Medical display in digital imaging system and matching (1)

Digital Imaging System (PACS, DR, CR, DSA, etc.) with the IT industry, maturing, and soon entered the field of medical radiology.

Because of its "soft reading tablets feature" and forward-looking, more and more favor domestic hospital, various medical digital imaging system was listed as the hospital's acquisition plans. However, due to cost considerations, digital image system configuration in the monitor area, are often ignored or discarded medical monitor configurations to a normal PC monitor or black and white display alternative to digital imaging system for image display effects greatly diminished, as in the development of a digital image of the "bottleneck".

Currently, many domestic manufacturers and integrators in digital X machine, CR, DR systems and PACs investment allocation ratio display matching parameters and investment will be used, show features of nature are relatively low, resulting in digital imaging system features available on the "barrel" effect, namely that the whole system function = minimum function, the part of this phenomenon is due to the domestic industry of the lack of awareness of the medical monitor.

In order for Radiology on digital imaging system of diagnostic accuracy problems have full understanding, understanding medical monitor in the role of digital imaging, we from medical monitor discussions on several aspects.

Medical display preferences:

1, a brightness of the eye's ability to distinguish the gray-scale so that as the brightness of different, with a linear relationship.

As the figure, the higher the brightness (Luminance), the human eye can discern in gray (JND-Just Noticeable Difference). Conversely, low brightness, the human eye on grayscale resolution. The higher the level of brightness, the human eye can distinguish the number of gray levels. In order to improve levels of resolution, a brightness of the monitor must be high. The higher the brightness (Luminance), the human eye can distinguish between the gray-scale (JND – Just Noticeable Difference). Physicians room ambient light on the monitor's brightness is influential, part of the image on the monitor depends on the brightness of the monitor, but the dark parts in addition to the display brightness, and environment brightness and refractive index of the display.

If the indoor illumination for 100lux, display refraction 2%, the brightness for 2 cd/M2.

When asked to contrast to 1: 100, display brightness should be at least 200 cd/M2 (General Office illumination often can reach 500lux, the brightness of 1000 on request can be met cd/M2), because the human eye of nonlinear grey to identify capacity and environmental factors of illuminance.

Design and manufacture of medical monitor with maximum brightness of 800-600 cd/M2.

General display brightness of 200 cd/M2-350. United States society of Radiology (ACR) provides digital x-ray images of maximum brightness should at least 170 cd/M2. 2001 March in Germany of x-ray imaging seminars, industry opinion is where using digital image brightness of the monitor requires at least 200 cd/M2. General perspective or CT image at least 100 cd/M2. So therefore, ordinary monitor brightness that seems to have reached the film reading requirements of brightness (many hospitals have just installed the monitor image is also quite satisfied). Considered to CRT or LCD monitor brightness will decay over time.

We hope that at least three years, the monitor's brightness can be maintained at a minimum brightness above, it is recommended that a new display brightness at least 500 cd/M2 or more.

However, because ordinary monitor does not have a brightness stabilization and correction functions, brightness over time decay and ambient light refraction, display brightness significantly discounted, cannot achieve the requirements of the film reading (on brightness problem, behind stability even in detail) and medical monitor's maximum brightness at installation, the use of optical correction tool calibration in accordance with DICOM standard, so that the brightness in a film reading requirements of brightness values. (Usually in the 400-500 cd/M2), and that in 3-5 million hours constant. This ensures that brightness of the stability and consistency of the image. Thus, ordinary monitor and medical monitor in medical radiology film reading room of the actual working environment is very different.