The DICOM Grayscale Standard Display Function (GSDF) was created to minimize the variation in how PACS images are rendered. The intended result, ultimately, was to be a consistent perceived range of grays in the displayed image. Implementations of
The DICOM Grayscale Standard Display Function (GSDF) was created to minimize the variation in how PACS images are rendered. The intended result, ultimately, was to be a consistent perceived range of grays in the displayed image.
Implementations of DICOM GSDF by PACS vendors, however, may be inconsistent or nonexistent. Hospitals can therefore expect to expend considerable effort to properly incorporate the GSDF.
Just how much effort was revealed in a study at the University of Texas M.D. Anderson Cancer Center in Houston.
"Because of different technological processes and how the human visual system reacts to light, the same images could look vastly different on two different media or even two different devices," said Stephen K. Thompson, a medical physicist at Anderson.
Thompson directed a study to evaluate the implementation of the DICOM GSDF standard in Anderson's digital imaging practice utilizing computed radiography and digital radiography.
"We found that while the vendors are thinking about complying with this standard, it is different from implementing it clinically," he said.
Since Anderson physicians had been using CR in their ICU setting, they had a set of favored image processing parameters. The problem was that they were printing these images to film through a printer setting (look-up-table, or LUT) that was not compliant with the DICOM GSDF. In order to use the GSDF for print, they were required to change all of their image processing parameters.
In another example, one vendor's DR system was designed to use the GSDF, but an important parameter used to create a GSDF print was incorrect in their configuration files. Anderson again had to change their parameters so the images will look good on a GSDF compliant display, Thompson said. Even so, he had praise for the function.
"The DICOM GSDF is an excellent part of the DICOM standard," he said. "In general, it does a great job of making dissimilar devices render images in a consistent fashion."
Since it is a relatively new part of the standard, vendors are still struggling with the implementation. Facilities like Anderson, which have legacy digital systems, will have the most difficulty realizing its benefits, Thompson said.