Proton Stopping Power Map Updates for Precise Therapy Planning
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Solution Overview
Problem
Current proton radiation therapy treatment planning methods face uncertainties due to inaccurate x-ray imaging for relative stopping power maps, patient setup issues, and anatomical changes, leading to potential overshooting or undershooting of the desired stopping depth in the target, causing tissue damage.
Innovation Solution
A method and system using individual proton measurement data for deformable image reconstruction and updating relative stopping power (RSP) maps without requiring entire proton radiography images, employing iterative techniques that minimize deviations and account for measurement uncertainties and correlations between voxels, allowing for efficient and fast updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If x-ray imaging is used for treatment planning to obtain relative stopping power maps, then treatment planning can be performed, but measurement precision of proton range is degraded due to inaccurate conversion from Hounsfield units
Solution Approach 1:
The patent introduces proton radiography as an intermediary measurement technique between x-ray imaging and proton therapy treatment. Proton radiography directly measures proton stopping power along the beam path, serving as a mediator that provides accurate RSP values without the conversion errors inherent in x-ray-based methods. This intermediary measurement enables precise proton range prediction while maintaining ease of treatment planning.
2Measurement precision
If current iterative algorithms are used to update RSP maps with proton data, then improved accuracy can be achieved, but processing time increases due to requirement of reconstructed pRad images
Solution Approach 1:
The patent extracts and utilizes only the essential proton measurement data (proton trajectories and stopping power measurements) from proton radiography, discarding the need for full pRad image reconstruction. By taking out only the necessary information elements required for RSP map updating, the method achieves accurate updates without the time-consuming full image reconstruction process.
Solution Approach 2:
The patent segments the proton radiography data into individual proton measurement records, processing each proton's trajectory and stopping power measurement independently. This segmentation allows direct updating of RSP maps using discrete proton data points without requiring reconstruction of complete radiographic images, significantly reducing processing time while maintaining accuracy.
Data Source
AI summary
Disclosed herein are systems and methods for proton radiation therapy treatment planning that perform deformable image reconstruction and relative stopping power (RSP) maps updating using individual proton measurement data without requiring use of an entire proton radiography image. The systems and methods are capable of using protons from an arbitrary set of angles and/or positions. The iterative method optimally fits protons, while minimizing deviations from the original or deformed RSP map. The systems and methods use a covariance matrix to account for different uncertainties. Each iteration correctly accounts for in the proton data from measurement uncertainties, optimizing the overall fit of the RSP map to the proton data even though each proton does not fit perfectly due to measurement uncertainties. Different weights for the deviations from the original or deformed RSP map may be assigned to different voxels. The different weights may account for correlations in the deviations between voxels.