What does the term 'anode heel effect' refer to?

The term 'anode heel effect' refers to the variation in intensity of the X-ray beam that occurs due to the geometry of the X-ray tube. Specifically, as the X-rays are produced at the anode, they must pass through the anode itself before exiting the tube. The anode is thicker at the cathode side and thinner at the anode side, leading to a differential absorption of X-rays. Consequently, the intensity of the X-ray beam is stronger on the cathode side and weaker on the anode side. This effect can impact image quality, particularly in imaging larger body parts where it is beneficial to position the denser area towards the cathode side to take advantage of the higher intensity. Understanding the anode heel effect is crucial for radiographers to optimize positioning and exposure settings for effective imaging.