Intra-fraction Motion Management Using Optical Tracking
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Solution Overview
Problem
Current radiation therapy systems face challenges in accurately and reliably monitoring intra-fraction patient motions, leading to potential damage to surrounding tissue due to the limitations of existing motion management systems, which are often complex, invasive, expose patients to radiation, or are not compatible with gamma radiation therapy systems.
Innovation Solution
An optical tracking system using patient and reference markers, preferably IR-emitting markers, to detect movements by capturing images and determining relative shifts within a local coordinate system, allowing for precise monitoring of patient motions without ionizing radiation, and integrating seamlessly with radiation therapy systems like Perfexion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If X-ray imaging or optical imaging methods are used for intra-fraction motion management, then motion detection capability is provided, but the system complexity and cost increase significantly
Solution Approach 1:
The patent extracts only the essential motion detection function from complex imaging systems by using simple IR markers and a single camera. Instead of using complex X-ray or optical imaging systems, the invention uses minimalistic IR markers placed on the patient and reference markers placed on the treatment couch, tracked by a single camera system, thereby significantly reducing system complexity while maintaining motion detection capability.
Solution Approach 2:
The patent employs inexpensive IR markers that can be easily placed and removed from the patient and treatment couch. These markers are simple reflective or emissive elements rather than complex imaging devices, reducing both the cost and complexity of the system while providing sufficient motion detection accuracy for radiation therapy monitoring.
2Reliability
If X-ray imaging is used for intra-fraction motion management, then motion detection is achieved, but patient radiation exposure increases
Solution Approach 1:
The patent replaces ionizing radiation-based X-ray imaging with non-ionizing optical/infrared imaging. Instead of using X-rays to capture motion, the system uses IR markers that reflect or emit infrared light, detected by a camera. This substitution eliminates radiation exposure to the patient while maintaining the ability to detect and monitor motion throughout the radiation therapy treatment.
3Measurement precision
If invasive solutions are used for intra-fraction motion management, then motion monitoring accuracy is improved, but patient comfort and safety deteriorate
Solution Approach 1:
The patent uses IR markers as intermediaries between the patient's body and the motion detection system. Instead of directly measuring body movements through invasive sensors, the system places markers on the patient's surface and on the treatment couch, then uses optical detection to infer motion. This intermediary approach maintains measurement accuracy while avoiding direct invasive contact with the patient's body.
4Ease of operation
If surface tracking systems like C-rad catalyst are used, then non-invasive motion tracking is achieved, but the ability to detect small motions of the target beneath the mask is lost
Solution Approach 1:
The patent addresses the limitation of surface tracking by adding a reference dimension. Instead of only tracking the patient's surface markers, the system also places reference markers on the treatment couch and establishes a coordinate system relative to these references. This dimensional expansion allows the system to detect and compensate for small motions of the target beneath the mask by comparing the relative positions of patient markers and reference markers in three-dimensional space.
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 solution provides accurate and reliable intra-fraction motion detection, reducing the risk of tissue damage by continuously tracking patient movements and automatically interrupting treatment if significant deviations occur, while being user-friendly, cost-effective, and compatible with imaging methods like CT-imaging.
Implementation Method 1
An optical tracking system using patient and reference markers, preferably IR-emitting markers, to detect movements by capturing images
Data Source
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AI summary
The present invention relates to the field of radiation therapy. In particular, the invention concerns systems and methods for monitoring intra-fraction motions of patients in connection with treatment cancer in radiation therapy system. A patient marker is attached on the nose of the patient and images of the patient marker and reference markers of a reference tool is captured at predetermined time intervals, wherein the reference tool comprises The reference markers are arranged in a defined positions relative to a patient fixation arrangement for fixation of the patient during treatment. A position of the patient marker relative the reference markers is determined based on images captured by an optical tracking system, wherein changes in the position provide information if the patient or a part of the patient has moved.