Document Actions
Head CT Scan
Also available in PDf format: CT Head
CT scans use a special X-ray machine to get detailed information on head injuries, stroke, brain tumors, and other brain diseases. Read this document to learn how the CT of the head works, how to prepare for the scan, how the scan is performed, what to expect during the scan, and how to get your results.
What is a head CT scan?
CT (Computed Tomography, or CAT scan) uses a special X-ray machine to take detailed pictures of the organs and tissues of the head. CT scans provide more details on head injuries, stroke, brain tumors, and other brain diseases than plain X-ray pictures. CT can also show bone, soft tissues, and blood vessels in the same pictures.
How does the scan work?
Unlike standard X-rays, which produce pictures of the shadows cast by body structures of varying thickness, CT scanning uses X-rays in a much different way. In CT of the head, many X-ray beams are passed through the skull and brain at many angles, and special detectors measure the amount of radiation absorbed by different tissues. The X-ray tube revolves around you, and sends and records data from many angles of the head, forming crosssectional pictures (slices) of the head and brain.
How should I prepare for the CT scan?
- Dress comfortably, but any items that might obstruct imaging of the head – such as earrings, glasses, dentures, dental implants, or hairpins – should be removed.
- Eat your regular diet until 6 hours before your scan. Continue to drink clear liquids (water, juices, tea) until your scan. It is important for you to continue to drink frequently before and after your scan. Drinking water is very helpful in protecting your kidneys. Continue to take your regular medications as prescribed by your doctor.
- If an intravenous (IV) injection of a contrast material will be helpful, you will be asked in advance whether you have had allergies in the past or have ever had a serious reaction to any medicine. Contrast materials contain iodine, which can cause a reaction if you are allergic. If you have known allergies to other medicine, there may be a chance that you could have a reaction to the contrast material.
- Tell the technologist if you have asthma, multiple myeloma or any disorder of the heart, kidneys, or thyroid gland, or if you have diabetes – particularly if you are taking Glucophage.
- Tell your doctor or CT technologist if there is a chance you might be pregnant.
How is the CT scan performed?
- You will be put in a special head-holder that uses soft straps to keep the head and neck in the proper place. In some cases, you will lie on your back and in others on your stomach.
- You will lie very still on a table that will be guided into the center of the scanner.
- For the first few scans, the table will move quickly through the scanner to check the correct starting position. The rest of the scans are made as the table moves more slowly through the hole in the scanner.
- If contrast material is needed for your scan, a small needle connected to an IV line is placed in your arm or hand vein. The contrast material will be sent through this line.
- CT exam of the head and brain can take between 2 and 20 minutes. When it is done you will be asked to wait until the technologist checks the pictures for quality. More scans will be done as needed.
What will I feel during the scan?
- CT is painless, though you may feel some discomfort from staying still.
- If contrast injection is needed, you may feel discomfort at the
injection site. - You may notice a warm, flushed sensation during the injection of contrast material. You may also notice a metallic taste in your mouth that lasts for about 2 minutes. These reactions are normal, and go away within 1 to 2 minutes.
- Once in a while, a patient will develop itching and hives for up to a few hours after the injection; this can be relieved with medication. Light-headedness or shortness of breath may be due to a more severe allergic reaction. A doctor or nurse will be nearby during the exam to help you, if needed.
- Because CT uses X-rays, you may not have a family member or friend in the CT room during the exam.
Who interprets the results and how do I get them?
A radiologist skilled in CT scanning will review and interpret the CT findings, and will send a detailed report to your primary care or referring doctor. Your doctor will give you the results. The radiologist will not discuss the results with you.