StartNewStep("Find low densities areas");
// Pad images with air to prevent patient touching the image border
+ // But the lungs can touch the outside air. In such case, use primaryOpeningRadius with 1 kernel
typedef itk::ConstantPadImageFilter<InputImageType, InputImageType> PadFilterType;
typename PadFilterType::Pointer padFilter = PadFilterType::New();
padFilter->SetInput(input);