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### Chapter 5 Electromagnetic Radiation A photon is the smallest element of electromagnetic energy. Photons are energy disturbances moving through space at the speed of ... – PowerPoint PPT presentation

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1
• A photon is the smallest element of
electromagnetic energy.
• Photons are energy disturbances moving through
space at the speed of light.
• Photons have no mass but they do have electric
and magnetic fields.

2
• A field is an interaction between different
energies, forces or masses that can not be seen
but can be described mathematically.
• Electromagnetic Radiation can be represented by
the sine-wave model.
• Sine-waves have amplitude.Amplitude is one half
the range from crest to valley over a sine wave.

3
• The important properties of the sine-wave model
are frequency(f) and wavelength(?) and velocity.
• Frequency is the number of wavelengths passing a
point per second.
• Frequency is identified as oscillations per
second and measured in hertz (Hz).

4
• Wavelength is the distance from one crest to
another or from any point in the wave to the next
corresponding point.
• The wave parameters are very important. A change
in one affects the value of one or both of the
others.

5
• At a given velocity, wavelength and frequency are
inversely proportional.
• The Wave Formula
• Velocity Frequency x Wavelength

6
• With EMF we know the velocity so the formula is
simplified.
• c f? or f c/? or ? c/f
• As frequency increases, wavelength decreases and
vice versa
• For electromagnetic radiation, frequency and
wavelength are inversely proportional.

7
Electromagnetic Spectrum
• The electromagnetic spectrum includes the entire
• The frequency range is from about 102 to 1024 Hz
• Photon wavelengths range from 107 to 10-16m.
• Grouped together, these radiations make up the
electromagnetic spectrum.

8
Electromagnetic Spectrum
• Three important ranges.
• Visible light
• Others include
• UV
• IR and microwave

9
Electromagnetic Spectrum
• EMF can be measured in three formats
• Energy (eV) used to describe x-rays
• Frequency (Hz)
• Wavelength (m)

10
Visible Light
• Measured in wavelength.
• A prism is used to refract or change the
direction of the photons.
• Only form of EMF that we can sense.

11
Forms of Light
• Visible light ranges from 700nm to 400nm
wavelength.
• Infrared light have longer wavelength than
visible light but shorter than microwaves.
• Ultraviolet light is located between visible

12
• With radio, the frequency is used to identify the
station.
• Short wavelength radiofrequency are referred to
as microwaves.

13
• Unlike visible light or radiofrequency, ionizing
electromagnetic radiation is characterized by the
energy contained in the photon.
• When we use 70 kVp, the photon will have energy
varying from 0 to 70 keV.

14
• The frequency is much higher and wavelength much
shorter for x-rays compared to any other form of
• Visible light identified by wavelength
• X-rays identified by energy

15
• The only difference between X-rays and gamma rays
is their origin.
• X-rays are produced outside the nucleus.
• Gamma rays are produced inside the nucleus of

16
Wave-Particle Duality
• A x-radiation photon and a visible light photon
are fundamentally the same except that
x-radiation photons have a much higher frequency
and shorter wavelength.
• These differences change the way they interact
with matter.
• Visible light tends to behave as waves.

17
Wave-Particle Duality
• X-radiation tends to behave more as particles
than waves.
• Both types of photons exhibit both types of
behavior and this is referred to as the
• Photons interact with matter when the matter is
approximately the same size as the photon
wavelength.

18
Wave-Particle Duality
• Radio television photons wavelength is measured
in meters and interact with long metal rods
called antennae.
• Microwave are measured in centimeters and react
most easily with popcorn hotdogs.

19
Wave-Particle Duality
• Visible light wavelength is measured in
micrometers or nanometers, interacts with living
cells such as the rods and cones in the eye.
• Ultraviolet light interacts with molecules.
• X-rays interact with atoms and electrons.
• All radiation with wavelengths longer than x-rays
interact primarily as a wave.

20
Wave model Visible Light
• Vision is result of specially developed organ
that sense a very narrow portion of the
electromagnetic spectrum.
• When a visible light photon strikes an object, it
sets the molecule of the object into vibration.

21
Wave model Visible Light
• The orbital electrons become excited by the
higher energy. This energy is immediately
irradiated as another photon of light. This is
referred to as reflection.
• Atomic and molecular structure determine which
wavelength of light are reflected.

22
Wave model Visible Light
• Light photons not reflected are either absorbed
or transmitted.
• There are three degrees of absorption
• Transparency
• Translucency
• Opacity

23
Degrees of Absorption
• If all of the light is transmitted almost
unaltered, it is transparent.
• If only some of the light passes through , it is
called translucent.

24
Degrees of Absorption
• If all of the light is absorbed, it is called
opaque.
• Attenuation is the sum of scattering and and

25
• Terms used to describe the appearance of objects
on the x-ray film.
• Objects that absorb the radiation are called

26
• Structures that attenuate the x-rays are referred

27
Inverse Square Law
• I1 D22
• ____ _____
• I2 D12
• Radiation intensity is inversely related to the
square of the distance from the source.
• The decrease is due to the light being spread
over a ever increasing area.

28
Inverse Square Law
• If the source is not a point but a line such as a
fluorescent lamp, the inverse square law does not
hold at distances close to the source.
• The inverse square law can be applied to
distances greater than seven times the longest
dimension of the source .

29
Inverse Square Law
• The Inverse Square Law is used in radiography to
adjust technical factors for changes in distance.
• It is also used for radiation protection. The
farther you are away from the source, the lower
the exposure.
• To use the formula, you need to know three of the
4 factors which are two distances and two
intensities.

30
Particle Model Quantum Theory
• Unlike other forms of electromagnetic radiation,
x-ray energy is measured in electron volts (eV).
• X-ray energies range from 1 to 50 MeV
• X-ray wavelengths range from 10-9 to 10-12m.
• X-ray frequency range from 1018 to 1021Hz

31
Range of X-ray Energies
• Diffraction uses less than 10 kVp.
• Grenz rays with energies of 10 to 20 kVp are used
in dermatology.
• Diagnostic Radiography uses the range of 30 kVp
to 150 kVp.
• Therapy uses energies from 200 to 1000 kVp

32
X-ray Waveform
• X-rays have both electric and magnetic fields.
• One wave represents the electric field and one
the magnetic field varying at right angles to
each other.

33
Plancks Quantum Theory
• X-rays are created at the speed of light or they
dont exist at all.
• The energy of a photon is directly proportional
to its frequency.
• A photons energy is inversely proportional to
the photon wavelength.
• E hf where E is the photon energy h is
Plancks constant or 10-15eVs or 6.63 x 10-34Js
and f is the photon frequency in hertz.

34
Matter and Energy
• Like the law of the conservation of matter, the
law of conservation of energy states that Energy
can be neither created or destroyed.
• Plancks quantum physics and Einsteins physics
of relativity greatly extended these theories.

35
Matter and Energy
• According to quantum physics and physics of
relativity, matter can be transformed into energy
and vise versa.
• Although matter and energy are interchangeable,
it is energy from the x-ray photon interacting
with tissue and the image receptor that forms the
basis of x-ray imaging.

36
Mass Energy Relationship
• Mass and energy are two forms of the same medium.
This scale shows the equivalence of mass measured
in kilograms to energy measured in electron volts.

37
Summary
• X-rays are just one type of photon of
• The following are used to describe the
electromagnetic spectrum.
• Frequency
• Wavelength
• Velocity
• Amplitude
• These factors are what determines such radiation
interacts with matter.

38
39
X-Ray and Chiropractic
• First used by B.J. Palmer at PSC in 1910.
• He referred x-rays of the spine as spinographs.
• Originally take to prove existence of the
subluxations later used to evaluate spine for
misalignment and pathology..

40
X-Ray and Chiropractic
• 1924 first erect spinal radiographs at Universal
Chiropractic College in Pittsburgh, Pa. This was
the first time that the effects of gravity on the
spine was evaluated.
• Until 1938 all films taken at P.S.C. by Doctor
Ray Richardson.

41
X-Ray and Chiropractic
• Dr Warren Sausser was a 1917 graduate of Palmer
School of Chiropractic.
• He was a radiologic technologist in the Army
during WW1.
• He is one of the pioneers of radiography. Thanks
to him Chiropractors were allowed to take x-rays.

42
X-Ray and Chiropractic
• He is responsible for D.C.s in New York being
able to take x-rays.
• He founded what is now the Chiropractic College

43
X-Ray and Chiropractic
• He was the first chiropractor to take full body
• He also did extensive research in full spine

44
X-Ray and Chiropractic
• Dr Hugh Logan stressed the importance of upright
full spine films making the procedure popular.
Dr. Sausser was impressed by his approach.
• Dr Warren Sausser reported the first single
exposure full spine taken with the 14 x 36
film. Standard X-ray Company designed the x-ray
machine . Kodak developed cassette, film and the
special hangers needed to process the film. The
cassette weighed 50 pounds.

45
X-Ray and Chiropractic
• Dr. Sausser developed filters to equalize the
exposure.
• The tube was placed nine feet from the patient
and a 12 second exposure was needed to produce
the image.
• Dr. Sausser also developed full body exams but
only the full spine remains today.
• The full body radiograph went the way of the
x-rays to fit shoes.

46
X-Ray and Chiropractic
• Like many of the early pioneers of x-ray, he died
in 1958 as a result of the affects of radiation
exposure.
• He had tumors down his side that was not behind a
barrier during the exposures.
• He would often peek around the barrier to check
on the patient.

47
X-Ray and Chiropractic
• Films taken recumbent until 1938 at Palmer School
of Chiropractic.
• All forms of radiography was done at P.S.C.
including fluoroscopic contrast studies of G.I.

48
X-Ray and Chiropractic
• The use of radiography started as a means to see
the subluxations. Today it is used to image the
entire body and not just the spine.
• Today the scope is generally limited to plain
film radiography of the spine, chest, abdomen and
extremities.

49
X-Ray and Chiropractic
• As early as 1922, they used x-rays for the
detection of pathological processes, fractures
and anomalies that impact the patients health as
well as chiropractors determinations of what to
do or not to do.
• This is still true today.

50
End of Lecture