SUMMARY

In recent years, there has been much improvement in radiation therapy delivery systems used in the treatment of cancer; however in order to fully exploit this enhancement, the computational methodology associated with radiation therapy must improve as well. It is important to accurately determine where the radiation is depositing its energy within the patient. In the Computational Reactor and Medical Physics Group here at Georgia Tech, a heterogeneous coarse-mesh transport method (COMET) has been developed. COMET decomposes a large, heterogeneous global problem into a set of small fixed source local problem. Response functions are obtained for each local problem. These are all precomputed and stored in a library. The solution to the global solution is then bound by a linear superposition of the local problems. In this project, COMET is now being applied to the transport of photons in human tissues to determine the amount of energy (dose) deposited. To determine the strengths and weaknesses of the current system, it is important to construct benchmark problems for comparison. This project will encompass a number of benchmarks. The first will involve modeling a simple two dimensional water phantom. A second benchmark problem involves the use of a heterogeneous phantom composed of different tissues. A third benchmark problem will involve using the data from a CT scan. A last benchmark problem will involve transport through slabs of aluminum, water, and lung tissue. This is not a clinically relevant problem; however, it is very stringent on the method. For each of these cases the results from COMET will be compared to the computational results obtained from EGSnrc, a Monte Carlo particle transport code.