Monte Carlo Investigation into Superficial Cancer Treatments of the Head and Neck

Abstract

This thesis presents the findings of the investigation into the Monte Carlo simulation of superficial cancer treatments of the head and neck region. The EGSnrc system of codes for the Monte Carlo simulation of the transport of electrons and photons through a phantom representative of either a water phantom or treatment site in a patient is utilised. Two clinical treatment units are simulated using the BEAMnrc system of codes: the Varian Medical Systems Clinac® 2100C accelerator for 6MeV electron fields and the Pantak Therapax SXT 150 X-ray unit for 80kV and 100kV photon fields. Depth dose, profile and isodose curves are compared against those measured from a PTW MP3 water phantom with good agreement being achieved. Quantitative dose distributions are determined for both MeV electron and kV photon fields with treatment sites containing high atomic number materials, rapidly sloping surfaces and different density interfaces. This highlights the relatively high level of dose deposition of dose in tissue-bone and tissue-cartilage interfaces in the kV photon fields. From these dose distributions DVH and dose comparators are used to assess the simulated treatment fields.