A comparison between GafchromicTM EBT3 film and Delta4® phantom in IMRT technique of a heterogeneous chest phantom

Introdution: In advanced radiotherapy techniques such as intensity modulated radiation therapy (IMRT), the quality assurance (QA) is essential. This study aimed to compare the performance between GafchromicTM EBT3 film and Delta4® phantom (2D and 3D) in heterogeneous chest phantom using IMRT technique. Methods: In this experimental study, two IMRT plans (A and B) were prepared for radiotherapy of heterogeneous chest phantom. EBT3 film and Delta4 were used for dose measurement in the phantom. The 95% global gamma index accepted by the criteria of  3.3% mm and the dose threshold 20% as the standard criteria were considered in this study. The gamma index of the film and Delta4 were acquired by the verisoft and Delta4 software, respectively. Results: The mean gamma index with standard criteria between treatment planning system (TPS) dose calculations and film measurements was 96.95%, while it was equal to 97.7% and 98.45% between TPS calculations and 2D and 3D Delta4 cases, respectively. The mean 3D gamma analysis of the Delta4 with the given standard criteria was 0.75% and 1.5% higher than their 2D gamma analysis of the Delta4 and film, respectively. The mean gamma index value of film and Delta4 according to the plan B at the standard criteria was 0.24% higher than plan A (97.7% vs 97.46%). Conclusion: Both film and Delta4 showed acceptable standard gamma index for two plans implemented on the chest phantom using IMRT technique. So, according to the results of this study, it is concluded that in the centers where Delta4 is not available, EBT3 films with a simple heterogeneous phantom can be an alternative method