Flashcards : Fundamentals of Ionizing Radiation in Medicine — 10 cartes

Ionizing radiation has enough energy to create ion pairs by ejecting electrons from atoms or molecules. It includes electromagnetic types like X-rays and gamma rays, as well as particles such as electrons, protons, alphas, and neutrons.

Energy capable of ionizing atoms or molecules.

The photoelectric effect involves photon absorption where an inner-shell electron is ejected, dominant at low energies with high atomic number materials. Compton scattering is when photons scatter off electrons, transferring part of their energy, important at intermediate energies (~4-25 MeV). Pair production occurs when a photon with energy above 1.022 MeV converts into an electron-positron pair near a nucleus, relevant at energies >10 MeV.

A = λN (decay rate).

LET is the energy deposited by radiation per unit length traveled in tissue, measured in keV/μm. High LET radiation (e.g., alpha particles) causes dense, localized damage that is often irreparable, leading to higher biological effectiveness, while low LET radiation (e.g., X-rays) results in more spread-out, reparable damage.

More likely with higher Z and lower energy.

Cause ionization via Coulomb interactions.

Cause nuclear reactions, produce secondary charged particles.

DNA and water molecules.

Biological effect relative to reference radiation.