Which tube-detector geometry is used by third-generation CT scanners where the X-ray tube and detectors rotate around the patient to collect views?

• A. Rotate-rotate technology
• B. Stationary-rotate geometry
• C. Electron gun-detector array
• D. All of the above

Answer: (A)

In third-generation CT, the X-ray tube and the surrounding detector array rotate together around the patient, collecting projection data from many angles in a single continuous rotation. This rotate-rotate geometry lets the system capture a complete set of views quickly and with high fidelity because the detector ring moves with the tube, keeping the geometry consistent as gantry angle changes. The patient remains still while the gantry spins, and data is gathered from the full circular array of detectors.

Stationary-rotate would imply the detector stays fixed while the tube moves, which isn’t how third-generation CT operates. Electron gun-detector array describes components rather than the geometric arrangement. All of the above isn’t correct because only the rotate-rotate setup matches how third-generation CT collects views.