A review of the F792 test object completed last year at the behest of DHS identified several issues that would benefit from the coordinated attention of vendors and users of modern checkpoint scanners. Among their findings were discrepancies in the placement of certain test objects (between the test kits and the F792-08 document), recommendations for expanding and refining both the Test 2 (Useful Penetration) and Test 4 (Simple Penetration) artifacts, and a proposal to do away with an artifact in Test 6 (IQI Sensitivity) because none of the current systems was able to distinguish most features. Subsequent to this, it was noted that specifications of most artifacts admitted a wide range of densities or called for materials that are susceptible to corrosion or whose commercial availability may be limited, carrying implications for tests of materials discrimination and, potentially, inviting difficulties in the manufacture or replacement of components over time. The report prepared for DHS addressed the foregoing issues in detail, amassing nearly 20 proposed revisions to the F792 test object that would tighten up materials specifications, do away with the one IQI artifact, extend the range of wire gauges in Test 2 and double the number of steps in the step wedge of Test 4. In addition, a recommendation was made that the test object be positioned orthogonal to the beam during testing so that the result would provide a reliable measure of the intrinsic imaging quality of the various systems under test. Shortly after submitting the report, I had a conversation with Australian colleagues who were of the opinion that more extensive revisions than those I had proposed would be necessary to test the capabilities of newer, dual-energy and/or multiview scanning systems that are being deployed. Others have mentioned the desirability of implementing more objective, machine-vision methods for assessing image quality.
Keywordscontrast sensitivity; effective atomic number; explosive device; explosives; IQI; IQI sensitivity; organic differentiation; organic/inorganic differentiation; radiation chamber; radiation monitor; scatter block; security system; simple penetration; spatial resolution; thin organic imaging; useful organic differentiation; useful penetration; weapons; wire display; X-ray; Baggage inspection; Cargo environments/processing; Controlled access search/screening; Explosions/explosives; Illumination; Image analysis; Ionizing radiation; Luggage inspection; Nuclear facilities; Radiation exposure--security applications; Security systems and equipment; Weapons detection; X-ray monitoring/processing;
Nicholas Paulter, Jr
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