Dental Radiography Summary (copy)

DENTAL RADIOGRAPHY EQUIPMENT

  • Components of dental radiography unit: Control panel, Arm, Tube head, Positioning indicator device (PID), Master switch.

X-RAY TUBE STRUCTURE

  • X-ray produced in Coolidge Tube.

  • Basic elements: Glass tube (vacuum), Filament (cathode), Target (anode), Window (exit for primary beam).

  • Insulating oil surrounds tube to prevent overheating.

X-RADIATION

  • Wavelength: Distance between wave crests; shorter wavelength = higher energy/penetrating power.

  • Energy and penetration affected by wavelength and distance from source.

CATHODE & ANODE

  • Cathode (negative): tungsten filament supplying electrons; heating increases electron production.

  • Anode (positive): tungsten target converting electrons into x-ray photons.

ELECTRICITY IN X-RAY PRODUCTION

  • Transformer alters voltage; types include Step-up, Step-down, Auto.

  • Measurements: Ampere (current), Kilovoltaic peak (KVp) is peak voltage during exposure.

CONTROL PANEL SETTINGS

  • Settings include time, amperes (mA), and kilovoltage (KV/kVp).

  • Longer exposure increases contrast; contrasts ranging from high (darker) to low (lighter).

X-RADIATION PRODUCTION PROCESS

  1. Press activation button.

  2. Electron cloud formation.

  3. Propulsion of electrons to anode.

  4. Collision generates heat and x-radiation.

  5. Radiation exits through port into PID.

RADIATION BEAM COMPONENTS

  • Aluminum disc filter removes low energy wavelengths.

  • Collimator controls beam size/shape, reducing patient exposure.

  • Positioning Indicator Device (PID) aids beam alignment, reduces exposure; lengths of 8, 12, 16 inches recommended.

FACTORS AFFECTING PENETRATING POWER

  1. Wavelength: Shorter wavelengths = greater energy.

  2. Distance: Shorter distance = greater penetration.

  3. Density: Less dense = greater penetration.

TYPES OF RADIATION

  1. Primary: Useful rays from x-ray tube.

  2. Stray: Rays from non-window areas (faulty tube).

  3. Scatter/Secondary: Reflected rays from objects in path (reflective surfaces).

RADIOPAQUE vs. RADIOLUCENT

  • Radiopaque: High absorption, appears white (e.g., enamel, bone).

  • Radiolucent: Low absorption, appears dark (e.g., pulp).