Investigation of The Compliance of Planned Dose Distribution on The Treatment Planning System with Measured Dose Distribution in Rando Phantom For IMRT and Conformal Radiotherapy Applications

Purpose This study investigates planned and measured dose differences for 3 dimensional conformal radiotherapy (3DCRT), Field in Field (FinF) and Intensity-Modulated Radiation Therapy (IMRT) techniques for breast cancer radiotherapy. Material and Method Breast shaped phantom (BSP) was fabricated with water equevelent bolus material and BSP was placed on Alderson rando phantom, then planning computerized tomography (CT) images were obtained. Target volume andnormal tissues were delineated on these images. Treatment planning was performed for 3DCRT, FinF and IMRT techniques (Varian, Eclipse 8,6, PencilBeam). EBT2 films were placed into sagittal and transverse planes of BSP which intersect with the isocenter. After thatfilms were irradiated for each calculated plans in two times. The measured doses with film from the isocenter and from the axes passing 1 cm anterior-posterior, superior – inferior and right-left of the isocenter were compared with the doses read from the treatment planning system (TPS) on the same axes. Results Among applied techniques, the maximum and minimum dose differences for measured and calculated doses were 4.5 % and 0.05 % for FinF and IMRT techniques, respectively. Measured doses were higher than calculated doses for 66.6% of all points; however 93% of total points had a difference less than 3 %. Dose differences were minimum on axes that intersect with the isocenter and were directly correlated with the distance from the isocenter. There was no relation between dose differences and directions on axes. Conclusion Dose distributions calculated in TPS were found to be compatible for all three techniques when compared to dose distributions measured by film on rando Phantom. The best compliance was found for IMRT technique.