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

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

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

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

Electromagnetic Spectrum MRI Nuclear Medicine Ionize matter

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

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

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

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

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

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

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

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

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

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 10-15 eV-sec) used to calculate photon energies based on frequency f= frequency of photon

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

Work it Out What is the frequency of electromagnetic radiation if the wavelength is 1 x 10-11 m? f= c/λ 3 x 108 m/s 3 x 108 m/s ÷ 1 x 10-11 m 3x1019 HZ

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 10-4 M

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)

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

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

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

Class work