RADIATION

Radiation

the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles that cause ionization.

• ionizing

• non-ionizing

Radiation can be classified into two main types

Ionizing Radiation

Has enough energy to remove tightly bound electrons from atoms, leading to ionization.

Examples: X-rays, Gamma rays

Non-Ionizing Radiation

Lacks sufficient energy to ionize atoms.

Examples: Radio waves, Microwaves, Infrared

Radiation

• Can travel through a vacuum (does not require a medium).

• Can penetrate materials to varying degrees, depending on the type and properties of the material.

• Has both beneficial (e.g., medical imaging) and harmful (e.g., radiation sickness) effects.

Inverse Square Law

Radiation intensity decreases as distance from the source increases.

• Particulate Radiation

• Electromagnetic Radiation

Classification of Radiation

Particulate Radiation

composed of subatomic particles that are emitted from the nucleus of an atom during radioactive decay.

Particulate Radiation

Consists of subatomic particles emitted from the nucleus.

• Alpha Particles

• Beta Particles

• Neutrons

Particulate Radiation Types

Alpha Particles

positively charged and consist of two protons and two neutrons.

Alpha Particles

• Positively charged

• Composed of 2 protons and 2 neutrons

• Low penetration (can be stopped by paper or skin)

Beta Particles

high-speed electrons that are emitted from the nucleus during radioactive decay.

Beta Particles

• High-speed electrons emitted during radioactive decay

• Moderate penetration (stopped by plastic or aluminum)

Neutrons

neutral particles that are emitted from the nucleus during nuclear reactions.

Neutrons

• Neutral particles released during nuclear reactions

• High penetration power (stopped by concrete or water)

Electromagnetic Radiation

Consists of energy waves without mass.

Electromagnetic Radiation

a type of energy that travels through space in the form of electromagnetic waves.

• Gamma Rays

• X-rays

• Ultraviolet

• Visible Light

• Radio Waves

Electromagnetic Radiation Types

Gamma Rays

high-energy electromagnetic radiation that is produced during nuclear reactions and the decay of radioactive elements.

Gamma Rays

High-energy radiation from nuclear reactions & radioactive decay.

X-rays

a form of electromagnetic radiation that is used in medicine to image the interior of the body.

X-rays

Used in medical imaging.

Ultraviolet

a form of electromagnetic radiation that is present in sunlight.

Ultraviolet

Present in sunlight.

Visible Light

a form of electromagnetic radiation that can be seen by the human eye.

Visible Light

Detectable by the human eye.

Radio Waves

a form of electromagnetic radiation that is used for communication and navigation, including television and radio broadcasting, cell phone communication, and GPS.

Radio Waves

Used in communication (TV, radio, cell phones, GPS).

Inverse Square Law

The intensity of radiation (or any physical quantity that spreads radially) is inversely proportional to the square of the distance from the source.

Inverse Square Law

• Radiation intensity decreases as the distance from the X-ray source increases.

• Describes the relationship between radiation intensity and distance

• Radiation Intensity from the x-ray tube varies inversely with the square of a distance from the target.

I1​/I2​=(d2​/d1​)^2

Inverse Square Law Formula

I1

initial intensity of radiation

d1

initial distance

d2

final distance

I2

final intensity

Activity

• Old Unit: Curie (Ci)

• New Unit: Becquerel (Bq)

• Conversion: 1 Ci = 3.7 × 10^10 Bq

• Bq = dis/s

Absorbed Dose

• Old Unit: Rad

• New Unit: Gray (Gy)

• Conversion: 1 Gy = 100 rad

• J/kg, m2/s2

Equivalent Dose

• Old Unit: Rem

• New Unit: Sievert (Sv)

• Conversion: 1 Sv = 100 rem

• J/kg, m2/s2

Exposure

• Old Unit: Roentgen (R)

• New Unit: Coulomb per kilogram (C/kg)

• Conversion: 1 R = 2.58×10^−4 C/kg

Radiation Absorbed Dose

• A measure of the amount of energy absorbed by a material or organism due to ionizing radiation.

• J/kg

• Essential in radiation protection and safety to quantify potential harm to living organisms.

Radiation Absorbed Dose

• Measures the amount of energy absorbed per unit mass from ionizing radiation.

• Used for all types of radiation and any material.

• Refers to the dose received by patients in medical radiation exposure.

D=E/m

Radiation Absorbed Dose (D) Formula

E

Energy (Joules, J)

m

Mass (kilograms, kg)

Equivalent Dose

• Measures the biological effect of ionizing radiation on human tissue.

• Sv

Equivalent Dose

• Considers the type of radiation and its relative biological effectiveness (RBE) in causing harm.

• Used to compare biological effects of different radiation exposures.

• Helps establish radiation protection guidelines.

Equivalent Dose

Measures the amount of radiation received by radiation workers, considering the type and effectiveness of radiation in causing harm.

H=DQN

Equivalent Dose (H) Formula

H

Equivalent dose

D

Absorbed dose (Gy)

Q

Quality factor (dimensionless)

• 20 for alpha radiation

• 10 for protons and neutrons

• 1 for X-rays and gamma rays

N

Further modifying factor (always = 1)

Equivalent Dose

• Used to determine the dose limits for radiation workers.

• Helps in radiation protection guidelines by accounting for biological effects of different radiation types.

Sv or rem

The unit of Equivalent Dose (H)

1 Gy ≈ 1 Sv

Gy or rad

The unit of Absorbed Dose (D)

1 rad ≈ 1 rem

10³ Gy

1 kGy

1000 mSv

1 Sv