PRELIM 2 - Interactions of Radiation with Biological Matter

Superoxide (O₂•−), Hydroxyl radical (•OH), Hydrogen peroxide (H₂O₂)

All of these are Reactive oxygen species (ROS)

Target theory

Which type of radiation damage primarily involves water radiolysis?

Hydroxyl radical (•OH)

The most common free radical in biological systems is?

Linear energy transfer (LET)

Which property describes the energy deposited by radiation per unit distance traveled?

Dense ionization and significant biological damage

High LET radiation, such as alpha particles, causes?

Specific ionization

The number of ion pairs produced per unit path length

Direct

he relationship between LET and specific ionization

Neutrons

Which is typically used as a reference radiation when calculating RBE

Single-hit model

Which model suggests that a single hit to DNA can cause biological damage?

Threshold effects

Deterministic effects are also known as

Severity increases with dose

Which characteristic best applies to deterministic effects

Deterministic effects

Radiation burns, cataracts, and ARS are examples of

Dose-independent

What is the severity of stochastic effects?

Increases with dose

The probability of stochastic effects

Latent stage

Which stage of Acute Radiation Syndrome (ARS) involves apparent recovery?

2 Gy

At what dose does skin erythema typically appear?

Leukemia

Which cancer is most associated with radiation and appears within 2 years?

Skin cancer

Which cancer is most likely to develop 10+ years after exposure?

Stochastic

Genetic mutations caused by radiation are?

Direct action

The process by which high-energy radiation excites or ionizes DNA directly

Free Radicals

The unstable molecules with unpaired electrons caused by radiation

Hydroxyl Radical (•OH)

The most damaging free radical in the body.

Relative Biological Effectiveness (RBE)

The measure of biological effectiveness compared to X-rays.

Target theory

The theory suggesting DNA is the main target of radiation

Stochastic effect

Radiation effect with no threshold, probability-based.

Deterministic effect

Radiation effect with a threshold, severity increases with dose

2–3 Gy

The dose range causing temporary hair loss

Eye Lens

The organ damage associated with cataracts

Breast Cancer

The cancer that often appears 5 years after radiation exposure

10 years or more

The latency period of thyroid cancer after radiation

Water (H₂O)

The main medium in the body where indirect radiation action occurs.

Hydroxyl radical (•OH)

The product of water radiolysis that causes most DNA damage

Antioxidants

Substances that neutralize free radicals by donating electrons.

Reactive Oxygen Species (ROS)

The term for oxygen-derived free radicals.

Gray (Gy)

The measurement unit for absorbed dose

Superoxide (O₂•−)

A free radical involved in both immune defense and cellular damage, denoted as O₂•−

Deterministic effect

The radiation effect where severity increases with dose and has a threshold

Relative Biological Effectiveness (RBE)

The radiation property that measures biological effectiveness compared to a reference radiation

Stochastic effect

The radiation effect where probability increases with dose but severity is random

0.5–1 Gy

The threshold dose range for acute radiation syndrome (ARS)

Prodromal stage

The ARS stage characterized by nausea, vomiting, and fatigue shortly after exposure

The ARS stage where patients appear to recover temporarily.

Latent stage

The ARS stage when symptoms of hematopoietic, GI, and CNS damage manifest.

Manifest illness stage

The ARS stage that results in either recovery or death depending on dose.

Recovery or death stage

The skin effect occurring at about 2 Gy dose, characterized by reddening.

Skin erythema

The skin effect occurring around 6–10 Gy dose, characterized by peeling.

Desquamation

The tissue reaction that causes thickening and scarring, usually above 5 Gy.

Lungs

The organ most affected by radiation-induced ______ disease.

Genetic mutations

The radiation-induced hereditary effect observable in subsequent generations