IVUS-OCT Imaging Core Synchronization Using Encoder Pulse Conversion
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Solution Overview
Problem
The challenge lies in synchronizing the triggers of ultrasound and optical coherence tomography signals in an imaging apparatus, as the ultrasound signal is synchronized with a scanner motor, while the optical coherence tomography signal is based on wavelength sweeping, making it difficult to align with the scanner motor's encoder signal.
Innovation Solution
The imaging apparatus includes a motor drive unit connected to the catheter, conversion means to adjust the pulse signal frequency for ultrasound tomographic image generation, and a mechanism to determine valid pulses for optical tomographic image sampling, ensuring both images are synchronized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the imaging apparatus uses separate trigger mechanisms for IVUS (motor-synchronized) and OCT (wavelength-sweeping), then each imaging modality can operate independently with optimized performance, but synchronization between ultrasound and optical tomographic images becomes difficult to achieve
Solution Approach 1:
The patent introduces a synchronization signal as an intermediary that mediates between the motor drive unit's encoder signal (for IVUS) and the light source modulation signal (for OCT). This synchronization signal, generated based on the encoder signal, acts as a common reference that coordinates both imaging modalities, enabling them to operate independently while maintaining temporal alignment between their respective tomographic images.
2Loss of information
If the imaging apparatus synchronizes ultrasound and optical signals, then synchronized diagnostic images can be acquired, but the system complexity increases due to the need for coordination between different signal sources
Solution Approach 1:
The synchronization signal serves multiple functions simultaneously: it acts as a trigger for the ultrasound transceiver, a reference for the optical coherence tomography system, and a timing reference for image generation and processing. This multi-functional approach consolidates what would otherwise require separate coordination mechanisms, reducing overall system complexity while achieving synchronization.
3Measurement precision
If the imaging apparatus uses motor-driven rotation for the imaging core, then consistent angular positioning can be achieved for ultrasound imaging, but synchronization with wavelength-sweeping-based optical coherence tomography becomes challenging
Solution Approach 1:
The system uses the encoder signal from the motor drive unit as feedback to generate the synchronization signal. This feedback mechanism ensures that the synchronization signal is directly tied to the actual rotational position and timing of the imaging core, allowing the wavelength-sweeping-based OCT system to align its acquisitions with the motor-driven ultrasound system's angular positioning, thereby maintaining both precision and synchronization.
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 configuration allows for the acquisition of synchronized ultrasound and optical tomographic images, enhancing diagnostic capabilities by aligning the imaging processes effectively.
Implementation Method 1
an ultrasound transceiver that transmits and receives an ultrasound wave
Implementation Method 2
an optical transceiver that transmits and receives light
Implementation Method 3
a catheter which rotatably accommodates an imaging core provided with an ultrasound transceiver and an optical transceiver
Data Source
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AI summary
A pulse signal corresponding to rotation of an imaging core is input, and a repetition frequency of the input pulse signal is converted in accordance with the number of radially-aligned lines configuring an ultrasound tomographic image. Based on the pulse signal of which the repetition frequency has been converted, a drive signal for an ultrasound transceiver is generated to obtain an ultrasound tomographic image with the number of lines, and the generated drive signal is transmitted to the ultrasound transceiver. A valid pulse is determined in accordance with the number of lines from the pulse signal of which the repetition frequency has been converted. A signal having a pulse train selected, based on the valid pulse from a pulse signal representing a cycle of a light source of light for interfering with the light from an optical transceiver is generated as a pulse signal representing a timing of sampling of an optical coherence signal for generating an optical tomographic image.