A CT scan (or CAT scan) is a series of pictures of the body made with x-rays and a computer. The images are created in crosswise stacks and are often likened to the slices of a loaf of bread. CT scans are one of the most powerful tools that radiologists use to examine many parts of the body. The most common CT scans are of the head, chest, abdomen and pelvis, but almost any part of the body can be examined by CT scan if necessary. CT scans are made from x-rays and therefore use ionizing radiation. They are only ordered when the doctor feels that the information from the study is more important than the very small risk of radiation injury.
If you have any allergy to iodine contrast or problems with your kidneys, BE SURE to tell the ordering doctor or the CT technologist before your exam begins. If you take any oral medicines for diabetes, be sure and mention that also. Most CT scans require little if any preparation. When you schedule your exam, you will receive any special instructions which may be important for your personal exam. If your exam includes the injection of contrast in a vein, then it is a good idea to say well hydrated by drinking a reasonable amount of water (a few extra glasses) in the days or hours before your study. This will help your kidneys clear the contrast agent from your blood.
Usually, you will be taken to a changing room where any necessary changes of clothing can take place. You may be asked to wear an examination gown. All metallic clothing or objects in the region to be examined which can be removed should be removed. If your exam requires any kind of contrast agent then you will be given the contrast. The preparation for the exam may take anywhere from 5 min to 30 min or more, depending on the contrast requirements. Once you are on the CT examining table, the table top will move you slowly through the center of a large “dognut” shaped scan device for the scan. You may go back and forth within the device a few times during the exam. The technologist will probably tell you to “hold your breath” during the individual scans which last several seconds. The entire CT exam usually takes from 5 to 20 minutes, again depending on the particular exam ordered. Exams of the abdomen and pelvis or those done “with and without” contrast take the longest. If there are any other special instructions, you will receive them after the exam.