objective: to develop and implement a software based on the manual calculation algorithm for verification of the calculations in radiotherapy monitor units and to establish acceptance levels as a mechanism of quality assurance. materials and methods: data were obtained from clinac 600c and 2100c varian linear accelerators and the computerized treatment planning system used was cadplan？. results: for the 6 mv beams the acceptance levels for deviations among the calculations of monitor units, divided by treatment area, were the following: breast (0.0% ± 1.7%), head and neck (1.5% ± 0.5%), hypophysis (-1.7% ± 0.5%), pelvis (2.1% ± 2.1%) and thorax (0.2% ± 1.3%). for the 15 mv beams the suggested level for pelvis in all the treatment techniques was (3.2% ± 1.3%). conclusion: the present data are sufficient to justify the use of the software in the clinical practice as a tool for the quality assurance program.