Scattered Beam Correction in Dual-Source CT
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Solution Overview
Problem
Current methods for scattered beam correction in dual-source CT scans face challenges such as incorrect estimation of scattered beam profiles due to increased z-coverage, require additional hardware, or result in aliasing errors and increased image noise, especially during spiral scanning.
Innovation Solution
An iterative method for determining transverse scattering intensities from reconstructed image data, using variants like calculation from retracing beam paths, surface-based estimation, and Monte Carlo simulations to correct raw data, without additional sensors or hardware demands, allowing for more precise and flexible modeling of transverse scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If model-based estimation of scattered radiation is used, then scattered beam correction can be implemented, but the estimation becomes increasingly incorrect with increased z-coverage and pitch during spiral scanning
Solution Approach 1:
The patent transitions from 2D scattered beam profile estimation to 3D estimation by incorporating z-direction information. The scattered beam profile is determined as a function of z-position, allowing the correction to adapt to different z-coverage and pitch values during spiral scanning, thereby resolving the contradiction between estimation accuracy and z-coverage capability
Solution Approach 2:
The patent changes the parameters used for scattered beam estimation by incorporating z-position dependent parameters. Instead of using fixed 2D profiles, the system uses 3D profiles that vary with z-position, allowing the estimation to remain accurate across different scanning conditions including varied pitch and z-coverage
2Measurement precision
If dedicated sensors are used to measure scattered radiation, then scattered beam profile can be measured, but additional hardware is required which increases manufacturing costs
Solution Approach 1:
The patent applies self-service by using the existing detector systems to measure both primary and scattered radiation. The detectors serve dual purposes: capturing primary radiation for image reconstruction and capturing scattered radiation for profile determination. This eliminates the need for dedicated scattered radiation sensors while maintaining measurement capability
Solution Approach 2:
The existing detectors are made multi-functional by using them for both primary radiation detection and scattered radiation measurement. The same detector elements that capture primary beams are also used to detect scattered photons, allowing the system to perform multiple functions with a single hardware component
3Measurement precision
If alternate blanking of primary radiation is used to measure transverse scattering, then direct measurements can be obtained, but aliasing errors increase and image noise increases
Solution Approach 1:
The patent maintains continuous data acquisition without blanking the primary radiation. Both primary and scattered radiation are measured continuously during the scan, eliminating the interruptions caused by alternate blanking. This continuous measurement approach prevents aliasing errors and maintains image quality while still enabling scattered radiation measurement
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 provides an improved approximation of scattered beam intensity, reducing artifacts and noise, and avoiding ambiguities in scattered beam profile estimation, while maintaining dose efficiency and precision in CT image reconstruction.
Implementation Method 1
x-ray quanta on the object to be measured are scattered by an x-ray emitter
Implementation Method 2
x-ray quanta on the object to be measured are scattered by an x-ray emitter of a first emitter detector system into a detector of a second emitter detector system
Data Source
AI summary
A method and a computer system are disclosed for scattered beam correction in a CT examination of an object in a multi source CT. In at least one embodiment, the method includes generating original projection data records; reconstruction of the object with the original projection data records of at least one detector; determining the scattered radiation generated by each emitter exclusively in the direction of the original beams of the at least one other emitter relative to its opposing detector; generating corrected projection data records by removing the calculated scattered radiation from the original projection data records; reconstruction of the object with the corrected projection data records, and implementing a further iteration of the method when determining the scattered radiation or issuing the reconstruction result if at least one predetermined abort criterion applies.