Sunset integrals at finite volume

Chiral Perturbation Theory is a useful tool to aid in performing the various extrapolations needed in lattice QCD calculations of physical quantities. These include extrapolations in quark mass, finite lattice spacing and finite size of the lattice. Especially the latter will becomemore important when the quark masses on the lattice become smaller. Here we develop the needed two-loop integrals at finite volume to do the calculations for masses and decay constants for all general mass cases. I will present results based on an expansion in Bessel functions as well as on a version using theta functions and compare their efficiency. Work is in progress to combine these results with two-loop ChPT calculations.