We consider the minimum radiation path problem in areas with wireless heterogeneous networks. Namely, given a set of spatially distributed wireless transmitters, it is required to find a trajectory between given source and destination points such that the total amount of radiation absorbed by an entity moving from the source to the destination is minimized. We propose to deal with this problem using the sparse structure of Voronoi diagrams, instead of exploring the 2D plane. We show through software simulations that certain weighted Voronoi diagrams contain low radiation trajectories and can be used for constructing low radiation paths. The average overhead of radiation on radiationoptimal trajectories computed over weighted Voronoi diagrams compared to the minimum radiation trajectories is around 8%.