Which imaging modality generates a three-dimensional image from a large series of two-dimensional X-ray images taken around a single axis of rotation?

• A. TTP
• B. CT Scan
• C. Endoscopy
• D. Idiopathic

Answer: (B)

This question is about how a three-dimensional image is created from many two-dimensional X-ray pictures taken around a single axis. A CT scan does this. In CT, the X-ray source and detectors rotate around the patient on a gantry, collecting attenuation data from numerous angles in a single rotation (and sometimes over multiple rotations). Those many 2D projections are then reconstructed with algorithms to form cross-sectional images, which can be stacked into a 3D volume. This is distinct from endoscopy, which uses a camera to view inner surfaces directly and yields 2D images, and from terms that aren’t imaging modalities.