The rendering on the left uses the Deferred Lighting rendering. The one on the right is the default rendering. The scene graph is defined in the $OIVHOME/src/Medical/Rendering/Techniques/deferredLighting/medicalDeferredLighting.iv file. Set deferredLighting field from SoVolumeRenderingQuality to TRUE in order to activate the deferred lighting.
SoVolumeRender, SoVolumeRenderingQuality