X- ray Image Formation

• What are X-rays a form of?

  Electromagnetic radiation
• What is electromagnetic radiation?

  A form of energy that travels through space
• What basic concepts are needed to understand X-rays?

  Matter, charge, and energy
• How is mass measured?

  In grams (g) or kilograms (kg)
• How does mass differ from weight?

  Mass is constant; weight varies with gravity
• What is density defined as?

  Mass per unit volume
• In what units is density usually expressed?

  kg/m³ or g/cm³
• What do electrons occupy around the nucleus?

  Discrete energy levels called shells
• How many electrons can the K-shell hold?

  2 electrons
• What is the atomic number (Z)?

  Total number of protons in an atom
• What is binding energy?

  Energy required to release an electron
• How can an electron move between shells?

  By absorbing or releasing energy
• What is electric charge?

  A basic property of matter
• What are the two types of electric charge?

  Positive and negative

  
• What is the unit of charge?

  Coulomb
• What happens when two objects have the same charge?

  They exert a repulsive force on each other
• What is Coulomb's Force?

  The force between charged objects
• How is the electric field defined?

  Force exerted on a positive unit charge

  
• What indicates a stronger electric field?

  Closer contours in the field lines
• What happens when a charge moves at constant velocity?

  Both electric and magnetic fields are observed
• What occurs when a charge is accelerated?

  Electric and magnetic fields lag behind
• What is electromagnetic radiation?

  Energy transported as electric and magnetic fields
• What is the wavelength range for diagnostic X-rays?

  0.1 to 1 Angstroms
• How is EM radiation produced?

  By accelerating a charged particle
• What is wave-particle duality?

  EM radiation exhibits both wave and particle behavior
• How fast does EM travel in a vacuum?

  $3 \times 10^8 \text{ m/s}$
• What is the relationship between wavelength and frequency?

  $C =$$\lambda \nu$
• What do short EM waves like X-rays react as?

  Particles called photons
• How are X-ray photons produced?

  When electrons interact with a target material
• What does photon energy measure?

  Ability to penetrate matter
• How many X-ray photons are in a radiographic exposure?

  About one million per mm²
• What is attenuation in X-ray beams?

  Reduction in intensity as it traverses matter
• How is X-ray beam intensity defined?

  Number of photons per unit area
• What is the photon fluence?

  Photons/mm² during exposure
• What is the relationship between tissue type and attenuation?

  Bone has higher attenuation than muscle
• What are the two processes of X-ray attenuation?

  Photoelectric absorption and Compton scattering
• What creates a latent image in X-ray detection?

  Selective attenuation of X-ray photons
• What was used in early image recording for X-rays?

  Photographic film
• What is the limitation of screen film radiography?

  Requires chemical processing and dark rooms
• What is computed radiography (CR)?

  A less common digital imaging technology