Inverse-Geometry CT System Radiation Dose Reduction
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Solution Overview
Problem
Computed tomography (CT) scans, particularly in cancer imaging, expose patients to high radiation doses, leading to increased cancer risk, especially in young patients, and conventional CT systems face challenges in reducing radiation while maintaining image quality.
Innovation Solution
An inverse-geometry CT system with a stationary ring of multi-focus X-ray sources and a rotating collimator-detector assembly, utilizing a small-area detector and adaptive exposure techniques to reduce radiation exposure and improve dose efficiency, while maintaining image quality through iterative reconstruction methods and photon-counting detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional CT systems use large-area detectors and rotating X-ray sources, then image quality can be maintained, but radiation dose to patients is high
Solution Approach 1:
The patent inverts the conventional CT geometry by placing a small-area detector close to the patient and using a large-area source array positioned away from the patient. This inverse configuration reduces the radiation field size at the patient interface, thereby lowering radiation dose while maintaining image quality through the small detector's high spatial resolution and the large source array's comprehensive sampling capability.
Solution Approach 2:
The patent divides the X-ray source into multiple focal spots arranged in an array, with each spot independently controllable. This segmentation allows selective activation of only the necessary source spots for each projection angle, reducing overall radiation exposure while maintaining complete sampling of the object for high-quality reconstruction.
2Volume of stationary object
If CT scan coverage volume is increased to cover large anatomical regions, then diagnostic utility is improved, but radiation dose increases
Solution Approach 1:
The patent employs dynamic control of the source array and detector positioning, allowing the system to adaptively adjust the active source spots and detector regions based on the specific anatomical region being scanned. This dynamic optimization enables comprehensive volume coverage while minimizing radiation exposure to areas outside the region of interest.
Solution Approach 2:
The patent applies different radiation exposure levels to different regions of the scan volume based on diagnostic requirements. The large-area source array enables localized high-dose regions for areas requiring detailed examination while using lower dose or no exposure for surrounding areas, achieving optimal diagnostic utility with minimized overall radiation dose.
3Measurement precision
If CT acquisition speed is increased to reduce motion artifacts, then image quality is improved, but radiation dose rate increases
Solution Approach 1:
The patent uses a large-area source array with multiple independently controllable focal spots that can operate continuously without the mechanical rotation required by conventional single-source systems. This continuous operation enables fast acquisition times for motion artifact reduction while distributing the radiation dose across multiple source spots, preventing excessive dose rate at any single location.
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
The system achieves a significant reduction in radiation dose, potentially lowering it by a factor of four compared to conventional CT systems, with improved image quality and faster acquisition times, reducing the risk of cancer from radiation exposure.
Implementation Method 1
A vacuum bell bonded to an X-ray radiation-permeable window that can emit X-ray radiation from a plurality of spots
Implementation Method 2
X-ray radiation-permeable window that can emit X-ray radiation
Implementation Method 3
The radiation-permeable window and vacuum bell can be bonded with a brazed or electron beam-welded connection
Implementation Method 4
The radiation-permeable window and vacuum bell can be bonded with a brazed or electron beam-welded connection
Data Source
AI summary
The present invention pertains to an apparatus and method for X-ray imaging a human patient. A vacuum bell bonded to an X-ray radiation-permeable window that can emit X-ray radiation from a plurality of spots located 1 cm from its edge, a collimator, and a detector are used. A ring of stationary X-ray sources can also be used with a stationary collimator and a rotating slot collimator and detector. An X-ray beam can be aligned in an X-ray system by establishing a position of the beam with respect to a moving collimator at a number of points in time, monitoring the velocity of the collimator, navigating the beam to a calculated position of a hole in the collimator, and correcting the alignment of the beam based on the location of the beam on the detector.