Filter:

Submit Search

#### Calibrating the measurement scale

A measurement scale is required in the following cases:

| • | To measure linear distances (see Drawing lines and measuring linear distances)

| • | To measure the area and perimeter of the Elliptical ROI (see Adding and measuring the Elliptical Region of Interest (ROI))

The measurement scale is calibrated individually for each image. It can be calibrated automatically or manually.

Automatically calibrating the measurement scale

The measurement scale may be automatically calibrated from the image DICOM header. If the scale indicator exists, the measurement scale for the image is automatically calibrated. See Displaying or hiding the scale indicator.

Manually calibrating the measurement scale

You need to calibrate the measurement scale only if the image does not contain it. To determine whether the image contains the measurement scale, use the Distance tool to measure a linear distance. See Drawing lines and measuring linear distances.

If the measurement unit is not displayed, the image does not contain the measurement scale. Typically, scanned film and digitized analog video images would not contain a measurement scale. Digitally acquired images should contain a scale. If this is not the case, please contact your modality vendor.

Note: To calibrate the measurement scale, the image must display an object of known size or dots that correspond to standard distances, such as the 1cm measurement on US images.

To manually calibrate the measurement scale:

| 1. | Select the Calibrate tool:

| • | Click the Annotate icon on the main toolbar.

| • | Click the Calibrate tool on the Annotation Control Panel.

For other ways to select the tool, see Selecting an annotation tool.

| 2. | Draw a line:

| • | Drag the mouse pointer across the image.

| • | Release the mouse button.

A line with a double-headed arrow is displayed on the image.

| 3. | Type the length of the line in the Distance box. Depending on your preferences, the measurement unit is expressed in mm or cm.

| 4. | Click Update.

The measurement scale is added and displayed on the image.

| 5. | Draw a line to measure a linear distance on the image. Follow the steps in Drawing lines and measuring linear distances.

The line is displayed with the calibrated measurement.

Related Topics

Your search for returned result(s).