Which of the following is directly related to photon energy?

Photon energy is fundamentally associated with the kilovoltage (kV) used in X-ray production. Kilovoltage refers to the peak voltage applied across the X-ray tube, and it directly influences the energy of the emitted photons. As the kilovoltage increases, the energy of the X-rays also increases, resulting in higher penetration power and improved image quality in radiographic imaging. This relationship arises from the physics of how X-rays are produced; higher kilovoltage creates more energetic electrons that strike the target anode, thereby producing X-rays with greater energy.

While milliamperes (mA) and wavelength are important factors in the overall process of X-ray production and image acquisition, they are not directly related to photon energy itself. Milliamperes measure the tube current, which affects the quantity of X-rays generated rather than their energy. Wavelength is inversely related to photon energy according to the equation (E = \frac{hc}{\lambda}), where (E) is energy, (h) is Planck's constant, (c) is the speed of light, and (\lambda) is wavelength. However, wavelength is just a different expression of the same relationship, and in this specific context