CT Scan Purpose and Technique

Purpose of CT Scans

• CT scans provide detailed cross-sectional images of internal structures such as internal organs, blood vessels, bones, and soft tissue
• CT scans are used for diagnostic purposes, guidance for treatment or further tests, surgeries, biopsies, and radiation therapy
• CT scans are used to detect and monitor conditions such as cancer, heart disease, lung nodules, and liver masses

CT Scan Technique

• Digital geometry processing is used to generate a 3D image of the inside of the body from a large series of 2D X-ray images taken around a single axis of rotation
• The CT scanner has a circular opening with a flat "patient couch (table)" that can be adjusted upwards, downwards, frontwards, or backwards to position the patient for imaging
• The patient lies flat on the table, which moves into the gantry while the X-ray tube rotates around the patient
• The scanner gantry contains the rotating portion that holds the X-ray tube generator and the detector array
• As X-rays pass through the patient, they are detected and a computer system acquires and performs the necessary calculations to create a viewable image
• One cross-sectional slice of the body is obtained for each complete rotation
• Multiple shots are taken as the scanner rotates, resulting in around 1,000 "profiles" per rotation
• A 2D image (slice) is formed when a full set of profiles from each rotation are analyzed by a computer and compiled