Important Notes on X-Ray Imaging System

The function of the X-ray Imaging System is to provide a controlled flow of electrons intense enough to produce an X-ray beam appropriate for imaging.

1. X-ray Tube
2. Operating Console
3. High-Voltage Generator

Operating Console – is used to control the voltage applied to the X-ray tube, the current through the X-ray tube and the exposure time.

“The many different type of X-ray Imaging Systems are usually identified according to either the energy of the X-rays they produce or the purpose for which those X-rays are intended”.

Basic Control of Operating Console

1. On/off Control
2. mAs Selection
3. kVp Selection
4. Table/wall unit activation
5. Exposure Switch

Additional Components of Some Modern Control Console

1. Adjustment of the Line Compensator
   • Line Compensator – measures the voltage provided by X-ray unit and adjust the voltage to precisely 220V.
2. Separate mA and Time Exposure Control
   • Automatic Exposure Control/ Phototimer – the mAs control only is present.

• kVp Meter – placed across the outwood terminal of the autotransformer
  - read the Volt (V) not the kVp
• Pre-reading Voltmeter – allows the voltage to be monitor before the examination.
• mAs Selection – Number of electron flowing from Cathode to Anode.
• mA Control – number of electron emitted by the filament (filament needed).
• Spinning Stop Timer – simple device that can be used to check the accuracy of X-ray timer in half-wave and full-wave rectified units and used by medical.
• Fluoroscopic X-ray Tube – located under the examining table.
• Radiographic X-ray Tube – attached to an overhead movable crane assembly that permits easy positioning of the tube and aiming of the X-ray beam.
• Examination Table – may be flat or curved but must be uniform in thickness and as transparent to X-rays as possible.
• Carbon Fiber Table Top – are strong and absorb little X-ray radiation and contributes to reduced patient dose.
• Bucky Tray – hold the cassette and grid.
  - discovered by Gustave Bucky and Hollis Potter and known as Potter-Bucky Tray.
• Half Wave Layer – the thickness of the material to reduce its intensity to half of its original value.

Two Types of AEC

1. Photomultiplier Sensing Device
2. Ionization Chamber
   

• Solid State Radiation Defectors – used for exposure time check and replace the spinning top.
• High-Voltage Generator – responsible for increasing the output voltage from the autotransformer to the kVp necessary for X-0ray production.

Three Primary Parts of High-Voltage Generator

1. High-Voltage Transformer
2. Filament Transformer
3. Rectifier

• Voltage Rectification – required to ensure that electron flow from Cathode to Anode.
• Rectifier – electronic device that allows current flow in only one direct.
  - all diode rectifier were vacuum tubes called Valve Tube; those have been placed by solid-state rectifier mad of silicon.
• Thermionic Emission – if a large current is passed though this filament, it heats up and “boil” electron soft it surface.

therm – refers to the heat ,

ion-refer to charged particles ,

emission – to give (process of giving off electron from a heated surface.

• Simple Vacuum Tube – conducts electron in only one direction, from Cathode to Anode, sometimes called a diode.