| Περίληψη: | Total body irradiation (TBI) is a radiation therapy technique, which is applied to patient who have a hematological cancer type. The purpose of this treatment is to irradiate the whole bone marrow to kill the cancerous cells and finally to immune-suppress the patient. TBI is usually applied in combination with a chemotherapy scheme to improve therapeutic results in organs, which chemotherapy cannot work. The goal of treatment is to prevent the rejection of donor stem cell and to have a successful hematopoietic stem cell transplantation.This thesis expounds a summary of the background biology and physics of TBI. In addition, it analytically explains this special procedure of TBI and the challenging distribution of a homogenous dose.
A Monte Carlo (MC) simulation technique has been developed and applied to collect dose distribution data for organs of interest using a computational, high detailed anthropomorphic phantom. A beam barrier and lung shielding are modeled and simulated to produce a homogeneous dose distribution and protecting the lungs.The purpose of this study is to develop a MC simulation tool for TBI, which will be able to generate dose distribution data at each organ of interest and finally can estimate the dose distribution to a patient’s body. The results shows that the highest amounts of dose were delivered to the bones, where the hematopoiesis is occurring, as expected. Consequently, the production of cancer cells will potentially be considerably reduced allowing transplantation, as proposed by the literature. Adding lung shielding develops a significant reduction to lung dose, avoiding the risk of pneumonitis. Many studies have utilized GATE MC simulations toolkit for studying the interaction of radiation with matter, for dosimetric studies. GATE incorporates physics models of high accuracy, provided by the Geant4 community. In addition, GATE can model complex geometries and incorporate high detailed computational anthropomorphic mathematical phantoms, which is crucial in dosimetry of high accuracy.As future prospect, adding shielding at other organs of interest, such as the kidneys and/or brain, may had a positive impact. Furthermore, an amount of bolus could be used to make the surface of the patient flattened, thus producing a more uniform dose distribution. Finally, this study needs be assessed with experimental and/or clinical data.
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