Medical Grade LCD Displays

A discussion on Medical Grade LCD displays requires a thorough understanding of the importance of high-quality display in the context of a medical setting. In any given healthcare facility, display nodes feature as parts of workstations through which medical reports and scan reports can be viewed.

In order to assess the impact of improvements in display and imaging technology on the health industry, we present the following facts:

  1. There has been a significant improvement in the accuracy of breast cancer diagnosis owing to the development of advanced imaging techniques.
  2. Imaging techniques such as Multiparametric MRI, PSMA PET/CT, and whole body MRIs have shown accuracies ranging from 83%-93%when used to diagnose bone metastases.
  3. Translabial Ultrasounds are a new imaging technique used to evaluate Vaginal Mesh using Static and Dynamic MRIs. It has resolved the issues associated with the diagnosis of more complex pelvic structures.
  4. Clinical and Neuroscientific communities agree that there is a need to develop new modalities that allow for higher accuracy of diagnosis for neurological conditions, without the trade-off with invasiveness.
  5. The vast differences in symptoms exhibited by patients suffering from vascular disease requires more accurate imaging techniques that allow for accurate diagnosis of the condition.

Neither conventional, off-the-shelf LCDs nor LCDs manufactured for commercial use are built to accommodate the variety of modalities that facilitate diagnosis. Leading from this consideration, we will identify the standard display characteristics needed to be achieved for it to qualify as medical grade as well as built-in compliance features that would facilitate timely customer support and uphold safety standards in hospitals.

There are two basic sources medical standards namely; Picture Archiving and Communications Systems and guidelines on diagnostic display devices by the Royal College of Radiologists and DICOM, keeping in mind the two types of images used in the process of diagnosing:

  1. Grayscale Images
  2. Color Images

Standards for Grayscale

Digital Imaging and Communication in Medicine (DICOM), also known as the NEMA standard PS3 and ISO standard 12052:2017, is the global standard for the communication and management of data in the context of healthcare. It was developed as a standard set of attributes that a grayscale output must fulfill to facilitate a diagnosis of patient conditions.

The standard is based on the Grayscale Standard Display Function, a mathematical equation that prescribes the optimal contrast settings for images given the platform used to produce the output and the adaptability of the human eye with regards to perceived contrast. DICOM constructed manuals that prescribe output settings that would allow for the optimal grayscale output, based on Luminance levels, Just Noticeable Differences (JND) and Pixel Values (DDL) measured for any display module. For anyone wishing to go through manual and implementation of DICOM, this is the link to the original report.

There is no one standard for grayscale images in the sense that only one particular black to white contrast ratio is the best, the standard was designed keeping in mind the human eye’s ability to adapt and perceive contrast ratios in different environments. DICOM standards for grayscale outputs were designed to allow for the best possible display given a specific display module and account for a highest possible noticeable difference to allow for the best possible output given human adaptability and environmental conditions.

The DICOM does not concern itself with color images.

Standards for Color Images

This set of guidelines was produced by the Royal College of Radiologists, includes the following specifications that distinguish “Off the shelf” display devices from medical grade display modules.  The report specifically mentions:

  1. Medical grade displays offer a 2048 x 1536 pixel display, while off the shelf display products rarely go beyond 1920×1200.
  2. Medical displays offer improved luminance levels, uniformity and constancy, contrast ratio, viewing angles and compliance with DICOM Greyscale Standard Display Function.
  3. Medical displays should include remote quality assurance and automatic quality assurance report generation.
  4. Medical displays achieve higher resolution by the use of a smaller pixel pitch, with most display devices for primary diagnosis being limited to a size of approximately 22 inches.
  5. Medical grade display devices should achieve maximum luminance values >500 cd/m2 and contrast ratios >800:1.

Assuming that an LCD can conform to the DICOM Grayscale Standard Function and the conditions as set out by either the ACR or RCR, it qualifies as a medical grade display output.

One other consideration for medical grade monitors is the requirement for Support features which should include:

  1. Self diagnosis
  2. Remote support and technical assistance

Assuming that these conditions have complied with an LCD will qualify a medical grade LCD. For more information on industry-specific display units and to access a list of industrial and commercial grade display panels visit https://revointeractive.com/.

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