"Scatter" on a CBCT image is caused by?

The correct response, indicating that "scatter" on a Cone Beam Computed Tomography (CBCT) image is primarily caused by very dense objects, can be understood by examining how X-rays interact with different materials during imaging.

When X-rays pass through dense objects, such as bone or metal, they encounter significant attenuation. This interaction leads to scattering—where some X-ray photons are deflected from their original path. The result is degradation in image quality, as the scattered photons contribute to noise and can obscure fine details, making interpretation of the image more challenging.

Dense materials produce scatter because they increase the likelihood of photon interactions, resulting in a broader distribution of X-ray photons. This contributes to the scattering phenomenon seen on the resultant images.

In comparison, objects with low density do not significantly contribute to scattering, as they allow X-rays to pass through more freely, resulting in less degradation of the image. Therefore, while both types of objects can influence the overall image quality, the primary contributor to scatter in CBCT imaging is indeed dense materials. Understanding this aspect is crucial for interpreting CBCT images correctly and mitigating the effects of scatter through proper imaging techniques and settings.