Originally designed to take pictures of the brain, the CT scanner was developed in 1972. It is now used to photograph many different parts of the body, painlessly and in great detail. It is essentially a specialized x-ray machine that sends out a number of beams at once, from different angles. A computer then joins these images together, to give your doctor a 2-dimensional image of the inside of your body. Certain newer CT scanners are even able to produce 3-dimensional images. These scans are much clearer and more detailed than conventional x-rays.
The abbreviation CT stands for Computed Tomography. (Tomography refers to pictures being taken in sections.) Sometimes you may also see the procedure described as a CAT-scan, which refers to Computed Axial Tomography. This is just another name for the same procedure.
How does a CT scan differ from other diagnostic tests?
Unlike conventional x-rays, a CT scan gives very detailed images of many parts of your body. In the past, doctors would have to perform surgery to be able to see the level of detail provided by a simple CT scan. It is best at capturing images of dense tissues such as bone, lungs, kidney and brain. It is somewhat less effective than MRI for scanning softer tissues such as the bowel and bladder.
A CT scan typically scans a larger area than an MRI. As well, it is less sensitive to patient movement than MRI and may be performed on patients who have implants. Today, CT scans are sometimes used in conjunction with PET scans to provide even more detail.
How is a CT scan most useful?
An CT scan can help doctors detect and diagnose:
- Brain problems such as: bleeding in the brain, aneurysms or tumours
- Kidney problems such as kidney stones
- Heart and lung problems such as blockages or tumours
- Tumours and abscesses throughout the body
- Bone problems from fractures to tumours
- The location of an infection
- Internal injuries and bleeding
Why do I have to wait so long for my CT scan?
Although CT scanners are more common in Canada than some other non-invasive diagnostic tools, there are still not nearly enough to meet demand. Per capita, Canada has fewer of these machines than most other countries in the developed world. As a result of rationing of care by the Canadian public health system you may be required to wait weeks or even months for your scan. If your case is urgent or the required wait is unacceptable to you, Timely Medical Alternatives can help you find a private clinic to expedite the test you need. Contact us for a free consultation.
How is the procedure performed?
When you go for your appointment at the CT scan clinic, you will be asked to lie on a table that is connected to the scanner, a large donut-shaped machine. The table then slides into the hole or opening and the scanner moves around your body. The table will move as well and you may hear a clicking or buzzing sound as either the table or the CT scanner changes position. It is important to lie still throughout the procedure.
The technician will not be in the room as the photographs are taken, but you will be able to speak with him or her by microphone.
If you need to be given dye, you may receive an IV (needle) in the arm or a joint, or given a catheter (narrow tube) to the bladder or rectum or you may be or you may be asked to drink something. You may feel a sensation of warmth or a metallic taste in your mouth as the dye travels through your body.
The exam typically takes 30 to 60 minutes but may take as long as two hours.
How should I prepare for my CT scan?
You should wear comfortable, loose-fitting clothing. You may have been asked to fast beforehand if it is possible you will require an injection of dye.
Be sure to inform your doctor if you have asthma, allergies, diabetes, heart disease, kidney problems or thyroid conditions. Your doctor may also order a blood test, prior to the scan, to check your kidney function to ensure it is able to handle the dye.
Also, if you have had an x-ray using barium or have taken a medication with bismuth (such as Pepto-Bismol) in the previous four days, be sure to alert your doctor. Both barium and bismuth will show up on the scan, making the pictures much harder to read.
Who interprets the CT Scan results and how do I get them?
A radiologist at the CT scan clinic will analyze the images and send a report with his or her interpretation to your doctor.