Photodetector Laser Interferometry for CT Table Positioning
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Solution Overview
Problem
In computed tomography (CT) imaging systems, the increasing use of smaller detector elements and variable table speeds necessitate more stringent constraints on table positioning accuracy and stability, making precise measurement of table position critical for accurate image reconstruction.
Innovation Solution
A system and method using a photodetector configured to detect laser energy, providing position information, and a processor to compute the change in position of a support within the imaging system, which includes an x-ray source, detector, and a support, allowing for accurate determination of position changes and vibrations in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If smaller detector element sizes are used in CT imaging systems, then image resolution is improved, but table positioning accuracy requirements become more stringent
Solution Approach 1:
The patent replaces mechanical positioning measurement systems with an optical interferometry system. A laser source emits light that reflects off a mirror attached to the table, and a photodetector measures the reflected light position. This optical system substitutes for traditional mechanical encoders or scales, providing non-contact, high-precision measurement that doesn't add mechanical complexity to the table drive system.
Solution Approach 2:
The patent introduces a mirror as an intermediary element between the table and the photodetector. The mirror reflects laser light to the photodetector, enabling indirect measurement of table position. This intermediary allows the system to measure position without direct contact or complex mechanical linkages, achieving high precision while maintaining mechanical simplicity.
2Productivity
If variable table speed is used during CT scan, then scanning efficiency is improved, but measurement of table position becomes more critical
Solution Approach 1:
The patent implements a feedback system where the photodetector continuously monitors table position and feeds this information back to the control system. The processor uses this real-time position data to associate images with corresponding positions and correct for position errors or vibrations. This closed-loop feedback ensures accurate position measurement even during variable speed operation, maintaining both efficiency and precision.
3Reliability
If real-time position measurement is implemented, then image reconstruction accuracy is improved, but system complexity increases
Solution Approach 1:
The patent replaces complex mechanical positioning systems with a simpler optical measurement system. The interferometric setup using laser, mirror, and photodetector provides real-time position data without requiring complex mechanical encoders, resolvers, or laser interferometers with multiple beams. This substitution reduces mechanical complexity while maintaining measurement reliability.
Solution Approach 2:
The optical measurement system is self-contained and requires minimal external calibration or adjustment. The laser provides its own light source, the mirror passively reflects the beam, and the photodetector automatically detects position changes. The system serves itself without requiring complex external measurement equipment or frequent calibration procedures, reducing operational complexity.
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
Enables accurate real-time determination of support position and vibration, improving image reconstruction by associating images with corresponding positions and correcting for position errors or vibrations, thereby enhancing image quality.
Implementation Method 1
a photodetector configured to detect laser energy that provides information regarding the position
Data Source
AI summary
A method for determining a change in a position of a support is described. The method includes determining the change in the position of the support used in an imaging system, where determining the change includes computing the position by operating a photodetector configured to detect laser energy that provides information regarding the position.