Which exposure modification will increase the anode heel effect?

Which exposure modification will increase the anode heel effect?

• A. Decreased SID
• B. Increased SID
• C. Lower mA
• D. Higher kVp

Answer: (A)

The thing being tested is how geometry of the x-ray beam creates the anode heel effect. Because the anode is angled, photons emitted toward the anode side pass through more of the anode material, so there’s more attenuation there and the cathode side appears relatively brighter. The magnitude of this gradient depends on how divergent the beam is across the image receptor. When you decrease the source-to-image distance, the beam becomes more divergent. That increased divergence makes the difference in attenuation from the anode side to the cathode side more pronounced, so the heel effect is stronger. Conversely, increasing the SID makes the beam more parallel and reduces the effect. Changing mA or kVp doesn’t alter this geometric distribution in the same way; they mainly affect the total number of photons and their energy, not the relative intensity drop across the field caused by the anode’s angle.

The thing being tested is how geometry of the x-ray beam creates the anode heel effect. Because the anode is angled, photons emitted toward the anode side pass through more of the anode material, so there’s more attenuation there and the cathode side appears relatively brighter. The magnitude of this gradient depends on how divergent the beam is across the image receptor.

When you decrease the source-to-image distance, the beam becomes more divergent. That increased divergence makes the difference in attenuation from the anode side to the cathode side more pronounced, so the heel effect is stronger. Conversely, increasing the SID makes the beam more parallel and reduces the effect.

Changing mA or kVp doesn’t alter this geometric distribution in the same way; they mainly affect the total number of photons and their energy, not the relative intensity drop across the field caused by the anode’s angle.