AC Vs. DC X-Ray Generators – Match On! - The Dental Equipment & Dental Office Blog

With the rise of digital radiography, equipment manufacturers have been releasing DC x-ray machines and touting them as the ‘best x-ray’ machine for digital radiography.

‘Best’ is of course, often a sales strategy. So what is a DC x-ray, and is it really better?

AC x-ray machines use an alternating current to drive the tube head to produce x-rays. This is usually the same 120v AC supply that powers our home; the voltage alternates from +60 to -60 volts, giving 120v of potential across two wires. The tube head produces x-rays for only about 1/2 of the total exposure time, as radiation is produced only during the positive alternation of the AC waveform. This method has been used to produce dental x-rays since their inception. It is a relatively simple technology and works very well.

DC x-rays are actually high frequency AC machines – rather than a 60 Hz waveform like an AC x-ray, they produce a very high frequency (often around 70 kHz) waveform, and only produce positive pulses. The end result is a much more constant output of radiation from the tube head.

What this means to the user is that during very short exposure times, the DC x-ray will produce more consistent radiation than the AC unit, by as much as 1/3 on a .04 sec exposure. As a result, images taken with a DC x-ray tend to be more consistent from image to image. However, this advantage disappears rapidly as the exposure time increases. Someone taking standard film-based bitewings at .25 seconds would not see the difference.

DC x-ray machines can provide more consistent images from low exposure time settings, but there is no need to replace x-ray machines just to go digital. The AC x-ray generator that currently hangs on your wall is more than capable of producing high quality, diagnostic images, even with digital radiography. However, if you are building a new practice or looking to replace an x-ray machine in the near future, it is worth taking a closer look at a DC unit.

If you are looking dental x ray machines check the listings of new or used dental x ray machines on our site.