Oh, that is what “Scissors” effect do. I thought it’s for eraring.
It seems it’s not a filled rectangle. I found there is waring: Irregular volume geometry detected, but maximum error non-zero but is within tolerance (maximum error of 0.000576862 mm, tolerance threshold is 0.001 mm).
I check this post. And set apply regualarization transform in the application setting, but still get this warning.
as you could see, the image is rotated a little. Any issue with the DICOM data?
PixelSpacing: 0.9375, 0.9375
SliceThickness: 1
ImagePositionPatient: -112.38102987944, -116.43096361169, 83.608241714
ImageOrientationPatient: 0.99926579596646, 0.00441271653949, 0.03805781055539, -0.0017440497062, 0.99755447631478, -0.0698714897148