RST

• 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
• The prefix kilo stands for 1000; 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)
• Electron volt (eV)


  Unit of energy often used 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, including energy from 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
• 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

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


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


  Radiation 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 Earth-based materials
• Collectively, natural environmental radiation results in approximately 0.02 to 0.1 microgray (μGy)/hr at waist level in the United States
• 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, contributing 3.2 mSv/yr</b>
• The increase in medical radiation exposure is principally attributable to the increasing use of computed tomography (CT) and high-level fluoroscopy
• The currently accepted approximate annual dose resulting from medical applications of ionizing radiation is 3.2 mSv
• Other man-made sources contribute very little to our annual radiation dose, around 0.1 mSv
• Discovery of x-rays

  1. Roentgen was experimenting with a Crookes tube when he observed the fluorescence of a barium platinocyanide plate

  2. Roentgen investigated the properties of this "X-light" by interposing various materials between the tube and the plate

  3. Roentgen reported his experimental results to the scientific community before the end of 1895 and received the first Nobel Prize in physics in 1901

  4. Roentgen recognized the value of his discovery to medicine and produced the first medical x-ray image of his wife's hand in early 1896