chapter 9: radiation protection concepts and equipment

Particulate radiations

High- energy electrons

Neutrons and protons

alpha particles

High energy helium nucleus

Two protons two neutrons

Large amount of mass and charge

Highly ionizing due to size and charge

Beta particles

Electrons from decaying radioactive material

Little mass and charge Highly

More penetrating in tissue

X-rays

Originate from electrons

Gamma rays

Emitted by the nuclei of radioactive material

Direct interaction

Photon sets a particle on motion

Indirect interaction

Absorption of radiation occurs in water molecule producing free radicals

Most biological damage

Somatic

Cataracts, erythema, cancer formation

Genetic

Results in damage to reproductive germ cells

Evident in offspring of individual

NCRP No.82

Established an international standard for dose measurement and exposure

Natural

Cosmic radiation

Terrestrial radiation

Radionuclides naturally present

Man-made

X rays

Radiopharmaceuticals

Consumer products

Air travel

Nuclear fuel production

Fallout

NCRP No.160

Identifies medical imaging modalities contributing to medical exposure

1 Gray

1 J/kg

1 Gy

100 rad

Absorbed dose

The amount of energy absorbed by a structure depends on the

Atomic number

Mass density

Energy of the incident photon

Kerma

Unit Gy

Air Kerma

Kinetic energy released per unit mass of air

Integral dose

Total amount of energy deposited in matter

Equivalent dose

The type and energy of the radiation in question

Dose x weighted factor

Sievert

X rays and gamma rays

1

Neutrons, energy < 10 keV

5

10 keV -100 keV

10 keV

>100 keV -2keV

20

>2 Mev -20 MeV

5

Protons

2

Alpha particles #

20

Effective dose

Sum Of equivalent doses of specific tissues

Affect tissue radio sensitivity

0.20

Gonads

0.12

Red bone marrow, colon, lungs, stomach

0.05

Bladder, Breast, liver, Esophagus, thyroid, Remainder

0.01

Bone and skin

Activity

Measured in curie or becquerel

Field survey instruments

Portable device used to measure radiation in a given location

Personnel monitoring devices

Instruments worn by healthcare workers

Geiger-muller survey

Gas-filled detector

Used in particulate radiation

Scintillation detection device

Emit light when stimulated by ionizing radiation

Used in nuclear medicine and CT

Ionization chamber

Evaluates

Equipment performance

Leakage radiation

Patient exposure

OSL monitor

Most common type of personnel monitor

Filters of copper and tin and an open window

Film badge

Has copper, cadmium and aluminum sensitive to 10 mermaids

TLD

Lithium fluoride crystals

Used for extremity badges