An X-ray is a quick, painless test that produces images of the structures inside your body — particularly your bones.

X-ray beams pass through your body, and they are absorbed in different amounts depending on the density of the material they pass through. Dense materials, such as bone and metal, show up as white on X-rays. The air in your lungs shows up as black. Fat and muscle appear as shades of gray.

For some types of X-ray tests, a contrast medium — such as iodine or barium — is introduced into your body to provide greater detail on the images.

Why it's done

X-ray technology is used to examine many parts of the body.

Bones and teeth

• Fractures and infections. In most cases, fractures and infections in bones and teeth show up clearly on X-rays.
• Arthritis. X-rays of your joints can reveal evidence of arthritis. X-rays taken over the years can help your doctor determine if your arthritis is worsening.
• Dental decay. Dentists use X-rays to check for cavities in your teeth.
• Osteoporosis. Special types of X-ray tests can measure your bone density.
• Bone cancer. X-rays can reveal bone tumors.

Chest

• Lung infections or conditions. Evidence of pneumonia, tuberculosis or lung cancer can show up on chest X-rays.

Chest X-rays may be used to diagnose, stage and treat lung cancer. In low doses, X-rays may be used to construct images of structures inside the body to detect and stage a tumor. Chest X-rays help doctors determine how well treatments are working and are often performed before surgery so doctors are able to see the structures in the chest in advance.

• Enlarged heart. This sign of congestive heart failure shows up clearly on X-rays.
• Blocked blood vessels. Injecting a contrast material that contains iodine can help highlight sections of your circulatory system to make them visible on X-rays.
• Breast cancer. Mammography is a special type of X-ray test used to examine breast tissue.

Abdomen

• Digestive tract problems. Barium, a contrast medium delivered in a drink or an enema, can help reveal problems in your digestive system.
• Swallowed items. If your child has swallowed something such as a key or a coin, an X-ray can show the location of that object.

Risks

What Is a Mammogram?

A mammogram is an X-ray picture of the breast. Doctors use a mammogram to look for early signs of breast cancer. Regular mammograms are the best tests doctors have to find breast cancer early, sometimes up to three years before it can be felt.

Tips for Getting a Mammogram

• Try not to have your mammogram the week before you get your period or during your period. Your breasts may be tender or swollen then.
• On the day of your mammogram, don’t wear deodorant, perfume, or powder. These products can show up as white spots on the X-ray.
• Some women prefer to wear a top with a skirt or pants, instead of a dress. You will need to undress from your waist up for the mammogram.

ULTRASOUND

 An ultrasound scan uses high-frequency sound waves to create images of the inside of the body. It is suitable for use during pregnancy. Ultrasound scans, or sonography, are safe because they use sound waves or echoes to make an image, instead of radiation.

The images can provide valuable information for diagnosing and treating a variety of diseases and conditions.

Most ultrasound examinations are done using an ultrasound device outside your body, though some involve placing a device inside your body.

 Why it's done

Ultrasound is used for many reasons, including to:

• View the uterus and ovaries during pregnancy and monitor the developing baby's health
• Diagnose gallbladder disease
• Evaluate blood flow
• Guide a needle for biopsy or tumor treatment
• Examine a breast lump
• Check your thyroid gland
• Detect genital and prostate problems
• Assess joint inflammation (synovitis)
• Evaluate metabolic bone disease

Risks

Diagnostic ultrasound is a safe procedure that uses low-power sound waves. There are no known risks.

How you prepare

Most ultrasound exams require no preparation. However, there are a few exceptions:

• For some scans, such as a gallbladder ultrasound, your doctor may ask that you not eat or drink for certain period of time before the exam.
• Others, such as a pelvic ultrasound, may require a full bladder. Your doctor will let you know how much water you need to drink before the exam. Do not urinate until the exam is done.
• Young children may need additional preparation. When scheduling an ultrasound for yourself or your child, ask your doctor if there are any specific instructions you'll need to follow.

During the procedure

Gel is applied to your skin over the area being examined. It helps prevent air pockets, which can block the sound waves that create the images. This water-based gel is easy to remove from skin and, if needed, clothing.

A trained technician (sonographer) presses a small, hand-held device (transducer) against the area being studied and moves it as needed to capture the images. The transducer sends sound waves into your body, collects the ones that bounce back and sends them to a computer, which creates the images.

Sometimes, ultrasounds are done inside your body. In this case, the transducer is attached to a probe that's inserted into a natural opening in your body. Examples include:

• Transesophageal echocardiogram. A transducer, inserted into your esophagus, obtains heart images. It's usually done while you are sedated.
• Transrectal ultrasound. This test creates images of the prostate by placing a special transducer into the rectum.
• Transvaginal ultrasound. A special transducer is gently inserted into the vagina to get a quick look at the uterus and ovaries.

An ultrasound helps doctors look for tumors in certain areas of the body that don’t show up well on x-rays. Doctors often use them to guide a needle during a biopsy. Ultrasounds are usually quick and most don’t require special preparation.

A computerized tomography (CT) scan combines a series of X-ray images taken from different angles around your body and uses computer processing to create cross-sectional images (slices) of the bones, blood vessels and soft tissues inside your body. CT scan images provide more-detailed information than plain X-rays do.

A CT scan can be used to visualize nearly all parts of the body and is used to diagnose disease or injury as well as to plan medical, surgical or radiation treatment.

•  CT scans can show a tumor’s shape, size, and location. They can even show the blood vessels that feed the tumor – all without having to cut into the patient.
• Doctors often use CT scans to help them guide a needle to remove a small piece of tissue. This is called a CT-guided biopsy. 
• By comparing CT scans done over time, doctors can see how a tumor is responding to treatment or find out if the cancer has come back after treatment.

 Why it's done

Your doctor may recommend a CT scan to help:

• Diagnose muscle and bone disorders, such as bone tumors and fractures
• Pinpoint the location of a tumor, infection or blood clot
• Guide procedures such as surgery, biopsy and radiation therapy
• Detect and monitor diseases and conditions such as cancer, heart disease, lung nodules and liver masses
• Monitor the effectiveness of certain treatments, such as cancer treatment
• Detect internal injuries and internal bleeding

 Note:- Tell your doctor if you're pregnant. Although the radiation from a CT scan is unlikely to injure your baby, your doctor may recommend another type of exam, such as ultrasound or MRI, to avoid exposing your baby to radiation.

 Contrast material

A special dye called contrast material is needed for some CT scans to help highlight the areas of your body being examined. The contrast material blocks X-rays and appears white on images, which can help emphasize blood vessels, intestines or other structures.

Contrast material might be given to you:

• By mouth. If your esophagus or stomach is being scanned, you may need to swallow a liquid that contains contrast material. This drink may taste unpleasant.
• By injection. Contrast agents can be injected through a vein in your arm to help your gallbladder, urinary tract, liver or blood vessels stand out on the images. You may experience a feeling of warmth during the injection or a metallic taste in your mouth.
• By enema. A contrast material may be inserted in your rectum to help visualize your intestines. This procedure can make you feel bloated and uncomfortable.

What are the possible complications and side effects?

Some people react to the contrast dye. Possible reactions include:

• Rash
• Nausea
• Wheezing
• Shortness of breath
• Itching or facial swelling that can last up to an hour

These symptoms usually are mild and most often go away on their own. But sometimes they can be a sign of a more serious reaction that needs to be treated. Be sure to let your radiology technologist and your health care team know if you notice any changes after getting the contrast dye.