CT scan preparation takes much longer than the scan itself. CT Scan preparation can take up to 2 hours before you have the scan if your doctor orders it with oral and IV contrast. This is because oral contrast can take about 2 hours to travel through the entire length of the intestinal tract after you start drinking it. But the scan itself takes only minutes.
The need for contrast material depends on what your doctor is looking for, the type of symptoms you may be having and other factors. You should wear comfortable, loose-fitting clothing for your CT scan. You may be given a gown to wear during the procedure. The best thing to wear, most of the time, is a jogging suit or sweats if you're going to have anything below your head scanned. CT scan preparation is casual so a jogging suit with out zippers or sweat suits can sometimes be worn during the scan and you may not have to change into a gown. It depends on the rules of the place where you go to have your CT scan.
For better CT scan preparation, it's best not to wear jewelry on the body part being scanned. For example, if your brain is being scanned, you shouldn't wear ear rings, hearing aids or nose piercings but rings on your fingers are ok to wear because they're not on the body part that's being scanned. Tongue piercings will have to be removed if your face or sinuses are being scanned. When the ct scan x-ray beam comes in contact with thick jewelry, it causes the x-ray beam to spray out or splash out like water landing on a hard flat rock. The result ruins the images causing white streaks called "streak artifact". It also happens when the x-ray beam hits any fillings you may have in your teeth, but there's nothing that can be done about that.
Metal objects including jewelry, eyeglasses, dentures and hairpins may affect the CT images and should be removed prior to your exam. You may also be asked to remove hearing aids and removable dental work.
Any movement during the scan causes the images to be blurry. It's important that you hold very still while the scanner takes the images.
You may be asked not to eat or drink anything for several hours beforehand, especially if a contrast material will be used in your exam. You should inform your physician of any medications you are taking and if you have any allergies, especially to contrast materials.
Some institutions may have a CT Technologist available to speak with you if you have technical questions, or preparation questions but in most cases, the CT Technologists spend all their time preparing and scanning and aren't able to talk on the phone. Information must come from your physician ordering the test or his office staff.
Women should always inform their physician or technologist if there is any possibility that they are pregnant.
Click on this Safety Page link for more information about pregnancy and x-rays.