[en] The introduction of TPS Precise Plan and the installation of an Elekta linear accelerator Entailed Precise Radiotherapy Service HHA 2DRT the evolution of a 3DCRT, the latter being a term used to describe the design and delivery planning radiation treatments based on 3D images, with fields individually shaped to the target volume and improved procedures evaluation of plans. Because of this it is necessary to estimate uncertainty in the delivered dose, which is evaluated in the 2D process 3DCRT, with emphasis on obtaining anatomical information (contour-meter vs TAC) design fields (open field vs MLC), dosimetric calculations, evaluation treatment plan and verification of isocenter. In this work took only internal processes in the treatment, such as location of the target volume and organs at risk, correction for inhomogeneities, etc. We excluded the uncertainties common to both modalities, such as: camera calibration, repeatability errors, among others. It took 40 cases treated: 20 with technical and 20 technical 2DRT 3DCRT for estimate the uncertainty of the delivered dose given each factor separately, say those involved in the planning process and supply of the treatment. This study implements a methodology which maintains or always reported decreasing uncertainties will lead to an increase quality of care. (author)