THE AAPM RSNA PHYSICS TUTORIAL FOR RESIDENTS - X-RAY GENERATORS/

The x-ray generator delivers the electrical power to energize the x-ra y tube and permits the selection of x-ray energy, x-ray quantity, and exposure time. Major internal components of the generator include tran sformers, diodes and rectifier circuits, filament and stator circuits, timer switches, and kilovolt and milliampere meters. Single-phase, th ree-phase, high-frequency, and constant potential generators produce d ifferent voltage waveforms (ripple) and x-ray beam spectra. Phototimer and automatic brightness control subsystems measure radiation exposur e incident on the image receptor to give instantaneous feedback for op timal radiographic film densities and fluoroscopic image brightness, r espectively. At the generator control console, the operator sets the t ribe voltage, tube current, exposure time, phototimer film density, sp ot film acquisition, and fluoroscopic parameters. Selection of generat or power and options depends on the intended clinical use. X-ray tube focal spot size and power loading capability should be matched to the x-ray generator and clinical imaging requirements. Single and multiple exposure rating charts as well as anode and housing thermal character istic charts indicate power input and dissipation rates specific to a generator and x-ray tube target and housing.