SUMMARY

Spatially fractionated radiation therapy (grid) collimates megavoltage radiation. As such, only the volume under the open grid areas receive direct irradiation, and the other areas only see scattered radiation, facilitating regrowth of normal tissue. Although the grid dose distribution is non-uniform, the clinical regression of the tumor is uniform. Protons have two advantages over megavoltage x-rays: they scatter less in tissue, and they have a fixed range in tissue. This project computationally and experimentally assesses the use of the grid method with clinical proton beams. The proton pencil beams at Provision Proton Therapy in Knoxville, Tennessee, are used to computationally find the dose distributions at various depths using MCNP6 and RayStation. The same proton beams are used to experimentally find the dose distributions using Gafchromic EBT3 film. A comparison of these results is presented as well as a comparison of spatially fractionated proton therapy to traditional photon grid therapy.