How to convert ct images to .g4dcm format

hi geanters:
I have recently been working on an experiment that intends to use ct images to build a brain model. For this purpose I started to learn DICOM examples. I found that the model built by this example uses .g4dcm format images, so I would like to ask how to convert the common .dicom format images to .g4dcm format
Thank you for your answers, as a newbie I really need your help!