Radiation Therapy Planning Safety Margin Adjustment
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Solution Overview
Problem
Current radiation therapy planning methods are not robust enough to account for inaccuracies such as target volume movement, positioning errors, and changes in tissue density, leading to potential deviations in the delivered dose from the intended plan.
Innovation Solution
A method and device that determine a safety margin and weighting of irradiation fields based on density heterogeneity indices to create a robust radiation treatment plan, which includes specifying a data set representing the object to be irradiated, determining the target volume, and calculating a measure for density heterogeneity to adjust the safety margin and entry angle of the treatment beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety margin is placed around the target volume to account for inaccuracies, then the reliability of dose delivery is improved, but the manufacturing precision of the irradiation plan deteriorates due to increased uncertainty in dose distribution
Solution Approach 1:
The method performs preliminary determination of density heterogeneity measures and calculates appropriate safety margins before finalizing the irradiation plan. By pre-assessing the impact of tissue density variations and positioning inaccuracies, the system can optimize the safety margin size in advance, ensuring reliable dose delivery while minimizing unnecessary expansion of the safety margin that would compromise plan precision
Solution Approach 2:
The system dynamically adjusts the safety margin parameter based on the determined density heterogeneity measure. Instead of using a fixed safety margin, the method modifies this parameter according to the specific characteristics of each irradiation scenario, allowing the safety margin to be larger when density heterogeneity is high and smaller when density is more uniform, thus resolving the contradiction between reliability and precision
2Reliability
If the safety margin is increased to account for target volume movement and positioning errors, then the reliability of treatment is improved, but the dose distribution homogeneity deteriorates
Solution Approach 1:
The method applies different safety margin values to different regions of the target volume based on local density heterogeneity characteristics. By determining density measures for specific areas and adjusting safety margins locally rather than uniformly across the entire target volume, the system maintains dose distribution homogeneity in regions where it is already good while providing enhanced reliability in regions with higher uncertainty
Solution Approach 2:
The system performs preliminary calculation of density heterogeneity measures and determines optimal safety margin values before dose distribution calculation. This preliminary assessment allows the optimization of both reliability and homogeneity simultaneously by finding the appropriate safety margin size that ensures reliable dose delivery without excessively compromising dose distribution uniformity
Data Source
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AI summary
The invention relates to a method for creating a treatment plan, comprising the following steps: specifying a data set in which an object to be treated is represented; determining a target volume to be treated within the object; determining a measure that characterizes density heterogeneity for an area that will be hit by the planned treatment beam; determining a safety margin for the target volume to be treated depending on the determined measure; and further, a method comprising the following steps: specifying a data set in which an object to be treated is represented; determining a target volume to be treated within the object; specifying at least two treatment fields with which the target volume is treated from different directions.For each irradiation field, determine a measure that characterizes the density heterogeneity for an area that will be irradiated by the respective irradiation field during the planned irradiation; determine a weighting of the at least two irradiation fields depending on the determined measures. The invention further relates to devices for carrying out the methods.