Advances In Digital Radioraphy (DR)


The transition away from x-ray film and Computer Radiography (CR) to Digital Radiography (DR) is advancing rapidly. There are a number of reasons DR is quickly becoming the x-ray digital output of choice.

The most compelling factor, as always, is prices are falling. Today a DR subsystem can be purchased for less than a high performance CR system. This is a direct result of the reduction in cost of DR flat panel detectors, the primary component of the DR system. Therefore, when you have a choice of having the fastest image access, the highest quality images, the lowest exposure dose and favorable pricing — the choice is easy, DR wins hands down.

The major producers are not only lowering flat panel detector prices but they are re-engineering the detectors to accommodate different applications, performance and price levels. Your application may dictate the style of detector. You may choose a fixed panel (which is permanently interfaced to a x-ray bucky) and the least expensive. You may choose a tethered detector (which can be moved between different bucky's — like a table bucky and chest stand bucky) and more expensive than the fixed panel. Or you may choose a wireless detector which can be extremely versatile and be moved from device to device or used with multiple systems, ie a fixed x-ray system, a portable x-ray system and / or a rad / fluoro system.

The most challenging issue associated with DR was the method used to interface it with the x-ray device. The most common method was to cable a detector interface device between the x-ray generator and the flat panel detector or it's holder. This would allow the generator to signal the detector that was was getting ready to make an exposure and that the detector should be activated to accept the exposure. Often a second device was also connected to the DR interface device so the detector could be interfaced to the DR console PC workstation. These interface devices would need to be integrated into the x-ray system, thenby changing the original system design and requiring the x-ray system to be again cleared with the FDA to accommodate the revised design incorporating the DR interface devices. Getting FDA clearance is generally a difficult task because the time and expense associated with FDA approvals.

Detector manufacturers have now developed a design to eliminate interface devices. Automatic Exposure Detectors (AED) are now available with most detectors. AED enables the detector to interface any x-ray source wireless. A detector with AED can be used with any x-ray system without a cable connection to the x-ray system or to the DR console PC workstation. The detector with AED senses the exposure, captures the image data and can send it to the console device. This means a x-ray tech can walk around with a DR detector and a PC (the PC can be a notepad, lap top or any mobile PC) and use this portable two component DR system with any or multiple analog x-ray systems fixed, mobile, RF, etc). Immediately multiple CR and / or DR systems can be eliminated and replaced with one portable AED DR system. Savings can be intense.

Today's detectors are available using Amorphous Silicon thin film transistors with a layer of scintillator material used to convert x-ray to light that can be converted to image data. The scintillator material is available in either gadolinium oxysulfide (Gd202S) or cesium iodide (CsI). The Gd202S based detector is less expensive with similar image quality but requires significant more x-ray exposure (dose) than the CsI detectors. The CsI based detector is effective in minimizing dose but has a significantly higher cost.

The manufacturers are now providing cost effective solutions to implementing DR by eliminating costly interference, providing a single DR system that can be used with multiple x-ray systems and allowing a choice between lower costing systems which require higher x-ray dose or more expensive DR systems with less x-ray dose. These innovations are enabling facilities to move into the most effective digital diagnostic imaging solutions available at affordable prices.

Charles Patti