Laser Therapy Pulse Control Using Tissue Volume Feedback
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Solution Overview
Problem
Existing laser therapy systems for treating retinal disorders lack a direct and objective method for temperature control during high-power laser irradiation, leading to potential under-treatment or over-treatment and uncontrollable collateral damage due to the rapid heating of tissue, especially with high-power lasers exceeding 10 W.
Innovation Solution
A laser therapy device that uses a pulsed laser source with automatic power regulation, employing a detection device to measure volume changes caused by laser absorption, and an arithmetic unit to adjust subsequent laser pulses to achieve precise temperature control and effect monitoring, utilizing optical or acoustic detection methods to record thermal expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-power laser pulses are used for rapid tissue heating, then treatment time is reduced and productivity is improved, but temperature control precision deteriorates leading to uncontrollable collateral damage
Solution Approach 1:
The patent implements real-time feedback control by measuring the actual temperature increase during laser irradiation using optoacoustic or optical detection methods, then automatically adjusting subsequent laser pulse parameters based on this feedback to maintain precise temperature control even with high-power pulses
Solution Approach 2:
The system performs preliminary measurement of tissue optical properties and thermal response before delivering therapeutic laser pulses, allowing pre-calculation of optimal pulse parameters to achieve target temperature while avoiding overheating
2Device complexity
If fixed laser settings are used for simplicity, then device complexity is reduced, but treatment effectiveness deteriorates due to fluctuations in light transmission and variable RPE absorption
Solution Approach 1:
The laser system automatically adapts to individual patient characteristics by measuring tissue properties and self-regulating pulse parameters without requiring manual intervention, making the system as simple to operate as fixed settings while achieving customized treatment effectiveness
Solution Approach 2:
The system dynamically adjusts laser pulse parameters (energy, duration, repetition rate) based on measured tissue optical properties and thermal response, transforming a static fixed-setting system into an adaptive system that maintains reliability across varying patient conditions
3Measurement precision
If separate measurement and therapy lasers are used for temperature monitoring, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the therapeutic laser source perform dual functions by using its pulse structure to both deliver therapy and enable optoacoustic temperature measurement, eliminating the need for a separate measurement laser and reducing overall system complexity while maintaining measurement precision
Solution Approach 2:
The system merges the measurement and therapy functions into a single integrated laser source, where the therapeutic laser pulses serve both treatment and temperature monitoring purposes, simplifying the device architecture while preserving measurement accuracy
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 self-regulated, sparing therapy with high-power laser pulses, ensuring accurate temperature control and objective effect assessment, reducing the risk of collateral damage and allowing for real-time monitoring of therapeutic outcomes.
Implementation Method 1
optical detection of the transient volume change of the irradiated tissue through reversible thermal expansion and contraction during heating with laser light
Implementation Method 2
reversible thermal expansion and contraction during heating with laser light
Implementation Method 3
a optoacoustic method is known, in which by means of repetitive short pulsed laser radiation... the retinal absorbers are thermoelastically stimulated, and the emitted pressure transients on the cornea of the eye can be picked up by an ultrasonic transducer
Implementation Method 4
During the laser irradiation of the back of the eye, primarily the light-absorbing layers, the retinal pigment epithelium (RPE) and choroid are heated, from where the heat spreads into the adjoining layers
Implementation Method 5
the light-absorbing layers, the retinal pigment epithelium (RPE) and choroid are heated
Data Source
AI summary
A laser therapy device comprises a pulsed laser light source. Each triggering of tissue irradiation causes application of a first heating laser pulse of a first power and a first pulse duration and at least a second heating laser pulse of a second power and a second pulse duration to the tissue. Changes in volume resulting from the rising and the decreasing power gradient of the first laser pulse are detected. The therapy device, on the basis of the measured values relative to the change in volume and taking into consideration at least the predetermined rises of the power gradients of the first heating laser pulse, determines an estimated value for the temperature increase in the tissue during irradiation of the first heating laser pulse, and generates, from the estimated value, a command that causes adjustment of the second power and/or the second pulse duration of the second laser pulse.