Weak current College】 【medical monitor role and how to choose.

<br> 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". <br> <br> 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. <br> <br> Medical display preferences: <br> <br> 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-JustNoticeableDifference). 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 - JustNoticeableDifference). 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. <br> <br> If the indoor illumination for 100lux ., display refraction 2%, the brightness of 2cd/M2. When asked to contrast to 1: 100, display brightness should be at least 200cd/M2 (General Office illumination often can reach 500lux, monitor brightness will require to achieve 1000cd/M2) ., because the human eye of nonlinear grey to identify capacity and environmental factors of illuminance. <br> <br> Design and manufacture of medical monitor with maximum brightness of 800-600cd/M2. General display brightness is 200-350cd/M2. United .States society of Radiology (ACR) provides digital x-ray images of maximum brightness at least should be 170cd/M2. 2001 March in Germany of x-ray imaging seminars, industry opinion is where using digital image brightness of the monitor requires at least 200cd ./ M2. General perspective or CT images at least 100cd/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. <br> <br> 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 should at least above the 500cd/M2 .. 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 400-500cd/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. <br> <br> 2. Gray eye on .Gray's reaction is not a linear relationship. Our eyes on the dark part of reaction than the bright portion is sensitive. DICOM3.0 chapter XIV to display grayscale images provides a standard display function (fig. 5). Use the standard display function in different .brightness of the display to display images on the system, and can provide a certain degree of similarity. After this function into the gray levels approximate the human eye's reaction is linear relationship. Therefore a good medical monitor, must have had to adjust grayscale display curve .in order to comply with the provisions of the gray-scale in DICOM3.14 display function. But there is a high brightness of the display system is able to show more distinguished gray (JND). <br> <br> In diagnostic radiology, .the grayscale difference (differential tissue density small), likely in early diagnosis lesion of great help. The display shows the number of grey to black and white images and graphics are related, General graphics more concerned about color display parameters, such as: memory, .speed, color of digits, etc. However, the Windows system is 8bit output shows that reflect the grey to black and white images, or 256 gray-scale windows in palette. due to exclusive 20 colors, image actually only 236 grey, this is .the normal video often encounter the problem of the gray-scale is not continuous. To achieve the perfect reproduction of grey to black and white images continuously, you should choose a professional output of gray in the above video 10bit. <br> 3. resolution .resolution refers to the unit area shows the number of pixels, while the cost of the monitor and resolution are proportional. Select the normal display resolution of 1024 × 768, for Office text could be met. But in low resolution adopted on software to display high .-resolution image, you need toOn the display of the content to make changes, such as changing the content of some medical pixels, then pass on the pixels surrounding pixels for comparison, the "build" new PIX, inserted into the display screen. < .br> <br> Obviously, this change means displaying content will inevitably lead to "distortions" screen. This also changes the basic medical imaging display requirements, therefore, the resolution, not only to select medical monitor, depending on the system to select a .different resolution. Monitor resolution and the resolution of the image itself has very close relations. appropriate select monitor resolution can effectively reduce the display's acquisition costs; General resolution of the image as follows; Cardiovascular Angiography, digital gastrointestinal machine: 1024X1024 (single image), .plus menu for 1280X1024MRI: 256X256 or 512X512 (single image) CT: 512X512 or 1024X1024 (single image) DR / CR: 5 million plus (single image) to DSA, CT, MRI, displays a single image only need 1280X1024 resolution monitor can meet .your needs, but if you want to watch multiple images, such as 4X5 CT3X4 or multiple images, resolution up to 1536X2048 and 2048X2560. at this point you need higher resolution displays, such as 3 or 5 million pixels of the monitor. <br> .<br> DR and CR images of resolution is usually more than 5 million pixels, it is best to use as 3 million or five million pixels of the monitor above configuration choices for Radiology doctors do image diagnosis used and the clinical observation can be generally appropriate .to reduce the resolution as one million pixels or 2 million pixels to save costs. <br> <br> 4. response time, response time is the LCD monitor on the input signal reaction speed, which is a liquid crystal by off or by light .dimmer response time. Usually in milliseconds (ms). Response in General is divided into two parts - Rising (rise time) and Falling (fall time), but what we call response time referring to the sum of the two. The human eye " .Visual residues "phenomenon, that is in motion picture in human form short impression, people will be able to accept the picture display speed is 24/seconds, this is a movie every second, 24 cell origin of the playback speed, if the speed is .lower than the standard, people will obviously felt screen pause and discomfort. Calculation in accordance with this standard, each screen displays the time required is less than 40ms, according to the actual use of liquid crystals, response time: 30ms (1/0.03 = .33.3 Chen / sec), or appear to tail phenomenon, not suitable for dynamic real-time playback of medical imaging. Response time 25ms (1/0.025 = 40-/seconds) could meet clinical cardiovascular DSA's real-time playback. <br> .<br> 5. in the selection of medical monitor, CR, DR static images on the response time is too high. But playing dynamic image of the system configuration, such as cardiovascular machines and digital, gastrointestinal machine preferred response time 25ms following medical monitor .. 5, the monitor's size medical monitor's size and resolution or incidental. The higher the resolution, the larger size, but is not directly proportional relationship. production plant in manufacturing are taken into account and the dimensions of the film close to consistency. General monitor .the considerations. CRT monitor size distribution in 17 inches to 21 inches. liquid crystal (LCD) monitor size in 18 inches to 22 inches. <br> <br> 6, hengping and vertical-screen on the monitor is select hengping or vertical- .screen problems, and no standards or regulations have a radiation image horizontal, vertical subject image may be the best choice for cross-, vertical adjustable LCD. the medical LCD monitor manufacturers have taken to the physicians practices and requirements, design anyway can convert functions, .much easier to clinical use. <br> <br> Medical monitor stability, integrity and consistency: <br> <br> 1. the stability relative to the normal display, gray-scale monitor prices for medical use are more expensive. We hope .that life can be in 5 years-whether CRT monitor or LCD display, brightness will decay over time; General monitor life is defined as when the brightness falloff to maximum brightness in 50% of the time-based LCD monitors, this time about 30,000 hours .to 50,000 hours even in life time, brightness and not every day the same so periodically (approximately three months to six months), the monitor must to do calibration of brightness and contrast-enhanced in order to ensure the consistency of the monitor. If the .monitor number, the workload is considerably more advanced monitor internal sensor (Sensor), can detect changes in the brightness of the display automatically adjusts the display when using the-life of can keep brightness and stability. LCD brightness is not very stable brightness will it .with temperatures differ. now some monitors internal sensor (Sensor), can detect changes in the brightness of the monitor automatically adjust-so that you can save a lot of manpower. <br> <br> In addition the LCD monitor in the post, .the brightness is not immediately up brightness. approximately 20 - 30 minutes before going up the brightness in the brightness is not up to the time set for Peugeot, the display is unsuitable for diagnostic use. Users often other services and discontinue use of the monitor, .after some time, the screen saver will start to start the monitor power off-the extension of the monitor-ordered is beneficial. but when users start using the monitor again, the monitor is turned on, and just have to wait for 20-30 .minute temperature machine time-as a result, use quite inconvenient. If the turn off screen protection, and reduce the service life, therefore, cake and not much good design jian monitor, use the built-in sensor that detects the brightness when powered on .if the brightness is not up to standard, then increase the power supply voltage, so that the monitor in 30 seconds to reach the preset brightness. as a result, did not wait for the temperature-time, and in danger when the screen saver starts ., the extension of theMonitor life. <br> 2. consistency and overall consistency means: If after a period of time, the same image display quality is the same as if watching the same piece of film. Integrity refers to different locations within the hospital's .workstation display the same image its brightness, gamma, contrast, and so is exactly the same, so the doctor can see different locations is the same image; when the printed image and display the image on the monitor is the same. So no matter what .the media are also on the image is the same. The original hospital diagnosis using film, QA (quality assurance QualityAssurance) is placed in the film processor. Radiology every day to check the processor speed of the film, the concentration and temperature drops to- .ensure that each film washing out of quality is the same in all institutions in the implementation of hospital-PACS System, QA (quality assurance QualityAssurance) is placed on the monitor will display the number of a-few-in different brands, different usage, .monitors purchased at different times, to ensure the integrity of the image, at the same brightness, the same display function become a important topic therefore in the select a monitor, in addition to the above mentioned points, monitor manufacturers can provide monitor QA (quality .assurance QualityAssurance) and PM (preventivemaintenance & plannedmaintenance preventive maintenance) tool and the monitor is a QA function, are also important considerations. <br> <br> <br>.