How X-Ray Machines Work: Generation, Filtration, Collimation & Detection

X-ray machines (radiography) produce controlled ionizing radiation for non-invasive internal imaging.

Core Process

1. Electron Generation: Heated cathode filament emits electrons, focused into beam.
2. Target Impact: High-speed electrons strike rotating anode (tungsten); sudden deceleration produces:
    • Bremsstrahlung (continuous spectrum) – 99% heat
    • Characteristic X-rays – ~1% useful photons
3. Filtration: Aluminum/copper filter removes low-energy photons (reduce skin dose, improve contrast).
4. Collimation: Lead shutters shape beam to region of interest (minimize scatter, patient dose).
5. Patient Exposure: Beam passes through body; differential attenuation by tissue density.
6. Detection: Digital detector (flat panel) or film cassette converts transmitted photons to image.

Safety

• Lead-lined walls/doors, interlocks, dosimetry monitoring
• ALARA principle: As Low As Reasonably Achievable exposure

Essential for fracture, pneumonia, dental, mammography, fluoroscopy guidance.