Introduction to Radiation Protection Practice Flashcards

Comprehensive vocabulary flashcards covering basic radiation physics, types of ionising radiation, biological effects, history, measurement units, and safety principles based on the Introduction to Radiation Protection lecture.

Ionisation

The process in which an electron is given enough energy to break away from an atom, resulting in the formation of 2 charged particles or ions.

X-Rays

Electromagnetic radiation produced by electrons external to the nucleus or when electrons strike a target; used in diagnostic radiography and radiation therapy.

Gamma rays

Electromagnetic radiation emitted from an excited nucleus after it undergoes radioactive decay; high energy and able to pass through many different materials.

Alpha particles

Particles composed of 2 protons and 2 neutrons tightly bound, emitted from the nucleus during radioactive decay; highly ionising but low penetration.

Beta (-ve) particles

High speed electrons ejected from the nucleus during radioactive decay when there are too many neutrons; more penetrating than alpha particles.

Beta (+ve) / Positrons

Emitted from unstable radioisotopes with too few neutrons; these annihilate with electrons to convert into energy, emitting 2 gamma rays in opposite directions.

Stochastic (Probabilistic) Effects

Radiation-induced effects like cancer induction and hereditary effects where the probability of damage is dose related, follow statistical probabilities, and have no known threshold.

Linear, no-threshold (LNT) hypothesis

The presumption that the proportion of risk and dose observed at higher doses continues through all lower levels of dose down to zero.

Non-Stochastic (Deterministic) Effects

Effects with a threshold above which damage is expected in all individuals; severity increases as radiation dose increases once the threshold is exceeded.

Hemopoietic syndrome

An acute syndrome of total body irradiation affecting the bone marrow, resulting in immunosuppression and bleeding.

Gastrointestinal syndrome

An acute syndrome of total body irradiation characterized by intestinal ulcers and the gut becoming nonfunctional.

Cerebrovascular syndrome

The most severe acute radiation syndrome involving nausea, coordination issues, and coma, leading to death within $2-3$ days.

Law of Bergonie and Tripondeau (1906)

States that radiosensitivity is a function of the metabolic state of the cell; radiosensitivity increases with high metabolic rate and cell immaturity.

Absorbed Dose ($D$)

Measured in Gray ($Gy$), representing the amount of energy transfer from radiation.

Dose equivalent ($H$)

Measured in Sievert ($Sv$), a measure of biological effect calculated by multiplying the absorbed dose by a factor for the specific type of radiation.

Effective dose ($E$)

Measured in Sievert ($Sv$), accounts for the radiosensitivity of organs by summing the dose equivalents multiplied by factors for specific organs.

Becquerel ($Bq$)

The unit of measurement for activity, describing how many atoms in a sample disintegrate per unit time.

Natural Background Radiation

Radiation consisting of cosmic radiation from space, terrestrial radiation from soil/rocks, and inhaled radon gas, averaging approximately $1.5\,mSv/yr$.

Justification

The ICRP principle stating that the benefit of using radiation must outweigh the risk.

Optimization (ALARA)

The ICRP principle to keep radiation doses "As Low As Reasonably Achievable."

Occupational Dose Limit

The ICRP recommended limit of $20\,mSv$ per year averaged over 5 years, with no more than $50\,mSv$ in a single year.

Newton’s inverse square law

The physical law stating that doubling the distance from a radiation source reduces the radiation dose by a factor of four.

Half Value Layer (HVL)

The thickness of a material that will reduce the number of radiation photons to one-half of their initial number.

Thermoluminescent Dosimeter (TLD)

A device used to measure occupational exposure; it stores radiation energy in excited electrons which emit light proportional to exposure when heated.

Pregnancy Dose Limit

Once a pregnancy is declared, a limit of $1\,mSv$ is applied to the surface of the abdomen for the remainder of the pregnancy.