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# EM Radiation

### Wave and Quantum Theories

Question | Answer |
---|---|

Define Photon. | Discrete bundle of energy. (darcie haha!) |

Does a photon have mass or form? | no |

How do photons travel? | sinusoidal waves |

Define Electromagnetic Radiation. | oscillating electric and magnetic fields that travel in a vacuum with the velocity of light |

Define velocity. | speed of light in a vacuum Conventional: 186,000 miles/sec MKS: 3 x 10^8 m/sec CGS: 3 x 10^10 cm/sec |

What is amplitude? | height of the wave |

What is wavelength? How is it measured? What is it's symbol? | Distance from crest to crest or trough to trough; Angstroms; lambda |

What is frequency? How is it measured? what is its symbol? | # of waves per unit of measure; Hertz; Nu |

What is the formula for velocity? | C = frequency x wavelength |

What is the relationship between wavelength and frequency? | indirect |

what is the relationship between energy and frequency? | direct |

What is the formula for energy? | E = frequency x plank's constant (h) |

How is the electromagnetic spectrum arranged? | ionizing vs. non-ionizing; by energy; by frequency; by wavelength (dx.between .1-.5 angstroms) |

What is plank's constant? | 4.15 x 10^-15 eV |

What are some factors that affect attenuation? | patient, grid, filter, etc. |

What is the relationship between kVp and attenuation? | indirect; more kVp= more penetration= less absorption= less attenuation; less kVp= less pentration= more absorption= more attenuation |

How does e-/gram or density of matter affect attenuation? | More density means more attenuation. ex. bone more attenuation; air = less attenuation |

Define LAC. | Linear attenuation coefficient: numerical value assigned to each pixel represents degree of blackening based upon the attenuation |

Define MAC. | Mass Attenuation Coefficient= numerical value assigned to each pixel represents degree of blackening based upon the attenuation, varies per state of matter |

Radio-opaque vs. radiolucent | blocks xrays... lets xrays through |

Relate the following: kVp, attenuation, LAC, Density | low kVp= high attenuation= high LAC= low density / High KvP= low attenuation= low LAC= high density |

What is the inverse square law? | The intensity of radiation is inversely realted to the distance squared. I1/I2= D2^2/D1^2 |

What is the formula for relativity? | E= mc^2 Energy= Mass x Constant^2 C= speed of light in a vacuum |

Unit of measure for power | watts |

unit of measure for electrical charge | coulomb (C) |

unit of measure and symbol for wavelength | angstrom, lambda |

unit of measure for frequency | hertz (Hz) |

Conventional and standard international units of measure for radioactive decay | Curie (conv) Becqlurel (SI) |

Conventional and standard international units of measure for exposure in air | Roentgen=R (conv)Coulombs per kg/Air kirma (SI) |

Conventional and standard international units of measure for absorbed dose | Rad (conv) Gray (SI) pt. dose |

Conventional and standard international units of measure for Dose equivalent | REM (conv) Sievert (SI) |