Transverse Motion Multileaf Collimator for Tumor Tracking
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Solution Overview
Problem
Conventional radiation therapy techniques face challenges in accurately delivering treatment doses due to patient organ movement, particularly during breathing, which can result in overdose to healthy organs or underdose to tumors, and require lengthy treatment times or undesirable patient movement.
Innovation Solution
A multileaf collimator system with a support body and beam blocking leaves that can move transversely to the leaf travel direction, allowing the entire collimation assembly to rotate about the radiation source, enabling precise adjustment and tracking of tumor motion without the need for individual leaf movement in non-matching directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gating the radiation beam is used to account for organ movement, then treatment accuracy is improved, but treatment time increases significantly
Solution Approach 1:
The collimator is made dynamically movable in the transverse direction to track organ motion in real-time, allowing continuous treatment without beam gating. The motion assembly enables the collimator to adapt its position dynamically during treatment, maintaining accuracy while eliminating treatment interruptions.
Solution Approach 2:
A motion assembly acts as an intermediary mechanism between the fixed radiation source and the moving organ, allowing the collimator to compensate for organ motion without requiring patient movement or beam interruption. This intermediary mechanism resolves the conflict between maintaining fixed beam geometry and tracking moving targets.
2Measurement precision
If moving the patient on a tracking couch is used to keep the tumor stationary, then treatment accuracy is improved, but patient comfort deteriorates and uncertainties increase
Solution Approach 1:
Instead of moving the patient to track the tumor, the invention inverts the approach by moving the collimator to track the tumor's motion. This inversion eliminates patient movement entirely, maintaining treatment accuracy while avoiding all associated discomforts and uncertainties.
Solution Approach 2:
The collimator performs self-adjustment in the transverse direction through the motion assembly, automatically tracking organ motion without requiring external patient movement or complex couch mechanisms. This self-service capability maintains accuracy while simplifying the overall system and improving patient comfort.
3Device complexity
If conventional multileaf collimators are used with leaves movable only in one direction, then device complexity is reduced, but adaptability to tumor motion deteriorates
Solution Approach 1:
The invention adds a second dimension of motion to the collimator by enabling transverse movement in addition to the conventional longitudinal leaf motion. This dimensional enhancement allows the collimator to accommodate tumors moving in any direction within the treatment field, significantly improving adaptability while maintaining reasonable structural complexity.
Data Source
Figure 1
Figure 2~3B
Figure 4A~5A
AI summary
A collimation assembly includes a multileaf collimator and motion assembly. The multileaf collimator includes a support body and a plurality of pairs of beam blocking leaves supported by the support body. The beam blocking leaves are longitudinally movable in a first direction. The motion assembly includes an actuator and a guide assembly operable to move the support body and thereby allowing the plurality of pairs of beam blocking leaves to move in a second direction generally transverse to the first direction.