Tailored Laser Pulses for Stone Fragmentation With Low Retropulsion
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Solution Overview
Problem
Conventional high-energy laser systems for lithotripsy cause undesirable retropulsion and large stone fragments, necessitating additional extraction methods and potentially damaging the laser system components.
Innovation Solution
A laser system that generates quasi-continuous laser pulses by directing a series of temporally spaced-apart electrical pulses to a lasing medium, optimizing energy levels below the lasing threshold and extending pulse duration to reduce peak power, thereby minimizing retropulsion and enhancing fragmentation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high energy laser is used to increase fragmentation efficiency, then stone fragmentation efficiency is improved, but retropulsion effects and large stone fragments occur
Solution Approach 1:
The patent applies periodic pulsed laser action with optimized pulse duration (200-1700 microseconds) and frequency (3-100 Hz) to achieve effective stone fragmentation while minimizing retropulsion. The periodic pulsing allows controlled energy delivery that prevents excessive force generation, resolving the contradiction between fragmentation efficiency and retropulsion effects.
Solution Approach 2:
The patent changes key laser parameters including pulse duration (200-1700 μs), pulse energy (0.2-8.0 Joule/pulse), and frequency (3-100 Hz) to optimize the balance between fragmentation efficiency and retropulsion minimization. By adjusting these parameters, the system achieves effective stone breakdown without generating harmful retropulsion forces.
2Productivity
If high energy laser is used to increase fragmentation efficiency, then stone fragmentation efficiency is improved, but large stone fragments are produced requiring additional extraction devices
Solution Approach 1:
The periodic pulsed laser delivery system produces controlled fragmentation that generates smaller, more manageable stone particles. This periodic action with optimized pulse characteristics eliminates the need for complex retrieval baskets and extraction devices, as the laser alone can reduce stones to passable fragment sizes.
Solution Approach 2:
The laser energy is used to extract and remove stone material directly through ablation and fragmentation, eliminating the need for separate mechanical extraction devices. The laser pulse parameters are optimized to fragment stones into small particles that can be naturally passed or easily removed without additional complex equipment.
3Productivity
If high pulse energy is used to achieve quick fragmentation, then fragmentation speed is improved, but damage to laser system components may occur
Solution Approach 1:
The system uses periodic pulsing with controlled duty cycle and frequency (3-100 Hz) to deliver high total energy while allowing cooling intervals between pulses. This periodic operation prevents thermal accumulation that could damage laser components, maintaining both fragmentation speed and system reliability.
Solution Approach 2:
The laser system dynamically adjusts pulse energy, frequency, and duration based on treatment requirements. This dynamic control allows the system to operate at high power levels when needed for rapid fragmentation while reducing power during intervals to protect components, balancing speed and durability.
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
The quasi-continuous laser pulses effectively fragment stones with reduced retropulsion and large fragments, improving efficiency and minimizing damage to the laser system components.
Implementation Method 1
a lasing medium configured to output a quasi-continuous laser pulse in response to the optical pumping
Implementation Method 2
a device that optically pumps a lasing medium
Implementation Method 3
energy of this wavelength is highly absorbed by water, a constituent of virtually all tissues
Data Source
AI summary
A laser system may include a controller configured to direct a plurality of temporally spaced-apart electrical pulses to a device that optically pumps a lasing medium, and a lasing medium configured to output a quasi-continuous laser pulse in response to the optical pumping. The plurality of temporally spaced-apart electrical pulses may include (a) a first electrical pulse configured to excite the lasing medium to an energy level below a lasing threshold of the lasing medium, and (b) multiple second electrical pulses following the first electrical pulse. The quasi-continuous laser pulse is output in response to the multiple second electrical pulses.