Fiber Bragg Grating Motion Tracking for Adaptive Radiotherapy
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Solution Overview
Problem
Current radiation therapy techniques face challenges in accurately tracking interfraction and intrafraction motion, leading to deviations in the delivered radiation dose due to limited spatial and temporal resolution of existing motion tracking methods, which can result in underdosing of tumors and overdosing of normal tissues.
Innovation Solution
A therapy system that uses optical fibers with fiber Bragg gratings as surrogates for targets and organs at risk, providing high spatial and temporal resolution for real-time motion tracking, combined with dosimeters for precise dose measurement, allowing for adaptive treatment planning and motion compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image-based approaches (CBCT, fluoroscopy, MRI, ultrasound) are used to track motion, then spatial resolution is improved, but temporal resolution deteriorates due to additional dose deposition limiting frequent usage
Solution Approach 1:
The patent introduces optical fibers with fiber Bragg gratings as intermediary sensors that indirectly track organ motion without requiring repeated high-dose imaging. These fibers are implanted near the target and convert mechanical deformation into optical signals, providing continuous motion information without the dose constraints of CBCT or fluoroscopy.
Solution Approach 2:
The patent replaces the mechanical/imaging-based motion detection system (CBCT, fluoroscopy) with an optical sensing system based on fiber Bragg gratings. This substitution eliminates the need for repeated ionizing radiation exposure while providing continuous high-resolution motion tracking through optical wavelength measurements.
2Loss of time
If non-image-based approaches (EM tracking) are used to track motion, then temporal resolution is improved, but spatial resolution deteriorates due to limited transponder count
Solution Approach 1:
The patent segments the motion tracking function into multiple distributed fiber optic sensors along the length of the optical fiber. Each fiber Bragg grating acts as an independent sensing point, providing high spatial resolution through distributed measurements rather than relying on a limited number of discrete transponders.
Solution Approach 2:
The patent changes the measurement parameter from electromagnetic field tracking to optical wavelength detection. Fiber Bragg gratings measure strain and position through shifts in reflected wavelength, providing higher spatial precision compared to EM tracking while maintaining high temporal resolution through continuous optical monitoring.
3Reliability
If margins are increased to account for motion uncertainty, then target coverage is improved, but dose to surrounding normal tissue increases
Solution Approach 1:
The patent implements real-time feedback through continuously monitored optical fiber sensors that track actual organ motion during treatment. This feedback information is used to dynamically adjust the radiation beam positioning and intensity, eliminating the need for static safety margins and enabling precise dose delivery that spares surrounding normal tissue.
Solution Approach 2:
The patent transitions from static treatment planning with fixed margins to dynamic adaptive radiation therapy. The system continuously updates motion compensation parameters based on real-time optical fiber measurements, allowing the treatment plan to adapt dynamically to actual organ positions and reduce unnecessary dose to healthy tissues.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables more accurate tracking of targets and organs at risk with high temporal and spatial resolution, reducing treatment margins, facilitating hypofractionation, and verifying the delivered dose distribution, thereby improving the precision and efficacy of radiation therapy.
Implementation Method 1
optical fibers with fiber Bragg gratings as surrogates for targets and organs at risk, providing high spatial and temporal resolution for real-time motion tracking
Implementation Method 2
dosimeters for precise dose measurement, allowing for adaptive treatment planning and motion compensation
Data Source
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AI summary
A therapy system (10) includes one or more processors (98, 100). The processors (98, 100) are programmed to receive one or more of: (1) dosimetric data from dosimeters (26, 28, 202, 204, 206, 208, 210, 212) implanted within a patient and/or positioned on a vest (200); and (2) motion data from surrogates (18, 20, 22, 24) implanted within the patient. Based on the motion data, a current location and/or shape of a surrogate (18, 20, 22, 24) is determined and deviations between the current location and/or shape and a reference location and/or shape are determined. Based on the dosimetric data, a delivered dose distribution is compared with a planned dose distribution and deviations therebetween are determined. The deviations determined from the motion data and/or the dosimetric data are employed for adaptive planning, alignment, post treatment analysis, and safety.