DETERMINACIÓN DE LA DOSIS ABSORBIDA EN DIFERENTES MEDIOS HOMOGÉNEOS

Abstract

Radiation therapy is an effective method for treating most primary tumors, which attempts to attack the lesion volume avoiding damage to healthy tissue. In radiation therapy linear accelerators the beam is adapted to distribute the dose needed to destroy cells in the affected tissue volume, therefore it is vital to be certain that the dose is required and providing the beam illuminating radiation is only volume to be treated. Dummies are used for this used to verify the dose before applying the treatment to the patient. For Dummies cost on the market are inaccessible to most hospitals in Mexico. For this reason, the idea of this work is to determine what material and geometry can be used to represent a head for use in the verification of radiotherapy treatments. The materials studied were solid water, polystyrene, nylon 6 and tissue equivalent. Using MCNP5 code was designed linear accelerator head and modeled a mannequin made of tissue equivalent BOMAB, head of the dummy models included the tumor and the pituitary gland and determined the photon flux and dose treatment system with a 6 MV linear accelerator. This same model was assessed homogeneous phantoms (sphere, cube and cylinder) with different materials to determine the model that best emulates the response of the human brain. In order to establish a treatment protocol used a bucket of water was irradiated solid with a 6 MV accelerator, the dose was measured with thermoluminescent dosimeters activated lithium fluoride with magnesium and titanium (LiF:Mg,Ti), planning treatment was done with the business planning system XiO. The results of the experimentally measured doses were compared with results obtained in the simulation with MCNP5. According to the results the most suitable material to emulate the human brain tissue is water and solid geometry which behaves more like the cube.