How is the CT Brain Scan procedure performed?

In a CT brain scan, several x-ray beams pass through the brain at various angles. Special sensors measure the amount of radiation absorbed by different tissues within the brain, including lesions and tumours.

In order to undergo a CT brain scan, your general physician must write you a letter of referral stating why he or she believes a CT brain scan is necessary in your situation. A CT brain scan will take place in either a hospital or in an outpatient radiology center.

Prior to a CT brain scan, some patients may receive an injection of a contrast material. Contrast material, such as barium, highlights the brain tissue and makes it stand out against other structures in the CT image. This contrast material is injected through a small needle connected to an intravenous line inserted into a vein in the arm or hand. In some cases, the contrast material will be administered by mouth or by enema.

During a CT brain scan, the patient lies still on a table. The table is rolled into the center of the CT scanner. The CT scanner revolves around the patient and emits and records x-ray beams. The different areas of the brain absorb different amounts of x-ray. Meanwhile, detectors on the scanner revolving opposite to the x-ray beams detect the differences between the amount of x-ray that went into the body, and the amount coming out. A special computer program then forms graphical cross-sections, or “tomograms,” based on these x-ray absorption differences.

Once the patient enters the scanner, the technologist may turn on special lights to ensure the patient is positioned properly for the CT brain scan. Some types of CT brain scan require a special head holder made of soft straps to ensure the head and neck remain correctly aligned throughout the exam. Though the technologist will not actually be in the room with the patient, an intercom within the scanner allows the patient and technologist to communicate throughout the procedure.

A CT brain scan can take up to 45 minutes. The actual imaging takes about 30 seconds to a few minutes; the rest of the time is preparation. The duration of the CT brain scan depends on the number of images needed to get the information the doctor requires. At the conclusion of the CT brain scan, the technologist will look over the images to ensure sufficient images have been created to provide the radiologist with the necessary information. If more images are necessary, the technologist will ask the patient to stay for further scanning.