CT Scanner Tabletop Motion Algorithm Vibration Reduction

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Solution Overview

Problem

Conventional trapezoidal and s-curve motion algorithms used in CT scanners cause unwanted vibrations and organ motion during axial and perfusion scans, leading to an unpleasant patient experience and suboptimal image quality due to high acceleration and jerk, despite efforts to mitigate these issues with rigid structures.

Innovation Solution

Implementing sinusoidal harmonic, filtered time delay compensated, and profile shaping motion algorithms for the subject support to reduce vibrations and organ motion by smoothing acceleration profiles and accounting for resonant frequencies, while maintaining move duration and speed similar to traditional algorithms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional trapezoidal or s-curve motion algorithms are used for tabletop translation, then the scanning speed and coverage are improved, but tabletop vibration and organ motion increase due to high acceleration and jerk

Engineering Contradiction:

Improvescanning speedVSAvoidtabletop vibration

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the motion profile parameters from conventional trapezoidal or s-curve algorithms to a specifically designed motion algorithm that limits acceleration and jerk while maintaining scanning speed. The algorithm adjusts velocity and acceleration profiles to avoid resonant frequencies of the tabletop structure, thereby reducing vibration without sacrificing productivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies knowledge of mechanical vibration and resonance to design a motion algorithm that avoids exciting the resonant frequencies of the tabletop. By carefully controlling the frequency content of the motion profile, the system prevents resonant oscillations while maintaining efficient scanning speeds

Inventive Principle:

Principle #18Mechanical vibration

2Loss of time

If higher acceleration is used to reduce move time between scans, then scanning efficiency is improved, but organ motion and patient discomfort increase

Engineering Contradiction:

Improvemove timeVSAvoidorgan motion

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The patent optimizes the time-motion parameters by designing a velocity profile that achieves rapid positioning without excessive acceleration. The algorithm balances move time reduction with acceleration limits that prevent organ motion, using advanced motion control techniques to minimize the time spent in high-acceleration states

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If cyclic motion is used for perfusion scans to maintain continuous imaging, then image quality is improved, but secondary vibration increases due to repeated acceleration cycles

Engineering Contradiction:

Improveimage qualityVSAvoidsecondary vibration

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent designs the cyclic motion algorithm for perfusion scans to use periodic motion patterns that minimize vibration. By optimizing the cycle frequency and motion profile shape, the system maintains continuous imaging capability while reducing the amplitude of secondary vibrations generated by repeated acceleration and deceleration cycles

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent adjusts the motion parameters specifically for cyclic perfusion scanning, optimizing velocity, acceleration, and cycle timing to reduce vibration. The algorithm modifies the standard cyclic profile to minimize resonant excitation while maintaining the continuous imaging required for perfusion studies

Inventive Principle:

Principle #35Parameter changes

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

These new motion algorithms significantly reduce tabletop vibrations and patient discomfort, improving image quality and patient experience by minimizing secondary motion, with experimental results showing a 47% average vibration reduction for sinusoidal harmonic axial scans compared to s-curve algorithms.

Implementation Method 1

the tabletop is a lightly damped steel and composite structure with one or multiple resonant frequencies. Upon the moment of trapezoidal or s-curve point to point motion in the horizontal direction, the tabletop resonance can be aroused by the resonant component of the primary motion

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentEP2675359B1Imaging system subject support motion algorithm(s)

Publication Date: 2019.08.07 KONINKLIJKE PHILIPS NV

Figure 1(A)~1(C)
Figure 2(A)~2(C)
Figure 3(A)~3(C)

AI summary

An imaging system (400) includes a subject support (412) configured to carry a subject being imaged in an examination region of the imaging system and a subject support controller (418) that positions the subject support and hence the subject in the examination region for scanning the subject based on a motion algorithm which reduces subject support vibration during scanning relative to a trapezoidal or s-curve motion algorithm, for a given translation duration and a given translation distance.