Voxel Cone Tracing in Deferred pipeline?

I am working on a 6 month project where I have to implement voxel cone tracing for indirect light in C++/OpenGL. I already have a deferred renderer setup but most of the VCT examples I could find usually draw the scene once for voxelization and once with cone tracing shaders. Is it possible to run cone tracing shaders over a fullscreen quad and sample vertex data from the GBuffer or is that generally a stupid idea? Do I lose accuracy because I only have per pixel vertex data?