RESUMO
In this study, experimental verifications is done for output, dose profile percentage depth dose for open and modified [wedged and partially blocked] fields as compared with the calculated using Multidata code. Four typical configurations of irradiation were selected, regular fields, wedged fields, blocked fields and cases of internal inhomogeneity. Measurements were performed on cobalt - 60 unit Theratron 780E using Multidata water phantom. For blocked fields dose profiles were measured using radiographic films and then scanned using PTW densitometer. Data were analyzed in both of the low and high dose gradient regions of the measured and calculated profiles. Differences between the measured and the calculated dose were determined. The results indicate that the Multidata planning system calculations agree with the measured ones in situations. However, in the blocked field the mean deviation between measured and calculated dose under the block was [15.2%] although the blocks is drown according to the instructions by the system manufactures. The reason for such errors was found to be due to the implemented algorithm in the system