Which statement best describes the path of x-ray photons through matter?

Which statement best describes the path of x-ray photons through matter?

• A. X-rays travel in curved paths
• B. X-rays travel in straight lines
• C. X-rays travel in random patterns
• D. X-rays travel only in wires

Answer: (B)

X-ray photons move in straight-line paths between interactions with matter. When they travel through tissue, most of their journey is a direct line from source toward the detector, and their intensity is reduced only when they are absorbed or scattered. The straight-line assumption is what allows radiographs to form an image as shadows of the anatomy, with image brightness determined by how much the beam is attenuated along each line of travel. It’s true that absorption stops photons and scattering can change their direction, but the fundamental propagation between those events is along straight lines. The other statements imply curved, random, or restricted motion that doesn’t match how x-rays behave in matter.

X-ray photons move in straight-line paths between interactions with matter. When they travel through tissue, most of their journey is a direct line from source toward the detector, and their intensity is reduced only when they are absorbed or scattered. The straight-line assumption is what allows radiographs to form an image as shadows of the anatomy, with image brightness determined by how much the beam is attenuated along each line of travel. It’s true that absorption stops photons and scattering can change their direction, but the fundamental propagation between those events is along straight lines. The other statements imply curved, random, or restricted motion that doesn’t match how x-rays behave in matter.