Best method for importing CT datasets

Hello all,
I am currently writing a geant4 application to calculate the dose imparted to a sample during a CT scan. Until now I had thought the only way to import data into geant for was to first convert it to a surface mesh (such as stl) and then import that using CADMesh or something similar. However, while I’ve made a lot of progress using that method, I have just found there is another way to import data using DICOM files instead. I do not know anything more about it except that it exists and there is a example of it in the extended session, in hope of saving time would anyone be able to share their experiences on the pros vs cons of each method and whether it is worth switching over?

The dataset i want to import is 8Gb in size (1900x2150x500 pixels) and consists of at minimum three different materials. The main thing I am after right now is which is easier to work with and which will produce the most optimised solid for running x-ray scattering with. For using the stl files I have been imported them and then nesting the inner regions into the outer ones by assigning daughter volumes.

Thanks in advance for the help,