Desynchronizing Beam Scanning from Target Motion for Uniform Dose Distribution
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Solution Overview
Problem
Cyclic movements of a target area, such as a tumor due to breathing or organ movement, can lead to deviations in the dose distribution during irradiation, resulting in local overdoses and underdoses when the irradiation and movement are synchronized, making it challenging to achieve a uniform target dose distribution.
Innovation Solution
Desynchronizing the irradiation process with the cyclic movement by adjusting control parameters like scanning speed, temporal distribution of runs, and beam path, and dividing the irradiation into multiple passes to minimize local dose deviations, ensuring that the target dose distribution is maintained within acceptable limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the beam scans grid points sequentially to irradiate the target area, then the target area can be covered completely, but local dose deviations occur due to synchronization with cyclic movement
Solution Approach 1:
The patent applies dynamics by making the irradiation process adaptive to the moving target. The beam scanning system dynamically adjusts its operation based on real-time or predicted target position, transitioning from a static grid scanning approach to a dynamic tracking approach that compensates for cyclic movements, thereby maintaining dose uniformity while covering the entire target area.
Solution Approach 2:
The patent implements feedback mechanisms where the system monitors or predicts target position and uses this information to adjust the beam scanning pattern. This feedback loop ensures that the beam consistently targets the correct grid points despite cyclic movements, resolving the contradiction between complete coverage and dose uniformity.
2Manufacturing precision
If multiple passes are used to irradiate the target area, then dose distribution uniformity improves, but irradiation time increases
Solution Approach 1:
The patent segments the irradiation process into multiple passes, where each pass targets specific grid points or regions. This segmentation allows systematic coverage of the target area with controlled dose accumulation, improving uniformity while managing time through structured progression rather than repeated random scanning.
Solution Approach 2:
The patent employs preliminary actions by pre-calculating or pre-planning the scanning path and grid point sequence based on predicted target movement. This allows the system to execute multiple passes efficiently without redundant scanning, reducing overall irradiation time while maintaining dose uniformity through strategic point selection.
3Productivity
If the beam scanning speed is increased, then irradiation efficiency improves, but dose distribution precision deteriorates
Solution Approach 1:
The patent applies dynamics by making the scanning speed variable rather than constant. The system adjusts the beam scanning speed dynamically based on the target's predicted position, movement characteristics, and the current pass number, allowing high speed during stable phases and reduced speed when precision is critical, thus balancing efficiency and precision.
Solution Approach 2:
The patent changes operational parameters including scanning speed, beam intensity, and grid point selection based on the irradiation pass number and target movement state. By modulating these parameters adaptively, the system achieves high irradiation efficiency while maintaining precise dose distribution through coordinated parameter adjustments rather than fixed-speed scanning.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces local dose deviations to less than 30%, averaging out incorrect dosages over multiple passes and ensuring a more uniform dose distribution across the target area, even in the presence of cyclic movements.
Implementation Method 1
particle beams, in particular with protons, α-particles and carbon nuclei, are used in the irradiation of tumors
Implementation Method 2
towards their end they pass through a maximum in the energy deposition (Bragg peak)
Implementation Method 3
the beam moves to several grid points in a target grid one after the other
Implementation Method 4
deflection magnets etc. are set to the next raster point
Implementation Method 5
a depth modulation device, in which the penetration depth of the particle beam is continuously modulated
Implementation Method 6
by changing the energy of the beam
Data Source
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AI summary
The invention relates to a method for depositing an intended dose distribution in a cyclically moved target area (102) by multiple irradiation with a beam (105) which approaches grid points of a target grid in at least two passes, in which grid points are approached in succession in each of the passes. It is characterized by the following steps: setting the maximum tolerated local deviation from the intended dose distribution, de-synchronizing the procedure of the irradiation and the cyclical movement of the target area (102), and dividing the irradiation of the target area into a sufficient number of passes such that local deviations from the intended dose distribution correspond to at most the maximum tolerated deviation from the intended target distribution. Furthermore, the invention also relates to an irradiation device for carrying out such a method and a method for determining the control parameters for this irradiation device.