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Digital X-ray processing: How good is the technology?

It is now possible for the first time to determine the quality of digital medical X-ray image detectors in a reliable manner with a mobile measuring facility developed at PTB.

The new measuring device in operation.

In medical X-ray diagnostics, great effort is being made to replace conventional analog X-ray films by digital image detectors and the German medical technology industry has gained an outstanding position in the international competition. Main arguments to introduce digital systems are the reduced radiation exposure (and related risks) for the patients and the improved availability of the images via electronic data networks. It is frequently regarded as a disadvantage of these systems that their resolution does not yet come up to that of conventional analog X-ray devices. At PTB, a measuring facility has now been developed to investigate the performance of digital X-ray image detectors.

The project was supported by the European Commission and by the Federal Ministry of Economics and Labour (BMWA). Project aim was to develop a measuring facility and suitable measuring procedures for the physical characterization of digital X-ray detectors – in cooperation with industry. Since digital X-ray image detectors are usually stationary devices and form a unit with the X-ray source, the measuring facility was designed as a mobile device. To evaluate the recorded digital X-ray images, suitable image-analyzing programs were developed. Among other things the apparatus can measure resolution and quantum efficiency as well as the image noise of detectors as a function of the X-ray dose.

The results obtained with this measuring facility and the methods derived from them – for example, to measure the spatial resolution – had a direct influence on an IEC standardization project to determine the quantum efficiency of X-ray image detectors. That project has been completed in the meantime (IEC 62220-1). In addition, the measuring set-up was successfully used within the funded projects, and some digital X-ray image detectors were exemplarily measured. In result, the new digital image-recording techniques are found to be equivalent to conventional analog technology and even clearly superior concerning the quantum efficiency. Regarding the spatial resolving power, however, they do not yet really come up to the analog systems.

Contact at PTB:

Phone: +49-531-592-0