What happens during a CT scan?

• A. X-ray tube head rotates around a patient to create a narrow slice of the patient which is repeated many times.
• B. A magnetic field is used to align protons for imaging.
• C. Contrast dye is used to enhance soft tissue detail.
• D. Ultrasound waves are emitted to image organs.

Answer: (A)

CT scans work by the X-ray tube rotating around the patient in the gantry, emitting a thin X-ray beam through a narrow slice of the body. Detectors opposite the tube measure the transmitted X-rays from many angles as the tube and detector array circle the patient. The computer then reconstructs all those views into detailed cross‑sectional images of that slice. By moving the patient table to acquire adjacent slices, a series of thin sections is built up to create a complete image of the area of interest. Contrast dye can be used to improve visibility of certain structures, but the defining action is the rotation of the X-ray source to capture data from multiple angles for slice-by-slice imaging. This differs from MRI, which uses magnetic fields to align protons, and from ultrasound, which uses sound waves.