What is a Computed Tomography (CT) scan used for?
A CT scan can take images of body parts from many angles and combine them together to show clear-cut sections of your body. These images show much more than a typical X-ray image.
The following are common uses of CT scans of different parts of the body:
• Head CT scan - detects stroke, tumors, bleeding, and fractures. Also used to assist stereotactic surgery and radio surgery for treatment of brain tumors
• Lung CT scan - detects acute and chronic changes to lung structures and lung cancer screening
• CT pulmonary angiogram (CTPA) - for diagnosis of pulmonary embolism
• CT cardiac angiography - looks at the blood vessels that supply the heart
• Abdomen and pelvic CT scans - diagnosis of abdominal and pelvic diseases. Also used to diagnosis and staging of abdominal cancers
• CT colonography (also known as virtual colonoscopy or VC) - detects tumors in the lower gastrointestinal tract
• Extremities - assesses complex fractures, especially those around the joints, before surgery
Besides the above, CT scans can also be used to guide biopsies and determine location for radiotherapy, etc.
What preparation do I need to do before a CT scan?
Usually, there is little preparation involved. You may need to remove metal objects from your body such as jewelry, hair clips, etc. It is best not to wear clothes with metal zips, studs, etc. You may also be asked to not eat or drink for a few hours before your scan.
What will happen during a CT scan?
You may be given a special iodine-based dye as a drink or injected through your veins. This dye is relatively harmless and helps to see things in the body more clearly. This special dye, also known as an oral contrast agent, may give you a warm, flushed feeling, and an odd taste in your mouth which will soon disappear. For some people, this dye may cause nausea, vomiting, or itchy rashes that can be relieved with medications.
You will be asked to lie on a movable bed that will pass through a ring-shaped scanner. Stay very still during scanning so that images remain sharp and clear. It is also normal to hear some buzzing, clicking, or humming noises during the scan. Our CT technicians will see you through the glass window in the room next to you. We will be able to hear you at all times and also speak to you over the speakers. The whole procedure takes about 30 minutes.
What are the risks of doing a CT scan?
A CT scan uses a low dose of radiation and is thus a relatively safe test. However, we recommend that pregnant women avoid having a CT scan if possible, as there is still a small risk of the unborn child developing abnormally.
On rare occasions, the special dye used can cause an allergic reaction or kidney failure. Let your doctor or radiologist know if you have any of the following:
• Kidney disease or poor kidney function
• Diabetes or taking a medication called metformin
Your doctor and radiologist may request you to do a blood test to determine if you should continue the scan with a contrast agent.
Your doctor, radiologist, or nurse will advise you on how to take medications, when to contact us if you feel unwell, and how much fluid to drink to flush the dye out of your body. Do follow these instructions carefully, and ask them questions if you have any concerns.