What is the difference between them?
An X-ray shoots X-rays through you once. A CT scan takes a 3D picture by shooting X-rays through you over and over again from a bunch of different angles and working out the density of each point in your body.
MRIs are really magic though, they basically excite different atoms in your body and then see how long it takes them to relax. As the atoms relax, they release radio waves. The MRI scanner picks these up and can tell you the intensity of the radio signals.
How do MRI, Magnetic Resonance Imagers work? https://youtu.be/hlFGbiZRR5I
A CT or Computerised Tomography and CAT or Computerised Axial Tomography use X-rays to scan various parts of the body to give a three dimensional computer generated image of the part of the body being scanned. https://youtu.be/4Y617cFGHCg
Xray is a 2D image of your body. Usually from the side or front and back. You stand in front of an Xray sensitive film, the X rays shoot through your body and affect the film.
CT scan is still using X rays to take pictures of your body, although it does rotate around your body to construct a 3D image. Imagine if you took a video camera and panned it 360 degrees around a person. Even the though video is 2D, the information from the video is enough to construct a 3D shape.
MRI images a body similar to a CT scan but it doesn’t use Xrays. Instead it uses a strong magnetic field to align the magnetic moment of certain chemicals in the body to respond to certain electromagnetic waves.
* An x-ray is 100-year-old technology of shooting a bunch of high energy photons through the body from one angle and then into a piece of film where an image is captured. It’s one view of the body taken from one angle.
* A CT/CAT (computerized axial tomography) uses x-ray technology, but essentially shoots many different angles and then uses a computer to reconstruct the image.
* An MRI (magnetic resonance image) is a different and much newer technology, where the body is immersed in a strong magnetic field, and then hit with radio photons that cause the molecules in the body to vibrate in the magnetic field. This vibration gives off signals that are then reconstructed by computer to form the image.
They are all ways of seeing the internals of a body, but somewhat different in implementation.
X-ray is shooting rays through the body to see what’s inside in one or two projections. CT is the same rays but shot multiple times (like dozens or hundreds) from different directions to construct a 3D picture. MRI is using magnets to excite atoms in the body in specific ways to also construct a 3D picture. MRI differs from CT in that it doesn’t involve potentially dangerous radiation, and also the kind of body structures and anomalies that can be seen in CT and MRI are somewhat different.