This example demonstrates how to run Grow from seeds effect in batch mode (without GUI, using qMRMLSegmentEditorWidget) using 3D Slicer

SegmentGrowCutSimple.py

# Generate input data
################################################

import SampleData

# Load master volume
sampleDataLogic = SampleData.SampleDataLogic()
masterVolumeNode = sampleDataLogic.downloadMRBrainTumor1()

# Create segmentation
segmentationNode = slicer.mrmlScene.AddNewNodeByClass("vtkMRMLSegmentationNode")
segmentationNode.CreateDefaultDisplayNodes() # only needed for display
segmentationNode.SetReferenceImageGeometryParameterFromVolumeNode(masterVolumeNode)

# Create seed segment inside tumor
tumorSeed = vtk.vtkSphereSource()
tumorSeed.SetCenter(-6, 30, 28)
tumorSeed.SetRadius(10)
tumorSeed.Update()
segmentationNode.AddSegmentFromClosedSurfaceRepresentation(tumorSeed.GetOutput(), "Tumor", [1.0,0.0,0.0])

# Create seed segment outside tumor
backgroundSeedPositions = [[0,65,32], [1, -14, 30], [0, 28, -7], [0,30,64], [31, 33, 27], [-42, 30, 27]]
append = vtk.vtkAppendPolyData()
for backgroundSeedPosition in backgroundSeedPositions:
  backgroundSeed = vtk.vtkSphereSource()
  backgroundSeed.SetCenter(backgroundSeedPosition)
  backgroundSeed.SetRadius(10)
  backgroundSeed.Update()
  append.AddInputData(backgroundSeed.GetOutput())

append.Update()
backgroundSegmentId = segmentationNode.AddSegmentFromClosedSurfaceRepresentation(append.GetOutput(), "Background", [0.0,1.0,0.0])

# Run filter
################################################

# Create segment editor to get access to effects
segmentEditorWidget = slicer.qMRMLSegmentEditorWidget()
# To show segment editor widget (useful for debugging): segmentEditorWidget.show()
segmentEditorWidget.setMRMLScene(slicer.mrmlScene)

segmentEditorNode = slicer.mrmlScene.AddNewNodeByClass("vtkMRMLSegmentEditorNode")
segmentEditorWidget.setMRMLSegmentEditorNode(segmentEditorNode)
segmentEditorWidget.setSegmentationNode(segmentationNode)
segmentEditorWidget.setMasterVolumeNode(masterVolumeNode)

# Run segmentation
segmentEditorWidget.setActiveEffectByName("Grow from seeds")
effect = segmentEditorWidget.activeEffect()
# You can change parameters by calling: effect.setParameter("MyParameterName", someValue)
# Most effect don't have onPreview, you can just call onApply
effect.self().onPreview()
effect.self().onApply()

# Clean up and show results
################################################

# Clean up
slicer.mrmlScene.RemoveNode(segmentEditorNode)

# Make segmentation results nicely visible in 3D
segmentationDisplayNode = segmentationNode.GetDisplayNode()
segmentationDisplayNode.SetSegmentVisibility(backgroundSegmentId, False)

This is a code snippet, not a module, so you cannot load it as a module (it has not GUI, so if you replace a module with this script then the previous module GUI will disappear and nothing will be displayed instead).

The quickest is to copy-paste the code from here to Slicer's Python console. If you want to edit/rerun it with different parameters then I would recommend to use Jupyter notebooks with Slicer chosen as kernel.

Thanks for making this, would there be a way to manually paint the seeds and then run the script using the painted seeds?

Yes, of course. You can then simply use Segment Editor module in 3D Slicer and the "Grow from seeds" effect. See a simple example here: https://youtu.be/cybL5A0w3hw

what are the best segmentation methods of maxillary bone?

@DrMohamedAssadawy please post this question on the Slicer Forum.

When I run this code using my own CT data, there is an error as follows. How can I solve it?
File "qt-scripted-modules\SegmentEditorEffects\AbstractScriptedSegmentEditorAutoCompleteEffect.py", line 301, in onApply
previewContainsClosedSurfaceRepresentation = previewNode.GetSegmentation().ContainsRepresentation(
AttributeError: 'NoneType' object has no attribute 'GetSegmentation'