rad bio final

c = λv

Speed of light formula (wavelength × frequency)

SOL

3 × 10⁸ m/s

EqD = D × Wr

Equivalent dose formula

EfD = D × Wr × Wt

Effective dose formula

Atomic number (Z)

Number of protons

Exposure

C/kg or mR

Absorbed dose

Energy per unit mass (mGy)

Effective dose

Biological harm (mSv)

Diagnostic efficacy

Determines if imaging is justified

ALARA

As Low As Reasonably Achievable

Cardinal rules

Time, distance, shielding

BERT

Background Equivalent Radiation Time

Image Gently

CT dose reduction in pediatrics

Image Wisely

Reduce unnecessary radiation exposure

NEXT program

Nationwide Evaluation of X-ray Trends

Electron binding energy

Higher Z = higher energy

Tungsten/rhenium target

High Z and melting point

Attenuation

Reduction of beam intensity

Direct attenuation

No interaction

Indirect attenuation

Interaction with energy loss

Coherent scatter

Unimportant

Photoelectric effect

Inner shell electron ejected

Photoelectric byproducts

Photoelectrons + characteristic photons

Characteristic photons

Secondary radiation, low energy

Auger effect

Electron ejected instead of photon emitted

Compton scatter

Outer shell interaction, scatter radiation

Pair production

1.022 MeV → electron + positron

Photodisintegration

10 MeV → neutron emitted

Thickness doubled

Absorption doubles

Positive contrast

Barium, iodine

Negative contrast

Air, gas

All radiation speed

3 × 10⁸ m/s

Ionizing radiation

X-ray, gamma, high-energy UV

Nonionizing radiation

Visible light, IR, microwave, radio

Alpha particles

+2 charge, low penetration

Beta particles

-1 charge, moderate penetration

Proton

Positive charge

Neutron

No charge

Isotope

Same protons, different neutrons

Radioisotope

Unstable, emits radiation

Absorbed dose factors

Z, density, photon energy

Equivalent dose

Accounts for radiation type

Effective dose

Accounts for tissue + radiation

Natural dose

3.1 mSv/year

Artificial dose

0.1 mSv/year

Medical dose

2.3 mSv/year

Total annual dose

5.5 mSv

X-ray discovery

Nov 8, 1895

First radiation death

Clarence Dally (1904)

Skin erythema dose

Redness dose (1900–1930)

Roentgen adopted

1928

Early tissue effects

Nausea, fatigue, erythema, hair loss

Late tissue effects

Cataracts, fibrosis, sterility

Stochastic effects

Cancer, genetic

Exposure (X)

Radiation concentration

Air kerma

Energy per mass (Gy)

DAP

mGy·cm²

Weighting factor (x-ray, beta, gamma)

1

Neutron <10 keV

5

Neutron 10–100 keV

10

Neutron >100 keV–2 MeV

20

Proton weighting

2

Alpha weighting

20

ColEfD

Population dose (person-Sv)

TEDE

Total effective dose equivalent

TEDE worker limit

0.05 Sv

TEDE public limit

0.001 Sv

Personnel dosimetry

Monitors occupational exposure

OSL

Aluminum oxide, detects 10 µSv

Direct ion storage

USB readable dosimeter

TLD

Lithium fluoride, reusable

Survey instrument requirements

Durable, reliable, tissue-equivalent

Cutie Pie

Ionization chamber meter

Geiger Muller

Detects radiation, no precise readout

ICRP

Sets dose recommendations

UNSCEAR

Evaluates global exposure

NRC

Oversees nuclear industry

EPA

Environmental radiation control

FDA

Regulates x-ray equipment

OSHA

Worker safety

RSO authority

Stop unsafe operations

Radiation Control Act 1968

Protects public from exposure

Consumer-Patient Act 1981

Ensures safe medical radiation

Radiation hormesis

Low dose benefit (not proven)

Occupational EfD

50 mSv/year

Cumulative dose

Age × 10 mSv

Eye dose (occupational)

150 mSv

Skin/extremities

500 mSv

Public continuous

1 mSv

Public infrequent

5 mSv

Public eye

15 mSv

Public skin

50 mSv

Embryo/fetus monthly

0.5 mSv