What are the requirements for brightness and dark spots of LCD screens for medic
Medical display equipment has strict requirements for the brightness and dark spots (bad spots) of LCD screens to ensure diagnostic accuracy and clinical reliability. The following are the main standards and requirements:
Medical display equipment has strict requirements for the brightness and dark spots (bad spots) of LCD screens to ensure diagnostic accuracy and clinical reliability. The following are the main standards and requirements:
1. Brightness requirements
High brightness stability:
-Medical displays, especially those used for radiological diagnosis, typically require a brightness range of 400-1000 cd/m ² (nits), depending on the application.
-Breast mammography displays require higher brightness (≥ 1000 cd/m ²) to distinguish low contrast microcalcifications.
-Brightness uniformity:
-The brightness difference between different areas of the screen should be controlled within ± 10% to avoid misdiagnosis caused by uneven brightness.
-Long term stability:
-The brightness decay should be slow and support automatic calibration (such as DICOM Part 14 standard) to ensure long-term compliance with DICOM GSDF (Gray Scale Display Function) curve.
2. Dark spot (bad spot) requirements
-Strict no bad dot standard:
-Medical displays typically require zero bad pixels (including bright spots, dark spots, and color spots), especially for displays used in radiological diagnosis (such as CT, MRI, DR).
-Ordinary commercial displays allow for a small number of bad pixels (ISO 9241-307 standard), but medical grade displays must comply with stricter medical imaging certifications (such as FDA, IEC 61223).
-Pixel defect tolerance:
-Some standards allow for a very small number of bad pixels (such as ≤ 1), but they must not be in the central display area (to avoid affecting the diagnostic focus area).
3. Other key requirements
-Contrast ratio:
-The static contrast ratio should be ≥ 1000:1 to clearly display grayscale differences (such as subtle grayscale changes in X-rays).
-Resolution:
-Diagnostic grade displays need to support 2MP (million pixels) to 8MP, and for breast diagnosis, 5MP or more is required.
-Color gamut and grayscale:
-Grayscale display should support 10 bits or more (1024 levels of grayscale) to ensure smooth transitions.
-Environmental light adaptability:
-It is necessary to have an anti ambient light interference design (such as anti glare coating), and the lighting conditions during calibration should comply with DICOM standards (usually ≤ 50 lux).
4. Relevant standards and certifications
-DICOM Part 14: Define grayscale representation and calibration specifications for medical displays.
-IEC 61223: Acceptance testing standards for medical imaging systems.
-FDA 510 (k): Certification of Medical Display Devices in the United States.
Summary
Medical LCD screens need to meet core requirements such as high brightness, zero bad pixels, high uniformity, and long-term stability to ensure the accuracy of image diagnosis. Ordinary commercial displays cannot replace medical dedicated displays, which require strict medical certification and regular calibration.
