Implementación dosimétrica de la técnica de irradiación a cuerpo entero con electrones de 6 MeV por termoluminiscencia

Abstract

The paper presents experimental results of implantation dosimetric technique of Total Skin Electron Therapy (TSET). Which arises from the need to know precisely the dosimetric characteristics of the patient's treatment plan in different anatomical parts of the patient. For this treatment was used four dual fields technique using a linear accelerator Elekta brand to generate electrons from 6 MeV in mode high dose rate (HDR), which can deliver 10 cGy per Unit Monitor (UM). The research was conducted on the premises of the Hospital General of Mexico in the Department of Medical Physics in the Oncology Department. The main objective was to determine whether the choice of beam angulation and scatterer-degrader were correct, so as to obtain adequate dose uniformity over the patient's skin, for which measurements were performed "in vivo" of dose the patient received each treatment session of his whole body irradiation. The distribution of dose over the treatment plan was measured for dual beams angled at 252 ° and 285 °, using thermoluminescent dosimeters were placed in a solid water phantom which is composed of polymethylmethacrylate (PMMA) and oxide Titanium (TiO2). For treatment of whole body irradiation using a beam of electrons whose energy was 6 MeV in "high dose rate" and because this energy is excessive for this type of treatment, stood in the path of an electron an acrylic plate 1cm thick and 100cm x 200cm cross-sectional area located approximately to 11 cm from the patient, in order to decrease the energy of the electrons and more homogeneous dose in the treatment plan. To measure the dose the patient receives in each body part were used TLD100 thermoluminescent dosimeters, which were placed for treatment on the patient's skin at various parts of his anatomy. We performed the analysis of the distribution of the percentages of dose in the treatment plan, which allowed us to determine the distribution of isodose curves on the surface of that plane. As the three-dimensional distribution of dose rates, from which it follows to obtain vertical and horizontal profiles. Results obtained using the material to be used as a dispersant-degrader (PMMA) in the path of the electrons are not as homogeneous as there is a variation of 51% compared to the maximum dose, these results suggest that it may modify the technique irradiation of 4 fields to 6 fields could contribute to improve the homogeneity of the dose.