What is DICOM calibration?
DICOM calibration is a form of medical calibration to ensure compliance with the DICOM GSDF (Grayscale Standard Display Function) standard. The DICOM standard defines how grayscale images must be shown on medical displays so they can be displayed consistently.
About DICOM
DICOM stands for Digital Imaging and Communication in Medicine. It is a medical standard that describes how medical imaging information should be exchanged and managed. Related to that is DICOM Part 14, which was published by the National Electrical Manufacturers Association (NEMA) and the American College of Radiology (ACR).
DICOM Part 14 provides strict guidelines for how grayscale display function calibration and quality assurance tests should be performed on displays used for medical imaging.
Subtle details in medical images are more visible when the image is DICOM calibrated.
Color is coming
DICOM Part 14 provides guidelines for grayscale displays only. However, with the rise of color modalities in medical imaging, there is a need to revise the standard. Currently, color medical displays are calibrated according to the GSDF standard or healthcare professionals simply use consumer-level color displays. This is not sufficient to view accurate medical images in color.
That’s why the Color Standard Display Function (CSDF) was recently proposed as an extension to the DICOM GSDF. This new standard will help ensure a high level of accuracy for medical images in color.
How does DICOM calibration work?
DICOM calibration of medical displays requires a high-precision, front-of-screen photometer that is attached to the display face and is internally baffled to exclude extraneous light sources. Why front-of-screen sensors? Because they will measure luminance where the images are being viewed, and not just the output of the display’s backlight.
This kind of photometer will precisely measure and record the luminance of the display and enable adjustments in real time. The most accurate measurements are achieved with fixed photometers. They provide accurate and traceable measurements of the complete DICOM curve twice per second and over the full lifetime of the display.
An LCD screen with a high-precision photometer at the front of the screen (I-Guard) to ensure stable DICOM calibration.
Conclusion
Displays used for medical imaging should comply with the DICOM GSDF standard, which defines an accepted range of grays and blacks for viewing critical details on medical displays. For color medical displays, new guidelines are being defined. All displays used for medical imaging should be calibrated according to these standards in order to present clinicians with pixel-perfect images.