Beam-Off Motion Thresholds for Breath-Hold Radiation Therapy
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Solution Overview
Problem
Conventional radiation therapy systems face challenges in accurately managing patient motion during breath-hold-based treatments, leading to extended breath-holds and discomfort for patients due to frequent beam holds, which are often based on external measurements that do not precisely represent internal anatomical structures.
Innovation Solution
Implementing beam-off motion thresholds determined dosimetrically for individual patients, which are adjusted dynamically during treatment based on dose acquisition in non-target tissues, to minimize dose trade-offs between target volume and critical anatomical structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If beam-off thresholds are based on external measurements, then device complexity is reduced, but measurement precision deteriorates because external measurements do not precisely represent internal anatomical structures
Solution Approach 1:
The patent introduces an intermediary computational model that maps external measurements to internal anatomical structures. This model acts as a mediator between the simple external sensors and the complex internal target volume, allowing the system to maintain both low device complexity and high measurement precision by translating external motion data into accurate internal position estimates through dosimetrically-informed transformations.
Solution Approach 2:
The patent creates a virtual copy or representation of the internal target volume position based on external measurements. Instead of directly measuring the internal structures, the system generates a computational model that replicates the behavior and position of the target volume using external sensor data, thereby avoiding the need for complex internal sensing while maintaining measurement accuracy.
2Reliability
If beam-off thresholds are set conservatively to ensure dose limits are not violated, then reliability is improved, but productivity deteriorates due to frequent beam holds and extended breath-hold durations
Solution Approach 1:
The patent implements dynamic beam-off thresholds that are adjusted in real-time based on the actual position and motion of the target volume. Instead of using static, conservatively low thresholds that cause frequent beam holds, the system continuously adapts the thresholds to match the dosimetrically-determined safe limits, allowing the beam to remain on longer while still ensuring dose compliance, thus improving treatment efficiency without sacrificing reliability.
Solution Approach 2:
The system incorporates feedback loops that continuously monitor target volume position and adjust beam-off thresholds accordingly. By using real-time position data from external measurements and the computational model, the system provides feedback to the control system, which then dynamically modifies the beam-off thresholds to optimize the balance between dose limit compliance and treatment delivery efficiency.
3Measurement precision
If dosimetrically-determined beam-off thresholds are implemented, then measurement precision is improved, but device complexity increases due to the need for dosimetric analysis and dynamic threshold adjustment
Solution Approach 1:
The patent performs dosimetric analysis and threshold determination in advance, before the actual treatment delivery. By pre-calculating the beam-off thresholds based on dosimetric simulations and patient-specific anatomy, the system reduces the computational complexity during real-time treatment. The pre-computed thresholds are then applied during treatment with minimal real-time processing, thereby achieving high measurement precision without excessive device complexity during operation.
Data Source
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AI summary
A computer-implemented method (1100) of performing a treatment fraction of radiation therapy comprises: determining (1102) a current position of a target volume of patient anatomy; based on the current position of the target volume, computing (1131) an accumulated dose for non-target tissue proximate the target volume; determining (1132) that the accumulated dose is less than a current value for a dose budget of the non-target tissue; and in response to the accumulated dose being less than the current value for the dose budget, applying (1142) a treatment beam to the target volume while the target volume is in the current position.