Quantitative and analytical comparison of isodose distributions for shaped electron fields from ADAC Pinnacle treatment planning system and Monte Carlo simulations

We assess the accuracy of ADAC Pinnacle3 commercial treatment planning system (TPS) in computation of isodose distributions for shaped electron fields. The assessment is based on comparison of dose profiles generated by TPS and a Monte Carlo model for different beam energies, applicator sizes, and percentages of field blocking. Dose differences of up to 14% are observed at the depth of maximum dose. These discrepancies, often ignored in clinical evaluations, are attributable to inadequate modeling of scatter from applicators and blocks by TPS.