The higher x-ray intensity on the cathode side of the beam is primarily due to what factor?

The phenomenon of higher x-ray intensity on the cathode side of the beam primarily relates to the inherent design and operation of an x-ray tube. X-rays are produced when electrons collide with the anode target, and this process results in more x-ray photons being emitted in the direction of the cathode. The intensity is greater on the cathode side due to the anode heel effect, where some x-rays are absorbed by the anode itself, leading to a diminished intensity on the anode side.

This effect shows that the geometry and the materials used in the anode contribute significantly to the distribution of x-ray intensity. As a result, because the anode absorbs a portion of the x-ray photons, the intensity remaining on the cathode side is relatively higher. Understanding this aspect is essential in radiography for optimizing image quality and managing radiation dose effectively.

In contrast, the other options do not accurately explain the principle behind the higher intensity observed on the cathode side. The production of x-rays occurs at the anode, not the cathode, while the distance from the source to the cathode plays a role in exposure but does not account for the distribution of intensity. Similarly, the quality of the x-ray filter primarily affects the