Following an algorithm by Coulangeon, Nebe, Braun and Schönnenbeck to compute unit groups of orders in finite simple Q-algebras, we will again talk about the Voronoi algorithm for finding perfect forms. In this case we will work with a generalized version by Opgenorth in the context of dual cones and consider a combination with Bass-Serre theory regarding groups acting on trees via automorphisms, which yields information about the structure of said unit groups, which will be acting on a Voronoi-graph. In particular we are going to focus on finding unit groups of maximal orders in indefinite Quaternion algebras over Q and compute an example.