IMAGING: LOW-DOSE CT

How It Works

A Computed Tomography (CT) scan is
a painless procedure used to obtain
cross-sectional “sliced” images of
the body. The scan combines a series
of X-ray views taken from many different
angles and computer processing to create
cross-sectional images of the bones and
soft tissues inside your body.
The images are then viewed on a monitor.

Why We Do It

A CT scan can be used for most parts of the body. It is a useful tool for isolating the location of a tumor, infection or blood clot and can detect internal injuries and internal bleeding. A CT can also detect and monitor diseases and conditions, including lung nodules, liver masses, cancer and heart disease. These are just a few reasons for a CT; there are many other uses.

The Experience

Depending on your physician’s request, you may receive a “contrast” material by mouth and/or IV. This “contrast” does exactly as it says: it helps provide greater contrast and information so we can better read the image. During the scan, you will lie down on a CT table. The table moves through the CT scanner opening while obtaining images. The CT procedure can take from 15 to 45 minutes.

Prep & Safety

Unless otherwise indicated, do not eat or drink anything but water four hours prior to your study. We encourage drinking water prior to your exam. Some patients may be asked to drink oral contrast before their study, which enhances the images. Typically, we ask patients to arrive one hour in advance to drink oral contrast; however some patients may receive oral contrast in advance with instructions specific to their study. In some cases, no oral contrast may be necessary.

  • If drinking contrast, please arrive one hour and 15 minutes prior to your exam time.
  • If your study does not require contrast, please arrive 15 minutes prior to your exam.

Some studies require different preparations. Please be sure to review the details for your particular study.

Safety

Please notify our scheduling department and technologists if:

  • You are pregnant
  • You have severe allergies, or if you have ever had an allergic reaction to X-ray dye or iodine.
  • You have any medical conditions such as asthma or diabetes.
  • You have a history of renal failure, liver or kidney transplant.
  • You are diabetic. Diabetic patients should discontinue use of Metformin containing drugs the day of the exam and 48 hours after the procedure.

Prep Forms

Your Results

A highly specialized radiologist will interpret your images and prepare a diagnostic report for your physician. If the examination was ordered “stat” your physician will be notified the same day. If the examination was routine, the results are provided to your physician within 48 hours. Your physician will determine how the radiologists' report can be used to develop a treatment plan and speak with you about your results.

COMMON QUESTIONS
Q.
What are the risks of a CT?
A.
This procedure is extremely safe, though it does use radiation to produce the images. At Oregon Imaging Centers, we use the least amount of radiation by utilizing a “low dose” technology which decreases the radiation exposure by up to 70%.
Q.
Why did my doctor order a CT if radiation is a concern?
A.
CT is a valuable diagnostic tool that uses radiation to peer into the body and produce 3-D images. Based on your symptoms or the area being scanned, a CT scan will provide your doctor with the most detailed information.
Q.
What steps do you take to reduce radiation?
A.
We adhere to the As Low As Reasonably Achievable (ALARA) principle, using tools that automatically adjust the radiation dosage based on body type and anatomy. As part of that commitment, we invested in a new technology called iDose that lowers the amount of radiation patients receive by 50% to 70%. The amount of radiation you receive varies by body type and the anatomic region being scanned. Your CT technologist can estimate your radiation dose at the time of your scan. If you had the same CT scan at Oregon Imaging Centers prior to our iDose, your technologist can determine the percentage of radiation reduction.
Q.
Does iDose technology apply to Cardiac CT Angiograms (CCTAs)?
A.
For CCTAs, Oregon Imaging Centers offers a technology called Step & Shoot Cardiac, which reduces radiation by up to 80%. Step & Shoot allows us to capture images when the heart is at rest, or in between beats – the most desirable time to capture data. In other words, the CT scan takes snapshots of the heart at precisely the right time instead of taking a video for the full scan time.
Q.
Is there an IV involved with the CT?
A.
Depending on your physician’s request, you may receive an “intravenous contrast,” which is needed for many exams.
Q.
How should I prepare for my CT?
A.
You will receive instructions when you schedule your appointment. You can also refer to the “prep” section of the website. Be sure to review the instructions for your particular study, as they can vary based on type of study.

Types of scans

Abdomen

What: An abdominal CT is a non-invasive way for your doctor to evaluate your internal organs and tissues including the liver, spleen, pancreas and kidneys. The test can help diagnose abdominal pain. Some of the more common reasons for an abdominal CT scan are for the evaluation of tumors, infections, kidney stones or appendicitis.

Angiogram

What: CT angiography is used to examine blood vessels.

Physicians may use the procedure to:

  • Identify disease and aneurysms in the aorta or in other major blood vessels.
  • Guide surgeons making repairs to diseased blood vessels, such as implanting or evaluating a stent.
  • Identify dissection in the aorta or its major branches.
  • Screen individuals for arterial disease, especially patients with a family history of arterial disease or disorders.
  • Detect thrombosis (clots) in veins.

The images captured in this scan allow the radiologist to construct a three-dimensional image of your heart and measure blood flow, as well as narrowing of the arteries.

This study will require IV injected contrast agents to help us visualize certain tissue or blood vessels. Some patients describe a metallic taste or tingling sensation right after the injection. This is normal and usually subsides very quickly.

Calcium Scoring

What:Calcium screening is most appropriate for men, ages 35 to 70 and women 40 to 70 who have any of these risk factors: family history of heart disease, smoking, diabetes, high cholesterol, high blood pressure or overweight. CT calcium scoring requires an order from your licensed primary or specialty provider. Medicare members require an order from a provider other than a chiropractor or naturopath.

This test allows the radiologist to determine if calcium build-up, or plaque, is present on the walls of the arteries of the heart, also known as your coronary arteries. The radiologist will report to your physician on how severe the blockages are.

No prep is required for this study; you may eat and drink before the procedure.

Cardiac Angiogram

What: Cardiac CT Angiography is used to examine blood vessels in and around the heart.

Physicians may use the procedure to:

  • Guide surgeons making repairs to diseased blood vessels, such as implanting or evaluating a stent.
  • Show the extent and severity of atherosclerosis in the coronary arteries.
  • Plan for a surgical operation, such as coronary bypass.
  • Screen individuals for arterial disease, especially patients with a family history of arterial disease or disorders.

Your doctor will be ordering a beta blocker for you to take the morning of the exam. This is to slow your heart rate down.

The images captured in this scan allow the radiologist to construct a three-dimensional image of your heart and measure blood flow, as well as narrowing of the arteries.

This study will require IV injected contrast agents to help us visualize certain tissue or blood vessels. Some patients describe a metallic taste or tingling sensation right after the injection. This is normal and usually subsides very quickly.

In addition to the general CT prep guidelines, please refrain from consuming caffeine in any form 12 hours prior to exam.

Chest

What: A CT scan of the chest may be ordered by your physician when there is a chest injury or if a tumor is suspected. It can also help determine the size, shape and position of internal organs and help your doctor look for bleeding or fluid in the lungs. A chest scan can find abnormalities in the aorta and disease or damage to the heart.

Head & Neck

What: A CT scan of the head can provide valuable information about head injuries, tumors, stroke or diseases of the brain. The test can also help evaluate conditions of the eyes and sinuses.

KUB

What: A CT KUB makes it possible to evaluate the kidneys, ureter and bladder. Since CT scans can distinguish between solid and liquid, it is extremely valuable in examining the type and extent of kidney tumors or other masses, such as stones or cysts, distorting the urinary tract. You do not need to fast or avoid liquids before this study.

Lung

A CT scan of the lungs is often ordered when your physician is trying to determine if there is bleeding or fluid in the lungs. It may also be ordered if a tumor is suspected or to determine the size, shape and position of a known tumor.

Sinus

What: CT of the sinuses primarily is used to:

  • Detect the presence of inflammatory diseases.
  • Plan for surgery by defining anatomy or giving further information about tumors of the nasal cavity and sinuses.
  • Evaluate sinuses that are filled with fluid or thickened sinus membranes.
  • Help diagnose sinusitis.

Spine

What: The most frequent use of spinal CT is to detect — or rule out — spinal column damage in patients who have been injured.

In patients with narrowing of the spinal canal, vertebral fracture, infection or degenerative disease such as arthritis, CT of the spine may provide important information when performed alone or in addition to magnetic resonance imaging (MRI). CT scanning of the spine is also performed to:

  • Evaluate the spine before and after surgery.
  • Detect various types of tumors in the vertebral column, including those that have spread from another area of the body. Some tumors that can arise elsewhere are first identified by finding deposits of malignant cells in the vertebrae; prostate cancer is an example.
  • Help diagnose spinal pain, such as a herniated intervertebral disk.
  • Accurately measure bone density in the spine and predict whether vertebral fractures are likely to occur in patients at risk of osteoporosis.

Virtual Colonoscopy

What: The major reason for performing CT colonography is to screen for polyps and other lesions in the large intestine. Polyps are benign 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. Most physicians agree that everyone older than 50 years should be screened for polyps every seven to 10 years. Individuals at increased risk should be screened 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.

How it works: Using a CT scanner's X-rays we will take cross-sectional images of your abdominal cavity and colon. These images will be assembled by a computer into a three-dimensional rendering allowing the radiologist to 'fly-through' or virtually examine the colon. During the study, a small enema tip is inserted into the rectum and air is used to inflate the colon.

GoLytely Preparation Instructions

Bowel Preparation Instructions:

  • Step 1:

    12:00 noon: Start to drink the bottle of GoLytely as prepared above. Please note that it may take some people longer than others to finish the entire bottle. We recommend that you start by noon, but you may start earlier if you feel more time will be needed, keeping in mind you will need to finish the bottle by 5pm. Try to drink one 8oz glass every 10 minutes. If you start to feel sick to your stomach, stop drinking until the nausea passes. Begin to drink again, but at a slower rate (an 8oz glass every 15-20 min). You must continue to drink the solution until it is all gone.

    About one hour after you start to drink the GoLytely you will likely begin to have diarrhea. You will want to stay close to a bathroom. You may also have some cramping in your lower abdomen. This is normal. Keep drinking until the prep is gone. If you start to have severe steady stomach pain, get lightheaded or dizzy, or you don’t expel any of the solution, call your primary doctor.

  • Step 2

    6:00pm (or one hour after you finish the GoLytely): Drink 250mL of Barium Sulfate

  • Step 3

    9:00pm, or 3 hours after you finish the Barium (choose one option):

    • Option A: Drink one bottle of Omnipaque. You may find it tastes better if you quickly drink it then follow it with 8oz water, clear juice or soda.
    • Option B: Mix one bottle of Omnipaque with 8oz of clear juice, soda. You need to finish all of the liquid you mix it with.

If you can’t finish the GoLytely, but your stool is clear, continue on as instructed with the barium and Omnipaque. Then call Oregon Imaging Centers CT department in the morning. We may still be able to complete your exam.

Bowel Prep Complete. You may keep drinking clear liquids until midnight.

Do not eat or drink anything after midnight the night before your exam. You may take your prescribed medicines as scheduled with a very small sip of water.

**If you have diabetes, test your blood glucose level more often when you can’t eat, as well as before your exam. You should adjust your insulin or oral diabetes medicine as discussed with your doctor. Resume your normal schedule after you receive the exam result phone call and are eating again. If your blood glucose level is low (less than 70mg/dl) or you have symptoms, please drink a clear liquid with sugar or take a glucose tablets. Keep checking your blood sugar levels to insure it stays above 70. We can still do the exam unless you need to eat solid food to maintain your blood glucose. It is better to maintain your blood glucose then to have the exam. We can always schedule your Virtual Colonoscopy in the future.

You need to pick up the Barium and Omnipaque from Oregon Imaging at our University District site. The Golightly prep will be ordered by your doctor to be picked up at a pharmacy.

Overview: Proper bowel cleaning is needed for the best exam. To get a clean and empty colon, you will start to prepare the day before your exam. Both a clear liquid diet and the contents of the bowel prep kit are needed to clean out the colon. The bowel prep kit contains laxatives and contrast medicines. The laxatives will help clean out the bowel for the exam. The contrast will help to highlight leftover stool on the CT pictures.

The day before your exam: Starting at breakfast, you may drink as many clear liquids as you want. Do not eat any solid foods. Drink only clear liquids for breakfast, lunch, dinner, and snacks. Drink plenty of fluids to avoid dehydration and make the laxative work better. Please avoid red liquids (i.e. red gelatin or cranberry juice).

Clear liquids may include:

  • Water, tea or coffee (no cream or milk; sugar is OK)
  • Sports drinks
  • Bullion or broth
  • Gelatin, ice pops (no fruit or cream added)
  • Apple or white grape juice (no orange, tomato, grapefruit or prune juices)
  • Soda such as Sprite, 7-Up, ginger ale or cola
  • Lemonade (no pulp)
  • Clear hard candy, gum

How to prepare the GoLytely Solution: (If you take other medicines, don’t take them while taking GoLytely. Take them 1 hour before starting the GoLytely or at least 1 hour after finishing the GoLytely bottle)

  • Please read the directions on the GoLytely bottle, Add water to the “fill” mark on the bottle. Shake it until all the powder has been dissolved. Do not add ice. Do not add any other liquids or flavors except, if desired, two packets of Crystal Light lemonade powder with Nutrasweet. You may do this by the glass to make it easier to drink.
  • You may find it easier to drink if it is chilled. Refrigerate but do not add ice. Because you are drinking a lot of liquid quickly you may become chilled. This is normal. It can be helped by wearing clothing or drinking the liquid at room temperature.