Centretown Veterinary Hospital

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Radiology: How Radiographs Are Made

Radiographs are the actual pieces of film your veterinarian shows you in the doctor’s office. They are commonly called X-rays because it is the X-rays which create the image on that film. Basically what happens is this: the X-ray machine creates X-rays that are directed at the patient who is lying on a piece of film. The X-rays make their way through the body and a certain proportion of the X-rays are absorbed by the organs in the body. The amount of X-ray each organ absorbs relates to both how thick it is and how dense the actual tissue which makes up the organ is. The more X-rays which make it through, the darker the image created on the film beneath the body. That is why bones are white but the lungs, which are mostly full of air, are black. So when the image comes out you have to shift your mind around because it’s the reverse of what you would expect. All of the soft tissue organs, like the kidneys, bladder, heart and intestines, all absorb similar but slightly different amounts of X-ray and so show up as different levels of grey. By interpreting the contrast in these different layers of grey, the veterinarian is able to make out the shape and to some extend the normalcy of each individual organ. When an organ is affected by disease it will quite commonly change its shape or even change its contrast with respect to other organs. By looking for these changes your veterinarian can pick up on subtle changes in organ structure.