Is a CBCT an actual cone beam?

• A. Yes
• B. No, it's a cone beam
• C. No, it's a rotating fan beam
• D. No, its a parameter beams

Answer: (D)

CBCT uses a cone-shaped X-ray beam. The X-rays diverge from the source in a cone as they travel to a 2D detector, and the gantry rotates around the patient to collect a series of cone-beam projections that are reconstructed into a 3D volume. So, yes, it is an actual cone beam. Describing the beam as a rotating fan beam or as “parameter beams” doesn’t match the geometry CBCT uses. The cone shape is what defines the CBCT geometry and its reconstruction approach.