Radiation Protection Basics

Comprehensive vocabulary flashcards covering the basics of radiation, its sources, types, and interactions with matter as described in the lecture notes.

Radiation

The emission of energy through space or a medium; energy in motion or in transit that travels as waves or bundles called photons.

Excitation

A process where some forms of radiation raise an electron to a higher energy state without removing it from the atom.

Radioactivity

The spontaneous emission of radiation from the nucleus of an unstable atom as it seeks to achieve stability; defined as the rate of decay of radioactive material.

Cosmic Radiation

Radiation produced by the sun and stars as it interacts with the Earth's atmosphere and magnetic field; dose increases at higher altitudes.

Terrestrial Radiation

Radiation found in soil, rocks, water, air, and vegetation; examples include the radioactive elements uranium and thorium.

Radon

A tasteless, colorless, odorless gas byproduct of uranium decay that diffuses through rocks and soil, accounting for the greatest amount of natural radiation exposure.

Internal Radiation

Radioactive materials found inside the human body, such as potassium 40, uranium, and thorium.

U.S. Average Background Dose

The total average dose of radiation received annually by a person in the U.S., which is approximately $300\,mrem/year$ including Radon.

Medical Radiation

Manmade radiation used for X-rays, radiation therapy treatments, and radiopharmaceuticals; it is the second greatest source of exposure after Radon.

Non-Ionizing Radiation

Radiation that does not have enough energy to remove electrons from atoms; examples include light, lasers, heat, microwaves, and radar.

Ionizing Radiation

Radiation with sufficient energy to remove electrons from atoms as it passes through matter, potentially causing biological effects.

Ion Pair

The combination of a positively charged ion (the atom that lost an electron) and a free electron resulting from ionization.

Directly Ionizing Radiation

Charged particles such as alpha particles, beta particles, and protons that interact directly with orbital electrons through Coulomb interactions.

Indirectly Ionizing Radiation

Uncharged radiation like X-rays, gamma rays, and neutrons that must first create a secondary charged particle to deposit energy into matter.

Electromagnetic Radiation

A form of energy resulting from oscillating electric and magnetic fields that travels at the speed of light ($3 \times 10^8\,m/s$) in a vacuum.

Wave-Particle Duality

The concept that electromagnetic radiation exhibits both wavelike behavior and particle-like behavior as individual packets of energy called photons.

Electromagnetic Spectrum

A wide range of energies extending from low energy, long wavelength radio waves to high energy, short wavelength X-rays and gamma rays.

Wilhelm Röntgen

The individual who discovered radiation on November 8th, 1895.

Cobalt 60

A radioactive isotope historically used in early megavoltage radiation therapy units as a source of gamma rays.

X-ray Photons

Electromagnetic radiation originating from orbital shells with no mass or charge, traveling in straight but diverging lines and exponentially attenuated by matter.

Attenuation

The reduction of the energy of an X-ray beam as it travels through matter due to absorption or scattering.

Gamma Ray Photons

Radiation nearly identical to X-rays in behavior but originating from the nucleus of an atom during radioactive decay.

Particulate Radiation

Radiation composed of subatomic particles moving at high speeds that possess mass and usually carry an electric charge.

Alpha Particles

Particles consisting of 2 protons and 2 neutrons (identical to a helium nucleus) with a $+2$ charge; they have high LET and low penetration ($0.7\,mm$ in tissue).

Neutrons

A unique type of particulate radiation with no electric charge, making them indirectly ionizing despite having mass.

Beta Particles

High-energy electrons (beta negative) or positrons (beta positive) that are emitted from the nucleus of a radioactive atom.

Linear Energy Transfer (LET)

A measure of the rate at which energy is deposited as radiation passes through tissue, which depends on the radiation's mass and charge.

High LET Radiation

Radiation such as alpha particles, neutrons, and protons that deposits energy quickly in a dense path, causing more biological damage over a shorter distance.

Low LET Radiation

Radiation such as X-rays, gamma rays, and beta particles that interact more sparsely and travel further through matter.