X-ray Technology introduction

X-ray Technology

1. 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.

2. What is X-ray

2.1 When was X-ray invented?

Nov. 5th 1895, W.C Roentgen found platinum cyanide barium painted paper is fluorescing from a distance during cathode ray experiment. 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. At that time, it was utilized for Radiography simply penetrating surface. 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

2.2 Characteristic of X-ray

1. Invisible light

2. Fluorescence effect – make fluorescene when expose to ZnS, CdS, Nal etc.

3. Ionization effect

4 High rate penetration

5. Same speed as light in Vacuum

6. Diffraction

7. Refraction rate is almost 1

3. 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.

4. Form of X-ray System

4.1 X-ray machine Components

4.2 Advantage of X-ray Inspection

- The broadest inspection for maximum productivity and product safety.

- X-ray and inspection machine is easy to operate and contains central user interface.

- Easy Verification of Missing Products in Sealed Packaging.

- It is Cost effective and Savings on Inspection Labor.

- Pick out the product which is defaulted and reduce the risk product recalls.

- It contains highest hygienic standards

5. Type of X-ray Tube

5.1 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

5.2 Closed Tube

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

5.3 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.

6. Type of X-ray Detector

6.1 Image Intensifier Detector (I.I detector)

X-ray is converted to visible light when absorbed by Scintillator through Aluminum (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

6.2 Flat Panel Detector (FPD)

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

6.3 Radiographic Film

1) X-ray does not pass through the specimen, the film will be black. 2) Giving the high quality image but it takes time to get the photo.