IMPAX 6.5.1 Client Knowledge Base: Extended > Reading studies > Marking up images > Measuring lines and areas on study images
Several different tools are available for measuring lines and areas on study images. The measurement values and units used depend on the calibration applied or available to the study.
For calibrated images, the accuracy is limited by the calibration provided with the image, and by the position of the start and end points of the line drawn which may vary by one pixel at each end. Based on the calibration provided, pixels are converted into millimeters and rounded to the nearest millimeter. For non-calibrated images, measurements are displayed in pixels (px) and the accuracy of the measurement is limited by the pixel position at each end of the caliper measurement.
If you have calibrated the image, series, or study, measurements are based on the value and units you selected and are suffixed with (ui). MR and CT studies with DICOM pixel spacing cannot be user calibrated.
If no user calibration is in effect, the DICOM pixel spacing calibration is used, if available, along with the default unit.
If no user calibration is in effect and DICOM pixel spacing is unavailable, ERMF is used, if it is available and has been enabled by default or has been applied to the image, series, or study. Measurements are suffixed with (EM).
If user calibration, DICOM pixel spacing, and ERMF are all unavailable, other calibration values residing in the image header are used, along with the default unit.
If no calibration values are available, pixel counts are used.
See also
Topic number: 8686 Applies to: IMPAX 6.5.1 Client Knowledge Base |