X-rays

X-ray imaging is perhaps the most familiar type of imaging. X-rays are painless, quick and relatively inexpensive. X-rays are not without dangers, however. Too much radiation can cause problems. Women of childbearing age need to be especially vigilant. If they are pregnant or might be pregnant, they should inform the people who are doing the x-ray. (Read about "Healthy Pregnancy")

X-rays are a type of penetrating radiation. They are made up of electromagnetic waves that have a shorter wavelength than light, so they are not visible. The x-ray emitter is placed in one position. Film or a digital receiver is placed opposite the emitter. The body part to be examined is placed between the two. Digital x-rays collect the data on computer instead of on a piece of film. This means that the image can be computer-enhanced, or areas can be magnified.

Images produced by x-rays are due to the different absorption rates of different tissues. Calcium in bones absorbs x-rays the most, so bones look white on a film recording of the x-ray image, called a radiograph. Radiologists are the specialized doctors that look at and interpret radiographs. Fat and other soft tissues absorb less, and look gray. Air absorbs least, so lungs look black on a radiograph.

The most familiar use of x-rays is checking for broken bones, but x-rays are also used for many other purposes. They can be used for early detection of cancer. (Read about "Cancer: What It Is") Mammograms use x-rays to look for tumors or suspicious areas in the breasts. (Read about "Mammograms" "Breast Cancer") Chest x-rays can be used to find primary lung cancer or to see if cancer has spread to the lungs from other primary tumor locations. (Read about "Lung Cancer")

Sometimes various contrast materials or dyes will be used to help make certain things stand out and help with diagnosis. It is important that you let the x-ray technicians know about any allergies you have. (Read about "Allergies") Some of the contrast dyes could cause you to have a reaction.

X-rays are used in many procedures and sometimes are called by different names. Here are just a few.

Arthrography - This is an x-ray of a joint. It is usually done using a type of x-ray that happens in real time called fluoroscopy. The image is produced on the screen so that the radiologist can see what is happening right away. A contrast material containing iodine is often injected into the joint, according to the American College of Radiology.

Bone x-ray - This is what many people think about when they think about x-rays. The x-ray is used to check for a broken bone or a fracture. (Read about "Bone Fractures")

Bone density scans - Bone density or DEXA scans check the mass or density of the bone. They can be used to diagnose osteoporosis. (Read about "Osteoporosis" "DEXA Scan")

Chest x-ray - The American College of Radiology says chest x-rays are the most commonly performed x-ray. A chest x-ray can create images of the heart, lungs, blood vessels and the bones of the spine and chest. (Read about "The Spine") It is used to diagnose, or eliminate a number of conditions such as heart failure, heart valve or blood vessel problems, congenital heart disease, as well as lung problems such as pulmonary edema, cancer and infections. (Read about "Congestive Heart Failure" "The Heart & Its Valves" "Vascular System: Arteries & Veins" "Congenital Heart Defects" "Respiratory System" "Lung Cancer")

Coronary angiography - Coronary angiography is a test that uses dye and special x-rays to show the inside of your coronary arteries. The coronary arteries supply blood and oxygen to your heart. (Read about "The Heart & Cardiovascular System" "Cardiovascular Tests")

CT scan - A computed tomography scan (also called a CAT scan) uses computer-controlled x-rays to create images of the body. However, a radiograph and a CT scan show different types of information. Although an experienced radiologist can get a sense of the approximate three-dimensional location of a tumor from a radiograph, in general, a plain radiograph is two-dimensional. A CT scan, on the other hand, uses x-rays to produce images representing "slices" of the body - like the slices of a loaf of bread. Each image slice corresponds to a wafer-thin section, which can be viewed to reveal body structures in great detail. (Read about "CT Scan - Computerized Tomography")

Cystogram - A cystogram is an x-ray examination of the bladder. The bladder is filled with a contrasting agent during this procedure. (Read about "Urinary System")

Fluoroscopy - Fluoroscopy uses x-rays to produce images on a monitor in real-time. Think of it as a live broadcast of what's going on inside your body. The Food and Drug Administration says it can display the movement of a body part, an instrument that is being inserted into your body or a contrast agent that is flowing through your body. Some of the procedures that may use fluoroscopy are barium swallows and enemas, catheter placement for angioplasty, joint and other orthopedic surgeries and blood flow studies. It is often used to diagnose conditions such as gastroesophageal reflux disease (GERD), heartburn and hiatal hernia. (Read about "Gastroesophageal Reflux Disease" "Heartburn" "Hernia")

Lower GI Series - A lower gastrointestinal (GI) series uses x-rays to diagnose problems in the large intestine, which includes the colon and rectum. The lower GI series may show problems like abnormal growths, ulcers, polyps, diverticular disease and colon cancer. Before taking x-rays of your colon and rectum, the radiologist will put a thick liquid called barium into your colon. This is why a lower GI series is sometimes called a barium enema. The barium coats the lining of the colon and rectum and makes these organs, and any signs of disease in them, show up more clearly on x-rays. It also helps the radiologist see the size and shape of the colon and rectum. (Read about "Colon Polyps" "Diverticular Disease" "Colorectal Cancer")

Mammography - Mammography uses x-rays to look for tumors or suspicious areas in the breasts. (Read about "Mammograms" "Breast Cancer")

Myelography - Myelography is a special check of the spinal column. It can check for things such as herniated disks, swelling of the spinal cord and/or spinal tumors. A contrast dye is often used. (Read about "Disk Problems" "The Spine")

Tomosynthesis - Tomosynthesis creates a three dimensional picture using multiple x-rays of the same area, taken from different angles.

Upper GI Series - The upper gastrointestinal (GI) series uses x-rays to diagnose problems in the esophagus, stomach and duodenum (first part of the small intestine). It may also be used to examine other areas of the small intestine. The upper GI series can show a blockage, abnormal growth, ulcer or a problem with the way an organ is working. During the procedure, you will drink barium, a thick, white, milkshake-like liquid. Barium coats the inside lining of the esophagus, stomach and duodenum, and makes them show up more clearly on x-rays. (Read about "Esophagus Cancer" "Stomach Cancer" "Gastroesophageal Reflux Disease" "Gastritis" "Peptic Ulcers")

Virtual Colonoscopy - Virtual colonoscopy (VC) uses x-rays and computers to produce two- and three-dimensional images of the colon (large intestine) from the lowest part, the rectum, all the way to the lower end of the small intestine and display them on a screen. The procedure is used to diagnose colon and bowel disease, including polyps, diverticulosis, and cancer. (Read about "Colon Polyps" "Diverticular Disease" "Colorectal Cancer")