CT Scanner Scatter Correction via Shielded Detector Elements
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Solution Overview
Problem
Wide beam CT scanners and other digital X-ray imaging systems face challenges in accurately measuring and compensating for scattered radiation, which degrades local contrast, Signal-to-Noise Ratio (SNR), and data accuracy, without adding steps to the imaging procedure or exposing subjects to additional radiation, and complicates shield positioning.
Innovation Solution
A system that uses radiation opaque shields embedded in a translucent carrier or positioned on the detector array to measure scattered radiation by shading a subset of detector elements, allowing direct radiation to be blocked while scattered radiation is detected, and employs interpolation and calibration methods to correct for scattered radiation across the entire detector array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shields are positioned between the radiation source and detector to measure scattered radiation, then scattered radiation measurement is enabled, but device complexity and shield positioning difficulty increase
Solution Approach 1:
The detector array itself performs the scattered radiation measurement function by having certain elements shielded during imaging. The system uses its own detector elements that are blocked from direct radiation to automatically measure scattered radiation, eliminating the need for separate external shield positioning mechanisms.
Solution Approach 2:
The detector array serves multiple functions: it images the subject using unshielded elements and simultaneously measures scattered radiation through shielded elements. This multi-functional approach consolidates what would otherwise require separate measurement devices into the existing imaging system.
2Measurement precision
If additional radiation exposure is applied to measure scattered radiation, then measurement accuracy improves, but subject radiation dose increases
Solution Approach 1:
The scattered radiation measurement is performed continuously during the normal imaging process without requiring additional radiation exposures. The shielded detector elements measure scattered radiation as part of the routine imaging sequence, eliminating extra radiation events.
Solution Approach 2:
The system measures scattered radiation using the same radiation that is already passing through the subject during normal imaging. No additional radiation is applied; instead, the existing radiation field is utilized to simultaneously obtain both imaging data and scattered radiation measurements.
3Measurement precision
If imaging procedure steps are added to correct scattered radiation, then data accuracy improves, but productivity decreases
Solution Approach 1:
The scattered radiation measurement and correction are merged into the single imaging procedure. The shielded and unshielded detector elements operate simultaneously during one scan, and the correction is applied automatically during image reconstruction, eliminating the need for separate measurement and correction steps.
Solution Approach 2:
The scattered radiation measurement is performed preliminarily during the imaging scan itself, before final image reconstruction. This allows the correction to be applied during the reconstruction process rather than requiring a separate post-processing step, maintaining imaging throughput.
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 effectively measures and corrects scattered radiation without additional radiation exposure or complex shield positioning, improving image contrast and accuracy by isolating scattered radiation and interpolating its distribution across the detector array.
Implementation Method 1
radiation opaque shields embedded in a translucent carrier or positioned on the detector array to measure scattered radiation by shading a subset of detector elements, allowing direct radiation to be blocked while scattered radiation is detected
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
A CT scanner with scatter correction device and a method for scatter correction are provided. The method comprises positioning shields for shielding some of the CT detector elements from direct X ray radiation, while allowing scattered radiation to arrive at said shielded elements; measuring scatter signals from said shielded elements, indicative of scattered radiation intensity; and correcting for scatter by subtracting scatter intensity values estimated from said measured scatter signals from signals measured by unshielded detector elements.