Validation of the CT scan calibration curve for the radiotherapy treatment planning system at the Instituto Nacional de Câncer

In the present work the effects of the different electronic densities were analyzed in the calculation of the dose prescribed for the radiotherapy treatment, implementing the tomograph calibration curve dedicated to Radiotherapy. The 062M CIRS phantom was used with nine different densities, referring to the most usual densities. The survey of the specific curve of the tomograph took into account the differences inserted by several factors and evaluated the protocols already defined in the service. With the curve made, the planning system was fed with the curves of Hounsfield units versus relative electronic density and Hounsfield units versus mass density. Finally, for validation a planning was performed on a phantom with tomography of said tomography and the experimental measurements corroborated with the plans, guaranteeing a maximum uncertainty of 2%, confirming the validation of the specific curve. (author)