Extended FOV X-ray Imaging with Offset Detectors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In external beam radiotherapy, on-treatment cone beam CT with a single detector provides a limited field of view, resulting in truncated images of large patient anatomy, which hinders accurate imaging and treatment planning.
Innovation Solution
An imaging system utilizing a gantry with two x-ray sources of different energies, one laterally offset and one centered, combined with detectors to reconstruct images with an extended field-of-view without requiring enlarged detectors, allowing for non-truncated imaging and improved dose map calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single traditionally sized detector is used for cone beam CT imaging, then the device complexity is low, but the field of view is limited resulting in truncated images
Solution Approach 1:
The imaging system is divided into multiple independent x-ray sources and detectors positioned at different locations around the patient. Each source-detector pair captures a portion of the anatomy, and the images are reconstructed and combined to form a complete extended field of view image, avoiding the need for a single large detector
Solution Approach 2:
Instead of increasing detector size in the traditional plane, the system adds spatial dimensionality by positioning multiple detectors at different angular and lateral locations around the patient. This multi-dimensional arrangement allows coverage of a larger field of view using standard-sized detectors
2Area of stationary object
If multiple x-ray sources and laterally offset detectors are used, then the field of view is extended, but the device complexity increases
Solution Approach 1:
The multiple x-ray sources and detectors serve dual functions: they capture different portions of the anatomy simultaneously and provide redundant views for improved image reconstruction. The system is designed to handle various imaging scenarios with the same multi-source configuration
Solution Approach 2:
The patent combines data from multiple x-ray sources and detectors through sophisticated image reconstruction algorithms. The partial images captured by each source-detector pair are merged into a single comprehensive image with extended field of view, achieving the benefit of multiple components while managing complexity through integrated processing
3Measurement precision
If a single detector is used, then the device complexity is low, but image accuracy is insufficient for accurate dose map calculations
Solution Approach 1:
Different regions of the patient's anatomy are imaged with optimized local quality by positioning detectors at specific lateral offsets. The laterally offset detectors provide enhanced visualization of peripheral structures while maintaining central structure detail, enabling accurate dose calculations across the entire treatment volume
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
Enables accurate three-dimensional dose map calculations and adaptive radiotherapy by providing non-truncated images with significant soft tissue differentiation, enhancing treatment planning and metal artifact reduction.
Implementation Method 1
A first x-ray source mounted on the gantry and configured to direct x-rays of a first beam energy through a peripheral portion of a target volume disposed in the bore and toward a first x-ray detector mounted on the gantry
Data Source
AI summary
Extended field-of-view imaging is enabled by combined imaging with a kilovolt (“kV”) x-ray source and a megavolt (“MV”) x-ray source, in which at least one of the corresponding x-ray detectors is laterally offset from the target isocenter by an amount such that the x-ray detector does not have a view of the target isocenter. This scan geometry enables the reconstruction of non-truncated images without resorting to the more expensive solution of outfitting the imaging or radiotherapy system with enlarged x-ray detectors.