All of these procedures show diagnostic images of the body.  However, they do it in different fashions. X-ray: This is radiation that are in the form of beams that show densities in the body.  Bone or metal show up as white. Air is black and muscle and fat appear as grey. CT (computerized tomography): This procedure uses x-ray technology for its images along with ionizing radiation.  CT scanner gets several angles in 2D images. After images are taken and a computer places them together on the monitor, When a computer places the results of the images, it becomes a 3D image of the inside of the body that can detect the presence of disease or injury. MRI:  They do not use ionizing radiation.  What MRI stand for is "magnetic resonance imaging."  It uses radio waves and powerful magnets to produce diagnostic images. An MRI scanner can apply a magnetic field that lines up all of your body’s protons. Radio waves are applied to these protons in short bursts, which in turn relate a signal that is picked up by the MRI scanner.  If an MRI is taken, it is usually a long process where you lay down for 20 or so minutes and stay completely still.  After the image is taken, the computer then analyzes the signals and generates a 3D image of the segment of the body being examined. How long do they take? CT scans and x-rays typically take diagnostic images more quickly than MRI scans. For example, a CT scan or x-ray can often be completed in less than 5 minutes while MRIs take an average of 30 minutes. MRIs are normally taken for tissues to find tears and inflammation, x-rays for bones and CT scans for different angles of particular areas of the body being examined.  CT scans are extremely helpful in diagnosing serious injuries to the head, chest, abdomen, spine and pelvis, especially fractures. CT scans are also used to pinpoint the size and location of tumors.