MLC Leaf Positioning for Target Rotation Compensation
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Solution Overview
Problem
Radiation treatment systems face challenges in compensating for rotational movements of targets within the body, particularly due to the limitations of ring-gantry geometry and the expense and discomfort associated with six-dimensional treatment couches, which can lead to additional target motion and increased complexity in collimation systems.
Innovation Solution
The implementation of a target rotation compensation system using a multi-leaf collimator (MLC) that adjusts leaf positions to shift the effective location of the treatment beam, rather than moving the couch or rotating the collimator, thereby automatically compensating for pitch, yaw, and roll setup errors without the need for a rotating collimator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a six-dimensional treatment couch is used to compensate for rotational movement, then the ability to compensate for target rotation is improved, but the system complexity and cost increase significantly
Solution Approach 1:
The invention segments the rotational compensation function from the treatment couch and assigns it to the collimation system. Instead of requiring the entire couch to move in six dimensions, the collimator leaves are independently adjusted to compensate for rotational movements, dividing the compensation task into smaller, manageable components that can be handled by existing system elements.
Solution Approach 2:
The collimation system, originally designed for beam shaping, is given the additional function of rotational compensation. By modifying leaf positions, the same collimator structure serves both its traditional purpose of defining beam geometry and the new purpose of compensating for target rotation, eliminating the need for dedicated rotational compensation mechanisms.
2Adaptability or versatility
If a six-dimensional treatment couch is used to compensate for rotational movement, then the ability to compensate for target rotation is improved, but the cost increases significantly
Solution Approach 1:
The collimation system serves itself by using its existing adjustable leaves to perform rotational compensation. The same mechanical components that define the beam shape are repurposed to correct rotational errors, allowing the system to compensate for target rotation without requiring additional expensive hardware or couch modifications.
Solution Approach 2:
The collimator leaves perform multiple functions: beam shaping and rotational compensation. This multi-functionality eliminates the need for separate rotational compensation mechanisms, significantly reducing system cost while maintaining the ability to compensate for target rotation.
3Adaptability or versatility
If the treatment couch is moved to compensate for rotation, then the target rotation compensation is improved, but patient comfort deteriorates due to additional motion
Solution Approach 1:
Instead of moving the patient on the couch to compensate for rotation, the invention inverts the approach by moving the collimator leaves while keeping the patient stationary. The beam geometry is adjusted to account for rotational misalignment, achieving compensation without subjecting the patient to additional motion or discomfort.
Solution Approach 2:
The collimation system compensates for rotation by adjusting its own leaf positions rather than requiring the patient to be repositioned. This self-adjustment mechanism maintains patient comfort while achieving the desired rotational compensation through beam geometry modification.
4Adaptability or versatility
If a rotating collimator is used to compensate for target rotation, then the rotational compensation capability is improved, but the device complexity increases
Solution Approach 1:
The invention segments the rotational compensation function from a potential rotating collimator mechanism and assigns it to individual adjustable leaves. Each leaf can be independently positioned to achieve the desired beam geometry adjustment, avoiding the complexity of a fully rotating collimator while maintaining rotational compensation capability.
Solution Approach 2:
The collimation system becomes dynamically adjustable through independent leaf positioning rather than requiring physical rotation of the entire collimator. The leaves can be rapidly repositioned to compensate for rotational movements, providing dynamic adaptation without the mechanical complexity of rotation mechanisms.
Data Source
AI summary
A method includes detecting a potential setup error in a radiation treatment delivery session of a radiation treatment delivery system, wherein the setup error corresponds to a change in a current position of a treatment target relative to a prior position of the treatment target, and wherein the change includes a rotation relative to the prior position of the treatment target. The method further includes modifying, by a processing device, one or more planned leaf positions of a multileaf collimator (MLC) of a linear accelerator (LINAC) of the radiation treatment delivery system to compensate for the potential setup error corresponding to the rotation of the prior position of the treatment target.