Exposure to radiation, especially at high dosage, has been linked to cancer. Most scientists believe that doses above 50 mSv will increase your risk of developing cancer and the higher the dose, the greater the risk. There have been many epidemiological studies of doses in the range of 5-50 mSv. These have shown a small, but real, increase in the risk of cancer. Learn more about medical imaging and radiation by clicking on a question to reveal the answer.
Why do we use medical imaging (like CT scans) if there's a risk involved?
In evaluating, diagnosing, and treating patients, medical providers make the decision to recommend one test or another as a way to get closer to helping a patient with their issue. As with most procedures and tests, there is the potential for benefit and the potential for harm. In medical imaging part of the risk comes from being exposed to additional radiation.
How do CT scans work?
CT scans are effectively a series of x-rays taken in quick succession. One side of the CT machine (the donut you’ll see in most CT scanners) produces x-rays while the other side is x-ray sensors that interpret the results. Various types of body tissue absorb more or less of the x-ray, which is what allows the technologists to produce images of the inside of the body. Bone for example absorbs far more of the radiation then the air inside your lungs — so the two show up as contrasting colors. A CT scan takes a lot of these 2D images (or slices) and then can put them together to produce a 3D image. A short video explaining how it works can be found HERE
Why are CT scans used?
CT scans give an invaluable view inside the body, and allow doctors and radiologists to examine potential health issues without invasive procedures. CT scans also don’t use magnetic fields so they can be safely used for someone with metallic medical implants or devices. CT scan times are faster and therefore less susceptible to patient movement.
What is the scan like?
Bloodwork is done prior to a scan (sometimes days before, sometimes on the day of the scan), and you'll be given a list of instructions outlining eating/drinking restrictions prior to the scan. When it's time to do the scan, you'll need to remove all metal, like jewelry, from your body (it can interfere with the scan). You may be asked to change into a hospital gown or scrubs. After filling out paperwork, you'll meet a CT technologist. They will position your body on the scanner bed for the best image possible. You will be asked to lie very still, and even hold your breath for around 10-15 seconds during the actual scan. The scanner bed moves through a doughnut-shaped ring. Inside the ring is an X-ray that rotates around the ring, capturing images called "slices". These slices will be combined in the computer to create a three-dimensional image of the inside of your body. You won't feel anything, but will hear noises. The technician will be in another room during the scan and will talk with you using microphones. The entire scan only takes a few minutes. Note that the technician can't interpret the scan. The images will be sent to a Radiologist who will look at the scan and report back to your doctor. Another appointment will usually be made to discuss the results of your scan. Learn more HERE.