Some DICOM images (usually ultrasound) might not be pre-calibrated so that the size of a pixel in the image is not known. For such images, measurements are displayed in pixels instead of a physical unit like centimeters, millimeters, etc. However, such those images can be easily calibrated by Ruler Tool since tool as long as they have a scale as a part of the image.
- Activate Ruler Tool tool by Tools > Measurement > Ruler
Draw a line to calibrate on the a scale which is a part of found on the image.
Note For more accurate results, it is recommended to use a calibration line as long as possible.
- Right-click on the calibration line, and select Calibrate
- Enter the length of the calibration line in a physical unit in the dialog shown as indicated on the scale where the line is drawn, and select OK
The calibration line is shown in a physical unit now, and all next measurement that will be drawn will be other measurements are shown in a physical unit.
Note Measurements Images can only be calibrated for images individually, so a calibration done for an uncalibrated image does not apply to other uncalibrated images.
Warning It is possible to calibrate pre-calibrated images as well, but you should be careful not to cause incorrect measures due to wrong calibration.