Laser Lithotripsy Waveform Control for Bubble-Synchronized Stone Crushing
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Solution Overview
Problem
Existing laser lithotripsy methods face challenges in efficiently delivering laser beams to urinary stones due to absorption by water or solvents, leading to insufficient energy transmission and reduced crushing efficiency.
Innovation Solution
A waveform control device and method that adjust the laser beam's output and emission to synchronize with the generation and disappearance of bubbles formed in the liquid, allowing efficient energy transmission to the stone by controlling the laser beam's repetition frequency and emission during bubble phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam is continuously emitted to crush the stone, then the stone can be effectively treated, but the laser energy is absorbed by water or solvent around the stone, reducing transmission efficiency
Solution Approach 1:
The laser beam is emitted in periodic pulses rather than continuously. The pulse frequency is controlled to match the bubble cycle, emitting laser energy only during periods when the bubble has dissipated and the path to the stone is clear, thereby reducing energy loss to water absorption while maintaining effective stone treatment
Solution Approach 2:
A first laser pulse is emitted to create a bubble that clears the water/solvent path ahead of the stone. This preliminary action prepares the transmission path by removing the absorbing medium, allowing subsequent laser pulses to reach the stone more efficiently
2Loss of energy
If a first laser pulse is used to generate a bubble, then the transmittance of subsequent laser beams is improved, but the treatment time increases due to the need to wait for bubble disappearance
Solution Approach 1:
The laser emission is made continuous in the sense that pulses are emitted back-to-back without idle waiting periods. The pulse frequency is set so high that the laser is continuously delivering energy during the brief windows when bubbles are absent, eliminating wasted time while maintaining high transmittance
Solution Approach 2:
The system uses periodic laser pulsing synchronized to the bubble lifecycle, but operates at such a high frequency that the cumulative effect approaches continuous treatment. This eliminates the need to wait for complete bubble dissolution between treatments, reducing overall treatment time
3Productivity
If the laser pulse frequency is increased to reduce treatment time, then productivity improves, but the bubble generated by previous pulses may still be present, reducing energy transmission
Solution Approach 1:
The system uses feedback control where the output of each laser pulse (bubble generation) informs the timing of subsequent pulses. The pulse frequency is specifically chosen based on the known bubble dissolution characteristics, ensuring that each pulse arrives at the optimal moment when the path is clear, thus maintaining high energy transmission even at high treatment speeds
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
Enhances energy transmission to the stone without waste, improving treatment efficiency and reducing the time required for stone crushing by modulating the laser beam in sync with bubble behavior.
Implementation Method 1
a temperature rise caused when an energy of the laser beam is absorbed in water in the stones
Implementation Method 2
generate a small-sized bubble... due to a temperature rise caused when an energy of the laser beam is absorbed in water
Implementation Method 3
the stones are crushed to a size that is equal to or smaller than a size that can be recovered in a basket or equal to or smaller than a size that can be naturally discharged by a steam explosion due to a temperature rise caused when an energy of the laser beam is absorbed in water in the stones
Implementation Method 4
naturally discharged by a steam explosion due to a temperature rise
Data Source
AI summary
Provided is a waveform control device for a laser lithotripsy apparatus including: a processor including hardware, the processor being configured to: pulse a laser beam; change an output of the pulsed laser beam; continuously emit the laser beam until a bubble generated from a laser emission end by an irradiation of the laser beam reaches a crushing target; and after the bubble generated from the laser emission end reaches the crushing target, reduce the output of the laser beam or turn off the irradiation of the laser beam during a period in which there is the bubble between the laser emission end and the crushing target, and the bubble does not couple the laser emission end and the crushing target.