Radiation Units and Protection Flashcards

Comprehensive flashcards covering radioactive units, exposure limits, absorption measurements, and biological effects of radiation based on the lecture notes.

Radioactivity

The rate at which unstable atoms break down (decay) in an attempt to become stable by releasing radiation from the nucleus.

Curie (Ci)

The traditional unit used to measure radioactivity decaying.

Becquerel (Bq)

The SI unit of radioactivity, defined as one disintegration per second ($1\,Bq = 1\,dps$).

Exposure

A measure of ionizations produced in air, determined by counting positive and negative ions generated when radiation ionizes air molecules.

Roentgen (R)

The traditional unit for exposure that measures ionization products in air due to X-rays or gamma rays, applicable up to $3\,MeV$.

Exposure SI Unit Conversion

The SI unit for Roentgen is Coulombs/kilogram ($C/kg$), where $1\,R = 2.58 \times 10^{-4}\,C/kg$ in air.

Absorbed Dose

The amount of radiation energy actually absorbed by a material or tissue, applicable to all types of radiation, energy levels, and media.

Rad

The traditional unit for absorbed dose, where $1\,rad = 1\,cGy$ and $100\,rad = 1\,Gy$.

Gray (Gy)

The SI unit for absorbed dose, where $1\,Gy = 100\,rad$.

Dose Equivalent

A unit that compares different types of radiation based on how harmful they are, calculated as Absorbed Dose $\times$ Quality Factor.

Quality Factor (QF)

A weighting factor used to adjust for biological damage; photons have a $QF = 1$ while alpha particles have a $QF = 20$.

Sievert (Sv)

The SI unit of dose equivalent, where $1\,Sv = 100\,rem$.

Effective Dose

A measure of the overall risk of exposure calculated as: $E = \text{Absorbed dose} \times W_R \times W_T$, where $W_R$ is the radiation weighting factor and $W_T$ is the tissue weighting factor.

NCRP Report No. 116

An advisory publication that outlines effective dose equivalent limits for occupational workers, the general public, and special populations.

Occupational Effective dose-equivalent limit

The annual limit for stochastic effects in workers, set at $50\,mSv$ ($5\,rem$).

Lens of Eye Dose-Equivalent Limit

The non-stochastic dose limit for the eye lens, set at $150\,mSv$ ($15\,rem$).

Cumulative Exposure Guideline

A guideline defined as $10\,mSv \times \text{age}$ or $1\,rem \times \text{age}$, used for occupational exposure.

Public Effective Dose-Equivalent Limit (Continuous)

The limit for frequent/continuous public exposure, set at $1\,mSv$ ($0.1\,rem$).

Embryo-Fetus Dose-Equivalent Limit

The limit throughout pregnancy is $5\,mSv$ ($0.5\,rem$), with a monthly limit not exceeding $0.5\,mSv$ ($0.05\,rem$).

Stochastic Effect

A radiation effect where the probability increases with dose but the severity does not; it has no threshold (e.g., cancer, genetic effects).

Non-Stochastic (Deterministic) Effect

A radiation effect that occurs only after a threshold dose is exceeded, where severity increases with dose (e.g., skin erythema, cataracts).