Principles of X-ray Production

Introduction

• Common misconceptions about X-rays:
  • Are they created by magic?
  • Are they harvested from unicorns?
  • Are they even real?
• Purpose of the lesson: Understand the main principles of X-ray production
• Key points: X-rays are real and created in a specific way

Requirements for X-ray Production

• Three essential requirements:
  1. Source of electrons
  2. Means of rapidly accelerating or energizing electrons
  3. Means of rapidly decelerating or de-energizing electrons
• Missing any of these requirements means no X-ray production

X-ray Tube Processes

• All steps take place inside the X-ray tube:
  1. Electron Production (Thermionic Emission)
     • Occurs at the cathode filament
     • Electrons are released in response to heat
     • Current through the filament heats it, creating a cloud of electrons
     • Similar to an incandescent light bulb filament
  2. Electron Acceleration
     • Achieved by applying a voltage called the kilovoltage peak (kVp)
     • kVp creates a negative charge in the filament, forcing electrons to the positively charged anode
     • Electrons are propelled by negative cathode and attracted by positive anode
  3. Electron Deceleration
     • High-energy electrons collide with the anode
     • Energy is released as heat and X-rays

Controls and Variables

• Operators Control:
  • mA (milliamperes)
  • kVp (kilovoltage peak)
  • Exposure time
• Effects of Controls:
  • Increasing mA (Tube Current):
    • Increases number of electrons produced
    • Increases number of photons (X-rays)
    • Reflects intensity or quantity
  • Increasing kVp (Tube Potential):
    • Increases energy of electrons
    • Higher voltage = Faster electrons
    • Increases both X-ray energy (Beam quality) and number of X-rays
  • Increasing Exposure Time:
    • Increases total number of X-ray photons created
    • More time = More electrons and X-rays produced

Summary

• X-rays are not produced by magic or unicorns, but by specific industrial processes
• Three main requirements for X-ray production:
  1. Source of electrons (Thermionic Emission)
  2. Means of acceleration (kVp)
  3. Means of deceleration (Anode)
• mA and Exposure Time: Affect total number of X-rays
• kVp: Affects both number and energy of X-rays