What is the anode heel effect?

• A. There is no variation in beam intensity across the field.
• B. The anode heel effect causes the anode side to be more intense.
• C. The cathode side is more intense.
• D. Variation in beam intensity across the field occurs due to the angled anode, with the cathode side more intense.

Answer: (D)

Anode heel effect arises because the X-ray tube’s target (the anode) is angled. That angle means photons traveling toward the anode side pass through more of the anode material and are more absorbed, while photons toward the cathode side pass through less material and are less attenuated. So the beam intensity is higher on the cathode side and lower on the anode side, creating a gradual variation across the field. This effect is more noticeable with larger field sizes and shorter source-to-image distances. In practice, you can place the region of interest toward the cathode side to take advantage of the higher intensity or adjust exposure factors accordingly.