AbstractID: 9140 Title: A comparison between Direct Aperture Optimization and two commercial
IMRT systems
Recently, significant attention has been paid to aperture-based optimization for IMRT. These
methods deviate from traditional IMRT techniques in that apertures are determined using a rulebased algorithm or automatically using computer optimization Direct Aperture Optimization
(DAO) is a method that utilizes the latter technique and simultaneously optimizes the relative
aperture weights. With DAO, the user pre-specifies the maximum number of segments to deliver
from each beam direction, resulting in a significant reduction in the number of segments as
compared with conventional IMRT techniques.
Some skepticism has developed regarding the proposal that similar treatment plans can be
generated with DAO using a significantly smaller number of segments as compared with
conventional IMRT techniques. In this talk, we attempt to dispel some of this skepticism by
performing a rigorous comparison between DAO and two commercial inverse treatment planning
systems, Pinnacle and Corvus.
Since different systems use different dose calculation algorithms, doubt can be cast on comparisons
between the systems. To minimize this, we extract the final fluence maps from all three systems
and use them as input to a home-grown dose calculation algorithm to perform the final dose
calculation.
Using the three systems, we tuned the optimization parameters to create similar plans for five cases:
lung, head-neck, breast, prostate, and pancreas. Identical angles and beam energies were used for
each case for all systems. For the DAO plans, we specified a maximum of five apertures per beam
direction. The results demonstrate that DAO can produce comparable plans using 50-90% fewer
segments.