Evaluation of the analytical anisotropic algorithm in an extreme water–lung interface phantom using Monte Carlo dose calculations

摘要: Our study compares the performance of analytical anisotropic algorithm (AAA), a new superposition-convolution recently implemented in Eclipse (Varian Medical Systems, Palo Alto, CA) Integrated Treatment Planning System (TPS), to that pencil beam convolution (PBC) an extreme (C-shaped, horizontal and vertical boundaries) water-lung interface phantom. Monte Carlo (MC) calculated dose distributions for variety clinical configurations at nominal energies 6-MV 18-MV are used as benchmarks comparison. Dose profiles extracted three depths (4, 10, 16 cm), two-dimensional (2D) maps differences, difference statistics quantify accuracy both photon-dose calculation algorithms. Results show AAA is considerably more accurate than PBC, with standard deviation differences within region encompassing lung block reduced by factor 2 more. Confidence limits were 4% or less all investigated; confidence ranged from 3.5% 11.2%. Finally, calculations small 4 x beam, which poorly modeled PBC (dose high 16.1%), provided same model beams commonly acceptable situations.