What Happens During A CT or CAT Scan

A CT technologist reassures a patient before entering the scannerThe CT scanner is a large donut-shaped machine that takes x-rays at different angles around the body.  A CT technologist will explain the procedure to the patient and have the patient lie down on a narrow table. The CT technologist will move to a room adjacent to the exam area where s/he can observe the patient, supervise the exam and monitor the images on the screen. 

The table will glide through the scanner's "donut hole," while the technologist, via intercom, instructs the patient to lie very still, and on occasion, hold his/her breath as the x-rays are taken.  The "donut ring" will rotate around the patient, taking x-rays from all angles.  Often a clicking or buzzing sound is heard as the table moves and the cylinder turns.  The digital x-rays are processed on a computer to produce high resolution image "slices" of the body, which are visualized on the computer monitor.  The actual CT scan takes only minutes, but, depending upon the area being scanned, exam times are from 15 to 30 minutes.

Some CT exams require a contrast material to highlight areas of the body.  Depending upon the area being scanned, the contrast may be given orally, intravenously, or a combination of methods.