Program Information
Spatiotemporally Integrated Radiotherapy Plan Optimization
A Adibi*, E Salari, Wichita State University, Wichita, KS
Presentations
TU-D-108-3 (Tuesday, August 1, 2017) 11:00 AM - 12:15 PM Room: 108
Purpose: This research aims at quantifying the extent of potential therapeutic gain that can be achieved from altering the radiation dose distribution over treatment sessions in fractionated radiotherapy.
Methods: A spatiotemporally integrated planning approach is developed, where the spatial and temporal dose modulations are optimized simultaneously. The concept of generalized equivalent uniform biologically effective dose (EUBED) is used to quantify and compare the clinical quality of spatiotemporally heterogeneous dose distributions in target and critical structures. This gives rise to a large-scale non-convex treatment-plan optimization problem, which is solved using global optimization techniques. The spatiotemporally integrated approach is used to design plans that deliver distinct dose distributions over treatment sessions. The plans are compared against those obtained using traditional equivalent uniform dose (EUD)-based planning methods that only allow for time-invariant dose distributions.
Results: The spatiotemporally integrated approach and the traditional EUD-based planning method were both applied to a phantom cancer case (from the test suite by AAPM Task Group 119). The EUBED improvement was calculated for different values of the radio-biological and EUBED parameters. The experimental results show that a gain of up to 16% and 6% for alpha-beta ratio of 2 and 10, respectively, can be obtained over time-invariant dose distributions. In particular, the gain is attributed to the irradiation of different regions of the target at different treatment sessions. Additionally, the trade-off between the therapeutic gain and the number of distinct dose distributions used was quantified, suggesting a diminishing marginal gain as the number of dose distributions increases.
Conclusion: In this research a spatiotemporally integrated radiotherapy planning approach was developed to quantify the additional therapeutic gain due to plan variation over the treatment course. Results validate additional therapeutic gains over time-invariant dose distributions. The extent of this gain depends on radio-biological and EUBED parameters.
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