1. Electromagnetic and Particulate Radiation
Stacy Kopso, M.E.d, RT(R)(M)

2. Electromagnetic Radiation
Electromagnetic Theory
James Maxwell
Electromagnetic radiation
No mass
Carries energy in waves
Travels at speed of light
3x108 m/s

3. Electromagnetic Radiation
A form of energy that originates from the atom
Electromagnetic radiation is emitted when changes in atoms occur
Electromagnetic energy
Travels through a vacuum

4. Electromagnetic Spectrum
Way of ordering/grouping different forms of electromagnetic radiation
All members have the same velocity
Speed of light
3 x 108 m/s
Vary only in their energy, wavelength and frequency

5. Electromagnetic Spectrum
MRI
Nuclear Medicine
Ionize matter

6. Radiowaves Low end of the spectrum MRI Does not ionize atoms
The nuclei of hydrogen atoms are magnetic
When placed in a strong magnetic field, the nuclei will absorb and reemit radiowaves of particular frequency
Through processing of these emitted radiowaves, images can be constructed
Does not ionize atoms

7. Microwaves A microwave generator is used to create microwaves
Hit the atoms of the food, giving them excess energy
The energy causes vibration of the atoms and molecules
The atoms release this excess energy as heat, which increases the temperature of the food
Does not ionize atoms

8. Infrared light
Signal sent from the television remote to change channels
Send information between portable devices
Does not ionize atoms

9. Visible light The colors visible to the human eye
White light consists of all of the colors visible to the human eye
Consists of all of the colors of the visible spectrum together
When we see a particular color, the object is absorbing all of the wavelengths of light except the one we see
The color black represents absorption of all of the color wavelengths
Does not ionize atoms

10. Ultraviolet light Closer to xrays and gamma rays Tanning beds Harmful
Stimulates melanin production in the skin cells, causing damage to the melanocytes, resulting in cancer
Does not ionize atoms

11. X-ray & Gamma rays Ionize atoms
Originate form a different energy source
Gamma
Originate in the nuclei of atoms
Represents the excess energy the atom is giving off to reach a stable state.
Nuclear medicine/Radiation Therapy
X-rays
Originate through interactions between electrons and atoms
Produced when fast moving electrons within the x-ray tube strike the atoms of the metal in its target
X-ray and Radiation Therapy

12. Ionization X-rays and gamma rays have the ability to ionize matter
When a photon possess sufficient energy, it can remove electrons form the orbit of atoms during interaction
Ionization
Removal of an electron from an atom
Dangerous in general and harmful to the patient if misused
Damage molecules and DNA
Cause chemical changes in cells

14. Wavelength & Frequency
Electromagnetic radiation exhibits properties of a wave depending on its energy
Wavelength
A measure of the distance from the peak of one wave to the peak of the next wave
Expressed in meters (m)
Amplitude
Maximum height of the wave
Frequency
The number of waves that pass a given point per second
Expressed in hertz (Hz)
Relationship between wavelength and frequency is inverse
An increase in wavelength= a decrease in frequency

15. Energy & Frequency Max Planck
Energy and frequency are directly proportional
As energy increases, frequency increases
Increase in kVp=increase in energy
Electromagnetic radiation can only exist as “packets” of energy= photons

16. Energy & Frequency Energy and frequency are related mathematically
E=hf
Unit of measure eV (electron volts)
E= energy
h =Planck’s constant (4.15 x eV-sec)
used to calculate photon energies based on frequency
f= frequency of photon

17. Wavelength & Frequency
Formula velocity
Velocity=frequency x wavelength
V=fλ
Replace v with c for the speed of light (3 x 108 m/s)
Formula for wavelength
λ=c/f
Formula for frequency
f= c/λ

18. Work it Out
What is the frequency of electromagnetic radiation if the wavelength is 1 x m?
f= c/λ
3 x 108 m/s
3 x 108 m/s ÷ 1 x m
3x1019 HZ

19. Work it Out
What is the wavelength of electromagnetic radiation if the frequency is 1.5 x 1012 HZ?
λ=c/f
3 x 108 m/s
2 X M

20. Draw a low energy wave and a high energy wave
Label the following describing each wave;
energy (increase or decrease)
frequency (increase or decrease)
wavelength (short or long)
kVp associated with it (high or low)

21. Particulate Radiation
Alpha and Beta particles
Physical particles originating from radioactive atoms with the ability to ionize matter
Nuclear medicine/radiation therapy
Radioactive materials
Radiium and uranium
Technetium

22. Particulate Radiation
Radioactivity
The process by which an atom with excess energy in its nucleus emits particles and energy to regain stability
Radioactive decay (Curie/Becquerel)
Half-life
The length of time it takes for half the remaining atoms in a quantity of a particular radioactive element to decay
Elements that are composed of atoms with unstable nuclei are said to be radioactive

23. Particulate Radiation
Alpha particle
2 protons bound to 2 neutrons
Travel slow, large, can not penetrate most objects
Beta particle
An electron that is emitted from an unstable nucleus
Does not originate in an electron shell
Lighter and smaller
Can penetrate skin but not organs

24. Class work