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Comparison of Dynamic Conformal Arc Lung SBRT Plans Calculated Using Four Dose Calculation Algorithms

V Pigrish

V Pigrish*, V Sarkar, L Huang, A Paxton, M Szegedi, P Rassiah-Szegedi, H Zhao, Y Huang, B Salter, University of Utah, Salt Lake City, UT


MO-L-GePD-T-2 (Monday, July 31, 2017) 1:15 PM - 1:45 PM Room: Therapy ePoster Lounge

Purpose: This work uses lung SBRT plans originally calculated using the pencil beam algorithm and recalculates the dose distribution with three more advanced dose calculation algorithms to see if there are any major differences in required prescription isodose lines with the new algorithms or the ensuing dose distributions.

Methods: Fifteen dynamic conformal arc lung SBRT plans originally created using the pencil beam algorithm in iPlan were recalculated using the Monte Carlo algorithm in iPlan as well as the AAA and AcurosXB algorithms in Eclipse. The prescription isodose line required to deliver the prescription dose to 95% of the PTV was determined for each algorithm for each plan. Once this normalization was done, DVHs were compared for the PTV and organs at risk.

Results: The pair-wise comparison of required prescription isodose line for all four algorithms shows significant differences (p<0.05) for all pairs. However, the ensuing DVHs for both PTVs and OARs did not show any major differences between AAA, AcurosXB and Monte Carlo. There was a markedly different dose distribution to the PTV for PB as expected.

Conclusion: While the prescription isodose lines were significantly different for the different algorithms, this did not seem to translate into clinically relevant differences in dose distribution for the three more advanced algorithms investigated here. This seems to indicate that any of those three algorithms can be used for lung SBRT plans in actual patients.

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