X-ray Technology

What is radiation?

Ionized radiation : Radiation causes ionization shooting orbital electron of atom outward

Alpha particle, beta particle, neutron, electron, proton, gamma ray, X-ray etc.

Non-ionizing radiation : Radiation does not cause ionization

Sunray, ultraviolet, infrared ray, visible ray etc.

What is X-ray?

  1. Nov. 5th 1895, W.C Roentgenfound platinum cyanide barium painted paper is fluorescing from a distance during cathode ray experiment.
  2. He confirmed fluorescence mechanism is occurred by unknown ray while experiment with shielded cathode. He named it X-ray, announced thesis and awarded as the first Nobel Prize in Physics in 1901.
  3. At that time, it was utilized for Radiography simply penetrating surface.
  4. X-ray is now being widely used to diagnose characteristic and structure of material by diffraction, fluorescence and total reflection.
  • Electronic wave at 10-11~10-9m wavelength
  • Strong penetrating power into material surface
  • Utilized as non-destructive inspection such as medical equipment and
    industrial inspection system by using differentiation of penetrating power

Characteristic of X-ray

  1. Photograph action
  2. Fluorescence effect – make fluorescence when expose to ZnS, CdS, NaI etc.
  3. Ionization effect
  4. High rate penetration
  5. Same speed as light in vacuum
  6. Diffraction
  7. Refraction rate is almost 1.

Principle of X-ray Generation

Characteristic X-ray : Accelerated electron interacts with orbital electron and outside electron is transferred.
Electric wave is emitted as the difference of energy and the wave is called characteristic X-ray.

Continuous X-ray : Accelerated electron is decelerated buy the Coulomb Potential Energy around a nucleus, and emits radiation as much as decelerated difference. This is called bremsstrahlung ray or continuous X-ray.

X-ray System

X-ray Tube Generates X-ray
Table Moves sample in radiation equipment
Detector Converts transmission electron to visible light
CCD Camera Converts visible light from Detector to digital data
Controller Controls image and entire system of inspection system
Shield cabinet Shields radiation

Advantage of X-ray Inspection

  • No need Vacuum unlike SEM
  • Non-destructive inspection by using high penetrating power
    No need preprocessing(cutting, destroying) for inside inspection
  • Simple inspection process and easy to operate

Types of X-ray Tube

Open Tube

Vacuum condition can be built from pump installed system
Higher magnification and resolution than Closed tube
Consumables(Target, Filament etc.) are replaceable and semi-permanent

Closed Tube

Vacuum condition sealed during manufacturing process
Unable to replace inside components
Change every set if broken

Types of X-ray Detector

  • X-ray is converted to visible light when absorbed by Scintillator through Al
  • input window (high transmission and low diffusion of X-ray)
  • Visible light is converted to photoelectron image by Photocathode
  • Photoelectron is accelerated by DC voltage
  • Focused by Focusing Electrode
  • Convert photoelectron image to visible ray again

1) X-ray signal is converted to visible light by scintillator

2) Visible light is converted to electric signal by Photodiode

3) Signal saved in each pixel by transistor is sent to computer with high speed

1) X-ray signal is directly converted to electric signal by Photoconductor

2) Signal saved in each pixel by transistor is sent to computer with high speed

Focal spot size

  • Focal Spot

     – The point electron colliding to Target

  • Focal Spot Size

     – Diameter of Focal Spot decides resolution. Smaller Focal spot size, better resolution.