X-Ray Interactions with Anatomic Tissues

X-Ray Photon Interaction

• Total absorption of incoming x-ray photons is primarily due to the photoelectric effect, where an x-ray photon is completely absorbed by an atom, resulting in the ejection of an inner-shell electron.

Contrast in X-Ray Imaging

• The degree of contrast in an x-ray image is controlled by differential absorption, which depends on tissue density and atomic number. Tissues with higher atomic numbers absorb more x-rays, creating greater contrast.

Important Interactions for X-Ray Imaging

• Key interactions that contribute to the formation of an x-ray image include:
  • Photoelectric Effect: Critical for image formation due to complete photon absorption.
  • Compton Scattering: Important for contributing scattered radiation, which can affect image quality.
  • Characteristic Radiation: Produced when ejected electrons fill vacancies in electron shells, contributing to the x-ray spectrum.

Type of Interaction Affecting Image Contrast

• The photoelectric effect significantly determines the degree of contrast in an x-ray image since it allows for varying absorption levels across different tissues, enhancing the visibility of structures.