[throwup238]

US currency is made with a mix of 75% cotton and 25% linen fibers, rather than wood pulp like paper. They're less dense so they probably don't look the same on an xray.

[SoftTalker]

But they have anti-counterfeiting metallic strips and ink, you'd think that would jump out on an x-ray image.

[throwup238]

XRay depends on density and the security features are way too thin to matter