Dual-Source CT Filter Arrangement for Full-Field Spectral Imaging
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Solution Overview
Problem
Conventional dual-source CT systems are limited by spatial restrictions in the CT gantry, where only one detector can cover the full measuring field, restricting data acquisition to a smaller field, which is insufficient for applications requiring data from the entire patient, such as electron density distributions in radiotherapy.
Innovation Solution
A filter arrangement with an inner and outer filter region is introduced, where the inner region covers the smaller fan-beam arc of the first X-ray source and the outer region, divided into two subregions, covers the larger fan-beam arc of the second X-ray source, allowing for spectral filtering and separate data acquisition for both energy spectra, enabling full-field data capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional dual-source CT system uses tube-side prefilters to increase spectral separation, then the spectral separation of X-ray radiation is improved, but the measuring field is restricted to a smaller diameter (26-35 cm) due to spatial restrictions in the CT gantry
Solution Approach 1:
The filter arrangement is divided into an inner filter region and an outer filter region. The inner filter region corresponds to the smaller fan-beam arc and maintains conventional spectral filtering, while the outer filter region extends coverage to the larger fan-beam arc, enabling full-field dual-energy data acquisition without compromising spectral separation
Solution Approach 2:
Different regions of the filter arrangement are assigned different spectral filter functions. The inner filter region uses conventional filtering for the smaller measuring field, while the outer filter region provides extended coverage for the larger measuring field, allowing each region to optimize its function locally
2Ease of operation
If only one detector covers the full measuring field in a dual-source CT system, then spatial restrictions are accommodated, but data from the entire patient is not available for applications requiring full-field coverage
Solution Approach 1:
The filter arrangement enables the second X-ray source with the larger detector to serve dual purposes: it can cover the smaller measuring field with conventional spectral filtering and simultaneously cover the larger measuring field with extended spectral filtering, making the system universally applicable to both conventional and full-field applications
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 solution allows for the capture of image data from large-size objects using X-rays with two different energy spectra, enhancing the ability to distinguish and image different structures, including those in the entire measuring field, thereby improving the diagnostic capabilities of CT systems.
Implementation Method 1
a filter arrangement (30) for a spectral filtering of the X-ray radiation of a CT system having a first and a second X-ray source
Data Source
AI summary
A filter arrangement is described. The filter arrangement includes an inner filter region, covering a cross-sectional area of a fan beam of a first X-ray source, and an outer filter region covering, together with the inner filter region, a larger cross-sectional area of a larger fan beam of a second X-ray source. The inner filter region has a first spectral filter function. The outer filter region is divided into a first subregion having a second spectral filter function and a second subregion having a third different spectral filter function. A computed tomography system is described. A method for producing a filter arrangement for a spectral filtering of X-ray radiation of a CT system having a first X-ray source and a second X-ray source is also presented. A method for reconstructing image data on the basis of projection measurement data is also described.