In conventional tomography, what moves to create a sectional image?

In conventional tomography, what moves to create a sectional image?

• A. The patient rotates
• B. The tube and receptor move in opposite directions
• C. The x-ray beam changes energy
• D. The detector moves in a circle

Answer: (B)

In conventional tomography, the sectional image is created by moving the X-ray tube and the image receptor in opposite directions around the patient during exposure. This opposite motion causes structures at different depths to shift relative to the focal plane, so out-of-plane structures blur while the chosen slice remains sharp. The thickness of that slice depends on the arc of movement and the geometry between the tube and receptor. The patient stays still during the exposure, the X-ray beam energy isn’t what selects the section, and the detector’s circular motion isn’t the mechanism here—the key is the opposite-direction travel of tube and receptor that encodes depth into the image.

In conventional tomography, the sectional image is created by moving the X-ray tube and the image receptor in opposite directions around the patient during exposure. This opposite motion causes structures at different depths to shift relative to the focal plane, so out-of-plane structures blur while the chosen slice remains sharp. The thickness of that slice depends on the arc of movement and the geometry between the tube and receptor. The patient stays still during the exposure, the X-ray beam energy isn’t what selects the section, and the detector’s circular motion isn’t the mechanism here—the key is the opposite-direction travel of tube and receptor that encodes depth into the image.