Comprehensive Guide to X-Ray Imaging Equipment and Circuits

James Maxwell

Developed electromagnetic theory in the late 1800s.

X-Ray Tube

External structure includes the support structure, the protective housing, and glass housing.

Cathode (C-)

Contains both the filament and the focusing cup; provides the source of electrons.

Filament

Made of tungsten; approximately 2mm in diameter and 1-2cm long; emits electrons when heated.

Focusing Cup

Metal shroud housing for the filament located on Cathode.

Space Charge

The upset of electrical characteristics within the tube, often leading to abrupt tube failure.

Arcing

Happens when tungsten vaporizes and is deposited on internal components.

Anode (A+)

Conducts electricity, radiates heat, and x-rays from the target.

Stationary Anode

Primarily used in Dental X-Rays; major disadvantage is rapid heat build-up that can damage the tube.

Rotating Anode

Works like a treadmill powered by an electromagnetic induction motor.

Stator

Part of the induction motor that rotates the anode.

Primary Circuit

Low voltage side of the x-ray imaging system.

Line Compensator

Measures the voltage provided to the x-ray imaging system and adjusts it to precisely 220 V.

Autotransformer

An adjustable transformer controlled by the kilovolt peak (kVp) selector on the operating console.

Exposure Switch

Regulates the length of exposure by the tech and timer.

High Voltage Generator

Contains three primary parts: High Voltage Step Up Transformer, Filament Transformer, Rectifiers.

High Voltage Step Up Transformer

"Steps Up Volts to kiloVolts"; increases voltage 500-1000x.

Rectifiers

Convert AC (Alternating Current) to DC (Direct Current).

Filament Circuit

Provides electrons for the x-ray tube current by boiling them off the filament.

Step Down Transformer

Used in the filament circuit to increase the current by reducing the voltage that is applied to the filament.

Automatic Exposure Control (AEC)

Device that measures the quantity of radiation that reaches the image receptor.

mA

Milliamperes; measures the current through the x-ray tube.

kVp

Kilovolt peak; controls the voltage applied to the x-ray tube.

Exposure Timer

Sets the time for the x-ray exposure.

Focal Spot

The area on the anode where the x-ray beam is focused.

Thermionic Emission

Process where the filament 'boils off' atoms and ejects them as electrons.

Induction Motor

Used to rotate the anode in a rotating x-ray tube.