Hyperthermia Assembly PID Control for Tissue Temperature Stability
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Solution Overview
Problem
Existing hyperthermia treatments using focused ultrasound face challenges in maintaining stable temperature control due to non-linear heat conduction characteristics in biological tissues, leading to unstable temperature servo-control.
Innovation Solution
A heat treatment assembly with energy generating means, spatial temperature distribution measurement, and a control unit that commands focal point movement along predetermined trajectories, adjusting energy distribution based on measured temperature using a Proportional-Integral-Derivative (PID) control law, accounting for thermal diffusion coefficients and modifying trajectories to achieve uniform temperature profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If linear modelling of tissue behaviour is used for temperature control, then the control system is simple to implement, but temperature servo-control becomes unstable due to non-linear heat conduction characteristics
Solution Approach 1:
The patent applies parameter changes by implementing a PID control law that dynamically adjusts control parameters (proportional, integral, and derivative terms) based on measured temperature deviations. This allows the control system to adapt to non-linear tissue heat conduction characteristics while maintaining stability, resolving the contradiction between simple implementation and reliable temperature control.
2Ease of operation
If focused ultrasound energy is applied to heat target tissue, then non-invasive deep tissue heating is achieved, but temperature distribution becomes difficult to assess due to tissue-specific physiological characteristics
Solution Approach 1:
The patent implements feedback control by continuously measuring temperature distribution in the target tissue using MRI thermometry and using this information to adjust the ultrasound energy delivery. The control unit compares measured temperatures with desired temperature profiles and modifies subsequent energy application accordingly, enabling precise temperature assessment and control despite tissue-specific physiological variations.
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 solution enables precise and stable temperature control in biological tissues, effectively maintaining a set temperature profile despite non-linear physiological effects, ensuring consistent and uniform heating across target regions.
Implementation Method 1
energy generating means to supply energy at a focal point of the region
Implementation Method 2
heat diffusion) of the tissue in the target area
Implementation Method 3
non-linear behaviour, in particular with respect to their heat conduction characteristics
Implementation Method 4
The control unit is able to take this thermal diffusion coefficient into account in the control law
Data Source
AI summary
An assembly for heat treating an area of biological tissue, including an energy generating device for supplying energy to a focal point in said area, a device for measuring the spatial temperature distribution in said area, and a control unit for controlling the movement of the focal point along a predetermined path to give a spatial temperature distribution consistent with a pre-sent distribution, characterized in that, as the focal point moves along the path, the control unit controls the distribution of the energy provided by the generating device depending on the measured temperature distribution and the pre-set distribution, in accordance with a control law including a proportional-integral-derivative term.