Chap#1

• Matter


  Anything that occupies space and has mass. It is the material substance of which physical objects are composed
• Atoms


  Fundamental building blocks of matter, arranged in various complex ways
• Mass

  Quantity of matter as described by its energy equivalence, measured in kilograms (kg)
• Mass

  Mutual attraction called gravity between the Earth's mass and the mass of an object
• Molecules


  Fundamental, complex building blocks of matter
• The kilogram, the scientific unit of mass, is unrelated to gravitational effects
• Kilo


  Prefix meaning 1000, so a kilogram (kg) is equal to 1000 grams (g)
• Although mass remains unchanged regardless of its state, it can be transformed from one size, shape, and form to another
• Energy


  Ability to do work, measured in joules (J) in the International System (SI)
• Electron volt (eV)


  Unit often used for energy in radiology
• Potential energy


  Ability to do work by virtue of position
• Objects with potential energy


  • Guillotine blade held aloft
  • Rollercoaster on top of incline
• Kinetic energy


  Energy of motion
• Chemical energy


  Energy released by a chemical reaction, e.g. energy provided to our bodies through food
• Electrical energy


  Work that can be done when an electron moves through an electric potential difference (voltage)
• Thermal energy (heat)


  Energy of motion at the molecular level, related to temperature
• Nuclear energy


  Energy contained within the nucleus of an atom, controlled in nuclear power plants and released in atomic bombs
• Electromagnetic energy


  Includes radio waves, microwaves, ultraviolet, infrared, visible light, and x-rays
• Matter and energy can be transformed from one type to another
• Matter and energy are interchangeable, as described by Albert Einstein's mass-energy equivalence equation
• Mass-energy equivalence equation

  E = mc^2, where E is energy, m is mass, and c is the speed of light
• Radiation


  Energy emitted and transferred through space
• Irradiated


  Matter that intercepts radiation and absorbs part or all of it
• Ionizing radiation


  Radiation capable of removing an orbital electron from an atom, creating an ion pair
• Ion pair


  The orbital electron that is removed and the remaining positive atom
• Ionization is the removal of an electron from an atom
• 1. rays, gamma rays, and ultraviolet light are the only forms of electromagnetic radiation with sufficient energy to ionize
• Alpha and beta particles are also capable of ionization
• Sources of ionizing radiation


  • Natural environmental radiation
  • Man-made radiation
• Natural environmental radiation

  Consists of cosmic rays, terrestrial radiation, internally deposited radionuclides, and radon
• Cosmic rays


  Particulate and electromagnetic radiation emitted by the sun and stars
• Terrestrial radiation


  Results from deposits of uranium, thorium, and other radionuclides in the Earth
• Internally deposited radionuclides


  Natural metabolites like potassium-40
• Radon


  Radioactive gas produced by the natural radioactive decay of uranium, present in trace quantities in the Earth
• Man-made radiation


  Includes diagnostic x-rays, nuclear power generation, research applications, industrial sources, and consumer items
• Diagnostic x-rays constitute the largest man-made source of ionizing radiation
• The benefits of x-rays in medicine are indisputable, but their use must be prudent and with care to reduce unnecessary exposure
• Radiologic technologists control the operation of x-ray imaging systems and have responsibility to reduce unnecessary exposure
• 1. rays were discovered by accident by Wilhelm Roentgen in 1895
• Roentgen's original properties of X-rays

  • Highly penetrating, invisible electromagnetic radiation
  • Electrically neutral, not affected by electric or magnetic fields
  • Produced over a wide range of energies and wavelengths
  • Release very small amounts of heat upon passing through matter
  • Travel in straight lines
  • Travel at the speed of light in a vacuum
  • Can ionize matter
  • Cause fluorescence of certain materials
  • Cannot be focused by a lens
  • Affect photographic film
  • Produce chemical and biological changes in matter
  • Produce secondary and scatter radiation