The full-body scanner used at airports is equipment designed to check for hidden weapons, explosives, metals, or non-metallic items on passengers' bodies. Most international airports use millimeter wave technology instead of X-rays.

How Full-Body Scanners Work

Millimeter-Wave Scanner

  • Operating Frequency: Approximately 24-30GHz non-ionizing electromagnetic waves

  • Operating Method:

    • Low-power millimeter waves emitted from both sides of the machine scan the person's body

    • They pass through clothing and reflect off hidden objects on the skin and body

    • The reflected signals are received, and the computer displays the location of external objects on the body

  • Screen Output: Displays an image in the form of an abstract silhouette rather than a real human image (for privacy protection)

Backscatter X-ray Scanner → Nearly phased out

  • Operating Principle: Shoots low-energy X-rays at the body to create reflected images

  • Issues: Due to X-ray exposure to the body, most countries, including the US TSA, have phased out or discontinued their use

  • Currently, it is rarely used

Advantages

  • Can detect non-metallic materials such as plastic, ceramic, liquids, rubber, and paper in addition to metals

  • Identifies various forms of contraband such as cell phones, fireworks, fake belt buckles, and small weapons

  • Significantly contributes to enhancing security levels before boarding

Limitations and Controversies

  • Difficult to identify objects hidden inside the body

  • Possible false alarms with artificial joints, pacemakers, etc.

  • Privacy concerns: There was controversy in the past when silhouettes were output similar to actual images
    → Currently improved to only display body outlines, with AI indicating anomalies

Precautions When Passing Through

  • Raise your arms and hold for about 3 seconds

  • Remove metal items (belts, coins, etc.) in advance

  • If selected for re-inspection, it may lead to ETD checks (hand checks or pad checks)

Now, most international airports use millimeter wave technology, which does not use X-rays that can affect the body, ensuring a safe method even for repeated searches.