Fiducial-less Tracking of Moving Bony Structures
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Solution Overview
Problem
Current radiosurgery techniques face challenges in accurately tracking moving targets during radiation treatment due to patient movement caused by respiration, with methods like breath-hold irradiation being inconvenient and fiducial-based tracking being uncomfortable and risky for patients.
Innovation Solution
The implementation of fiducial-less tracking using 4D CT scans and digitally reconstructed radiographs (DRRs) to determine the location of movable bony structures, allowing for accurate targeting without the need for implanted fiducials, by comparing intra-operative images with pre-treatment DRR pairs to track the target region's motion pattern and deliver radiation effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fiducials are implanted into the patient's body to track the target region, then the tracking accuracy is improved, but the patient comfort and safety are worsened due to discomfort and implantation complications
Solution Approach 1:
The patent extracts and removes the fiducial markers from the patient's body by using virtual fiducials generated from 4D CT imaging data. Instead of physically implanting markers, the system creates digital representations of fiducial points based on pre-treatment imaging, eliminating all physical implantation while maintaining tracking functionality through software-based registration and transformation algorithms.
Solution Approach 2:
The patent creates a digital copy of the fiducial markers by generating virtual fiducials from 4D CT scan data. These virtual fiducials are stored as part of the treatment plan and used for registration purposes, replacing the need for physical fiducials while maintaining the same functional role in target region tracking through computational geometry and image processing.
2Object-affected harmful factors
If fiducials are attached to the patient's skin to track the target region, then the patient comfort is improved, but the tracking accuracy is worsened because the fiducials are farther from the target region
Solution Approach 1:
The patent replaces the mechanical attachment of physical fiducials to the skin with a computational imaging system. The 4D CT scan captures the three-dimensional position of bony structures and soft tissue landmarks, and software algorithms automatically register these to create virtual fiducials at the exact location of the target region, eliminating the distance problem inherent in skin-attached markers.
3Measurement precision
If breath-hold irradiation is used to track the target region, then the tracking accuracy is improved, but the ease of operation is worsened due to patient training requirements and discomfort
Solution Approach 1:
The patent performs all target region localization and fiducial registration actions during the pre-treatment planning phase using 4D CT imaging. The virtual fiducials and treatment plan are prepared in advance, so that during actual treatment delivery, the system simply executes the pre-computed plan without requiring real-time patient cooperation or training, eliminating the breath-hold requirement while maintaining accuracy.
Data Source
AI summary
A method and an apparatus for fiducial-less tracking of a volume of interest (VOI) have been presented. In some embodiments, a pair of intra-operative images of a portion of a patient is generated during treatment of a target region in the patient to show a bony structure of the patient. The bony structure shown is movable responsive to respiration of the patient. Then the pair of intra-operative images is compared with a set of digitally reconstructed radiograph (DRR) pairs, generated from volumes of four-dimensional (4D) diagnostic imaging data, to determine a location of the movable bony structure that corresponds to a particular volume of the 4D diagnostic imaging data.