Arora Dhiraj, Skliar Mikhail, Roemer Robert B
Department of Mechanical Engineering, University of Utah, Salt Lake City, UT 84112, USA.
IEEE Trans Biomed Eng. 2005 Feb;52(2):191-200. doi: 10.1109/TBME.2004.840471.
The problem of controlling noninvasive thermal therapies is formulated as the problem of directly controlling thermal dose of the target. To limit the damage to the surrounding normal tissue, the constraints on the peak allowable temperatures in the selected spacial locations are imposed. The developed controller has a cascade structure with a linear, constrained, model predictive temperature controller in the secondary loop. The temperature controller manipulates the intensity of the ultrasound transducer with saturation constraints, which noninvasively heats the spatially distributed target. The main nonlinear thermal dose controller dynamically generates the reference temperature trajectories for the temperature controller. The thermal dose controller is designed to force the treatment progression at either the actuation or temperature constraints, which is required to minimize the treatment time. The developed controller is applicable to high and low-intensity treatments, such as thermal ablation and thermoradiotherapy. The developed approach is tested using computer simulations for a one-dimensional model of a tumor with constraints on the maximum allowable temperature in the normal tissue and a constrained power output of the ultrasound transducer. The simulation results demonstrate that the proposed approach is effective at delivering the desired thermal dose in a near minimum time without violating constraints on the maximum allowable temperature in healthy tissue, despite significant plant-model mismatch introduced during numerical simulation. The results of in vitro and in vivo validation are reported elsewhere.
控制非侵入性热疗法的问题被表述为直接控制目标热剂量的问题。为了限制对周围正常组织的损伤，对选定空间位置的峰值允许温度施加了约束。所开发的控制器具有级联结构，次级回路中有一个线性、受约束的模型预测温度控制器。温度控制器在饱和约束下操纵超声换能器的强度，以非侵入方式加热空间分布的目标。主要的非线性热剂量控制器动态生成温度控制器的参考温度轨迹。热剂量控制器旨在在致动或温度约束下推动治疗进程，这对于最小化治疗时间是必需的。所开发的控制器适用于高强度和低强度治疗，如热消融和热放疗。所开发的方法通过计算机模拟进行测试，针对具有正常组织最大允许温度约束和超声换能器受约束功率输出的肿瘤一维模型。模拟结果表明，尽管在数值模拟过程中引入了显著的对象模型不匹配，但所提出的方法能够在几乎最短的时间内有效提供所需的热剂量，同时不违反健康组织最大允许温度的约束。体外和体内验证的结果在其他地方报告。
