The Covid-19 pandemic has forced many Radiologists to work from home. This guide outlines some easy steps to set up a reporting room and computer display that meets professional standards.
Radiology Display Calibration
Setting up a display that meets professional radiology standards for home reporting can be achieved easily and cost-effectively if some basic room lighting, display selection, and display calibration guidelines are followed. There are a number of simple tricks and tips for improving ergonomics and fine-tuning visual performance that are worth taking the time to implement. With attention to detail, a home reporting station that meets or exceeds professional standards can be easily set up.
Important note: This guide is for all modalities except Mammography which has its own specific requirements not covered in this guide.
Frequently neglected, reflections from ambient light around diagnostic displays has a strong influence on contrast perception. A radiologist viewing an image may not be conscious of the reflections but it is easy to demonstrate the effect reflections have on their ability to perceive changes in image contrast. The simple solution is to keep ambient light levels low and minimise reflections off the display.
Tip: The Black Shoelace Test
If you are wearing black lace-up shoes, you should be able to see that you have your shoes on but difficult at a glance to see if your laces are done up. That is, dim but enough light to work comfortably and clearly see the keyboard but as low as you are comfortable working in.
Eliminate Reflections & Other Sources of Glare
To check for reflections simply turn the display off and look for them on the display surface from a normal reading position. Eliminate as many reflections as possible e.g. by facing the display away from windows or moving the offending light source. Other computer displays with bright colour themes can contribute to reflections and high ambient luminance. Similarly, bright light sources in your peripheral vision can reduce visibility and should be minimised. e.g. switching off, replacing light bulbs with low output variants etc
This is often the most problematic part of establishing a professional setup, and advice from your colleagues, PACS support, PACS vendor and medical physicist will be helpful in identifying a suitable choice.
Different professional groups have outlined performance specification for radiology displays. Some of the key specification from the ACR/RANZCR/RCR recommendations are summarised below.
Professional Display Specifications
|Source||ACR–AAPM–SIIM TECHNICAL STANDARD FOR ELECTRONIC PRACTICE||Standards of Practice for Clinical Radiology||Standards for interpretation and reporting of imaging investigations||-|
|Matriz Size||-||>= 3MP||1600x1200 (2MP) min||>=3MP|
|Pixel Pitch||approx 0.2 (<0.21)||-||0.25||approx 0.2 (<0.21)|
|Orientation||-||-||Landscape or Portrait||-|
|Max Lumiance||350 cd/m2||>=350 cd/m2||250||350 cd/m2|
|Min Lumiance||1.0 cd/m2||1.0 cd/m2||1||1.0 cd/m2|
|Grey Scale Calibration||DICOM GSDF (+/-10%)||DICOM GSDF (+/-10%)||DICOM GSDF (+/-10%)|
|Ambient Reflection (Lamb)||1/4 Lmin||-||-||1/4 Lmin|
|Bit Depth||8 bit||8 bit||-||8 bit|
|Modalities||US/CR/DR/CT/MRI||US/CR/DR/CT/MRI||US/CR/DR/CT/MRI||All except Mam|
|Aspect Ratio||3:4 or 4:5||-||-||3:4 or 4:5|
Table 1: Key performance requirements from 3 different professional standards
Other Display Selection Considerations
The computer display market is fast-moving and there are offerings from most manufacturers that will meet the requirements in the highest specifications column in table 1 above. The list includes but is not limited to LG, Dell, HP, Samsung, EIZO, Barco, BenQ, Asus.
Discussing the selection with your IT support can save a lot of post-purchase pain.
To achieve a consistent presentation of greyscale images the displays need to have the same luminance characteristics. This is performed by calibrating the display to the standard DICOM Part 14 Greyscale Display Function while taking into account the ambient luminance, minimum luminance and maximum luminance. This requires software combined with a suitable photometer to measure the display characteristics, calculate a correction table and apply the table to correct the display to the DICOM Standard. We have developed a downloadable application called ViewIQ which works with an X-Rrite photometer (OEM version only) that we are able to supply for performing this calibration.
Tips for improving performance
Tip: The graphics card should be set to drive the display in its native resolution to get best resolution performance from the display.
Tip: Only use digital outputs and connections between the graphics card and the display. i.e A Display Port, or DVI-D to prevent the signal distortion possible with analogue connections.
Tip: Apply Dark Themes to other displays in the reporting area.
Set the display of other nearby displays to a Dark theme to reduce glare and reflections on adjacent image displays
Windows 10: To Change to a Dark Colour Theme
Right Click on the screen. Click Personalise, then Colours, then in the “Choose your colour” dropdown select Dark.
Tip: Apply Dark Background to other displays in the reporting area.
Windows 10: To Change to a darker Background image
Right Click on the screen. Click Personalise, then Background and then either choose a dark themed image or darker colour background.
Note: Some experimenting with this may be needed as may not work with colours of menus on some of your applications.
Run some final checks of performance. Either download the free test image generation application from here, or click on these links to the web versions of the test images below:
- Display black image and then look for reflections;
- Check the greyscale calibration and room lighting;
- Set the optimal viewing angle by adjusting the image sequence until the first letter visible appears. The tilt the display until the letters are best displayed over the diagnostically useful area of the display;
- Display A Very Simple Test final overall check of performance.
For more information on this service please visit the ViewIQ Display calibration page.
- Room Lighting & reflections
- The display black level being too dark
- Display calibration not meeting the DICOM standard
- Display maximum brightness
We are able to supply display calibration software for any sized organisation from large distributed radiology providers to the sole radiology practitioners. Please send us a message if you would like to know more.