RESUMO
Breast tangentiual irradiation is one of the most common treatment techniques used in most radiotherapy practice applied to this area. The difficulty with tangential fled irradiation to the breast or chest wall has always been in achieving a homogenous radio-therapeutic dose. The aim of this study was to evaluate the uncertainties in the breast tangential fields, which was calculated as a 2-D technique where the plan was produced by assessing dose distribution on te central axis slice only. This plan was then recalculated at a 3-D technique using the entire CT data set with the changes in the beam parameters to meet the requirements for 3-D technique. This study was performed by using the Advantage Radiation Therapy System [ARTS] treatment planning system. The two planning methods were compared using dose-volume histograms [DVH[s]] and isodose districbutions in the upper and lower slices. From the comparison, we concluded that a single-slice plan [2-D method] is unsatisfactory in providing sufficient information about the dose variation across the treatment volume and that ideally a 3-D plan with DVHs should be produced