How do x-rays interact with biological tissues?

• A. By scattering only
• B. By absorption and ionization
• C. By reflection
• D. By diffraction

Answer: (B)

X-rays interact with biological tissues primarily through absorption and ionization processes. When X-rays encounter biological tissues, their energy can be absorbed by the atoms within the tissues. This absorption can lead to the ejection of electrons from atoms, resulting in ionization. Ionization is a critical interaction because it can cause molecular damage to cellular structures, which may lead to biological effects such as changes in tissue function, mutations, or even cancer if the damage is not repaired.

This process is prominent because various materials, including biological tissues, have different atomic compositions. Tissues with higher atomic numbers, such as bones, absorb X-rays more effectively than softer tissues, affecting the contrast observed in radiographic images. This interaction forms the basis for diagnostic imaging, as the varying degrees of absorption result in the contrasting shades seen on X-ray films.

The other options, such as scattering, reflection, and diffraction, play relatively minor roles in the overall interaction of X-rays with biological tissues. Scattering does occur and can affect image quality, but it is not the primary mechanism. Reflection is negligible for X-rays in medical imaging contexts because X-rays generally penetrate rather than bounce off tissues. Diffraction is also not significant in the context of typical radiographic imaging, as it refers to