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 PET and SPECT systems. Tumors are approximated by arbitrarily complex analytically defined five-dimensional (x,y,z,t/sub geometry/,t/sub activity/) compartments which can be placed into tomographic or mathematical phantoms. Various models for tumor growth have been developed or are implemented such as sigmoidal growth according to the Gompertz equation or compartment models for heterogeneous metastatic tumors, as well as model extensions that account for various therapy strategies. With this approach, Monte Carlo simulation studies can be performed repetitively in static or dynamic acquisition mode at any given time of projected tumor growth. This novel simulation technique provides the basis for deriving allometric relationships between growth rate and tumor representation in a sequence of simulated tomographic images.