Which statement best describes the beam geometry of CBCT according to the material?

• A. A CBCT uses a true cone beam
• B. A CBCT uses a rotating fan beam
• C. It is not a true cone beam; it's a parameter beams
• D. It uses a linear beam

Answer: (D)

CBCT is built around a true cone-beam geometry. The X-ray source emits a cone-shaped beam that sweeps around the patient, while a flat-panel detector captures many projections in a single rotation. This cone-beam approach allows volumetric data to be reconstructed into a 3D image from multiple angles, rather than sampling with a narrow, line-like beam. A rotating fan beam describes a different system that samples a slice at a time with a linear detector, which isn’t how CBCT is configured. A linear beam or non-cone geometry wouldn’t provide the volumetric data CBCT is designed to produce.