What Are X-Rays?
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X-Rays - Properties, Uses, and Risks

Published on Oct 17, 2022   -  6 min read


X-rays are an imaging procedure used to look at the structures inside your body. Read this article to learn about X-rays.


An X-ray or X- radiation is high-energy electromagnetic radiation that produces images of the body. They can pass through the body structures onto the special plates, which produce “negative” type pictures. X-ray is referred to as Rontgen radiation, named after the scientist Wilhelm Conard Rontgen, who discovered it. The more solid structures of the body appear whiter in the film. The soft tissues in the body, such as skin, blood, and muscle, allow most of the X-rays to pass through and appear dark gray on the film or the screen. Hard tissues such as bone or tumors allow only a few of the X-rays to pass through and appear white on the film. The air present in the lungs appears black in the X-ray film.

Computed radiography is the digital replacement of conventional X-ray film radiography. It uses x-ray sensitive photo-stimulable phosphor plate (imaging plate) to create a digital image. It eliminates the use of conventional X-ray film. Digital radiography is another form of radiography that uses x-ray sensitive image plates to produce a digital radiographic image on a computer.

What Are the Properties of X-Rays?

X-rays are electromagnetic energy. They are produced by energy changes in electrons external to the nucleus, which moves from higher energy level to lower level causing excess energy to be released. X- rays have enough energy to break up molecules and thus damage living cells. They have a wavelength ranging from 10 picometers to 10 nanometers, and the frequencies range from 30 petahertz to 30 exahertz. The energies of X-ray range from 145eV to 124keV. The wavelengths of X-rays are shorter than UV rays and longer than those of gamma rays.

What Are the Uses of X-Ray?

X-rays are widely used in many fields such as medical, industrial, and research. Diagnostic medical X-rays are the most common way of exposure in your lifetime. X-ray is used to examine different parts of the body.

Bones and Teeth:



  • Accidental swallowing of objects in children and adults can be viewed clearly with the help of X-rays.

  • Digestive tract problems (swallowing barium may reveal digestive tract problems).

  • Intestinal obstruction.

  • Free fluid in ascites (collection of fluid in the abdominal cavity).

  • Free air from visceral perforation (presence of a hole in the gastrointestinal tract).

  • Gallstones.

  • Kidney stones.

What Are the Factors to Be Considered Before Taking X-rays?

  • Pregnancy - Inform your technician if you are pregnant. Radiation exposure will cause birth defects to the fetus in the womb.

  • Breastfeeding - If you are breastfeeding women, you may be instructed not to feed for about 24 hours after the scan because the contrast material may pass through the breast milk.

  • Kidney Diseases - You should inform your doctor if you are having kidney failure or other kidney disorders.

How Is an X-Ray Taken?

  • The patient might be asked to remove any clothing or jewelry which might interfere with the imaging process and to wear the hospital gown.

  • The patient is positioned between the X-ray machine and cassette containing x-ray film or specialized plate. Other body parts not being imagined may be covered with a lead apron which prevents unnecessary radiation exposure.

  • Patients will be asked not to move during imaging which may affect the image quality. They may ask to hold their breath for a few seconds at varying times to produce clear images.

  • Once you are ready, the X-ray machine will produce a safe level of X-ray beam that will be targeted into the area to be examined. Depending on the parts of the body to be examined, X-rays will be taken at different angles.

  • A chest X-ray may be taken from front, back, sides, etc.. This procedure usually takes just a few minutes for simple X-rays and a longer time for an imaging technique that uses contrast material.

  • If the patient is a child, the caretaker or one of the parents may be allowed to stay in the room. They must wear a lead apron to prevent radiation exposure. If the child is not cooperative, they might use restraints or other techniques to hold them in place during imaging. It does not harm your child. It prevents your children from increased radiation exposure by repeating the process.

  • Once an X-ray is taken, the images will be displayed on the computer screen within minutes. The conventional X-ray technique requires developing the film to get the images. After your X-ray, you can continue your regular diet and activities.

Contrast Material:

Before some type of X-rays, you may be asked to swallow contrast material, or it may be injected into your vein through an intravenous (IV) line. Contrast materials are special dyes such as barium and iodine used to outline the body structures to be examined. After scanning with contrast, you may be asked to drink plenty of water to flush out the contrast materials from the body. However, contrast materials are not used with most X-rays.

What Are the Different Types of Medical X-Rays?

  1. Projectional Radiography: Projectional radiography is also called conventional radiography, which produces two-dimensional images of the structures by X-ray radiation. Plain radiography or roentgenography refers to projectional radiography, which does not use any advanced techniques such as computed tomography that produces three-dimensional (3D)images. Plain radiography produces single static images and does not use any contrast materials in imaging.

  2. Computed Tomography: Computed tomography (CT) is a specialized imaging technique used to examine different structures of the body. In a CT scan, the X-ray beam is projected to the targeted area. The scanner detects this and transfers it to the computer. The computer processes the information into two-dimensional images (slices), which will then be arranged into three-dimensional images on the screen.
  3. Fluoroscopy: Fluoroscopy is an imaging technique used to get moving images of the internal structures of the patient. In fluoroscopy, the patient is placed between the X-ray source and the fluorescent screen. X-ray beams passed through the body will be absorbed based on the type of tissue, which produces an image on the fluorescent screen.

What Are the Typical Values of X-Ray Doses Used in Medical Imaging?

Typical values of effective dose for various medical X-rays are:

  • Dental- Intraoral - 0.008/mSv (millisievert).

  • Dental- Orthopantomogram - 0.014/mSv.

  • Chest radiography - 0.025/mSv.

  • Limbs and joints - 0.07/mSv.

  • Head (+eye,+jaw,etc.,) - 0.07/mSv.

  • Cervical spine - 0.2/mSv.

  • CT pelvimetry - 0.32/mSv.

  • Screening mammography - 0.4/mSv.

  • Pelvis/hip - 0.6/mSv.

  • Abdomen - 1/mSv.

  • Chest fluoroscopy - 1/mSv.

  • Cerebral angiography - 2/mSv.

  • Lumbar spine- 2/mSv.

  • Head CT - 2.6/mSv.

  • Urography - 3/mSv.

  • Upper gastrointestinal - 3/mSv.

  • Lower intestinal - 6/mSv.

  • Cardiac angiography - 7/mSv.

  • Body CT - 10.6/mSv.

What Are the Risks Associated With X-Rays?

Radiation Exposure - Ionizing radiation can damage your DNA and cause cancer. The risks of developing deadly cancer in CT scans are about 1 in 2000. The risk may increase with every X-ray exposure in a lifetime. Sensitivity to radiation depends on the age of the patient. Ionizing radiation is more harmful to children as they are growing. You should discuss with your doctor the benefits and potential risks of an x-ray before the scan.

Allergic Reactions to the Contrast Material- Side effects of iodine contrast are:

  • Itching.

  • Headache.

  • Hives (skin rashes).

Some of the severe symptoms of contrast materials are:

  • Breathing difficulties.

  • Hypotension (low blood pressure).

  • Swelling of the body parts.

How to Limit Radiation Exposure During an X-Ray?

Diagnostic X-rays provide necessary information about the disease in patients that helps your health provider to treat the condition appropriately. The rate of getting cancer from radiation exposure is typically less than 0.01 percent. Usage of a lead apron will minimize the radiation exposure to sensitive body parts. Modern X-ray equipment has features that can limit the dose and area irradiated. ALARA (as low as reasonably achievable) is a radioprotection principle which means that, even if it is a small dose, and it has no direct benefit, you should try to avoid it.


An X-ray is a painless, quick test used in medical diagnosis. X-rays are also used as a guiding tool in biopsy and treatment procedures. The radiation exposure from an X-ray is low, and the benefits from these tests are more significant than the risks. X-rays are even used in the screening of cancer which prevents them by treating them earlier.

Last reviewed at:
17 Oct 2022  -  6 min read




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