Which statement is true regarding the effect of increasing the anode angle?

Which statement is true regarding the effect of increasing the anode angle?

• A. Increases the focal spot size
• B. Decreases the focal spot size
• C. No change to the focal spot size
• D. Only affects exposure, not focal spot

Answer: (A)

The line-focus principle governs how the focal spot is perceived on the image. The actual focal spot on the anode is fixed in size, but what you see as the effective focal spot on the image is a projection of that spot along the beam direction, shaped by the bevel angle of the anode. When the anode angle is increased, the projection becomes shorter in the direction of the beam, so the apparent (effective) focal spot size decreases. This improves geometric sharpness of the image because there’s less blurring from the focal spot’s finite size. The trade-off is that changing the angle affects heat distribution on the anode, not the exposure itself, which is still governed by the tube current and exposure time.

The line-focus principle governs how the focal spot is perceived on the image. The actual focal spot on the anode is fixed in size, but what you see as the effective focal spot on the image is a projection of that spot along the beam direction, shaped by the bevel angle of the anode. When the anode angle is increased, the projection becomes shorter in the direction of the beam, so the apparent (effective) focal spot size decreases. This improves geometric sharpness of the image because there’s less blurring from the focal spot’s finite size. The trade-off is that changing the angle affects heat distribution on the anode, not the exposure itself, which is still governed by the tube current and exposure time.