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Doctors use imaging tests to take pictures of the inside of your body. Imaging tests can be used to look for cancer, find out how far it has spread, and to help see if cancer treatment is working.
An imaging test is a way to let doctors see what’s going on inside your body. These tests send forms of energy (like x-rays, sound waves, radioactive particles, or magnetic fields) through your body. Your body tissues change the energy patterns to make an image or picture. These pictures show how your insides look and work so that health care providers can see changes that may be caused by diseases like cancer.
Imaging tests are used for cancer in many ways:
Imaging tests are only part of cancer diagnosis and treatment. A complete cancer work-up also includes talking about your medical history (asking questions about your symptoms and risk factors), a physical exam, and blood work or other lab tests.
Many health care providers plan x-rays or other imaging tests before treatment starts. These pictures are then used to track changes during treatment. These are called baseline studies because they show how things looked at the start. They can be compared with later images to see the results of treatment over time.
Imaging test can often be very helpful, but they have limits. For instance, most of the time, these tests alone can’t show for sure if a change is caused by cancer.
Imaging tests can find large groups of cancer cells, but no imaging test can show a single cancer cell or even a few. In fact, it takes millions of cells to make a tumor big enough to show up on an imaging test. This is why treatment may continue even when cancer cells can no longer be seen on an imaging test. The goal is to get any surviving cancer cells. Even one can grow and, over time, become a tumor that will again be big enough to cause problems and/or show up on an imaging test.
On the other hand, sometimes imaging tests can show something that looks like cancer, but further tests (such as a biopsy) show that it’s not cancer.
A doctor, a certified technologist, or other health professional may do an imaging test. The test may be done in a hospital, a special clinic or imaging center, or a doctor’s office. In larger medical centers, imaging tests are often done in the radiology or nuclear medicine department.
A radiologist is a doctor who specializes in imaging techniques; they usually read (interprets) the images made during the test. The radiologist writes a report on the findings and sends the report to your doctor. A copy of the report will become part of your patient records. Your other doctors (oncologists, surgeons, etc.) may look at the images, too.
Many different kinds of scans are used to get images of what’s happening inside the body. Some of the more common types of imaging tests, how they are done, and when you might need them can be found in these sections:
The tests your health care provider recommends may depend on a number of factors, such as:
If you have questions about a test that your health care team wants you to have, ask them. You may want them to explain why you need the test, what it could find, the pros and cons of having the test, and if there are any other options to the test. Also be sure to ask about cost. Will your insurance cover the test? Do you need to OK it with your insurance before getting the test? (This is called pre-certification.)
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.
American College of Radiology/Radiological Society of North America. RadiologyInfo. Accessed at www.radiologyinfo.org on March 16, 2015.
Hricak H, Akin O, Bradbury MS, et al. Advanced imaging methods: Functional and metabolic imaging. In: DeVita VT, Hellman S, Rosenberg SA, eds. Cancer: Principles & Practice of Oncology. 7th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2005:589-720.
Last Revised: November 30, 2015
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