Spectral CT Projection Data Correction via Reference Detector
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Solution Overview
Problem
Spectral computed tomography systems face challenges in generating high-quality images due to variations in the spectral properties of radiation devices over time, leading to artifacts in reconstructed images.
Innovation Solution
A system and method that include a radiation device providing polychromatic radiation, a spectral projection data generation device, a reference values generation device for determining energy-dependent reference values from radiation not traversing the examination zone, and a spectral parameter providing unit to monitor and correct spectral properties, ensuring improved image quality by adjusting or replacing the radiation device as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spectral computed tomography projection data is generated using a radiation device with varying spectral properties, then the system can provide imaging functionality, but image quality deteriorates due to artifacts in reconstructed images
Solution Approach 1:
The system performs preliminary measurement of spectral properties using a reference detector before actual imaging. Energy-dependent reference values are measured in advance to characterize the radiation device's spectral output, which is then used to correct the projection data during image reconstruction, preventing artifacts caused by spectral variations
Solution Approach 2:
The system continuously monitors spectral properties through a reference detector and uses this feedback information to correct the spectral computed tomography projection data. The spectral parameters derived from reference measurements are applied to compensate for variations in the radiation device's spectral output, maintaining consistent image quality over time
2Measurement precision
If energy-dependent reference values are measured using radiation that has not traversed the examination zone, then spectral properties can be accurately monitored, but the system complexity increases
Solution Approach 1:
The reference detector serves multiple functions: it measures energy-dependent reference values for spectral characterization, provides feedback for correcting projection data, and enables monitoring of spectral property changes over time. This multi-functionality reduces the need for separate dedicated measurement systems
Solution Approach 2:
The reference detector acts as an intermediary between the radiation device and the imaging system. It measures spectral properties without being in the direct path of the examination beam, providing indirect information that is then used to correct the actual imaging data, thus simplifying the overall system architecture
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 effectively monitors and corrects spectral properties, leading to enhanced image quality by accounting for changes in the radiation device's spectral output, thereby reducing artifacts and maintaining image fidelity over time.
Implementation Method 1
an x-ray source for emitting x-ray radiation
Implementation Method 2
The spectral properties of the radiation device may vary over time due to, for instance, a roughening of an anode of an x-ray tube
Implementation Method 3
a radiation detector for detecting the x-ray radiation after having traversed a subject to be examined
Implementation Method 4
a monitor detector irradiated by radiation emitted by the x-ray source, which has not traversed the subject, wherein the monitor detector is configured as an energy-resolving detector to provide energy-resolved current dose measurement data
Data Source
AI summary
The invention relates to a system (31) for generating spectral computed tomography projection data. A spectral projection data generation device (6) comprising an energy-resolving detector generates spectral computed tomography projection databased on polychromatic radiation (4), which has been provided by a radiation device (2), after having traversed an examination zone (5), and a reference values generation device generates energy-dependent reference values based on radiation, which has not traversed the examination zone. A spectral parameter providing unit (12) provides a spectral parameter being indicative of a spectral property of the radiation device based on the energy-dependent reference values. In particular, spectral properties of the radiation device can be monitored over time, wherein this information can be used for, for instance, correcting the spectral computed tomography projection data, and/or, if undesired spectral properties of the radiation device are indicated, triggering a replacement of the radiation device.