Blob segmentation

Blob segmentation
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In a PET exam, you can use this module in order to isolate a region according to a local maximum. A blob is a region around a minimum or a maximum. Here is the steps of this segmentation :

Click on a point with Shift + left button near an extremum.
The algorithm searches for the closest maximum.
From this maximum, the region grows under 2 conditions :
- the region's size must not exceed the maximum size given by the field region max size (in mm3).
- the values must not be lower than the threshold given in the field percentage of extremum.
When the segmentation is over, the region is displayed.
NB : it can occur that the region doesn't contain the original voxel, the a warning message indicates that you have to click closer.

Table 9.12. Blob segmentation

Field name	Description
Region max size	Maximum volume for the blob in mm3. For example, if the voxel resolution is 4x4x4 mm (the volume of a voxel is 64mm3) and you set 1280 mm3, the region size is 20 voxels.
Percentage of extremum	Percentage of the maximum value. It is possible to change between a maximum and a minimum using keys Shift+B (to a maximum) and Control+B (to a minimun).

Field name

Description

Region max size

Maximum volume for the blob in mm3. For example, if the voxel resolution is 4x4x4 mm (the volume of a voxel is 64mm3) and you set 1280 mm3, the region size is 20 voxels.

Percentage of extremum

Percentage of the maximum value. It is possible to change between a maximum and a minimum using keys Shift+B (to a maximum) and Control+B (to a minimun).

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