Transcript PHOTONS - Montgomery College

PHOTONS
Bushong, Chapter 4
PHOTONS
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Smallest quantity of electromagnetic energy
Bundle of energy AKA Quantum
No Mass- electric/magnetic fields- sine waves
Travel at speed of light
Energy disturbances interact with matter
Exists over wide energy range
James Clerk Maxwell discovered light and
x-rays have electric and magnetic
properties.
 Sine Wave Model used to help describe
the properties of photons.
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Amplitude-
Frequency-
Wavelength-
C=fXLambda
Relationships Between These
Terms
Velocity
(C or V)
Decreases
Increases
Frequency
(F)
Decreases
Increases
Decreases
Decreases
Increases
wavelength
(Lambda)
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Electromagnetic Energy
 Frequency
 Wavelength
 Energy
 What
does this relationship tell us about
imaging systems?( let’s look at following slide)
Match the Units of measurement
HZ
Energy
Meter
Frequency
Volts
Wavelength
Ionizing Radiation
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Ionizing means that the radiation is able to
cause changes in the structure of an atom.
80 kVp produces x-rays in the 0-80 keV range
X-rays are artifically produced in an x-ray tube
electron cloud
Gamma rays come from inside the nucleus of a
radioactive atom
Wave and Particle Theories
Visible light identified by wavelength
 RF identified by frequency
 X-rays are identified by energy
 Visible light acts like wave
 X-rays act like particles
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Size of the object VS size of wave
(water compared to photons)
Energy attenuation and reduction
in intensity from scatter and
absorption.
Energy is reflected when waves crash into
a bulkhead. It is absorbed by a beach. It is
partially absorbed or attenuated by a line
of pilings.
 Light is also reflected, absorbed, or
attenuated, depending on the composition
of the surface on which it is incident.
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Radiolucent VS Radiopaque
Definitions
ENERGY
 Reflection
 Transmission
 Absorption
LIGHT
 Transparent
 Translucent
 Opaque
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Important in
Radiology
 Attenuation
 Radiopaque
 Radiolucent
Inverse Square Law
Intensity VS Distance