Lecture Notes: Radiation Biology & Protection — Vocabulary

Vocabulary flashcards covering particulate and electromagnetic radiation, biological effects, sources, and radiation measurement units mentioned in the notes.

Alpha radiation

Heavy particulate radiation (helium nucleus); highly ionizing but has very limited penetrating power.

Beta radiation

Lighter particulate radiation (fast electrons/positrons); more penetrating than alpha but less ionizing per unit path than alpha.

X-rays

High-energy electromagnetic radiation produced in X-ray tubes; used for medical imaging.

Gamma rays

High-energy electromagnetic radiation emitted from atomic nuclei; highly penetrating.

Ionizing radiation

Radiation capable of removing electrons from atoms, causing ionization and potential biological damage.

Dose rate

The rate at which radiation energy is delivered or dose is received; influences biological response.

Absorbed dose

Energy deposited by radiation per unit mass of tissue; measured in gray (Gy).

Gray (Gy)

SI unit of absorbed dose; 1 Gy = 1 joule per kilogram of tissue.

Roentgen (R)

Traditional unit of exposure in air; measures ionization produced in air.

Coulombs per kilogram (C/kg)

SI unit equivalent to exposure in air; amount of charge produced per kilogram of air.

Air kerma

Kinetic energy released in matter from photons in air; describes X-ray tube output; measured in Gy.

Equivalent dose

Absorbed dose weighted for the type of radiation; expressed in sieverts (Sv) or rem; accounts for biological effectiveness.

Effective dose

Equivalent dose adjusted for tissue sensitivity; estimates overall risk; unit in Sv.

Sievert (Sv)

SI unit of dose equivalent; 1 Sv = 100 rem; used for risk assessment of radiation.

Rem

Traditional unit of dose equivalent; 1 rem = 0.01 Sv.

Integral dose

Total energy deposited in matter during exposure (energy delivered over the irradiated volume).

Activity

Quantity of radioactive material present; measured in curies (Ci) or becquerels (Bq).

Curie (Ci)

Traditional unit of activity; 1 Ci = 3.7 x 10^10 decays per second.

Becquerel (Bq)

SI unit of activity; 1 Bq = 1 decay per second.

Background radiation

Natural environmental radiation from cosmic sources, terrestrial sources, radon, and internal radionuclides.

Cosmic radiation

Space-origin radiation from the sun and cosmic rays; contributes to natural background exposure.

Terrestrial radiation

Radiation from radioactive materials in the ground (soil/rock) that reaches humans.

Radon and thoron

Naturally occurring radioactive gases that can accumulate indoors; inhalation contributes to dose, especially in winter.

Internal radionuclides

Radioactive materials naturally present inside the body (e.g., potassium-40).

Man-made sources

Radiation from human activities: medical imaging, nuclear medicine, consumer products, aviation, and nuclear power.

Medical imaging contribution

Imaging procedures (X-ray, CT) contribute significantly to medical radiation exposure; CT can account for a substantial share (about 24%).

X-ray imaging input/output (air kerma)

Output of the X-ray tube quantified as air kerma; relates to dose delivered to patient during imaging.

Genetic effects

Heritable radiation effects resulting in mutations in offspring (embryo/fetus).

Somatic effects

Radiation effects on body tissues and organs (skin, blood, eyes); do not involve offspring.

Radiosensitivity

Relative susceptibility of cells/tissues to radiation damage; varies by tissue type and biological context.

Age and radiosensitivity

Radiosensitivity is higher in young/immature cells and tends to decrease with maturation.

Tissue radiosensitivity differences

Different tissues have varying sensitivity; reproductive tissues are highly radiosensitive.

Sex differences in radiosensitivity

Notes indicate females may be more radiosensitive than males for reproductive tissues.

Air travel exposure

Radiation exposure from high-altitude flight due to increased cosmic radiation.

Nuclear power plants

Industrial source of radiation; exposure considerations for workers and the public.