Rotatable Shield CT Scanner Scatter Correction
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Solution Overview
Problem
Wide beam CT scanners face challenges in accurately measuring and compensating for scattered radiation without adding steps to the clinical procedure or exposing subjects to additional radiation, as existing methods are either inaccurate or require additional scans.
Innovation Solution
The use of radiation opaque shields in the CT system to selectively shield detector areas at certain angles, allowing for the measurement of scattered radiation, which is then interpolated and subtracted from the total data to correct for scattering effects across the entire detector matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radiation opaque shields are positioned in front of certain parts of the detector during subject scanning, then scattered radiation can be measured and corrected, but some detector elements are shielded from radiation at all projection angles and do not contribute directly to the images
Solution Approach 1:
The radiation shields are made rotatable relative to the detector array, transitioning from static shielding to dynamic shielding. This allows the same physical shields to shield different detector elements at different rotation angles, ensuring that no single detector element is permanently shielded and all detector elements contribute to image formation across the complete rotation cycle.
Solution Approach 2:
The shields perform periodic shielding actions as they rotate, shielding specific detector elements during specific angular ranges and leaving them unshielded during other angular ranges. This periodic on/off shielding pattern ensures that each detector element receives direct radiation during portions of the rotation, maintaining its contribution to image data while still enabling scattered radiation measurement during shielded portions.
2Measurement precision
If existing scatter correction methods are used, then scattered radiation compensation can be achieved, but additional steps are added to the clinical procedure and/or additional radiation exposure is required
Solution Approach 1:
The scattered radiation measurement function is merged with the primary imaging function by utilizing the same detector array and integrating the measurement process into the standard scanning procedure. The rotatable shields enable both imaging and scatter measurement to occur during a single scan rotation, eliminating the need for separate measurement scans or additional clinical steps.
Solution Approach 2:
The detector array serves multiple functions: it simultaneously captures direct radiation for image formation and scattered radiation for correction measurements. The rotatable shields enable the system to switch between these functions dynamically during the scan, allowing one component to perform multiple roles without requiring additional specialized equipment or procedures.
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 method enables accurate correction of scattered radiation without increasing procedural complexity or radiation exposure, improving image accuracy and reducing statistical noise in CT imaging.
Implementation Method 1
radiation opaque shields placed in the imaging system... parts of the detector area are substantially irresponsive to direct radiation and responsive to scattered radiation while they are shielded from the first X ray source by the shields
Implementation Method 2
scattered radiation that was scattered by the subject... computing scattered radiation data indicative of the part of the X-ray data due to scattered radiation
Data Source
AI summary
A CT scanner with scatter correction device and a method for scatter correction are provided. The method of correcting CT images from artifacts caused by scattered radiation comprises affixing to the non-rotating frame of the CT gantry a plurality of 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.