how does an x-ray work?
Have you ever shined a bright flashlight through your hand and you were able to the red of your flesh and the dark outline of your bones?
That is also exactly how an X-ray machine works, but they are using photons that have more energy and penetrate much more easily. Which is why they can go through almost all of your flesh with no problem. And then they shine on either a photographic plate or the digital equivalent in order to make a picture.
Basically an X-ray is a light source and a camera in one machine. It shines energy toward a camera at wavelength (x-ray band, higher frequency than visible light and UV) that penetrates the body at rates which vary by tissue density. Over a given exposure, photographic brightness varies to render an image of the body’s internal structure.
X-rays are generated by passing electricity between conductors in a vacuum.
So, to step back for a minute:
When we are talking about x-rays, we are talking about the electromagnetic radiation spectrum in a specific band of frequencies – this is responsible for radio waves, light, and the ionizing radiation that we think of when we think of radioactive things. It’s all the same thing (photons moving) but as you get more energetic, the photons oscillate more rapidly.
The more energetic the EM radiation is, the smaller a space it can fit through. As a tangent, this is why you’ll notice a mesh of sorts on most microwave doors – those are sized so that the actual microwave radiation waves are too big to fit through the holes, but light goes through just fine.
X-rays have the property of being small enough to fit through the gaps in the molecular structure of flesh, but not quite small enough to go through the more dense bone structure.
So in that way, X-Ray imaging works a lot like a camera, except instead of catching an image of what the light bouncing off of you looked like, you’re capturing what the X-Rays bouncing off of you looked like.
Imagine you had a sheet of bullet proof metal in the shape of a skeleton and behind it was a big sheet of paper.
Now imagine you get a gun with a very high fire rate and start shooting at it.
Any bullets that miss the skeleton with go on to make a hole in the paper, and any ones that hit the skeleton will be stopped, not damaging the paper. Eventually if you look at the sheet of paper all that will be left is the shape of the skeleton.
That’s basically the idea. X-ray radiation penetrates flesh but not bones, so if you put somthing with bones it in between an x-ray detector and an x-ray emitter then turn on the emitter, everywhere that the emitter doesn’t detect getting hit is where a bone must be.
Basically what you see an bones in an x-ray image is the shadow bones cast on the x-ray detector.
Rays go through the body but don’t go through certain materials in the body which makes them show up