Introduction to the part of X-Ray Machine

BY: Huzaifa AtiqueSir Syed University of Engineering and Technology

Parts: -1. X-Ray tube.

2. Operating Console.

3. High Voltage transformer.

4. Tube Head or Protective Housing.

5. Collimator.

6. Patient Table.

7. Grid.

8. Bucky.

9. Radiographic film

X-Ray Tube: -vacuum

Protection housing Projectile

electron

1)-X-Ray tube theory:

It is an important component of x-ray machine which is inaccessible as it is contained in a protective housing.

It is a vacuum tube. Early tubes were called Crook’s tube and

were not vacuum. Modern tubes are known as Coolidge tube

and are vacuumed. There are two primary parts. 1) the cathode 2) the Anode.

2)- operating console: -

It is an apparatus in X-Ray machine that allows to control the x-ray tube current and voltage.

The Console Controls: - Line compensation. kVp. mA. Exposure time.

Circuit Diagram: -

It have 5 further parts:

1. Line compensator.

2. Auto transformer.

3. Current source.

4. Voltage source.

5. Exposure time.

Line compensation:

Most machine are designed to operate at 220 volts while some will work with 110 volts or 440 volts

The power company often cannot provide exactly 220 volts at all times.

Because of variations in power distribution to the hospital and in power consumption by the various sections of the hospital, the voltage to the x-ray unit may vary by 5%, which will result in large variations in x-ray output.

Autotransformer: The power supplied

to x-ray machine is delivered to a special transformer called an Autotransformer.

It works on the principle of electromagnetic induction but is very different from conventional transformer.

It has only one winding and one core.

The single winding has number of connections, or electric taps.

The purpose to use the Autotransformer is to overcome induction losses.

Its value ranges from 0 to 400V.

kVp Adjustment (circuit Diagram)

X-ray console have adjustments labeled major kVp and minor kVp.

By the combinations of these two, we can get the required kVp.

The low voltage becomes input to the high voltage step up transformer.

The kVp meter is placed across the output terminal of autotransformer.

mA control

The tube current, the number of electrons crossing from the cathode to anode per second is measured in milli Amperes (mA).

The quantity of electrons is determined by filament temperature.

The filament normally operates at currents between 3 and 5 A.

The Tube Current is controlled through a separate circuit called the filament circuit.

The transformer used for filament is step down .

Exposure Timers

It consists of a mechanical or electronic device whose action is to make and break the high voltage across the tube on the primary side of the high voltage section.

There are five types of timers: Mechanical Timers Synchronous Timers Electronic Timers mAs Timers Phototimers.

High Voltage Transformer

The high voltage transformer is a step-up transformer.

There will be more winding on the secondary side compared to the primary side.

The ratio of windings is referred to as the turns ratio.

The only difference between the primary and secondary waveforms is the amplitude.

The turn ratio for most x-ray high voltage transformers is between 500 and 1000.

The primary voltage is measured in volts, and secondary in kilovolts.

Protecting Housing

X-ray tube is always mounted inside a lead-lined protective housing that is designed to: Prevent excessive radiation exposure. Prevent electric shock to the patient and

operator (technologist) Incorporates specially designed high-

voltage receptacles. Provides mechanical support for the x-ray

tube and protects it from damage. Some tube housings contain oil in which

the tube is bathed. Some tube housings contain a cooling fan

to air-cool the tube.

When properly designed, they reduce the level of leakage radiation to less than 100 mR/hr at 1 meter when operated at maximum conditions.

collimator

The Collimator is attached to the x-ray tube below the glass window where the useful beam is emitted.

Lead shutters are used to restrict the beam.

Its purpose is to minimize field of view, to avoid un necessary exposure by using lead plates.

Grid

By virtue of function and material, collimator and grid are same but they have different location.

It is made up of lead. It is located just after patient. It is used to destroy scattered radiation

from the body.

Some of the X-Rays entering the body of a patient are actually scattered and no longer travel in a straight line, this scattering can cause blurring of X-Ray image.

The rays which are at 90’ can be passed .

Bucky

A Bucky is a component of x-ray units that holds the x-ray film cassette and moves the grid during x-ray exposure. The motion keeps the lead strips from being seen on the x-ray picture.The name refers to Dr. Gustave Bucky who invented the use of filter grids in 1913.

Radiographic film

Two types of x-ray photon are respnsible for density, contrast and image on a radiograph.

Those that pass through the patient without interacting and those that are scattered in the patient through compton interaction.

Together these x-rays that exit from the patient and intersect the film are called Remnant x-rays.

Film Construction Radiographic Film has two basic parts. Base Emulsion Most film has two layers of emulsion so it is referred to as

Double Emulsion Film

Emulsion

• The emulsion is the heart of the film. The x-rays or light from the intensifying screens interact with the emulsion and transfer information to the film.

Thank you