VOI name

Allows assigning a name to the VOI in the list. The name can be typed in or it can be Set using a predefine list of VOI names.

When the Set button is activated a dialog window opens for defining the name and the color:

Four lists with pre-defined organ names are available: DICOM, SMALL ANIMAL, DOSIMETRY HUMAN(Adult male) and DOSIMETRY HUMAN (Adult female) Select the appropriate one in the list selection in the upper left and proceed as follows:

1. Select an organ name from the selected list.

   Note: In the SMALL ANIMAL list, organs with trailing >> such as Tumor>> offer a substructure list. Other organs like the Kidneys offer a Laterality choice. Select as appropriate.

2. The VOI name shown in the text entry field is composed from the selections, but can be edited or completely redefined.
   CAUTION: An existing VOI with exactly the same name will be overwritten. In this case please add a suffix to differentiate (e.g. CerebellumLeft in the example above)
3. The ORGAN volume and mass are relevant for dosimetry studies. There are predefined values for HUMAN selection lists. These values can be edited if necessary for any selection.
4. Change the VOI color.
5. The Set VOI name and color button sets the VOI name in the VOI properties window. The Cancel button discards the definition.

Custom Organ List

In the end the VOIs list contains all structures of interest. It can easily be converted into a custom list of names for the assignment as illustrated below. Select a VOI in the list and access its properties. Activate the Set button and subsequently the + button. Specify a list name in the appearing dialog window and confirm the dialog window with ok.

From now on, this list can be used alternatively to the pre-defined lists.

Tracking

Allows defining the VOI type encoded in the VOIs list in the T column.

This definition is relevant for the tractography which is performed in the PGEM module. The tractography is based on VOIs which can play different roles:

• SEED VOIs: Tractography is started from the pixels in seed VOIs, following the local vector directions.
• END VOIs: Only tracks ending in this VOI will be used. To avoid excessive pruning of tracks, an END VOI should have sufficient volume.
• WAY VOIs: Only tracks passing through the WAY VOI will be used.
• EXCLUDE VOIs: Tracks passing through an EXCLUDE VOI will be removed.
• NEUTRAL VOIs: Such VOIs have no impact on tractography. Setting VOIs to NEUTRAL allows assessing the effect of END, WAY and EXCLUDE VOIs without the need of removing them.

/

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.