You can define the mm/pixel settings for images that do not include mm/pixel data, then use these settings to perform accurate measurements.
1. From the Viewer, select the image you want to calibrate.
2. In the Graphics tab of the toolbar, click Scale Calibration 
.
3. On the image, click once, and then a second time to select the required number of points in a straight line.
When you click on the second point, the Calibration Settings window appears.
NOTE: Try selecting points on the distance marker if available. If no marker is available, select points of a well-defined distance. The number of required points depends on the configuration that was defined during installation.
5. Type the value to be assigned to the distance between the points on the image.
6. Click OK.
The Vue PACS Client can be calibrated so that images display in True Size (that is, 1 cm on the screen equals 1 cm actual). True Size calibration is needed only once and is done by the authorized service representative when the Vue PACS Client is installed. Recalibration is necessary only when the monitor is physically changed or the display width and height are changed.
See this topic: