Multi-Leaf Collimator Gap Adjustment for Collision and Leakage Control
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Solution Overview
Problem
In radiation therapy, multi-leaf collimators (MLCs) face challenges in avoiding collisions between opposing leaf ends, which can damage the leaves or drive mechanism, and in minimizing radiation leakage through gaps between leaves, which can result in unintended tissue exposure.
Innovation Solution
The method involves determining an effective cross-layer leaf gap between leaf pairs in a multi-layer MLC, causing the leaves to move to form this gap, and adjusting in-layer leaf gaps to ensure they are no less than a threshold, thereby minimizing collisions and radiation leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a minimum gap is maintained between opposing leaves to avoid collisions, then the reliability of the MLC is improved, but radiation leakage through the gap increases causing higher actual dose
Solution Approach 1:
The patent introduces a multi-layer leaf structure where leaves are arranged in multiple layers along the radiation beam path. By adding this spatial dimension (multiple layers), the system can maintain larger in-layer gaps for safety while achieving effective cross-layer gap control for radiation shielding, thus resolving the contradiction between collision avoidance and radiation leakage prevention
Solution Approach 2:
The patent dynamically adjusts leaf positions and gap sizes based on treatment requirements. The controller modifies the effective cross-layer gap and in-layer gap parameters in real-time, allowing the system to optimize between safety margins and radiation dose control for different treatment scenarios
2Ease of operation
If the in-layer leaf gap is increased to avoid collisions, then the ease of operation is improved, but radiation leakage through the gap increases
Solution Approach 1:
By utilizing multiple layers of leaves, the system can increase in-layer gaps for easier and safer operation while compensating through cross-layer positioning. The layered structure provides an additional dimension for radiation shielding, allowing larger operational gaps without increasing radiation leakage
Solution Approach 2:
The controller acts as an intermediary that coordinates leaf positions across multiple layers. It ensures that when in-layer gaps are increased for safety, the effective cross-layer gap is appropriately controlled to maintain radiation shielding, thus mediating between operational ease and radiation protection
3Productivity
If leaves are moved faster to improve treatment efficiency, then productivity is improved, but the risk of collision between opposing leaves increases
Solution Approach 1:
The multi-layer structure provides additional spatial dimensions for leaf positioning, allowing faster movement within layers while maintaining safety through cross-layer coordination. Leaves can move quickly in their own layer while the layered arrangement and controller prevent collisions by managing positions across layers
Data Source
AI summary
The disclosure provides systems and methods for adjusting a multi-leaf collimator (MLC). The MLC includes a plurality of cross-layer leaf pairs, each cross-layer leaf pair of the plurality of cross-layer leaf pairs includes a first leaf located in a first layer of leaves and a second leaf opposingly located in a second layer of leaves. For at least one cross-layer leaf pair, an effective cross-layer leaf gap to be formed between the first leaf and the second leaf may be determined; at least one of the first leaf or the second leaf may be caused to move to form the effective cross-layer leaf gap; and an in-layer leaf gap may be caused, based on the effective cross-layer leaf gap, to be formed between the first leaf and an opposing first leaf in the first layer. A size of the in-layer leaf gap may be no less than a threshold.