Which condition may cause beam hardening in CT imaging?

Beam hardening in CT imaging is primarily caused by the differential absorption of X-ray photons as they pass through various tissues, particularly those with higher densities. High-density tissues, such as bone or contrast material, absorb lower-energy photons more effectively than higher-energy photons. As a result, the X-ray beam becomes “hardened,” meaning that the overall energy of the beam increases as more of the lower-energy photons are attenuated. This can lead to artifacts in the resulting images, such as streaking or shading, which can obscure important anatomical details.

In contrast, while the presence of metallic implants can also lead to artifacts, they do so through different mechanisms, such as scattering or beam attenuation, rather than beam hardening specifically. Excessive patient motion can blur images, but it does not directly cause changes in the energy spectrum of the X-ray beam. Inadequate calibration of equipment might lead to other inaccuracies in imaging results, but it is not a primary cause of beam hardening. Thus, the presence of high-density tissues is the most direct contributor to beam hardening phenomena in CT imaging.