Computed Tomography, widely known as a CAT scan, is medically referred to as simply CT.
CT is generally a relatively quick procedure that uses x-ray beams to create computer-generated images of soft tissue structures, such as the liver, spleen and other internal organs, including air cavities (sinuses, lungs).
It also has advantages in skeletal and neurological imaging. Its radiation doses to the human body are considered minimal due to the speed in which the x-rays deliver, as well due to the increased number of detectors which help to minimize radiation dose as compared to less sophisticated CT scanners.
CT-Scans Offered at Our Facilities:
- CT Head
- CT Sinus
- CT Orbits (Eyes)
- CT Temporal Bone
- CT Facial Bone
- CT Neck
- CT Chest
- CT Abdomen
- CT Pelvis
- CT IVP
- CT C-Spine
- CT T-Spine
- CT L-SPine
- CT Upper Extremity (Arm)
- CT Lower Extremity (Leg)
- CT Enterography
- CT Colonography
What to Expect
What is CT and how does it work?
CT stands for Computed Tomography, which is widely called a CAT scan. Based on x-ray technology, it creates three-dimensional, computerized images of internal tissues and organs. Unlike traditional x-rays, however, CT images reveal overlapping parts of the body.
The patient lies comfortably still on a flat padded table, which moves steadily through the center of a donut-shaped x-ray machine. X-ray beams from a number of positions are aimed at the area being studied. A special detector measures the amount of absorbed radiation. This data is transformed by a computer into a digital image, displayed as a cross-section of the x-rayed area on a computer screen.
What are the advantages of a CT scan compared to an MRI?
A key advantage of CT is its ability to show detailed images of bones, blood vessels, and soft tissue in the same image. Bones in the image don’t obscure the underlying tissues. A CT can also reveal tumors and measure a tumor’s size and location. CT is considered the best method of diagnosing different kinds of cancers. It is also commonly used in diagnosing vascular diseases, detecting bony abnormalities, and identifying traumatic injuries to internal organs.
Another advantage of CT: The procedure is faster and costs less than a MRI.
Is a CT safe?
While the patient is exposed to radiation from x-rays, the amount of exposure is considerably less than that of a normal x-ray. In fact, the amount of radiation received from a CT of the head and brain is about the same as the amount of natural radiation exposure received in the environment during a year.
When and why is “dye” used?
Whether or not you need a contrast liquid or injection depends on the type of study your physician has ordered. A contrasting agent containing iodine, often called “dye,” helps the radiologist to see more definition of the tissues and to visualize the blood supply to internal organs. The contrasting agent is administered by our staff intravenously.
In addition, oral ingestion of contrast to opacify the gastrointestinal system to include the stomach, duodenum, small and large intestine is also often required for CT examinations of the abdomen and pelvis. Our staff will let you know what to expect of the preparation at the time of scheduling your examination.
The iodine-containing “dyes” are generally quite safe. Our staff will screen your medical history to determine if there is any risk of adverse reactions to the contrasting agent.
How should I prepare for the exam?
Preparation can vary according to the type of CT exam, whether or not you will be receiving a contrasting agent, and your medical history.
Can I drive home after the CT?
CT typically requires no sedation and therefore you will be able to drive immediately after the exam, even if you received a contrasting agent. However, if you are scheduled for oral or intravenous sedation, you will require someone to drive you home.
How long does it take for my physician to get the results of the examination?
Once your examination is completed, the onsite radiologist will be reviewing all of the images and will issue a report the same day or the next morning. The report is then faxed and either mailed or delivered to your doctor’s office. If your case is an emergency, the radiologist will speak to your referring doctor as soon as the scan is finished.
Why do I need contrast?
There are two types of contrast: oral and intravenous. Oral contrast is a barium or gastrograffin based drink that is given to most patients receiving an abdomen or pelvic CT. This allows the radiologist to differentiate the small and large bowel from other structures in the abdomen. Intravenous contrast is used for CT and is given to patients with certain diseases or suspected diseases. The decision to administer intravenous contrast is determined either by the referring doctor or the onsite radiologist.
Are there any risks with intravenous contrast?
There is a slight risk of allergic reaction with CT (iodinated) contrast. A history of allergies to iodine will be asked at the time of scheduling for a CT scan. Patients with renal failure or poor renal function may not receive CT contrast. A renal function test is required prior to CT for all patients over 65 years of age, patients with diabetes, or patients with a history of renal disease. The renal function test will be performed at Sand Lake Imaging prior to the examination.
What forms should I bring to my appointment?
Your insurance card and the CT prescription from your referring doctor. In addition, a valid driving license or another form of positive identification is required.
Should I bring my old films?
If your previous exams were performed at Sand Lake Imaging, you do not need to bring your prior exams. If you have a prior imaging study at an outside institution and it is of the body part being examined at Sand Lake Imaging, please bring them to your appointment. The films will remain at the center until your report has been issued by the radiologist. The films will then be available for pick-up at your convenience.
Do I get films to take with me?
Printed films are available upon request (although this somewhat depends on the referring physician).
How soon can I schedule my exam?
In most cases, exams can be scheduled the same day. Scheduling may be delayed 24-48 hours if insurance preauthorization is required, except in emergency situations.
When should I arrive for my exam?
We request that patients arrive 10 minutes prior to the exam start time in order to fill out necessary paperwork. If oral or intravenous sedation is scheduled, please arrive 30 minutes prior to the exam start time.
How long will the exam take?
A CT scan takes between 5 and 10 minutes.
Do I have to remain still during the exam?
Yes. It is extremely important that patients not move during the scan. Any minor movement can make the images unreadable and will require repeating the scan. However, patients will only have to remain motionless for a period of 2 to 7 minutes at a time.
Can I wear my regular clothes during the exam?
Patients scheduled for CT may wear regular clothes. However, all metal objects will have to be removed due to image artifacts.
Are there any risks with CT?
CT scans emit x-rays and, therefore, there is a theoretical risk of radiation. However, there have been no definitive studies demonstrating the exact risk or the limit of how many CT scans a patient may have. Often, referring doctors and patients may opt for an MRI instead of a CT for this reason.
Can I eat before my exam?
If you are scheduled for a CT scan with intravenous contrast, you may not eat or drink for 2 hours prior. If you are scheduled for oral or intravenous sedation, you may not eat or drink for 6 hours prior. However, pediatric patients may have a few sips of water or juice 2 hours prior and no food 6 hours prior.