Line Scan Cone Beam CT Scanner for Low Dose Breast Imaging
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Solution Overview
Problem
Current breast cancer imaging modalities, such as x-ray screening mammography and three-dimensional x-ray imaging techniques, face challenges in detecting small lesions due to structure noise from overlapping breast tissues, leading to false-negative diagnoses and radiation inefficiency, with existing methods failing to achieve early detection at a median size of 3 mm.
Innovation Solution
A line scan cone beam CT imaging system that acquires multiple projection views at predefined angles with oppositely directed translational motion of the x-ray source and detector, allowing for image reconstruction from a limited range of view angles, reducing radiation exposure and enhancing in-plane spatial resolution and low contrast detectability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional x-ray CT is used for breast imaging, then three-dimensional imaging capability is achieved, but radiation dose increases substantially due to penetration through non-breast tissues
Solution Approach 1:
The patent segments the imaging task into two components: a low-dose conventional CT scan for three-dimensional localization, followed by a magnified projection view focused specifically on the region of interest. This segmentation allows the system to achieve 3D imaging capability while reducing the overall radiation dose by limiting the high-dose magnified exposure to only the necessary small area.
Solution Approach 2:
The patent transitions from conventional two-dimensional mammography to three-dimensional CT imaging, then combines it with magnified projection views. This dimensional approach enables comprehensive breast imaging with the ability to localize and closely examine suspicious areas without requiring the entire breast to be exposed to high radiation doses.
2Volume of moving object
If x-ray photons penetrate through non-breast tissues in conventional CT scan, then three-dimensional imaging is obtained, but dose efficiency deteriorates
Solution Approach 1:
The imaging protocol is segmented into a preliminary low-dose 3D CT scan followed by targeted magnified projection imaging. This allows the system to first obtain three-dimensional information efficiently, then focus subsequent higher-dose imaging only on specific regions of interest, thereby improving overall dose efficiency.
Solution Approach 2:
The patent performs a preliminary low-dose conventional CT scan to identify regions of interest and establish three-dimensional context before performing magnified projection imaging. This preliminary action prevents unnecessary exposure of non-breast tissues to high doses and optimizes the positioning and field-of-view for subsequent imaging.
3Measurement precision
If magnified projection view is used after conventional CT, then in-plane spatial resolution and low contrast detectability improve, but device complexity increases
Solution Approach 1:
The patent utilizes the existing conventional CT scanner to perform dual functions: first as a volumetric imager for 3D localization, then by repositioning the detector to provide magnified projection views. This multi-functionality approach improves spatial resolution and contrast detectability without requiring separate dedicated imaging devices, thereby limiting the increase in device complexity.
4Reliability
If conventional CT is used for early detection of small lesions, then sensitivity improves, but radiation exposure increases
Solution Approach 1:
The imaging process is segmented into a low-dose conventional CT component for comprehensive screening and three-dimensional assessment, followed by selective magnified projection imaging only for identified regions of interest. This segmentation maintains high sensitivity for detecting small lesions while minimizing overall radiation exposure by limiting high-dose imaging to necessary areas only.
Solution Approach 2:
The patent applies partial action by performing conventional CT imaging at reduced dose levels for initial screening, then applying magnified projection imaging with higher dose only partially to specific regions of interest rather than the entire breast volume, thereby optimizing the balance between detection sensitivity and radiation exposure.
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 high in-plane spatial resolution and excellent low contrast detectability, enabling earlier detection of breast cancer at a smaller size, potentially allowing for 18-month earlier treatment and reducing radiation dose, thereby improving sensitivity and specificity in breast cancer detection.
Implementation Method 1
x-ray photons have to penetrate through non-breast tissues in a conventional CT scan
Implementation Method 2
The x-ray source rocks around the breast in an arc trajectory
Data Source
AI summary
A line scan cone beam CT imaging system irradiates an object with an x-ray cone beam for multiple views. A projection data set of the object is acquired at each view. Between views, the cone beam and detector array are translated along parallel lines in opposite directions. An image is generated by converting the cone beam projection data set of the real object into a parallel-beam projection data set corresponding to a virtual object and using a total variation minimization image reconstruction algorithm to reconstruct a virtual image of the virtual object. The reconstruction algorithm includes the constraint that the Fourier transform of the reconstructed virtual image matches the known Fourier coefficients in the set of converted parallel-beam projections of the virtual object. The reconstructed virtual image is then transformed into an image of the real object.