3D Tumor Tracking via Single Gantry X-Ray Projection
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Solution Overview
Problem
Radiation therapy apparatuses face challenges in accurately tracking three-dimensional positions of moving targets, such as tumors, during CBCT imaging due to the limitations of single fluoroscopic X-ray imaging devices installed on the gantry, which restricts the ability to acquire three-dimensional information effectively.
Innovation Solution
A radiation therapy apparatus that utilizes a gantry with a fluoroscopic X-ray generation device and an X-ray flat panel detector for acquiring fluoroscopic X-ray images, combined with a CBCT imaging device and a two-dimensional moving object tracking system, which calculates three-dimensional coordinates of the tracking target object by determining its position within a predefined movement area and respiratory phase, allowing for accurate tracking and image reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single fluoroscopic X-ray imaging device is installed on the gantry, then the device complexity is reduced, but the measurement precision of three-dimensional tracking is insufficient
Solution Approach 1:
The patent applies dimensionality change by using a single fluoroscopic X-ray imaging device to capture images from multiple gantry angles, transforming two-dimensional projection images into three-dimensional position information through mathematical reconstruction. This allows accurate three-dimensional tracking without requiring multiple imaging devices, thus maintaining simple device configuration while achieving high measurement precision.
2Measurement precision
If fluoroscopic X-ray images are captured intermittently during gantry rotation, then the productivity of CBCT imaging is improved, but the measurement precision of tracking moving tumors is reduced due to motion blur
Solution Approach 1:
The patent applies preliminary action by tracking the tumor position on intermittently captured fluoroscopic images and using this tracking information to guide selective reconstruction. Only images captured when the tumor is within the acceptable movement range are used for CBCT reconstruction, ensuring high positional accuracy while maintaining imaging efficiency through targeted rather than continuous reconstruction.
Solution Approach 2:
The patent applies local quality by implementing motion range judgment that evaluates each captured image individually. The system determines whether to include each image in the reconstruction based on local motion characteristics of the tumor in that specific image, rather than applying a uniform reconstruction approach to all images. This selective reconstruction maintains high precision for tracked regions while preserving overall imaging productivity.
3Measurement precision
If the gantry rotates around the patient to capture images from various angles, then the measurement precision of three-dimensional reconstruction is improved, but the duration of the imaging process increases
Solution Approach 1:
The patent applies partial action by performing CBCT reconstruction only for images where the tumor movement is within the predetermined acceptable range. Instead of reconstructing all images captured during gantry rotation, the system selectively reconstructs only those images that meet the motion criteria, thereby reducing total reconstruction time while maintaining three-dimensional image quality through focused processing of relevant data.
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 enables highly accurate three-dimensional tracking and acquisition of high-quality four-dimensional CBCT images, improving the precision of tumor positioning and reducing radiation exposure to normal tissues by determining the respiratory phase accurately.
Implementation Method 1
a fluoroscopic X-ray generation device and an X-ray flat panel detector that are installed on the gantry and used for acquiring a fluoroscopic X-ray image
Implementation Method 2
an X-ray flat panel detector that are installed on the gantry and used for acquiring a fluoroscopic X-ray image
Implementation Method 3
The apparatus captures CBCT images using a fluoroscopic X-ray imaging device installed on a rotatable gantry provided to the radiation therapy apparatus for irradiating the affected area with radiation from various angles
Data Source
AI summary
Through the present invention, three-dimensional coordinates of a tracking object moving in an irradiation object can be calculated from fluoroscopic X-ray images captured and acquired from various angles in a single fluoroscopic X-ray device mounted to a radiation therapy apparatus. The three-dimensional coordinates of the tracking object are calculated on a straight tracking object presence line connecting an X-ray generating device for fluoroscopy and the position in an X-ray plane detector of the tracking object on the fluoroscopic X-ray image acquired by the X-ray generating device for fluoroscopy and the X-ray plane detector, and using line segment information included in a movement region of the tracking object set in advance.