Radiotherapy Dose Calculation Robustness via Stochastic Perturbation
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Solution Overview
Problem
Current methods for evaluating the robustness of radiotherapy treatment plans are either computationally intensive or provide inaccurate results, failing to account for systematic and random errors within and between fractions, which limits their ability to precisely assess clinical goal fulfillment.
Innovation Solution
A method that approximates dose distributions for various error scenarios by calculating a single beam contribution for each scenario, allowing for efficient and accurate evaluation of treatment plan robustness by considering systematic, interfractional, and intrafractional errors, and calculating voxel-wise dose statistics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exact scenario dose calculations are performed for all possible scenarios, then measurement precision of dose distribution is improved, but productivity is worsened due to time-consuming computations
Solution Approach 1:
The patent segments the dose calculation process by separating the deterministic dose calculation (performed once for the reference scenario) from the stochastic error simulation. The error scenarios are generated by applying random perturbations to the deterministic result, avoiding repeated full dose calculations. This segmentation allows high-precision dose evaluation for multiple scenarios while maintaining computational efficiency.
Solution Approach 2:
The patent performs preliminary deterministic dose calculation for the reference scenario before generating error scenarios. This preliminary action provides the baseline dose distribution that is then perturbed to create multiple error scenarios, eliminating the need to perform complete dose calculations for each scenario and significantly reducing computational time.
2Productivity
If the number of scenario dose calculations is reduced to improve productivity, then computational efficiency is improved, but measurement precision of dose distribution deteriorates
Solution Approach 1:
The patent uses inexpensive, computationally light random perturbation models to generate error scenarios instead of performing expensive full dose recalculations. Each error scenario is created by applying simple random shifts and scaling to the deterministic dose distribution, providing sufficient statistical precision for robustness evaluation at minimal computational cost.
3Reliability
If conventional margin approaches are used to account for setup errors, then reliability of treatment plan is improved, but device complexity increases due to additional planning constraints
Solution Approach 1:
The patent replaces the mechanical/margin-based approach to handling setup errors with a computational/statistical approach. Instead of adding physical margins to the treatment plan, the system uses stochastic simulation of error scenarios combined with deterministic dose calculation to evaluate and optimize plan robustness, simplifying the planning process while improving reliability assessment.
Data Source
AI summary
A method is proposed for evaluating the robustness of a radiotherapy treatment plan. The method comprises, defining a number of scenarios, each comprising one or more errors for each fraction of the plan, including interfractional and/or intrafractional errors, and calculating a dose distribution resulting from the scenario;The robustness of the plan is then evaluated based at least one of the followingi. the probability of fulfilling a set of clinical goals estimated as the clinical goal fulfilment over the scenariosii. the range of DVH values over the scenariosiii. dose statistics for dose distributions defined as voxel-wise aggregates over the scenario doses.