Patient-Specific CT Tube Current Modulation With ROI Noise Control
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Solution Overview
Problem
Current automatic exposure control (AEC) methods in computed tomography (CT) struggle with patient-specific, region-of-interest noise control due to limited pre-scan information, leading to inaccurate dose modulation and image quality requirements.
Innovation Solution
A method utilizing a noise propagation model and sparse-image slice sampling to determine a patient-specific AEC curve based on 3D pre-scan data, incorporating region-of-interest information and target image quality levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 2D radiographic images are used for AEC prediction, then the method is simple and fast, but sufficient tomographic image information cannot be acquired
Solution Approach 1:
The patent transitions from 2D radiographic images to 3D volumetric data by performing a low-dose pre-scan to acquire three-dimensional attenuation maps. This dimensional change provides comprehensive tomographic information about the patient's anatomy, enabling accurate patient-specific AEC prediction while maintaining computational efficiency through the use of the acquired 3D data structure.
2Productivity
If simple-model or look-up-table methods are used, then the processing is fast, but task-dependent patient-specific AEC requirements cannot be met
Solution Approach 1:
The patent changes the fundamental parameters used for AEC prediction by utilizing actual patient-specific 3D attenuation maps from pre-scans rather than relying on simplified models or lookup tables. This parameter change enables accurate, task-dependent AEC predictions that account for individual patient anatomy, size, and composition while maintaining processing efficiency through optimized computational algorithms.
3Measurement precision
If comprehensive patient information is collected for accurate AEC prediction, then prediction accuracy improves, but the complexity of the system increases
Solution Approach 1:
The patent applies preliminary action by performing a low-dose pre-scan before the actual diagnostic scan to acquire patient-specific 3D attenuation maps. This preliminary data collection provides comprehensive information about patient anatomy and composition, enabling accurate AEC prediction without increasing the complexity of the main diagnostic scanning system. The pre-acquired data is then used to optimize the subsequent scan parameters.
4Productivity
If region-of-interest specific control is implemented, then diagnostic efficiency improves, but the complexity of dose modulation increases
Solution Approach 1:
The patent implements local quality by enabling region-of-interest specific AEC control, where different noise levels and image quality requirements can be specified for different anatomical regions. The system calculates patient-specific AEC curves that optimize dose distribution locally for each ROI while maintaining overall scan efficiency. This approach allows diagnostic focus on specific areas without unnecessarily increasing complexity across the entire imaging system.
Data Source
AI summary
A method, apparatus, and computer-readable storage medium for controlling X-ray computed tomography (CT) imaging. A first set of projection data is acquired in a first CT scan of an object with a CT imaging apparatus. The first CT image data is reconstructed from the first set of projection data. X-ray tube current modulation information is determined for a second CT scan of the object, based on a noise propagation model between X-ray projection data and CT image data, and using, as inputs, the obtained first set of projection data, information indicating an imaging region-of-interest (ROI) for the second CT scan, and a target image quality level in the imaging ROI. The second CT scan of the object is obtained based on the obtained X-ray tube current modulation information.