When X-rays are absorbed by tissues, what occurs at the molecular level?

When X-rays are absorbed by tissues, what occurs at the molecular level?

• A. The molecules are ionized (atoms separate)
• B. The molecules become superconductive
• C. The molecules fuse together
• D. The molecules remain unchanged

Answer: (A)

X-ray absorption in tissue involves transferring energy to electrons. If the photon’s energy is enough to overcome the electron’s binding energy, an electron is ejected, leaving a positively charged ion—this is ionization. The ejected electron can go on to cause additional ionizations or form reactive free radicals, which is a key part of how radiation interacts with biological material. The other options don’t fit: superconductivity doesn’t occur in biological tissues at any practical temperature, fusion of molecules doesn’t happen with X-ray exposure, and saying the molecules remain unchanged contradicts the fact that absorption deposits energy and ionizes or excites matter. So ionization correctly describes what happens at the molecular level.

X-ray absorption in tissue involves transferring energy to electrons. If the photon’s energy is enough to overcome the electron’s binding energy, an electron is ejected, leaving a positively charged ion—this is ionization. The ejected electron can go on to cause additional ionizations or form reactive free radicals, which is a key part of how radiation interacts with biological material. The other options don’t fit: superconductivity doesn’t occur in biological tissues at any practical temperature, fusion of molecules doesn’t happen with X-ray exposure, and saying the molecules remain unchanged contradicts the fact that absorption deposits energy and ionizes or excites matter. So ionization correctly describes what happens at the molecular level.