find contraband in an X-ray image. Recommendations were made on the application of signal detection theory to the operation of the imaging system.