What happens when X-rays are absorbed by the tissues?

• A. Ionization of tissue molecules with potential damage.
• B. A slight warming of the tissues.
• C. Conversion of X-rays to visible light.
• D. Creation of new chemical bonds without damage.

Answer: (A)

Absorption of X-rays in tissue transfers the photons’ energy to electrons, causing ionization of tissue molecules. This means electrons are ejected, creating ions and reactive free radicals that can initiate chemical changes and potentially damage cellular components, including DNA. That ionization is the fundamental reason X-ray exposure carries a risk of biological effects, which is why dose control and shielding matter in dental radiography. A small amount of energy does contribute to heating, but the primary consequence of absorption is ionization and its potential damage. The other ideas—conversion to visible light, or forming bonds without damage—do not describe what actually occurs with X-ray absorption.