Impact of Gaussian uncertainty assumptions on probabilistic optimization in particle therapy.

Impact of Gaussian uncertainty assumptions on probabilistic optimization in particle therapy.
Phys Med Biol. 2020 Apr 27;:
Authors: Wieser HP, Karger CP, Wahl N, Bangert M
Abstract
Range and setup uncertainties in charged particle therapy may induce a discrepancy between planned and delivered dose. Countermeasures based on probabilistic optimization assume a Gaussian probability density to model the underlying range and setup error. While this assumption is generally taken for granted, this work explicitly investigates dosimetric consequences if the actual errors obey a different probability density function (PDF) over the course of treatment than the one used during probabilistic treatment plan optimization. Discrete random sampling was performed for conventionally and probabilistically optimized proton and carbon ion treatment plans utilizing various probability density functions modeling the setup and range error. This method allowed to assess the treatment plan robustness against different probability density functions of conventional and probabilistic plans, which both explicitly assume Gaussian uncertainties. The induced uncertainty in dose was quantified by estimating the expectation value and standard deviation of the RBE-weighted dose for each probability density function on the basis of 2500/5000 random dose samples. Probabilistic dose metrics and standard deviation volume histograms were computed to quantify treatment plan...

Source: Physics in Medicine and Biology - April 26, 2020 Category: Physics Authors: Wieser HP, Karger CP, Wahl N, Bangert M Tags: Phys Med Biol Source Type: research