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Electromagnetic radiation
Microwaves visible light x rays radio wave
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ALARA
As low as reasonably achievable
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Particulate radiation
Nuclear decay
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Particulate radiation examples
Alpha beta neutrons
Far more dangerous than electromagnetic radiation
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Equivalent dose
Means of equalizing the effects of different types of radiation so total dose can. T accurately expressed
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Biologic damage
- Photons ionize atoms
- cellular damage
- Genetic or somatic manifestations
- Organic damage
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Man made rad
- Consumer products
- Air travel
- Nuclear energy
- Fallout
- Nuclear accidents
- Medical applicants
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X ray absorption
Deposit energy interact with tissue
Absorption ionizes atom
Absorbed dose measure in rads or grays
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Natural radiation
Terrestrial cosmic internal
Background radiation
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Primary radiation
Radiation traveling in the primary beam
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Primary beam is
Polyenergetic not a single beam
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Attenuation
Absorption(photo electric effect) and scatter (Compton effect)
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Interaction probability
Absorption depends on beam energy,tissue atomic number thickness density
Scatter depends on primary beam
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Effective dose
Radiation protection
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RAD
Radiation absorbed dose
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Discovery of X-ray
November 1895 crookes tube
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First American fatality
Dally 1904
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Early awareness
- Radiodematitis
- Aplastic anemia
- Leukemia
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Investigation in to safety
British x ray and radium protection committee
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1900 - 1930 measure exposure
Skin erythema dose
Does not account for individual differences; inaccurate
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Tolerance dose
Keeping exposure below threshold dose for acute or early effects
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Roentgen 1937
Became internationally accepted measure for exposure to x ray and gamma radiation
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REM
Radiation equivalent man
Any exposure that produces the same Biologic effect as 1 rad of x- radiation
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Rad - absorbed dose oo
100 ergs per gram of tissue
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Si units of exposure
Roentgen is a roentgen
- 100 rads = gray gy
- 100 rem = sievert si
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Absorbed dose
Absorption based on effective Atomic number , tissue or mass density, part of thickness
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Produces differential absorption
Subject contrast
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LET
Iinear energy transfer
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High LET radiation
Deposit large amount of energy in small area
Thereby producing more damage
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Nuclear decay produces
Electromagnetic and particulate radiation
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Quality factors
X ray photons,beta particles gamma photons -1
- Thermal neutrons -5
- Neutron 20
- Alpha particles 20
Based on LET
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Equivalent dose
different types of radiation are more dangerous than others, applies a radiation weighting factor to them
Based on RBE
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Effective dose
Uses equivalent dose then factors type of tissue that have been irradiated
Some tissue are more sensitive;more damage
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Absorption atomic# of bones and skin
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Particulate radiation vs electromagnetic radiation
Particulate rad is Far more dangerous than electro rad
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Somatic
Can be early,late or syndromes
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Higher atomic number
Higher electrons
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RBE
Radiation Biologic effectiveness
used to evaluate the equivalent dose
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Alpha particles
Ingested
worst then thermal neutron
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Hydrated =
Better contrast
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Higher energy higher frequency
Shorter wave length
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Lower energy lower frequency
Longer wavelength
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Biologic effects
Damage to living tissue of animals and humans exposed to radiation
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BERT
Background equivalent radiation time
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Equivalent dose
- Radiation quantity used for radiation protection purposes when a person receives exposures from
- Various type of ionizing radiation
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ORP
Optimization for radiation protection
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Exit or image photons
Two photons emerge from tissue and strike IR
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Small angle scatter
Bending of its path
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Radiographic fog
Undesirable density
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Photo disintegration
High energy photon collides with the nucleus on an atom
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Roentgen
Unit of exposure to air
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Rem
Radiation equivalent man
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Rad
Absorbed dose in patient
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