Integrating kinetic models for Simulating tumor growth in Monte Carlo Simulation of ECT systems

We have developed an integrated framework for linking tumor growth models directly into a Monte Carlo simulation algorithm for positron emission tomography and single-photon emission computed tomography systems. Tumors are approximated either by analytically defined five-dimensional (x,y,z,t/sub geometry/,t/sub activity/) compartments or by compound cellular lattice inserts. Both representation models can be placed into arbitrarily complex tomographic or mathematical phantoms. Various models for tumor growth approximation have been developed or are implemented such as sigmoidal growth according to the Gompertz equation, compartment models for heterogeneous metastatic tumors including model extensions that account for various therapy strategies, and self-organizing multiparticle systems in the form of cellular automata. With this novel approach, Monte Carlo simulation studies can be performed repetitively in static or dynamic acquisition mode at any given time of projected tumor growth. The proposed simulation technique provides a basis for deriving allometric relationships between growth rate and tumor representation in a sequence of simulated tomographic images. We propose the introduced framework as an ideal experimental model environment for evaluating growth theories and acquisition/schedule strategies, especially under controlled conditions of the simulated imaging system under investigation.