X-Ray Screening Quiz: Practice Questions with Answers

Sixteen practice questions on airport and cargo X-ray screening — the kind that appear in aviation security awareness and screener training courses. Pick an answer to see whether you are right and why. Nothing is recorded or sent anywhere.

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1. ETD (explosive trace detection) works on which principle? Ion stability spectrometry Ion mobility spectrometry Gas chromatography Ionisation of particles

Answer: Ion mobility spectrometry. Most checkpoint ETD units use ion mobility spectrometry (IMS): sample vapour is ionised and the ions' drift time through an electric field identifies the substance. See ETD.

2. A backscatter X-ray body scanner produces an image of the body in how many dimensions? One Two Three Four

Answer: Two. Backscatter builds a two-dimensional image of the near-surface of the body from scattered photons, one pixel at a time. See backscatter X-ray.

3. A millimetre-wave body scanner (such as the ProVision family) produces an image of the passenger in how many dimensions? One Two Three Four

Answer: Three. Active millimetre-wave scanners rotate antenna arrays around the person and reconstruct a three-dimensional image; the operator sees only a generic avatar with flagged areas. See body scanners.

4. In the USA, baggage inspection X-ray devices are designed and manufactured to radiation-safety standards issued by the: TSA FAA FDA (Center for Devices and Radiological Health) Nuclear Regulatory Commission

Answer: FDA (Center for Devices and Radiological Health). Cabinet X-ray systems, including baggage scanners, must meet the FDA performance standard in 21 CFR 1020.40. TSA decides which equipment is qualified for security use, but radiation safety is the FDA's rule. See regulations.

5. On a dual-energy baggage X-ray, what does orange usually indicate? Metals Organic materials Material too dense to penetrate Glass and aluminium

Answer: Organic materials. Orange means organic (low effective atomic number) material — clothing, food, plastics, and also most explosives and drugs. See X-ray scanner colours.

6. On a dual-energy baggage X-ray, what does a solid black area mean? Organic material Empty space The beam could not penetrate the object A threat has been detected automatically

Answer: The beam could not penetrate the object. Black means the X-rays did not get through, so the scanner has no material information. The bag must be re-scanned or searched.

7. What does TIP stand for in X-ray screening? Threat Identification Protocol Threat Image Projection Target Inspection Procedure Total Image Processing

Answer: Threat Image Projection. Threat Image Projection inserts fictional threat images into real bag images to keep screeners alert and measure performance. See TIP.

8. Which physical effect produces the signal in a backscatter X-ray image? Photoelectric absorption Compton scattering Pair production Fluorescence

Answer: Compton scattering. At security energies, low-Z materials scatter photons by Compton scattering; detectors on the source side collect them.

9. Which passenger screening technology uses non-ionising radiation? Backscatter X-ray Transmission X-ray Millimetre-wave imaging Computed tomography

Answer: Millimetre-wave imaging. Millimetre waves are radio-frequency energy, not ionising radiation.

10. High-energy sea-container scanners typically use which X-ray source? A 160 kV X-ray tube A linear accelerator producing MeV X-rays A cobalt-60 source only A millimetre-wave antenna

Answer: A linear accelerator producing MeV X-rays. Container and truck scanners mostly use linear accelerators in the MeV range to penetrate steel containers; some older or mobile systems use radioactive sources. See container scanners.

11. What is the main advantage of CT over conventional 2-D baggage X-ray? It uses no radiation It produces a 3-D image that can be rotated and sliced It is cheaper It does not need an operator

Answer: It produces a 3-D image that can be rotated and sliced. CT reconstructs a 3-D volume, removing much of the overlap that hides objects in 2-D images. See CT scanners.

12. The US FDA limit on radiation leaking from a cabinet X-ray system is: 0.5 milliroentgen per hour at 5 cm from the external surface 1 µSv per scan 5 mSv per year at 1 m No limit applies

Answer: 0.5 milliroentgen per hour at 5 cm from the external surface. 21 CFR 1020.40 sets 0.5 mR/h at 5 cm from any external surface. See radiation safety.

13. The 'low-prevalence effect' in visual search means that: Screeners miss targets more often when targets are rare Rare items are always easy to spot Low-energy X-rays miss threats Few airports use X-ray

Answer: Screeners miss targets more often when targets are rare. Research (e.g. Wolfe et al., 2005) shows rare targets are missed more often; TIP is one countermeasure. See image interpretation.

14. On a dual-energy baggage X-ray, a steel knife blade usually appears: Orange Green Blue Pink

Answer: Blue. Steel is a high-Z metal and appears blue (or black if very thick).

15. Which item can actually be damaged by airport baggage X-ray? A laptop A memory card Undeveloped high-speed film Medicine

Answer: Undeveloped high-speed film. Only undeveloped film is at real risk. See film, electronics and food.

16. In checked-baggage screening, what does EDS stand for? Electronic Detection Station Explosives Detection System Enhanced Density Scanner Emergency Dispatch System

Answer: Explosives Detection System. An Explosives Detection System is an automated (usually CT) scanner certified to detect explosives in hold baggage. See checked baggage EDS.

These questions are written for self-study. They are not taken from, and do not replace, any official certification exam. For background, start with the airport screening overview and the glossary.

Note: This page is an independent educational overview. It is not official guidance from TSA, the FDA, ICAO, the EU or any other authority, and rules change — always check the current requirements of the relevant authority or airport. See our full disclaimer.

Last reviewed on 2026-10-04.

X-Ray Screening Practice Quiz