Which of the following factors primarily influence the quality of an x-ray beam?

The quality of an x-ray beam is primarily determined by factors that affect its penetrating power and overall energy. The kilovoltage peak (kVp) plays a critical role in this regard; it directly influences the x-ray beam's energy level, which determines how well the x-rays can penetrate different tissues. Higher kVp results in a more penetrating beam that can better pass through denser materials, yielding images with higher contrast and clarity.

Filtration is another essential factor in determining beam quality. It involves the use of materials (usually aluminum) that absorb low-energy x-rays that do not contribute to image formation. By filtering out these less penetrating x-rays, the quality of the resultant beam is improved, as it contains higher energy, more useful x-rays that contribute to the diagnostic image while reducing patient dose.

While other options mention valuable aspects of x-ray procedures, such as exposure time and patient positioning, they influence the quantity rather than the quality of the x-ray beam. Therefore, kVp and filtration are the primary factors affecting the quality of the x-ray beam.