What are the scans a doctor might use to diagnosis cancer?
The term scan is usually used in reference to a type of diagnostic imaging. Diagnostic imaging refers to several different technologies doctors use to look inside the body for clues about the type of cancer a patient might have and to find its exact location. The most common types of scans used for cancer diagnostics are:
X-ray — A picture of the inside of the body using electromagnetic radiation. X-ray is used to spot cancers in some parts of the body. Common cancer X-rays are mammograms and chest X-rays.
Computed tomography scan (CT or CAT) — A procedure that uses special X-ray equipment to create a cross-sectional or three-dimensional picture of the body. Used to detect cancer, find out if and where the cancer has spread and whether it is affecting the any organ function.
Bone scan — Shows cancer that has started or spread to the bone. A bone scan involves injecting a radioactive material (radiotracer) into a vein so it can travel to the bone and give off radiation as it wears away. This radiation is detected by a camera that slowly moves around you to take pictures of how much radiotracer collects in the bones. The images are taken after a three- to four-hour delay and the scanning part of the test will last about one hour.
Ultrasound — A test used to view the heart, blood vessels, kidneys, liver and other organs. Unlike X-rays, ultrasound does not involve exposure to radiation. During the test, a device will be moved over the body, bouncing high-frequency sound waves off the tissues inside your body. Images are created from the echoes that bounce back.
Magnetic resonance imaging (MRI) — Uses a large magnet and radio waves to look at organs and structures inside your body. MRIs are very useful for examining the brain and spinal cord. They are also used for examining the reproductive organs, as they do not use radiation.
Positron emission tomography (PET) — A test that uses a radioactive substance called a tracer to look for disease in the body. Cancer cells will absorb more of the tracer because of the energy they use. Once the tracer has been administered, it will take about an hour for it to collect in the internal tissues and organs.
For more information, contact Courtney Britton, librarian at Cancer Services of Greater Baton Rouge, at (225) 927-2273 or cbritton@ cancerservices.org, or visit the Education Center at 550 Lobdell Ave., Baton Rouge.
ä Internet Resources:
Diagnostic Imaging — National Library of Medicine Medlineplus, medlinplus.gov
Tests and Procedures — American Society of Clinical Oncology, cancer.net
This column is presented as a service by Cancer Services of Greater Baton Rouge, a United Way affiliate.