A computerized tomography scan, more commonly called a computed tomography (CT) scan, uses highly specialized X-ray equipment to produce a cross-sectional image of a specific area of the body — a virtual slice. The scan can be viewed as a two- or three-dimensional image, allowing detectable and recognizable soft tissue and bony structures to be clearly represented.
A CT scan is rapid, painless and non-invasive for the patient. In some instances, an iodine-based contrast agent is used to allows enhancement of non-bony structures, such as blood vessels or the gastrointestinal tract, to be rendered in much greater detail than a standard X-ray can render.
CT scans are often relied upon to diagnose disease, trauma or abnormalities. CT scans can also be used as a preventative measure for screening patients with no known symptoms for early detection of irregularities, such as tumors, clots or heart disease, and will therefore improve the prognosis for the patient.
CT scanners use a spinning gantry that has an X-ray tube and X-ray detector plates on the other side. The gantry spins around the patient to image them. The series of X-ray images are reconstructed as a 3-D volume, like a three-dimensional box, which can be slice on any axis to show the anatomy on different planes. The CT dataset is usually visualized using multiplanar reconstructions (MPR imaging), where the anatomy can be visualized in in a coronal, sagittal, oblique or other virtual cut planes. The size of the image slices are adjustable, but usually about 0.5 to 5 mm. The radiologist can flip through the images slice by slice to look for abnormal findings. These datasets can also be reconstructed into 3-D CT views that can be rotated on any axis.
Learn more about the difference between computed tomography vs MRI scan.