Efecto del material de contraste en las distribuciones de dosis asociadas a la braquiterapia de alta tasa con Iridio-192 para tratamientos del cáncer cérvico-uterino

Abstract

The effect in the doses distributions associated to cervical-uterine cancer treatments with high dose rate brachytherapy with Iridium-192 produced by the contrast material was quantified. This was done by the calculation of doses with the Acuros algorithm implemented in the Brachyvision planning system. For the calculations the CT numbers (Hounsfield units) associated with the electronic density of the bladder with different concentrations of contrast were identified which were from 0 % (0 HU, equivalent to water) to 10 % (316.18 ± 94 HU) and 236 points around the implant were located, 41 of which were inside the bladder. For each of these points the deviation of the dose was calculated in the presence of contrast in the bladder with respect to the dose in the presence of water. For 500 HU, the deviations were up to 0.10 % for points outside the bladder and up to 2.21 % for points within the bladder. For the optimum concentration for imaging of 8 %, the absorbed dose in a volume of 2 cm3 of the bladder, would be up to 0.44 % higher dose than dose for water. The increment in absorbed dose lies within the tolerances established in radiotherapy.