Computed Tomography Imaging with Segmented X-ray Beamlets
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Solution Overview
Problem
Computed tomography (CT) imaging faces challenges in achieving high resolution while minimizing ionizing X-ray radiation dose, as increasing resolution in three dimensions leads to a cubic increase in dose, limiting its sensitivity and detection capabilities.
Innovation Solution
A method involving an X-ray beam divided into finer beamlets by a mask with block regions and apertures, allowing each beamlet to probe a smaller region than the full width half maximum (FWHM) of the overall spread function, combined with a rototranslational motion of the subject to capture high-definition images at a lower dose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the X-ray resolution is increased in three dimensions, then the image quality is improved, but the radiation dose increases cubically
Solution Approach 1:
The patent divides the X-ray beam into multiple discrete beamlets using a mask with periodic apertures, creating a segmented illumination pattern. This segmentation allows the system to probe the subject at multiple spatial frequencies simultaneously, achieving high-resolution reconstruction without requiring a proportionally high dose across the entire field of view. The mask structure with period p and aperture width w creates beamlets that sample different spatial frequencies, enabling super-resolution beyond the mask period while maintaining dose efficiency.
Solution Approach 2:
The patent introduces temporal dimension by moving the subject through the beam path during data acquisition. By combining the spatial segmentation from the mask with temporal sampling from subject motion, the system accumulates projection data at multiple positions and angles. This multi-dimensional sampling approach (spatial segmentation + temporal motion) enables high-resolution reconstruction without the cubic dose penalty, as the same beamlets provide information for multiple spatial frequencies when combined through motion and reconstruction algorithms.
2Object-affected harmful factors
If the radiation dose is reduced, then the harmful effects are minimized, but the ability to detect lesions and maintain sensitivity is compromised
Solution Approach 1:
The mask segments the beam into beamlets that probe different spatial frequencies. By strategically positioning apertures and block regions, the system captures high-frequency information needed for lesion detection at reduced dose. The segmented approach allows selective sampling of critical spatial frequencies that contain lesion information, rather than uniformly distributing dose across all frequencies.
Solution Approach 2:
The mask acts as an intermediary element between the X-ray source and the subject. It modulates the beam pattern to encode spatial frequency information, enabling the system to extract high-resolution lesion detection capability from low-dose measurements. The mask's periodic structure with apertures and block regions transforms the direct beam into a coded pattern that, when combined with subject motion and iterative reconstruction, recovers high-frequency details necessary for sensitive lesion detection.
3Device complexity
If a mask with larger aperture period is used, then the device complexity is reduced, but the measurement precision and image definition are degraded
Solution Approach 1:
The patent compensates for the limited spatial frequency content of a simple periodic mask by introducing temporal dimension through subject motion. As the subject moves through the segmented beam, each beamlet probes different spatial locations at different times, effectively sampling a broader range of spatial frequencies. This temporal-spatial sampling approach allows the use of a relatively simple periodic mask structure while achieving high measurement precision through the combination of mask segmentation and subject motion.
Solution Approach 2:
The periodic mask structure creates multiple copies of the beam pattern at different spatial positions. By moving the subject through this replicated pattern, the system accumulates multiple measurements that collectively provide high-frequency information. The simple periodic mask generates a set of replicated beamlets that, when combined through motion and reconstruction, achieve high measurement precision without requiring a complex mask design.
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 enables the capture of high-resolution CT images at a lower dose by providing additional information at a smaller length scale, allowing for improved image reconstruction and maintaining sensitivity without excessive radiation exposure.
Implementation Method 1
using a mask having a plurality of block regions and a plurality of apertures having a period p in a first orthogonal direction x orthogonal to the beam direction to divide the beam into a plurality of X-ray beamlets
Implementation Method 2
generating an X-ray beam travelling in a beam direction z from an X-ray source having a focal spot; passing the X-ray beam through a subject; capturing an image on an X-ray detector
Data Source
AI summary
A computed tomography method seeking higher resolutions without imposing a dose increase is described. A mask (10) forms a plurality of X-ray beam lets (14) which are passed through a subject (6), and images are captured on X-ray detector (8). The subject (6) is moved with respect to the X-ray detector and mask, including a rotation around a y axis, and a computed tomography image is reconstructed from the plurality of measured datapoints. The beam lets (14) are of small size. FIGS. 4-8 are blurred, FIGS. 10, 11 and 16b contain too small letters/numbers.