For information about radiation exposure and medical imaging click here.

Did you know?
Rated by JAMA, we employ a state-of-the-art 128-slice CT scanner, which utilizes the lowest amount of radiation while producing the highest resolution images.

Peninsula Imaging also participates in the Image Gently campaign which ensures CT examinations are performed with the lowest possible dose of radiation.

As you may have read on our site, CT scanning is a noninvasive medical test that helps physicians diagnose and treat medical conditions. But CT Colonography, also known as Virtual Colonoscopy, uses CT scanning to obtain an interior view of the large intestine that is otherwise only seen with a more invasive procedure where an endoscope is used.

Virtual Colonoscopy's effectiveness is really used to look for signs of pre-cancerous growths, called polyps; cancer; and other diseases of the large intestine. Images of the large intestine are then computerized and put together to create an animated, three-dimensional view of the inside of the large intestine.


Help Center

Why would I need a Virtual Colonoscopy?
How should I prepare?
What should I expect during this exam?
What will I experience during and after the procedure?
When will I know the results of my test?
What are the benefits of Virtual Colonoscopy?
Are there any health risks associated with Virtual Colonoscopy?

[Chart to assist with this Help Center]

Why would I need a Virtual Colonoscopy?


The major reason for performing Virtual Colonoscopy, is to screen for polyps or cancers in the large intestine. Polyps are growths that arise from the inner lining of the intestine. Some polyps may grow and turn into cancers.

The goal of screening with Colonography is to find these growths in their early stages so that they can be removed before cancer has had a chance to develop. Almost all Physicians agree that everyone older than 50 years of age should be screened for polyps every seven to ten years. Individuals with increased risk or with a family history of colon cancer may start screening at age 40 or younger and may be screened at shorter intervals (for example, every five years). Risk factors for the disease include a history of polyps, a family history of colon cancer, or the presence of blood in the stool.

Back to Top

How should I prepare for my Virtual Colonoscopy?


You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure. Women should always inform their doctor and our CT Technologist if there is any possibility that they are pregnant. It is very important to clean out your colon the night before your Virtual Colonoscopy examination so that the Radiologist can clearly see any polyps that might be present.

Preparation procedure:
Before beginning the following steps, you will need the following:
  • MiraLAX 255g (Over the counter)
  • 4 Dulcolax tablets (Over the counter)
  • 64 oz. bottle of Gatorade
  • 1 box of Tagitol (Obtain from Peninsula Imaging)
  • 30 cc of Gastroview (Obtain from Peninsula Imaging)

3 days prior to the procedure:
Follow a low fiber/low residue diet. Drink lots of fluids - especially water. Stop fiber supplements. Avoid high fiber items such as beans, nuts, seeds, and whole grain items.

2 days prior to the procedure:
Same as above.

One day prior to your procedure (BUSY DAY):
With every meal:
Take a dose of Tagitol.
Drink only clear liquids for breakfast, lunch and dinner.
Solid foods, milk or milk products are NOT ALLOWED.
Clear liquids include:
Fruit juices (apple, grape, cranberry, white grape
Clear broth or bouillon
Plain jello and popsicles
Coffee or tea without milk or creamer

Soft drinks: carbonated or non-carbonated
At 3:00 pm - Take 2 Dulcolax tablets followed by 3-4 glasses of clear liquids.
At 5:30 pm - Mix the bottle of MiraLAX 255g in the 64 oz. bottle of Gatorade and begin drinking. Drink a glass every 15 minutes until you have finished the 64 oz bottle.
At 8 pm:
  • 1) Take the other 2 Dulcolax tablets.
  • 2) Mix the 30 cc of Gastroview with either Sprite, Gingerale, Cranberry Juice or other juice without pulp
  • 3) Drink 3 more glasses of clear liquids prior to midnight.
You may want to use Vaseline or A&D ointment to prevent irritation. You may want to substitute Tucks or baby wipes instead of toilet paper as well.
Do not have anything to eat or drink after midnight (unless your procedure is in the afternoon).

Day of procedure: You may have a drink of water to take medication on the morning of the procedure. If your exam is in the afternoon, you may have breakfast (clear liquids only).
Be sure to inform your physician if you have heart, liver or kidney disease to be certain that the bowel prep will be safe.
You will be able to resume your usual diet immediately after the exam.

Back to Top

What should I expect during this exam?


Our Technologist begins by positioning you on the CT examination table, usually lying flat on your back or possibly on your side or on your stomach. Straps and pillows may be used to help you maintain the correct position and to hold still during the exam. We will try to make this as comfortable as possible for you.

A very small, flexible tube will be passed two inches into your rectum to allow air to be gently pumped into the colon using a hand-held squeeze bulb. Sometimes an electronic pump is used to deliver carbon dioxide gas into the colon. The purpose of the gas is to distend the colon as much as possible to eliminate any folds or wrinkles that might obscure polyps from the physician's view.

Next, the table will move through the scanner. Patients are asked to hold their breath for about 7-10 seconds before turning over and lying on their back or side for a second pass through the scanner. Once the scan is done, the tube is removed. The entire examination is usually completed within 15 minutes!

Back to Top

What will I experience during and after the procedure?


The vast majority of patients who have a Virtual Colonoscopy exam report a feeling of fullness when the colon is inflated during the exam, as if they need to pass gas. Significant pain is uncommon. After the tube is inserted, your privacy will be respected. The scanning procedure itself causes no pain or other symptoms.

When you enter the CT scanner, special lights may be used to ensure that you are properly positioned. You will hear only slight buzzing, clicking and whirring sounds as the CT scanner revolves around you during the imaging process.

You will be alone in the exam room during the CT scan; however, our Technologist will be able to see, hear and speak with you at all times. After a CT exam, you can return to your normal activities.

Back to Top

When and how will I find out the results of my test?

One of our on-site Radiologists will analyze the images and send a report to your referring physician who will discuss the results with you.

Back to Top

What are the benefits of Virtual Colonoscopy?


  • This new minimally invasive test provides three-dimensional images that can depict many polyps and other lesions as clearly as when they are directly seen by optical colonoscopy.
  • Virtual Colonoscopy has a markedly lower risk of perforating the colon than conventional colonoscopy. Most of those examined do not have polyps, and can be spared having to undergo a full colonoscopy.
  • It is an excellent alternative for patients who have clinical factors that increase the risk of complications from colonoscopy, such as treatment with a blood thinner or a severe breathing problem.
  • Elderly patients, especially those who are frail or ill, will tolerate virtual colonoscopy better than conventional colonoscopy.
  • Virtual Colonoscopy can be helpful when colonoscopy cannot be completed because the bowel is narrowed or obstructed for any reason, such as by a large tumor.
  • If conventional colonoscopy cannot reach the full length of the colon - which occurs up to 10 percent of the time - virtual colonoscopy can be performed on the same day because the colon has already been cleansed.
  • Virtual Colonoscopy provides clearer and more detailed images than does a conventional barium enema x-ray examination.
  • Virtual colonoscopy is well tolerated. Sedation and pain relievers are not needed, so there is no recovery period.
  • Virtual colonoscopy is less costly than colonoscopy.
  • No radiation remains in a patient's body after examination.
  • X-rays used in the scans usually have no side effects.
Back to Top

Are there any risks involved with Virtual Colonoscopy?


  • There is a very small risk that inflating the colon with air could injure or perforate the bowel.
  • Women should always inform their physician and our technologist if there is any possibility that they are pregnant.
  • CT scanning is, in general, not recommended for pregnant women unless medically necessary because of potential risk to the baby.
Back to Top