African Fusion June 2015

NDT: DICONDE

DICONDE: Bridging NDT’s digital divide At an evening meeting at the SAIW earlier this year, Michael Beaugrand (right) from Larivière of the US presented on the latest technology for transitioning from film-based to digital radiography. African Fusion reports

N ow available in South Africa through GammaTec, VIDAR Systems Corporation, a 3D digital radiography systems company, is introducing a cost-effective industrial scanner to digitise radiographic film, which are then accessed and stored using ASNT’s DICONDE (digital image and communication for non destruc- tive evaluation) imaging standard for portability and compatibility with all digital NDT analysis software. “20 years ago, we saw the transition in photography from35mm film to digi- tal cameras. We have since seen a similar transition in

the medical market,” says Beaugrand, adding that the medical radiography transition is already 100% complete in Scandinavian countries and over 80% in most of the developed world. The NDT fraternity is now going though that same transition, albeit 15 years later, so Beaugrand expects the full transition to digital NDT to be nearing completion 10 to 15 years from now. Highlighting the advantages of digital radiography, he says that, in principle, the sources, shielding and collection techniques are the same as those use for film-based methods.

is easy; the image can be enhanced and processed; measurements can be applied and used in calculations and statistics; and annotations and stamps (metadata) can easily be incorporated directly into the image file. “I have seen an experienced Level 3 NDT Inspector being amazed by how much more in- formation can be revealed on a digital image simply by zooming into an area of interest and adjusting the contrast,” Beaugrand reveals. “The biggest problem with using digital systems, whether they are CR- or DR-based, is that companies all over the world havemillions of film-based radio- graphs, in vaults and filing cabinets, and these also need to be easy to access and use inone common system,”heexplains. Tomonitor changes over time, it is often necessary to compare a radiograph from the past with a current image, and it is very difficult to compare a film on a light box with an image on a computer screen, because the visual quality of the two technologies is far too inconsistent, he points out. “What was needed, therefore, was a platform that would enable archived radiographs to be digitised so that they couldbe accessed andusedon the same platform and to the same standards as newly collecteddigital images,” he adds. In transforming the medical radi- ography market, after an initial period with multiple file formats, the industry decided on a standard file format to streamline procedures and workflow, where all manufacturers adopted the same format. The idea was to enable any image to be transferred between doctors using equipment fromdifferent manufacturers without any compatibil- ity problems. This led to the develop- ment of the DICOM (digital imaging and communications in medicine) compat-

But a detector is used to capture the image instead of film – and there are two detector technologies cur- rently in use, computed radiography (CR) anddirect radiography (DR) detec- tors. “The post exposure im- age formation, however, is different from film. Instead of a light box, a computer and monitor are re-

quired to view digital radiographs, and instead of the grey

exposure shades fixed on photo- graphic film, ex- posure values are digitally stored as an array of pixels. Each pixel has a value proportional to its radiation expo- sure, which are con- verted into analogue grey values of varying brightness on thedisplaymoni- tor,” he explains. Key advantages of digital systems are: the brightness and contrast can be very easily adjusted to suit differ- ent areas of the image; magnification

The VIDAR NDTPRO industrial film digitiser uses the DICONDE standard for converting radiographic film into a transportable and accessible format for industrial users.

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June 2015

AFRICAN FUSION