Collimator Control for Predictive Target Tracking in Radiation Therapy
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Solution Overview
Problem
Conventional radiation therapy for moving target volumes faces challenges in achieving efficient treatment delivery due to patient motion, leading to increased exposure of healthy tissues and inefficiencies in resource utilization, despite existing methods like large irradiation fields and dynamic collimator control.
Innovation Solution
A system that determines the trajectory of a target volume, develops a treatment plan with specific irradiation fields corresponding to portions of the trajectory, and controls a collimator to restrict the treatment beam to these fields, ensuring accurate and efficient delivery by monitoring the target's position and delivering the beam only when it reaches designated control points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large irradiation field is used to account for target excursions, then the target volume is covered throughout its motion, but surrounding healthy tissue receives increased radiation exposure
Solution Approach 1:
The trajectory is divided into multiple portions with designated control points, and the irradiation field is segmented to match each portion. The collimator dynamically adjusts the field shape and position to correspond to specific trajectory segments, delivering radiation only when the target is within the predetermined tolerance zone at each control point, thereby covering the moving target while minimizing exposure to healthy tissues.
2Object-affected harmful factors
If gated treatment is used to deliver beam only during minimal movement windows, then healthy tissue exposure is reduced, but treatment duty cycle and efficiency decrease significantly
Solution Approach 1:
The system continuously monitors the target volume's position along its predetermined trajectory and provides real-time feedback to the collimator control system. Based on this feedback, the collimator dynamically adjusts the irradiation field to maintain alignment with the target within the tolerance zone, enabling continuous or near-continuous beam delivery while keeping healthy tissue exposure minimal, thus improving treatment duty cycle compared to gated approaches.
3Manufacturing precision
If dynamic collimator control is used to continuously reshape leaves to track target, then treatment precision is improved, but device complexity and operational difficulty increase
Solution Approach 1:
The trajectory of the target volume is determined in advance through imaging and registration systems, and control points with associated irradiation field parameters are predetermined along this trajectory. The collimator is controlled to match these predetermined field configurations at each control point, rather than requiring continuous real-time reshaping. This approach maintains treatment precision while significantly reducing the complexity of collimator control.
4Measurement precision
If dynamic collimator control with sophisticated imaging systems is implemented, then target tracking precision is improved, but system complexity and difficulty in achieving desired precision levels increase
Solution Approach 1:
The target volume's trajectory is determined in advance using imaging and registration systems before treatment delivery. Control points and corresponding irradiation field parameters are predetermined along this trajectory. During treatment, the system only needs to monitor whether the target reaches these predetermined control points and adjust the collimator accordingly, rather than requiring continuous sophisticated imaging and real-time trajectory calculation, thus reducing system complexity while maintaining precision.
Data Source
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AI summary
A system includes a processor to perform determ ination (S510) of a trajectory of a target volume, determination (S520) of a treatment plan identifying a portion of the trajectory of the target volume and an irradiation field (610) corresponding to the portion of the trajectory, the portion of the trajectory commencing at a control point of the trajectory, control (S540) of a collimator (300) to restrict a treatment beam to the irradiation field, monitoring (S550) of the trajectory of the target volume until it is determined that the trajectory is at the control point, and delivery (S560) of the treatment beam to the irradiation field in response to determining that the trajectory of the target volume is at the control point.