An ERMF (Estimated Radiographic Magnification Factor) can be applied to images in XA, RF, DX, or MG studies. ERMF calibrates images to compensate for the effects of projection onto film. You can set your modality preferences to apply ERMF by default to all studies from a modality, or you can set ERMF on a study-by-study basis with the User Image Calibration tool.
ERMF cannot be applied if user image calibration is in effect.
 | CAUTION! The DICOM header of an image may already contain pixel spacing values that account for the estimated radiographic magnification factor. In this case, you should not enable ERMF. To find out whether the pixel spacing from a particular modality includes ERMF, read the modality DICOM conformance statement. |
To apply ERMF calibration
From the Image area context or top toolbar, click User Image Calibration.
or
If using the context toolbar text menu (Ctrl + right-click), select Markup > User Image Calibration.
Click any two points on the image.
A calibration line appears.
To set the calibration line, right-click.
In the Calibrate Image dialog, under Scope, select whether to apply an ERMF to the Image, Series, or Study.
Under Calibration Source, select Modality.
Select the Estimated Radiographic Magnification Factor checkbox.
If the checkbox is grayed, ERMF is not available to this study.
Click Save.
ERMF calibration is now in effect on the current image, series, or study. The status bar indicates Modality (EM) as the calibration source. New measurements are suffixed with (EM). The Zoom True Size image display is also affected.