specific area of the body and onto a film. This produces a two-dimensional picture of the structures inside.
Bones and some other dense substances absorb more x-rays than other tissues, so they show up on the film as shadows that your doctor can interpret. But soft tissues can't be seen very well on x-rays. It is impossible to see the inside of a stomach, for example, without adding a substance that will prevent the x-rays from penetrating.
If your stomach is going to be x-rayed, you will have to swallow a barium "meal." The barium will improve the contrast and so produce a better picture. If your bowel is going to be seen, you will be given a barium enema . If your kidneys are going to be examined, another type of "contrast agent" may be injected into a vein to fill the kidneys, which will allow them to be seen.
A fluoroscope might also be used. This lets the doctor see a continuous, moving image. In this procedure, the x-ray beam strikes a small fluorescent screen and the image is amplified through a video system.
Nuclear Scans Radioactive isotopes that emit gamma rays can produce an image on photographic film or on a scintillation detector. Some of these isotopes, generally given by injection, are organ-specific, which means that they concentrate in that part of the body suspected of harboring cancer.
Different organs react to the isotopes in different ways. The isotopes used for liver scanning concentrate in normal tissues but are not taken up by cancer cells . So the image shows "cold spots" that may be cancerous areas. The isotopes used for bone scans, however, work in the opposite way. Cancer cells make the bone react to the isotope to a greater degree than normal bone, so "hot spots" light up the image of the skeleton. Hot spots can be produced by diseases other than cancer, however, such as bone injury or arthritis.
