An X-ray image usually brings to mind a bulky machine in a hospital. But such a picture can be taken by a device the size of a palm, assembled from hobbyist electronics. The authors took a Raspberry Pi mini-computer, a 12.3-megapixel camera, and a screen that glows under X-rays.
The principle is simple: invisible X-rays hit a screen coated with a substance that converts them into ordinary light. The camera sees this light, and you get an image. To ensure sharpness, the researchers tuned sensitivity and exposure settings, then measured resolution using the slanted-edge method. The result: 25 line pairs per millimeter at 50–70 kilovolts. For comparison, a human hair is about 0.1 millimeters thick, and here details several times finer are discernible.
This resolution is comparable to clinical X-ray systems, but the cost and size are incomparably smaller. A portable device would be useful in the field, in small clinics, and in teaching labs. And the modularity, the ability to swap different screens, expands its applications, from inspecting welds to analyzing minerals.
From cheap components, they assembled a scientific instrument that produces X-ray images at the level of professional equipment. The world where an X-ray machine fits in a backpack is one step closer.
The screen made of terbium-activated gadolinium oxysulfide glows green under X-rays, the same material is used in some medical screens.