Providence Health & Services
Imaging Center (PIC)
CT Scan (Computerized Tomography)
The CT scanners at Providence Radiology Services are state-of-the-art spiral CT and multi-slice scanners. Images can be viewed individually or in rapid sequence, or reconstructed by the technologist as a three - dimensional model that can be manipulated and rotated to provide the physician with an optimal image for review.
What is a CT?
CT scan or computerized tomography scan was first invented by Godfrey Hounsfield in the early 1970's at the EMI Laboratories in England. It is also referred to as CAT scan (Computerized Axial Tomography).
The technology uses x-rays and complex computers to create a cross sectional slice of the body. The CT scanner produces slices of the body in the same way a loaf of bread is sliced. Each image provides detailed anatomy of the body at the specific location or slice. This technology ushered in a new age in medicine and diagnosis as the images provided extremely high detail of body structures including bones, soft tissue, brain, organs and blood vessels.
How does it work?
The patient moves through the gantry (circular donut shaped part of the scanner) on a movable table. At the same time, a rotating x-ray machine inside the gantry moves around the body. As the patient moves through the gantry, the detectors constantly collect data as the radiation passes through your body, and with the aid of a complex computer, a two-dimensional image is created.
A completed scan may have as little as 20 images, such as CT of the brain, while others have several hundred images, as is the case with a CT of the abdomen. Each image represents a section of the body, which can be thick (10mm) or thin (0.5mm) depending upon the body part being examined. The CT examination is fast and painless.
High-tech history in the making
The original scanners could only be used to image the head. A single slice acquisition took four minutes. In 1976, whole body scanners became available, and the technology was in wide used by the early 1980's. Scanners today can take images in less than half a second. A complete body scan can be acquired in a matter of seconds. Further advances in the technology included volume imaging based on spiral data acquisition. With these state of the art scanners, a section of the body is scanned at one time and reconstructed as individual images after. These volume scanners provide detailed information that can be manipulated by the technologist to produce two and three-dimensional images of the body.
The technology has grown substantially in its relatively short history. Scanners are faster and more anatomy can be scanned in a shorter time. The units are comfortable for the patient and software development has permitted imaging techniques that were not available just a few short years ago. The technology continues to grow as does the team of professionals and the equipment used at Providence Alaska Medical Center. Today, we operate two state of the art spiral CT scanners, and offer high-end examinations like CT angiography of the brain and body, virtual colonoscopy and 3D imaging.
What to Expect
As with all medical exams, you will need to register before your exam. This can be accomplished through pre-registration (by phone-call 261-3149) or by stopping by the Admitting desk in the front lobby at least 15 minutes before your scheduled exam time. The staff in Admitting will enter your information into our registration system, and direct you to the Radiology/CT area.
This step will depend on the type of CT your doctor has ordered. Some scans require no preparation, such as a CT of the head without IV contrast. Other exams, such as a CT of the abdomen or pelvis, will require that you drink oral contrast (diluted barium) to highlight the bowel.
Some exams will also require IV contrast (iodine) which will be injected through an IV, which will be started when you reach the CT room. Providence Alaska Medical Center uses non-ionic IV contrast for all exams requiring IV contrast; this is the safest possible IV contrast available.
CT Scan Room
When you enter the CT scan room, you will be asked to lie on the CT table. If you need an IV, the technologist will start one at this time. The technologist will explain the procedure to you, instruct you on holding still, breathing, and any sensations you may experience. Once you are correctly positioned you will be asked to relax and not move. Positioning straps may be placed to ensure proper position is maintained through the scan. The technologist will leave the room and begin the scanning procedure from the computer console. The technologist can see and hear you at all time--each of you can communicate with each other via an intercom system.
Depending upon the type of scan, the table may move in increments or one continuous movement. The total examination time is usually less than 15 minutes. The technologist will check on you after the scan is completed, and remove the intravenous if one was started. You may leave the scan room at this time and return to normal activities unless otherwise instructed. The technologist will give you easy to follow instructions if required.
After you leave, the images are transferred to workstations where they are manipulated and reviewed by the radiologist. A report is sent to your referring physician approximately 5 - 10 days following your scan.
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