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 The measurement calibration Images can only be calibrated individually, so a calibration done for images individually, so you should calibrate multiple uncalibrated images separately if you have more than one uncalibrated imagean 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.