X-Ray Baggage Scanners |
(Chapter 3 Metal Detection, Continued)
Procedures for the operator
The actual operation of an x-ray baggage scanner is straightforward. Vendors will provide recommended procedures for operating their specific equipment, and each school will probably tailor this for its own environment. However, as with the radiologist who examines medical x-rays, the challenging part of operating x-ray equipment for weapon detection is knowing what to look for. The untrained or disinterested operator can negate any possible benefit that could be gained in a weapon detection program.
The TV monitor that displays the black-and-white x-ray images of baggage it is scanning can usually be used in the positive or negative, i.e., solid objects can be displayed as light or dark objects. There are two types of color systems on the market. There are colorized single-energy (one radiation source) systems in which the color is arbitrarily assigned based on the level of energy transmitted. The second type is a dual-energy (two radiation sources) system that assigns color based on the effective Z-number of the material. The first type is inexpensive but adds no useful information to the display. The second type adds useful information but would normally be cost-prohibitive for most schools (exhibit 3.13).
Some general guidelines for the operator of an x-ray detector are: