Because reading an X-ray image is a skill, not a glance. The operator is judging material by colour, shape by silhouette, and context by experience — quickly, hundreds of times per shift. The misses that matter are rarely "could not see"; they are "saw but misclassified", and they repeat in patterns that training can fix.
Use image libraries with known answers, and score the operator on false clears rather than speed. Train the specific pattern — "this is what a lithium battery looks like behind a laptop" — instead of general advice. Rotate operators every 30 minutes on busy lanes, and review every miss as an image, not as a scolding.
Basic image interpretation takes a few days of structured practice; competence builds over weeks of supervised screening. Certification requirements vary by market.
In most schemes yes, because material classification depends on colour discrimination. Screening for colour vision is standard practice.
It reduces the number of ambiguous images, but it does not remove the need to interpret them. It helps most where bags are dense and overlapping.
Commonly every 12–24 months, plus a session whenever the site introduces new equipment or a new threat pattern is identified.
