Why use a medical grade display monitor for medical applications compared to a commercial grade display monitor?

Why using a medical grade monitor to view X-rays?

I get this question all the time: why should I pay thousands of dollars for a medical grade monitor to diagnose digital X-ray (CR/DR), if I can buy a very nice looking commercial grade off-the-shelf, (COTS) monitors at the local computer store. I have boiled this argument down to 6 important reasons based on critical arguments, which are (hopefully) simple to understand and allow you to convey this to your radiologists or administrators who have little technical or physics background.

1.      A commercial grade monitor does not show all of the critical anatomical information. As the name implies, the COTS monitors are intended for office automation, to display documents to appear like a printed page. Therefore performance attributes are weighted heavily to being as bright as possible so that text is easily resolved with minimal eyestrain. Commercial displays therefore attain maximum luminance way before the graphic card input reaching its maximum input value. Remember that a typical graphics card can display 256 different input values, each representing a distinct piece of valuable diagnostic information. These monitors have been observed to max out as low as a value of 200, which means values 201 to 255 are being mapped to the same luminance value … maximum. This means that 20 percent of all the data is cropped or simply eliminated.

By contrast, medical grade monitors are calibrated to map each individual distinct pixel into something you can detect rather than following the natural response of a graphics card output. Unfortunately, it is normal for the natural COTS monitor response (un-corrected to DICOM) to yield the same luminance value (measured) for multiple sequential values, i.e., a flat spot in the response curve. These flat spots are especially obvious in the low range, i.e. the first 160 of the 256 values.

What is the impact of a flat response? Let’s take as an example, for a commercial grade monitor the pixel values of 101, 102, 103, 104, and 105, could be mapped into a single luminance value on the screen. That means that if there is a slight nodule, which is identified by a difference in value between 102 and 105, it will disappear, as there is no distinction between these values on the monitor. Note that since the better part of the clinical information from the imaging modalities is in the lower 50 percent of the luminance range, this means that these are in the most critical areas wherein the ability to resolve pixels at different luminance values is being compromised.

In conclusion, the potential to miss critical diagnostic information both at high luminance and due to flat spots in the response should be the number one reason to not even consider a commercial grade monitor. Therefore, the first requirement for medical monitors is to insist on a monitor that is calibrated according to DICOM standards, which truly maps each of the different pixel values into a luminance value on the screen that is detectable by the human visual system as noticeably different. It is best to have this calibration done at manufacturing to have an optimal mapping of the three RGB channels into the DICOM compliant curve.

2.      Many commercial grade monitors don’t have the required dynamic range. The maximum light output of a monitor is specified using the units of cd/m2 (candela/square meter).  A good quality commercial display can achieve 300 cd/m2, sometimes more if you are lucky. The maximum value of 300 cd/m2 would be at the low end of any medical grade monitor, which might be able to go up to 500 cd/m2 or more. Why do we need this much? The reason is that when a display is calibrated to DICOM, a percentage of the response is lost in the mapping process.  At 300cd/m  and applying DICOM corrections, the maximum value can be expected to decrease by about 10 percent.

The human eye has a 250:1 contrast ratio at the ambient conditions of the viewing environment. Assuming the commercial display was DICOM compliant with aftermarket software, the luminance ratio of the display and the eye would be very close. However, ambient light detracts from the ability to see low contrast information. This particular example would need to be in a low light room to achieve a 250:1 luminance ratio inclusive of ambient light.

Medical displays are designed to operate between 400 and 600 cd/m2 as corrected to DICOM with reserve luminance potential for extended life at those levels. Even if a monitor is calibrated, if there are not enough points to map the pixel data into, you clip off part of the information. For example, if you want to map 256 grayscale pixel values but have only 200 points available, you’ll lose that information. The required dynamic range depends on where you are going to use the monitor. As you are probably aware, the lighter, i.e. the brighter the room light, the more information you are going to lose in the dark, as you simply won’t be able to distinguish details in the dark.

There is a simple fix for that, the calibration takes into account the room light and makes sure the lowest pixel value is mapped to something you can detect. The whole range is shifted, which is important when using it in a light area such as ER or ICU. Also, it is good to have some “slack” at the dynamic range, the light source of the monitor will decrease (compare the output of an old light bulb), and get lower and lower over time). Therefore, the maximum brightness to facilitate mapping the whole data range should be about 350 cd/m2[1] assuming you use it in a dark environment. If you are using it in a bright area or if you want to make sure you have some slack to facilitate the decrease of monitor output over a period of let’s say 5 years, you might want to go with 450-500 cd/m2.

3.      A medical-grade monitor typically adjusts the output to compensate for start-up variations in output. The light output of a monitor varies as the temperature needs to stabilize for about 30-60 minutes. You can leave them on day and night, or switch them on automatically one hour before they are going to be used, however, either method will drastically reduce the lifetime. Better grade medical monitors typically have a feedback mechanism built in that measures the light output and adjusts the current to the light source to create the same output. The third requirement therefore is to have a medical grade monitor with a light output stabilizer.

4.      A medical grade monitor can usually keep a record and keep track of its calibration. One of my students in our PACS training told me that he had to deliver the calibration record of a specific monitor dated 2 years back for legal reasons, to prove that when an interpretation was made on a workstation, there was no technical reason that a specific finding was missed. In addition, you need access to these records on a regular basis, regardless, to make sure that the monitor is still operating within the acceptable range. This brings me to another point – many users seem to replace their monitors after a period of five years. If they are still within the calibration, there is no reason to do that. Therefore, the fourth requirement for a medical grade monitor is to make sure that you can retrieve and store the calibration records.

5.      A medical grade monitor is typically certified. There are recommendations that are defined by the ACR for monitors. They are somewhat technical and in my opinion not worded strongly enough. Also, most medical grade monitor manufacturers are FDA approved, which is actually only a requirement in case you are reading digital mammography. If you meet the requirements stated above, you should be OK, but FDA approval does not hurt. You can check the FDA website and look up the manufacturer to see if they have been approved. The fifth (optional) requirement is therefore to be FDA approved.

6.      In addition to being able to see all of the grayscale, which is characterized by the contrast resolution, you also need to be able to distinguish between the different pixels, i.e. your monitor needs to have the right spatial resolution to see the individual details. Let’s take a typical CR chest, which might have an image matrix size of 2000 by 2500 pixels, that results in 5 million pixels or 5MP. The standard configuration for a diagnostic monitor to look at X-rays is 3MP, because a physician has the capability to zoom or use an electronic loupe to see a one-to-one mapping of each image pixel element on the screen. One could actually argue that you can use a 2MP monitor as well, and yes that is correct as long as you realize that it will take more time to make a diagnosis, as you need to zoom more frequently. But if you are very cost sensitive, for example considering a system that is placed in a developing country where money is major issue, a 2MP configuration would do. So, the sixth and final requirement is to have a 3 MP monitor configuration (assuming time is more important than cost).

Does this mean that a commercial grade monitor cannot be used? It depends, if you are willing to manually calibrate the monitor and do this on a regular basis, by running a calibration check and making sure this can be applied by the monitor, if you make sure to take care of the warm-up time, if you have a monitor that meets the maximum brightness requirement, if you keep your calibration records, and are not worried that in case of a legal dispute the plaintiff does not have enough expertise to challenge you with the fact that you use sub-standard components that could impact patient care, well… it is up to you. But I would think twice about it, especially as the price difference between a good quality medical grade monitor and commercial grade monitor is not that great compared with the overall cost of a PACS system.

[1] The unit of measurement for luminance specified as brightness is called cd/m2 which stands for candela per square meter.

Article Credits: Herman Oosterwijk

Expert trainer/consultant on DICOM, HL7, PACS, EHR

Display Performance Required for Medical Imaging Displays

With the advance of computerization in the medical field, medical image displays are increasing in popularity as replacements for film. Consequently, much higher levels of reliability are demanded of medical image displays. Based on the concept: “Integration of Hardware and Software,” TOTOKU offers a full range of medical display solutions from displays to graphics cards to software.

Resolution requirements

Depending on modalities such as CT, CR, MRI, and FPD, resolution requirements can range from 1.3 megapixels to 5 megapixels. Generally, 3 megapixel and higer class displays are used for softcopy interpretation. Where higher accuracy and a subtle reproduction of grayscale are critical in applications such as mammography imaging, 5 megapixel resolution is required.

Stable luminance

Because grayscale properties vary with luminance variations, unstable luminance significantly impacts imaging diagnosis. When multiple displays are placed side-by-side, luminance stability and uniformity across displays take on importance in providing proper diagnosis. In reality, however, luminance fluctuates greatly due to temperature changes, startup drift, and aging. Therefore, medical image displays are usually equipped with luminance stabilizing systems to provide stable luminance.

Multi-shade display

Medical image displays must be able to reproduce and display subtle differences. However, 256 shades of gray that general displays are able to reproduce do not meet medical requirements due to unevenness and grayscale discontinuity. Therefore, medical image displays are usually equipped with a conversion table called LUT (look-up table) to enable smooth grayscale output. The capability to maximize the number of simultaneously available shades from 8bit (256 shades of gray) to 11bit (2048 shades of gray) is further demanded.

Grayscale faithful to DICOM GSDF

Medical image display systems are commonly calibrated to match their grayscale characteristics with GSDF (Grayscale Standard Display Function) defined by DICOM Part 14. Displays can have widely different grayscale characteristics (commonly called gamma characteristics) depending on manufacturer, models, individual difference, or luminance setting. An image displayed on displays with different characteristics will of course have a different appearance, significantly interfering with imaging diagnosis.

Accuracy management

Installing medical image displays implies tackling the challenge of how to maintain high quality images. The increased awareness of the importance of accuracy management is evident in the recent efforts to establish and implement standards and guidelines for image quality management in many countries. Those standards and guidelines mandate post – installation acceptance testing, periodic constancy testing, and monitoring of display accuracy. Thus, software solutions that take care of all these are necessary.

Others

The task of softcopy interpretation implies going performing image processing on large numbers of images, an environment capable of performing quick drawing is essential for stress-free operation when making diagnostic evaluations and decisions, especially considering the fact that chest X-ray images are displayed in portrait orientation.Recently, thanks to the improvements made to their luminance contrast, color displays are beginning to be introduced. This means that a single color display may be able to support all types of modalities.

Source Link: http://www.jvckenwood.com/healthcare/display/en/products/requiredformedical/

Sony UPD898MD A6 Digital B/W Printer

The Sony UPD898MD is a compact A6 medical grade black and white digital printer. It’s designed to be integrated into a wide range of compatible medical imaging environments. Environments such as digital ultrasound systems, mobile C-arms or cardiac catheterisation laboratory. The high quality thermal print engine can produce hard copy prints of still images captured by these systems for use in patient records and referrals.

The Sony UPD898MD is a successor to the popular Sony UP897 series of medical printers. Redesigned and upgraded. It offers several operational and ergonomic enhancements while retaining the same space-saving footprint and easy integration into medical carts. Usability is further enhanced by an enlarged LCD display panel and joystick for intuitive menu navigation.

The Sony UPD898MD is capable of delivering high-quality black & white prints in under two seconds. Advanced thermal printing technology delivers near-photo quality results using widely available print media.

For pricing and more information e-mail us at info@hiliex.com or visit our product page 

 

 

UPX898MD Black/White Hybrid Video Graphic Printer

Sony UPX898MD B/W Hybrid Video Graphic Printer

The Sony UPX898MD black and white video graphic printer is designed specifically for use with medical diagnostic equipment, such as ultrasound systems. The printer includes a USB interface that allows the user to capture images that are printed and store them on a small, portable USB storage device. High quality, photo-like prints are output in just approximately 1.9 seconds. The UPX898MD is extremely small and light weight. For additional convenience, the UPX898MD adds a jog dial to the front panel for easy operation.

For pricing and more information e-mail us at info@hiliex.com or visit our product page 

LMD2451MD Medical LCD Monitor

Sony LMD2451MD Medical LCD Monitor

The successor to our highly successful LMD2450MD, the Sony LMD2451MD full HD medical monitor meets the growing need for high quality, large screen monitors across demanding medical applications. With its unique built-in option slots and easy to-install body design, the LMD2451MD can be smoothly integrated into any environment – from operating theater to conference room to teaching facilities. The large screen full HD monitor for demanding medical applications Superb picture reproduction ChromaTRU Color Processing. For enhanced color reproduction accuracy, every LCD panel used in the LMD2451MD is precisely color calibrated to ensure consistent characteristics. The colormetry of an LCD display can, by nature, exhibit inaccurate color characteristics and gamma curves, which can make precise color matching between multiple monitors a challenge. The LMD2451MD solves this problem by precisely calibrating each LCD panel’s light output so that the RGB color co-ordinates are consistent for every monitor. A second calibration is also applied to ensure that white balance is maintained at a consistent color temperature throughout all gray-scale levels. This technology is invaluable for applications such as simultaneous monitoring in operating theaters and monitoring rooms. Outstanding brightness and contrast. The LMD2451MD provides high brightness and high-contrast images by utilizing super-wide aperture WUXGA LCD panels (1900 x 1200 pixels). Built-in option slots for ultimate flexibility. The LMD2451MD features two unique built-in option slots that enable users to easily expand, select, and change input/output signals, depending on the modality application. These built in option slots are designed to support a variety of option boards such as the BKM-250TG, which allow the monitor to accept a 3G-SDI input signal and transfer a 1080/60p signal via a single SDI cable. Use of the optional BKM-256DD board increases the monitor’s DVI input/output capability to accept up to two DVI-D inputs and one DVI loop-through output.

For pricing and more information e-mail us at info@hiliex.com or visit our product page 

Sony LMD2110MD Medical LCD Monitor

Sony LMD2110MD Medical LCD Monitor

Sony introduces a new medical LCD monitor – the LMD2110MD – which complies with medical safety standards and EMC standards while maintaining an excellent cost: performance ratio. Equipped with a 21.5-inch* full-HD (1920 x 1080 pixels) high-resolution LCD panel, the LMD2110MD delivers crisp high-definition (HD) images. Combined with a 10-bit digital signal processing system, this monitor offers stunning and smooth grayscale. The LMD2110MD is equipped with conventional versatile analog input interfaces and an HDMI input, which can accept HD signals up to 1080/60p. In addition, this monitor can input HD/SD-SDI signals using the optional BKM-341HS input adaptor. These features and benefits make this monitor a perfect cost-effective choice for a wide range of applications in healthcare settings.

Safety Listing and Compliance

The LMD2110MD is UL60601-1-listed and complies with CSA C22.2 No.601-1 and EN 60601-1 safety standards and EMC standards, making it suitable for use in a wide range of professional medical applications.

21.5-inch Full-HD (1920 x 1080 pixels) Resolution, 10-bit Signal Processing

Incorporating precisely manufactured high-purity RGB color filters and a high-speed response LCD panel, the LMD2110MD delivers accurate color reproduction and stunningly lifelike crisp images. All SD and HD input signals are converted into 10-bit digital signals without any picture deterioration via full digital imaging circuitry. This 10-bit signal processing achieves significant signal-to-noise ratio (SNR) improvement and smooth grayscale compared to 8-bit data processing.

Wide Range of Standard Input Interfaces

The LMD2110MD is equipped with a full range of analog inputs including a composite, Y/C (S-Video), analog component, and RGB. Also included is an HDMI, which can accept HD digital signals up to 1080/50p and 60p. DVI signals can be input via the HDMI input connector using a conversion cable.

Optional HD-SDI Interface

In addition, this monitor supports HD-SDI input with an optional BKM-341HS HD/SD-SDI input adaptor. This input versatility allows the LMD2110MD monitor to flexibly connect to HD-SDI digital environments.

Compact Design – Portable and Flexible

Unlike CRT monitors, terrestrial magnetic fields have no influence on LCD monitors. This means the LMD2110MD can be carried and used in any position and location. With the standard monitor stand, users can set the monitor anywhere and use it immediately. The LMD2110MD provides VESA™-standard mounting holes with 100 mm pitch, and is flexible enough to install with a VESA arm and on a medical cart.

Other Features

  • Conventional functions, including Contrast, Brightness, Chroma, Phase control, and Color temperature setting
  • Menu screen with seven selectable languages
  • Scan setting (Normal (0%), Over (5%), Full scan)
  • Standard monitor stand with tilt function
  • External parallel remote control

 

For pricing and more information e-mail us at info@hiliex.com or visit our product page .

LMD1951MD 19″ medical grade LCD monitor with LED backlight technology

Sony LMD1951MD 19″ medical grade LCD monitor with LED backlight technology

Sony introduces the LMD1951MD 19″ medical grade LCD monitor* to its comprehensive display line-up. The LMD1951MD offers a superb combination of newly employed LED backlight technology to reproduce brighter images along with a high quality SXGA (1280 X 1024) LCD panel. Designed to be used in both SD and HD systems, this new monitor also inherits an array of exceptional features from the popular LMD-2451MD including 10-bit signal processing to produce accurate and lifelike images, and enhanced viewing modes such as Picture-in-Picture and Mirror Image. The LMD1951MD is equipped with a full range of inputs including Composite,Y/C, RGB/Component, HD15, and DVI-D inputs. Furthermore, the two built-in option slots accept a variety of option boards to offer ultimate flexibility including 3G-SDI input signal and DVI input/output capability to accept up to two DVI-D inputs and one DVI loop-through output allowing users to easily expand, select, and change input/output configuration.

Features and Benefits:

  • SXGA LCD Panel with LED Backlight Technology: high quality panel that produces bright high-contrast images
  • Sony ChromaTRU Color Balance: advanced color space conversion and white balance calibration technology for vivid and accurate colors
  • Full 10-bit Digital Video Signal Processor: to produce accurate and lifelike images with smooth and natural gradation
  • Variety of Scan/Display Modes: including Mirror Image, and Picture-in-Picture which allows users to view two images at a time
  • 5:4 Aspect Ratio Signal Output: designed to be used with SD and HD systems
  • AC and DC Operation: depending on installation requirements. For DC Operation, the optional AC-110MD is required.
  • Two Built-in Option Slots: to easily expand, select, and change input/output signals via optional input adapter boards

For pricing and more information e-mail us at info@hiliex.com or visit our product page 

Mitsubishi P93W Monochrome printer

Mitsubishi P93W simple and Convenience to Operate: The most complete and convenience user interface. All principal functions are accessible from the front panel. Dependable, High Resolution Images for Medical Applications: Mitsubishi P93W High-density thermal head and thermal recording mode reproduce delicate lighting and shade. High resolution 1280 x 500 pixels and 256 grades for normal size printing (horizontal picture element density of 325 dpi)Speed and Detail, and the Best Size Image Every Time: Enlarge or reduce specific parts of images in an instant. Set the output from 0.5 to 2.0 in scale, at 0.1 increments, for the ideal print size every time, for each use.

 

For pricing and more information e-mail us at info@hiliex.com or visit our product page