X-ray Machine Circuits & Generators

Radiography in the Digital Age: Chp 8

Line voltage compensator

measures the incoming voltage from the power line and automatically compensates by adjusting the autotransformer up or down

Rectification

Conversion of alternating electrical current into direct or one-way current.

Thermionic emission

Release of free electrons from the filament of the x-ray tube when it is heated.

Filament circuit

the circuit that uses a stepdown transformer to increase the amperage to heat the filament and produce thermionic emission

mA meter

measures the milliamperage of the current that flows across the x-ray tube

kVp meter

measures voltage in the x-ray circuit before it is stepped up (pre-reading)

Single phase generator

Equipment in which the voltage waveform drops to zero at certain points because only a single phase is used. The 100% ripple causes the average kV to be about 1/3 the kVp.

Three phase generator

Equipment in which the voltage waveform never drops to zero, because three overlapping phases are used in either 6 or 12 pulses. This creates either 14% (6 phase) or 4% (12 phase) ripple.

High frequency generator

produce a nearly constant potential voltage waveform, improving image quality at lower patient radiation dose. Has about a 1% ripple.

AEC

The use of an electronic circuit and x-ray detectors to measure exposure rate near the image receptor and terminate the expo- sure when a preset level is reached.

thyratron

A device that presets the amount of charge a capacitor will hold in an AEC circuit