A comparison of two commercial treatment planning systems fo IMRT

Abstract

This study compared the clinical functionality of BrainSCAN (BrainLAB) and Helios (Eclipse, Varian) for intensity modulated radiation therapy treatment planning with the aim of identifying practical and technical issues. The study considered implementation and commissioning, dose optimization, and plan assessment. Both systems were commissioned for the same 6 MV photon beam equipped with a high resolution multileaf collimator (Varian Millennium 120 leaf). The software was applied to three test plans having identical imaging and contour data. Analysis considered three dimensional axial dose distributions, dose volume histograms and monitor unit calculations. The results show that each system requires somewhat different input data to characterize the beam prior to use, so that the same data cannot be used for commissioning. Also, whereas measured beam data was entered directly into Helios with minimal data processing, the BrainSCAN system required configured beam data to be sent to BrainLAB before clinical use. One key difference with respect to system commissioning was that BrainSCAN required high resolution data which necessitated the use of detectors with small active volumes. In terms of functionality, the BrainSCAN system uses a dynamically penalized likelihood inverse planning algorithm and calculates 4 plans at once with various relative weighting of the planning target and organ-at-risk volumes. Helios uses a gradient algorithm which allows the user to make changes to some of the input parameters during optimization. An analysis of the dosimetry output shows that, although the systems are different in many aspects, they each are both capable of producing substantially equivalent dose plans in terms of target coverage and normal tissue sparing.