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RadiAnt DICOM Viewer

Navigation: Basic Topics > Taking measurements

Ellipse

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Select  Ellipse  from the  Measurements  drop down menu (or press the  E  key).

 

RadiAnt_DICOM_Viewer_Adjust_Measurements_DropDownMenu_Ellipse

 

Press left mouse button and drag the mouse to draw an ellipse with pixel value measurement. Release the button to finish drawing.

 

RadiAnt_DICOM_Viewer_Adjust_Measurements_Ellipse

 

The values measured are:

 

Name

Description

Mean

Mean pixel value (Hounsfield Units for CT images)

SD

Standard deviation

Max

Maximum pixel value

Min

Minimum pixel value

Area (px)

Area in square centimeters and the number of pixels used for calculations

 

You can move the ellipse or change its size by dragging it or the surrounding cross-marks with the left mouse button pressed.

The label may also be dragged to a more convenient place if necessary.

 

Press  Shift  while drawing the ellipse to make it a perfect circle.

 

RadiAnt_DICOM_Viewer_Adjust_Measurements_Ellipse_Circle

 

When drawing an ellipse in a magnified image, you can press the  Ctrl  key to show the boundary of actual pixels taken into account in calculations.

 

RadiAnt_DICOM_Viewer_Adjust_Measurements_Ellipse_Actual_Pixels

 

Press  Esc  while drawing the ellipse to delete it.

 

SUV measurement

 

For PET images the ellipse tool can be used to measure the maximum, minimum, and average values of the Standardized Uptake Value calculated using body weight (SUVbw) for a specified area.

 

Radiant-Dicom-Viewer-Ellipse-SUV-Sample

 

The SUV measurement is possible only when there is necessary data included in the DICOM files (patient weight, radio pharmaceutical dose and time, etc.), otherwise, the ellipse tool will show the uptake measured in Bq/ml (or in other units specified in the 0054,1001 DICOM tag).

 

The SUV calculation is based on the formula below:

 

RadiAnt-DICOM-Viewer-SUV-Calculation

 

Hover the cursor above the ellipse and right click on the mouse. Select  Calculate SUVbw [g/l]  to switch between SUVbw and basic units.

 

Radiant-Dicom-Viewer-Ellipse-SUV-Switch-Units

 

Radiant-Dicom-Viewer-Ellipse-SUV-Basic-Units