Re-sampling vs Harden Transform for a dose volume


(Nick) #1

Operating system: Windows 10
Slicer version: 4.8.1 Stable

Hi there,

I have a general question about how Slicer handles and applies deformable registration files that are exported from TPS software with respect to grids.

I would like to apply a deformation vector field (DVF) to a dose volume. My question is,

If I apply the DVF to a dose volume within Slicer’s Transform module (i.e., Apply Transform -> Harden Transform) what happens to the grid spacing of the warped dose volume?
Is it still uniform (through some internal re-sampling?) or is the grid of the dose volume ‘smeared’ out in a warped non-uniform fashion?

For reference, here is the transform information of my Deformable Registration Grid

As an extra question 1)
What is the difference between using the Transforms module or a Re-sampling module when applying a DVF to a dose volume?

Extra question 2)
What is the difference between applying a ‘Displacement field’ transform and a ‘b-Spline’ transform to a dose volume?

Many thanks!

(Andras Lasso) #2

Transforms module’s harden function only resamples the volume if necessary (if a Non-linear transform is applied). If resampling is needed then the resulting grid has the same spacing and orientation as the original grid and linear interpolation is used.

If you use resampling modules then you have complete control over the output grid and interpolation method.

(Nick) #3

Thank you Andras, very helpful