Tips on getting started with volumetric rendering?

I'm brand new to Metal. I've googled, but can't get the right answer to come up. (Thanks, unhelpful ChatGPT generated answers polluting everything, but I digress...)

Ultimately, I'm trying to figure out how to use Metal to render 3D DICOM data on iOS specifically. If you're not familiar with DICOM, let's just say I've got a whole stack of CT image slices. Or to get really simple, I've got a cube of voxel values with differing values at each voxel coordinate.

Where do I even start in Metal to render something like this?

(I was trying to get the VTK toolkit compiled for iOS, which uses OpenGL, but that appears to be a dead end. And besides, Metal is supposed to be so much better.)

Thanks for any tips/leads/suggestions/general pointers.