An ultrasound test, which doesn't use dangerous radiation, may give results similar to those of a CT scan. If you are concerned about radiation exposure, ask your doctor if you can have an ultrasound instead of a CT scan.
Children who need a CT scan may need special instructions for the test. The child will likely need to hold his or her breath during the scan. If the child is too young to hold still or is afraid, the doctor may give the child a medicine (sedative) to help him or her relax.
If your child is scheduled for a CT scan, talk with your child's doctor about the need for the scan and the risk of radiation exposure to your child.
Special CT scanners called spiral (helical) CT scanners and multi-slice (or multi-detector) CT scanners are sometimes used for this test. Many modern scanners are multi-slice scanners. These scanners can be used for many conditions, such as finding kidney stones, a pulmonary embolism, an enlarged prostate gland, or atherosclerosis. These special CT scanners can:
Take better pictures of blood vessels and organs so other imaging tests may not be needed.
Complete scans and provide pictures in less time.
CT results are often compared to positron emission tomography (PET) results to help find cancer. Some new scanners do both scans at the same time.
An electron beam CT scan is another type of CT scan that can find atherosclerosis and coronary artery disease. An electron beam CT scan is much faster than a standard CT scan and can take a good picture of a coronary artery while the heart is beating. Electron beam CT scans are not widely available. Another type of CT scanner, the multi-slice CT scan, is nearly as fast as electron beam CT scanners and is more widely available.
A CT angiogram can show two- and three-dimensional pictures of blood vessels and the heart.
A spiral CT is a way to scan the lungs more quickly than with a standard CT. Some doctors recommend this to screen for lung cancer in people who are older than 55 and who are at high risk for lung cancer.
Experts disagree about the use of a CT method called full-body scanning to screen for coronary artery disease and cancers. Full-body scanning is expensive, can lead to unnecessary tests or surgery, and may increase the chance of cancer from the radiation exposure. Most doctors do not recommend these studies unless a person has a specific risk for a certain disease.