Ray-tracing based methods for 3-D modeling of magnetic field and particle motion in spiral scaling FFAG accelerators have been developed. They allow efficient simulation of particle motion in presence of the strong field non-linearities proper to FFAG magnets, and of possible field overlapping in configurations of neighboring magnets, thus yielding a performing tool for spiral FFAG lattice design and optimizations, and for 6-D tracking studies. It is applied for illustration to a principle design of a 200 MeV medical class proton FFAG now under study in the frame of the RACCAM hadrontherapy project
