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X-ray for Cancer
X-rays and other radiographic tests may be used to find cancer or plan further cancer treatment. You might also hear these called radiographs, roentgenograms, or contrast studies.
What is an x-ray?
X-rays and other radiographic tests use a controlled beam of radiation to create gray-scale images of your bones and other areas in your body, such as your lungs and kidneys.
A special type of radiographic test known as a contrast study combines x-ray with dyes or contrast materials. This helps certain parts of your body show up more clearly.
X-rays and other radiographic tests are usually fast, painless, and cost less than other scans. They can be used to get information quickly.
What do x-rays show?
X-rays and other radiographic tests help doctors find problems, including cancer. This is often the first type of imaging test used to look for possible problems in a bone or lung.
X-ray is also used to look at some organs and tissues. But MRI and CT scans often give better pictures of these areas.
Standard x-ray without contrast can:
- Find bone problems, including broken bones, osteoporosis, or cancer that has spread to the bone
- Look at the lungs to diagnose, treat, and monitor problems such as cancer, pneumonia, infection, or shortness of breath
- Screen for breast cancer via a mammogram (breast x-ray)
- Check if a central line is properly placed after it is inserted
X-ray with contrast helps organs show up more clearly on the x-ray. This can provide better images. For example:
- Upper or lower GI series exams help doctors look for cancer or other problems in the gastrointestinal (GI) system.
- Angiography can be used to see and treat problems including cancer, benign tumors, and bleeding through the blood vessels.
How do x-rays work?
A special tube inside the x-ray machine sends out a controlled beam of radiation. Tissues in the body absorb or block the radiation to varying degrees. This is picked up on the other side of the detector, creating a gray-scale image.
Bones and other dense tissues block radiation, so they appear white on an x-ray. Soft tissues, such as fat or muscle, block less radiation and appear gray. Air does not block any radiation. It appears black on an x-ray.
Tumors are not part of the normal tissue, so they may appear differently on x-ray. For example, bone tumors might appear as a less dense area in the bone. Or they might appear as more dense. This depends on the type of tumor. However, it may be difficult to find tumors on x-rays.
How do contrast studies work?
A contrast study is a special x-ray that uses iodine-based dyes or contrast materials to give your healthcare team information that a standard x-ray cannot. Barium is one example of a material used for these studies.
The contrast material outlines, highlights, or fills in parts of your body so that they show up more clearly on an x-ray.
Contrast material may be given:
- By mouth
- As an enema
- As an injection into a vein (IV)
- Through a catheter (thin tube) put into various tissues of the body
It will look bright white on the x-ray and outline the body part. The images are usually captured on x-ray film or a computer.
Common contrast studies
Test name(s) |
Organs studied |
Dye is given by |
|
Arteries throughout the body, including in the brain, lungs, and kidneys |
Catheter (thin tube) in an artery |
|
Mouth, throat, voice box, esophagus, and muscles used to swallow
|
Mouth |
|
Colon, rectum |
Enema |
|
Esophagus, stomach, small intestine |
Mouth |
|
Veins throughout the body, most often in the leg |
Catheter in a vein |
How do I get ready for an x-ray?
X-rays are usually done at an outpatient clinic, medical office, or hospital.
Standard x-rays
For a standard x-ray, you will be asked to remove metal objects that might interfere with the test. You do not need to do anything else to prepare.
Contrast studies
For a contrast study, you might be told to remove metal objects, not eat or drink anything before the test, or follow other directions. Your healthcare team or radiology center will tell you how to prepare.
If you are allergic to contrast dye, barium, seafood, or iodine: Tell your healthcare team if you’ve ever had a reaction to one of these. This may put you at risk for reacting to the contrast dye. Also let them know if you’ve ever had problems with barium. If you are at risk of an allergic reaction, you might be given a test dose of the contrast dye first. If you’ve had a severe reaction in the past, you may need to take a steroid or other medicines to help prevent another reaction. Sometimes, these medicines need to be started the day before the scan.
If you are allergic to chocolate, citrus fruit, or berries: Tell your healthcare team if you are allergic to chocolate, citrus fruit, or berries. The barium used for a modified barium swallow might be flavored.
What is it like having an x-ray?
Your experience will depend on the type of x-ray you have and the reason for the test.
Standard x-rays
Standard x-rays with no contrast are usually taken by an x-ray technologist (tech) in a special room. The room has an x-ray machine that can be moved around to aim the radiation at the right part of your body. If you are sick and unable to go to the x-ray room, the exam might be done with a portable machine.
Before the x-ray
For your safety and to get the best images, you might be asked to:
- Undress to uncover the body part being imaged
- Put on a gown or drape
- Remove jewelry or other metal objects that might interfere with the scan
Let your healthcare team or the x-ray tech know if you’ve taken any medicines with iron or bismuth in them or if you’ve had a recent contrast study with barium. These can interfere with x-rays of the abdomen.
During the x-ray
You will sit, stand, or lie down. This depends on what body part is being x-rayed. One side of your body will be put against a flat box or table that holds the x-ray film. The tech will then move the machine to aim the beam of radiation at the right area.
You may have special shields put over parts of your body near the area being x-rayed. This protects them from the radiation.
The tech will leave the room and operate the machine by remote control. They can hear and see you at all times. Your exposure to the x-ray is very brief, usually less than a second. You might hear buzzing or clicking sounds while the machine is working.
Chest x-ray: Two views are often needed for a chest x-ray. The first image is taken from the back while you stand with your chest against the x-ray film and your arms at your sides. The second image is a side view. This is usually taken with your arms either above your head or in front of you. The tech will tell you when to take a deep breath and hold still. If you are not able to stand, the film is put underneath your body and the picture is taken from the front.
Abdominal (belly) x-ray: For an abdominal x-ray, you will lie down on a table. You might be asked to change positions or sit up if more than one view is needed. You will hold your breath and lie still while the picture is taken quickly.
Contrast studies
Each type of contrast study is different. But in general, you usually have to do more to prepare for this than for a standard x-ray.
You will be asked not to eat before this test. In most cases, you’ll be given medicine to relax you before the test starts.
You will lie still on a table as the skin over the injection site is cleaned and numbed. A tiny cut will be made so a thin, plastic tube (catheter) can be put into a blood vessel and slid in until it reaches the area to be studied. The blood vessel used for this is usually the artery at the top of the thigh.
The contrast dye is put in through the catheter. A series of x-ray pictures are taken to see how the dye flows through the blood vessels.
If you are having a procedure such as an embolization to treat liver cancer, you will wait while radioactive beads, particles, or tiny beads that contain a chemotherapy (drug-eluting beads) are injected to kill cancer cells and block tumor blood supply.
The catheter is then removed and a closure device or firm pressure is placed on the catheter site to make sure it doesn’t bleed. You will also need to lie flat and keep your leg still for up to several hours to prevent bleeding at the catheter site.
Because of advances in technology, x-ray angiography is usually used during a procedure. If you need a diagnostic test without a procedure, your healthcare team will probably use CT angiography (CTA) or MR angiography (MRA).
The day before the test, you might be asked to:
- Stop eating
- Drink only clear liquids like broth, juice, plain tea, or black coffee
- Avoid dairy items
You will probably need to stop eating or drinking completely overnight or for several hours before the test. This includes clear liquids.
You will take laxatives and/or have enemas to clean out your bowel (large intestine).
In the x-ray room, you will lie on a table. You’ll be secured to the table for safety because it tilts. A series of x-rays are taken. After the x-rays, liquid barium is put into your bowel through a small, soft tube placed in your rectum. The liquid feels cool.
More images are then taken while the table tilts you into different positions. This helps the barium move through your bowels so they can be seen on the x-rays. You must lie still and hold your breath as each image is taken.
After the test, you can go to the toilet to pass the barium solution out of your bowels. It may take a few days until it’s all out. Your stool (poop) may be drier, harder, and light-colored during this time.
To get clearer pictures, a double-contrast exam is often done. This exam uses a smaller amount of thicker barium liquid. After the barium is in, air is put into your bowel. This can cause a sense of fullness and discomfort, along with an urge to empty your bowels.
A lower GI series may be done if a colonoscopy or CT colonography isn’t available. Because it uses radiation and contrast, you should talk to your care team to decide which test is best for you.
You might be asked to stop eating or drinking for 8 to 12 hours before this test.
You will lie down and be secured to a tilting table while a series of x-rays are taken as barium coats your esophagus and stomach. You will swallow the barium mixture a few times during the test. The barium mixture is thick and tastes chalky.
In some cases, substances other than barium are used. You might also be asked to swallow baking soda crystals to create gas in your stomach.
Sometimes, more pictures are taken a few hours later to show the small intestine, because it takes time for the barium to move there. This is called a small bowel follow-through.
After the test, you might be given a laxative to help get the barium out of your body. It still may take a few days until it’s all out. Your stool (poop) could be drier, harder, and light-colored during this time.
You might be asked to stop eating or drinking a few hours before the test and avoid smoking or chewing gum.
You will sit in chair or stand on a platform while eating food and drinking liquids that have been mixed with barium. The food and liquids will have different levels of thickness. The barium is thick and chalky.
If your child is getting the test, you might be asked to bring food and liquids they can and cannot swallow, along with their bottles, utensils, or cups.
Images of you swallowing are then taken. Your images will be reviewed by a speech-language pathologist (SLP) and a radiologist.
After the test, your stool may look white for a few days. You might also need a laxative if you have constipation.
As you lie still on a table, the skin over a vein is cleaned and numbed. This will be a small vein below the vein that might be blocked. For example, the foot for a vein in the leg or the hand for a vein in the arm. A thin, plastic tube (catheter) is then put into the small vein.
The catheter might be threaded in so that it passes into a larger vein closer to the one being studied. Or a tourniquet might be used so the dye flows into the deeper veins. A tourniquet is a constricting band that may be put above your ankle or knee, or in another location depending on the veins being studied.
Contrast dye is then put into the IV to make the veins show up on the x-ray, and a series of x-ray pictures are taken.
Depending on the reason for the test and what the x-ray shows, treatment can then be done. For example, if a blood clot is found in the vein, your care team can try to remove or dissolve the clot.
Before the catheter is removed, extra fluids might be put through it to help wash the dye out of your body. Firm pressure might be placed on the site for a while to make sure it doesn’t bleed.
Because of advances in technology, x-ray venography is usually used during a procedure. If you need a diagnostic test without a procedure, your healthcare team will probably use CT venography (CTV) or MR venography (MRV).
How long does an x-ray take?
- Standard x-ray: about 5 to 10 minutes
- Angiogram: several hours, but it depends on the procedure being done
- Lower GI series: 30 to 60 minutes
- Upper GI series: 30 minutes to 6 hours, depending on the part of the digestive system being tested
- Modified barium swallow: about 15 to 45 minutes
- Venogram: several hours, but it depends on the procedure being done
What are the possible risks and side effects?
Problems are rare and very unlikely with standard x-rays.
The risks and side effects of a contrast study depend on the type of test:
The contrast material may cause:
- Nausea
- Vomiting
- Flushing
- Itching
- A bitter or salty taste
- A feeling of burning or warmth
Other possible problems can happen, depending on the type of procedure. Your care team will discuss this with you.
In rare cases, people can have a severe allergic reaction to the contrast material that affects their breathing and blood pressure.
The contrast material can cause kidney problems, but this is rare. It is more common in people whose kidneys already don’t work well. If you have kidney problems and need this test, you may have to get extra IV fluids or avoid certain medicines before or after the test.
Other risks include:
- A blood clot forming on the other end of the catheter, which could block a blood vessel
- Damage to the blood vessel from the catheter, which could lead to internal bleeding
- A large collection of blood (hematoma) under the skin where the catheter was put in, if pressure isn’t kept on the site long enough
- Infection at the catheter site
- Body aches from lying still on the table for a few hours
The contrast material may cause:
- Nausea
- Vomiting
- Flushing
- Itching
- A bitter or salty taste
- A feeling of burning or warmth
Other possible problems can happen, depending on the type of procedure. Your care team will discuss this with you.
In rare cases, people can have a severe allergic reaction to the contrast material that affects their breathing and blood pressure.
The contrast material can cause kidney problems, but this is rare. It is more common in people whose kidneys already don’t work well. If you have kidney problems and need this test, you may have to get extra IV fluids or avoid certain medicines before or after the test.
Other risks include:
- A blood clot forming on the other end of the catheter, which could block a blood vessel
- Damage to the blood vessel from the catheter, which could lead to internal bleeding
- A large collection of blood (hematoma) under the skin where the catheter was put in, if pressure isn’t kept on the site long enough
- Infection at the catheter site
- Body aches from lying still on the table for a few hours
Side effects could include:
- Belly discomfort or cramping
- Fatigue or feeling tired
- Light-colored stools for a few days
- Constipation
Very rarely, the barium can cause a blockage (obstruction) or hole (perforation) in the bowels.
Side effects could include:
- Light-colored stools for a few days
- Constipation
A reaction to flavored barium may happen in people who are allergic to chocolate, citrus fruit, and certain berries.
There is a slight chance the barium might cause a blockage (obstruction).
Also, there is a slight chance of barium, stomach contents, or other fluids going into the lungs. This is called aspiration.
What else should I know about x-rays?
- Before having any of these tests, tell your healthcare team if you could be pregnant or are breastfeeding.
- Tell your healthcare team about any medicines you take or allergies you have.
- X-ray tests expose the body to radiation, but modern x-ray equipment uses much smaller amounts of radiation than in the past.
- Written By
- References
Developed by the P站视频 medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
American College of Radiology/American Society of Radiologic Technologists/Radiological Society of North America. Catheter angiography. Updated August 5, 2024. Accessed at https://www.radiologyinfo.org/en/info/angiocath on February 6, 2026.
American College of Radiology/American Society of Radiologic Technologists/Radiological Society of North America. Video fluoroscopic swallowing exam VFSE)/esophagram. Updated September 5, 2024. Accessed at https://www.radiologyinfo.org/en/info/modbariumswallow on April 24, 2026.
American College of Radiology/American Society of Radiologic Technologists/Radiological Society of North America. Chest x-ray. Updated September 27, 2024. Accessed at https://www.radiologyinfo.org/en/info/chestrad on February 6, 2026.
American College of Radiology/American Society of Radiologic Technologists/Radiological Society of North America. Lower GI x-ray. Updated April 22, 2025. Accessed at https://www.radiologyinfo.org/en/info/lowergi on February 6, 2026.
American College of Radiology/American Society of Radiologic Technologists/Radiological Society of North America. Upper GI x-ray. Updated September 1, 2024. Accessed at https://www.radiologyinfo.org/en/info/uppergi on February 6, 2026.
American College of Radiology/American Society of Radiologic Technologists/Radiological Society of North America. Venography. Updated July 15, 2023. Accessed at https://www.radiologyinfo.org/en/info/venography on February 6, 2026.
American Society of Clinical Oncology (ASCO). Barium enema. Cancer.net. Content is no longer available.
American Society of Clinical Oncology (ASCO). Mammograms. Cancer.net. Content is no longer available.
Chen A, Tafti D, Tuma F. Barium Swallow. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026. Accessed at https://www.ncbi.nlm.nih.gov/books/NBK493176/ on April 24, 2026.
Hill NE, Giampetro DM. Fluoroscopy Contrast Materials. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026. Accessed at https://www.ncbi.nlm.nih.gov/books/NBK572082/ on April 24, 2026.
Mathews S, De Jesus O. Thrombectomy. [Updated 2023 Aug 23]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026. Accessed at https://www.ncbi.nlm.nih.gov/books/NBK562154/ on April 24, 2026.
US Food and Drug Administration (FDA). Medical x-ray imaging. Updated February 21, 2023. Accessed at https://www.fda.gov/radiation-emitting-products/medical-imaging/medical-x-ray-imaging on February 6, 2026.
Last Revised: April 23, 2026
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