Testing the effect of different calculation grids on the accuracy of intensity modulated radiation therapy plans

Abstract

The goal of treatment planning for cancer radiation therapy is to adequately treat the patient's tumor volume while minimizing dose to the surrounding healthy tissue. In the case of intensity modulated radiation therapy (IMRT), this is accomplished by using complex computer models to calculate the dose to a given volume. These volumes and their resolution of defined by the calculation grid, which defines the space where the dose calculation models are applied and the resolution of that space. The resolution is determined by the size of the voxels (a 3-D pixel). IMRT procedures require a great deal of accuracy and much work has been done at Ball Memorial Hospital (BMH) to verify the accuracy of these treatments. However, the calculation grid has been generally left at a default value to minimize the amount of time that the treatment planning system needs to perform the dose calculations. The intent of the project is, therefore, to test the effect of very fine calculation grid resolutions on the accuracy of IMRT plans.