Dose distribution Verification of forward IMRT plans

Introduction & Aim: Intensity modulated radiotherapy (IMRT) is one of the most modern radiation therapy treatment techniques. Although IMRT can deliver high and complex conformational doses to the tumor volume, its implementation requires rigorous quality assurance (QA) procedures that include a dosimetric pretreatment verification of individual patient planning. Methods:Dose distribution verification usually involves measuring a small volume of absolute dose with an ionization chamber and checking bi-dimensional fluence with an array of detectors. The planning technique has tri-dimensional characteristics, but no tridimensional dosimetry has been established in the clinical routine. One of the strategy to perform three-dimensional dosimetry is to use Octavius phantom to evaluate dose distribution. Results and Conclusion:the results of distributed dose measured with detector array and Octavius phantom was compared with IsoGray treatment planning system (TPS) calculation from forward IMRT in breast cancer patient. More specifically, we used the gamma index to compare the results of threedimensional dosimetry to the expected dose distributions obtained with the treatment planning system.