Line profile : Intensity matching

Hi,
I’m using 3D Slicer to process two different images ( RT Dose volume and MRI volume ) of the same phantom and I would like to compare them in terms of relative intensity. In other words I would like to test if the intensity profiles of the two images match in a masked volume. The intensity profiles of the two images have the same shape but they belong to different scale : how can I match them ? Is there a tool that can help me doing that ?