VOI Level Properties

The VOIs section on the List tab contains the list of defined contour VOIs, and VOIs which are in the progress of outlining.

VOI List Tab

The New button creates an empty VOI in the list, with the plane direction P according to the currently selected plane in the image area. The buttons serve for deleting the selected VOI, or all VOIs, respectively. The arrow buttons on top of the list allow changing the VOI ordering by moving the selected VOI. VOIEditMode1 represents the mode, how VOI overlapping is handled. The + and - buttons to the right set all contours of the selected VOI to + and - respectively as described below. Similary, the and set the contour mode to straight line or B-spline connection.

VOI Properties

In addition to the plane orientation a VOI has several properties, which can be changed using the button. It shows the VOI properties dialog window illustrated below.

The window allows changing the properties, and immediately updates the display for providing a visual feedback. The property elements have the following meaning:

/	Static VOI : This property is only relevant for dynamic series. If a VOI is static, the same VOI definition is applied and shown at all times. Dynamic VOI : This property is only relevant for dynamic series. For dynamic VOIs, a different VOI definition can be used at different times. Note that a dynamic VOI is only shown when viewing the images of the time frame it was defined on. As long as only one VOI is defined, statistics calculation will apply this VOI at all times as with a static VOI. However, as soon as VOIs have been defined at more than one time, it is required that VOIs are defined at all times. Here the VOI propagate functionality may be helpful.
/	Filled VOI : All pixels inside the contours belong to the VOI. Tape VOI : The contour is interpreted as the center line of a VOI which includes pixels inside a band along the contour. The number of pixels inside and outside can be specified. This type of VOI was introduced for myocardium VOIs.
/	Full VOI : Uses pixels from all directions. Sector VOI : Only the pixels in a defined angular sector will be considered. The sector angle can be defined in the VOI Action Mode using the handles at the angle corners. This type of VOI was introduced for myocardium VOIs.
Location	X, Y and Z position of the VOI relative to the origin in [mm]. The location can be changed by entering new coordinates or using the incrementing arrow buttons.
Size	Size of the VOI bounding box in mm. The sizes can be changed and result in a proportional scaling in the corresponding direction. The sizes can be edited or incremented by the arrow buttons. Note that for contour VOIs consisting of planar ROIs the scaling is only supported within the ROI planes, not orthogonal to it. Object VOIs can be scaled in all directions.
Rotation	The VOI can be rotated in space. Note that for contour VOIs consisting of planar ROIs rotation is only supported around the axis orthogonal to the ROI plane. Object VOIs can be rotated around all directions. The angles can be numerically specified in degrees, or incremented using the arrow buttons.
	Color Palette. Allows changing the contour color. All contours belonging to a VOI have the same color.

The illustration below illustrates the effect of the different properties on the pixels used for VOI statistics.

Sector VOI