The use of EBT3 film and Delta4 for the dosimetric verification of EclipseTM treatment planning system in a heterogeneous chest phantom: an IMRT technique

This study aimed to evaluate the dose calculation accuracy of EclipseTM treatment planning system (TPS) in a heterogeneous chest phantom with the intensity modulated radiotherapy (IMRT) technique using EBT3 film and Delta4. Two IMRT plans (A and B) were prepared for radiotherapy of the heterogeneous chest phantom. Plan A was between the left lung and the surrounding soft tissue and plan B was carried out on the soft tissue. EBT3 film and Delta4 were used for dose measurement in the phantom. EclipseTM TPS was also used for dose calculation. Finally, the gamma index values of the TPS with film and TPS with Delta4 were obtained. A 95% passing rate of gamma index with the passing criterion of 3mm/3% and a dose threshold of 20% as the standard criterion was considered in this study. Furthermore, the passing rates of gamma indices of the film and Delta4 were compared with each other via Bland-Altman analysis. The mean passing rate of gamma index with standard passing criterion between the TPS calculations and film measurements was 96.95±0.22%, while it was equal to 97.7±0.56% and 98.45±0.21% between the TPS calculations and 2D and 3D Delta4 measurements, respectively. Additionally, the differences between the passing rates of gamma indices of the film and Delta4 were less than 5%. The findings demonstrate that the accuracy of dose calculations of EclipseTM TPS in a heterogeneous chest phantom with the IMRT technique is within the standard passing criterion. Furthermore, it can be concluded that there is a good agreement between the film and Delta4, as IMRT QA devices.