Multi-Leaf Collimator Clearance and Step Resolution
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Solution Overview
Problem
Current radiation therapy systems face challenges in accurately identifying and shaping the radiation field to target specific tissue volumes within a patient's body, particularly due to limitations in multi-leaf collimator design, such as insufficient clearance and resolution, which can hinder effective treatment, especially for larger patients or deeply located tumors.
Innovation Solution
A high-resolution multi-leaf collimator system with a clearance distance of at least 400 mm between the collimator and the isocenter, featuring leaves with a step resolution of 3 mm or less, and a gantry system that allows for precise adjustment and control of the radiation field shape using a computer-controlled positioning system, enabling precise radiation field shaping and accommodation of various patient sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the clearance distance between the MLC and isocenter is increased to accommodate larger patients, then the adaptability for different patient sizes is improved, but the device complexity increases
Solution Approach 1:
The MLC system employs dynamic positioning capabilities with computer-controlled adjustment mechanisms that allow the clearance distance to be optimized for each treatment scenario. The leaves can be precisely positioned at various distances from the isocenter (e.g., 100mm, 200mm, 300mm, or 400mm) depending on patient size and treatment requirements, providing adaptability without permanent structural modifications.
Solution Approach 2:
The system allows changing the operational parameters of the MLC, specifically the clearance distance parameter, to accommodate different patient sizes. By adjusting this parameter dynamically rather than designing for maximum clearance in all cases, the system achieves versatility while maintaining manageable device complexity.
2Manufacturing precision
If the step resolution of the MLC leaves is decreased to 3 mm or less for high resolution field shaping, then the manufacturing precision is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The MLC is divided into multiple independent leaves that can be manufactured separately with standard precision techniques. Each leaf contributes to the overall resolution through its individual positioning capability rather than requiring the entire structure to be manufactured with ultra-high precision in one piece, making manufacturing more feasible.
Solution Approach 2:
The system replaces purely mechanical precision manufacturing with a combination of mechanical structure and computer-controlled positioning systems. The precise positioning is achieved through controlled movement and digital control rather than relying solely on manufacturing tolerances, reducing the difficulty of manufacture while maintaining high resolution.
3Reliability
If the clearance distance is increased to 400 mm for deep tumors, then the treatment depth capability is improved, but the device complexity increases
Solution Approach 1:
The MLC system provides dynamic adjustment of the clearance distance to 400mm when treating deep tumors, rather than being fixed at a single distance. This dynamic capability allows the system to adapt to different treatment depths while using the same base structure, improving treatment capability without proportionally increasing device complexity.
Data Source
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Figure 1B
Figure 1C
AI summary
A system and method are provided for a high resolution radiation treatment system which provide for projecting a field of radiation energy at targeted patient tissue. The system uses a multi-leaf collimator (108), which is positioned such that a significant clearance (L1) is provided between the multi-leaf collimator and the isocenter plane (106) where the targeted tissue is located. The leaves of the multi- leaf collimator (108) are designed to provide for high step resolution in the projected radiation energy shape. Additionally, an embodiment of the system and method herein can provide for a high step resolution in the projected radiation energy shape, and for a dose calculation matrix which has matnx units which coincide with the high step resolution in the projected radiation shape.