Direct thermal dose control of constrained focused ultrasound treatments: phantom and in vivo evaluation
Direct thermal dose control of constrained focused ultrasound treatments: phantom and in vivo evaluation
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DOI：
10.1088/0031-9155/50/8/019
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发表时间：
2005-04-21
影响因子：
3.5
通讯作者：
Roemer, RB
中科院分区：
文献类型：
--
作者：
Arora, D;Cooley, D;Roemer, RB
第一个治疗控制系统，明确和自动平衡的疗效和安全性目标的非侵入性热治疗的描述，其性能进行评估，在phanomelia和在体内使用超声加热与一个固定的，集中的换能器。治疗效果根据递送到目标的热剂量来量化。所开发的反馈热剂量控制器具有级联结构，其中主非线性剂量控制器连续地产生用于次级约束模型预测温度控制器的参考温度轨迹。控制系统通过自动遵守用户指定的最大允许正常组织温度限制，确保正常组织的热安全性。为了反映硬件限制并防止空化，还可以对最大换能器功率施加约束。结果表明，所开发的控制器可以用来实现所需的热剂量的目标，而不违反安全约束，这是一个新的和临床上可取的功能的最小时间交付。所开发的控制器是基于模型的，并需要患者和站点特定的模型，其操作。这些模型是在预处理识别实验期间获得的。在我们的实现中，由自动治疗控制器内部使用的预测模型在每次新的温度测量变得可用时动态更新。内部模型的适应性保障了建模误差的不利影响，并确保了控制系统在存在先验未知治疗干扰的情况下的鲁棒性能。两个实验模型的热性能和超声性能有很大不同的成功验证表明，开发的治疗控制系统，以不同的解剖部位的适用性。
The first treatment control system that explicitly and automatically balances the efficacy and safety goals of noninvasive thermal therapies is described, and its performance is evaluated in phantoms and in vivo using ultrasound heating with a fixed, focused transducer. The treatment efficacy is quantified in terms of thermal dose delivered to the target. The developed feedback thermal dose controller has a cascade structure with the main nonlinear dose controller continuously generating the reference temperature trajectory for the secondary, constrained, model predictive temperature controller. The control system ensures thermal safety of the normal tissue by automatically complying with user-specified constraints on the maximum allowable normal tissue temperatures. To reflect hardware limitations and to prevent cavitation, constraints on the maximum transducer power can also be imposed. It is shown that the developed controller can be used to achieve the minimum-time delivery of the desired thermal dose to the target without violating safety constraints, which is a novel and clinically desirable feature. The developed controller is model based, and requires patient- and site-specific models for its operation. These models were obtained during pre-treatment identification experiments. In our implementation, predictive models, internally used by the automatic treatment controller, are dynamically updated each time new temperature measurements become available. The adaptability of internal models safeguards against adverse effects of modelling errors, and ensures robust performance of the control system in the presence of a priori unknown treatment disturbances. The successful validation with two experimental models of considerably different thermal and ultrasound properties suggests the applicability of the developed treatment control system to different anatomical sites.