How can I render an X-ray image from a volume data?

Say that I have a 3D VTU data consisting of values between 0 and 1. My goal is to render it as X-ray imaging, which means the lower the value, the more transparent the corresponding part should be.

For now, after importing the VTU data, ParaView just renders every voxel, which only gives a large cube.

Switch from “Surface” representation to “Volume” representation:
https://docs.paraview.org/en/latest/Tutorials/ClassroomTutorials/targetedComputationFluidDynamics.html#volume-rendering