A patient-specific quality assurance program for the dose delivery of intensity modulated radiotherapy

Objective: To establish a standard program of the dose delivery for every individual patient and to study the criterion of quality assurance in intensity modulated radiotherapy (IMRT). Methods: 33 nasopharynx cancer (NPC) IMRT treatment plan were designed, then transferred to the hybrid plan in a 3D treatment plan system (CMS Xio). The reference data were obtained. A ion chamber and Kodak EDR2 films were used to measure the absolute dose and the relative dose distribution, and difference between the reference value and measure value were evaluated with an advance criterion. Results: For 32 cases, the absolute dose value at the isocenter was below the tolerance limit of 5 %; for one case, the dose value exceeded the range, but re-meet the demand through adjusting the measure point to a flat region of dose distribution. For relative dose distribution, all cases meet the tolerance limit of 5 % and 3 mm distance difference. Conclusions: To establish a standard program for individual patient is very important for the exact implement of IMRT plan. (authors)