Focused CT Reconstruction for Low-Dose Imaging Outside the ROI
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Solution Overview
Problem
The increasing prevalence of computed tomography (CT) scans has led to significant cumulative radiation exposure for patients, posing a risk of long-term health complications, particularly cancer, as current methods expose the entire body to full radiation doses despite only a limited region of interest (ROI) being necessary for diagnosis.
Innovation Solution
A focused tomography method that uses variable sampling of x-rays, concentrating high dosage radiation through the ROI and reduced dosage outside the ROI, allowing for accurate reconstruction of the ROI with significantly lower total radiation, employing adaptive sampling techniques and dynamic attenuating filters to minimize non-local radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full radiation dosage is applied to the entire body during CT scanning, then complete diagnostic information is obtained, but patient radiation exposure and health risks increase significantly
Solution Approach 1:
The patent applies local quality by differentiating radiation dosage based on spatial location: high dosage is applied specifically to the region of interest (ROI) where diagnostic information is needed, while low dosage is applied to non-ROI areas. This is achieved through variable sampling of projection data, where data from ROI-passing paths are sampled at high rates and data from non-ROI paths are sampled at low rates, thereby reducing overall radiation exposure while maintaining diagnostic quality in the critical region.
Solution Approach 2:
The patent segments the projection data into two categories: data from x-ray paths that intersect the ROI and data from paths that do not intersect the ROI. This segmentation allows the system to apply different sampling rates and reconstruction strategies to each category, enabling focused high-quality imaging of the ROI while minimizing radiation to other areas through reduced sampling of non-ROI data.
2Object-affected harmful factors
If reduced radiation dosage is used outside the ROI, then patient safety is improved, but image quality and reconstruction accuracy may deteriorate
Solution Approach 1:
The patent ensures that reduced radiation dosage outside the ROI does not compromise overall image reconstruction accuracy by applying local quality enhancement: high-rate sampling is concentrated on ROI-intersecting paths, ensuring that the critical diagnostic region maintains high signal-to-noise ratio and reconstruction accuracy, while non-critical regions accept lower sampling rates with correspondingly reduced requirements for absolute accuracy.
Solution Approach 2:
The patent applies partial action by sampling only the necessary portion of projection data at high rates. Instead of uniformly high-rate sampling across all paths, the system performs excessive sampling (high rate) only where needed (ROI paths) and adequate but reduced sampling elsewhere, achieving the required diagnostic accuracy with minimal total radiation dosage.
3Object-affected harmful factors
If variable sampling rates are applied to different regions, then radiation dosage is optimized, but system complexity and data processing requirements increase
Solution Approach 1:
The patent manages system complexity by implementing local quality control in the sampling process: the variable sampling rate mechanism is triggered only based on whether x-ray paths intersect the ROI, using simple geometric criteria rather than complex real-time adjustments. This approach optimizes radiation dosage through differentiated sampling while keeping the control logic relatively simple and based on pre-defined ROI geometry.
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 reduces radiation dosage by up to 80-85% outside the ROI while maintaining image quality, preserving the detail and accuracy of the ROI images, thus minimizing patient exposure to harmful radiation.
Implementation Method 1
an x-ray transmitter 2710 of the CT scanner is modified so that the x-ray transmitter 2710 emits radiation at a first dosage level when a path of the radiation beam intersects a region of interest of the subject and emits radiation at a second dosage level when a path of the radiation beam does not intersect the region of interest
Implementation Method 2
a first computed tomography reconstruction 2750 is performed using projection data 2740 acquired during the CT scan
Data Source
AI summary
An exemplary focused tomography system and method involve obtaining a computed tomography scan image from a computed tomography scanner, wherein the computed tomography scan is an image of a subject that received a first radiation dosage level when a path of a radiation beam of the computed tomography scanner intersects a region of interest of the subject and that received a second radiation dosage level when the path of the radiation beam did not intersect the region of interest of the subject; computing an additive correction factor based on a radiation dosage factor that is applied to the areas outside the region of interest during computed tomography scanning; and applying the additive correction factor to the computed tomography scan image that improves a quality of the computed tomography scan image that corresponds to areas of the subject that received the second radiation dosage level.