The two types of scatter radiation are Compton scatter and what other type?

Compton scatter and coherent scatter are the two primary types of scatter radiation encountered in radiographic imaging. Compton scatter occurs when an x-ray photon collides with a loosely bound outer electron of an atom, resulting in the photon losing energy and changing direction. This type of scatter is significant in diagnostic imaging because it contributes to the overall radiation dose received by both the patient and the operator.

Coherent scatter, also known as classical or Rayleigh scatter, involves the interaction of low-energy photons with matter, where the photon is scattered without a loss of energy. This typically occurs at energies below about 10 keV and does not contribute to the image formation or patient dose as significantly as Compton scatter does. Understanding these two types of scatter is essential for radiation safety, as both can affect image quality and the amount of radiation exposure.

The other options, while related to the concept of scatter, do not represent recognized types of scatter radiation in the context of radiation safety and imaging. Coherent scatter is, therefore, the correct answer, as it is essential for understanding the different interactions that occur when x-ray photons pass through matter.