The main aim in radiotherapy is maximizing radiation dose into cancer cell and protecting health tissue around this cancer. Nowadays, with the development of technology the treatment of tumor becomes possible by small field size. This new technique, so called IMRT (Intensity Modulated Radiation Therapy) requires dosimetric confirmation. One of the most important things to be controlled is planned fields and treated fields in the treatment which it's especially, small field size and using multi field. The other important point is dose values according to calculated time in treatment planned unit and measured time in device.