bio-heat transfer

生物传热
  • 文章类型: Journal Article
    在将肿瘤组织内的磁性纳米颗粒暴露于交变磁场之后,磁性热疗将治疗温度调节在特定范围内以损伤恶性细胞。在忽略生物结构的不均匀性和微观结构响应之后,通常可以使用Pennes\'生物热方程来预测活组织的治疗温度。尽管文献中提出的各种生物传热模型解决了这些不足,目前仍然缺乏一份全面的报告,调查不同模型在磁热治疗背景下的差异。这项研究比较了四个不同的生物热方程在治疗温度分布和热诱导损伤情况下提出的几何模型,这是基于荷瘤小鼠的计算机断层扫描图像建立的。治疗温度也用作评估相位滞后行为的两个关键弛豫时间对生物传热的影响的指标。此外,这项工作评估了两种血液灌注速率对治疗温度和43°C下累积等效加热分钟的影响。数值分析结果表明,相位滞后行为的弛豫时间以及活组织的孔隙率直接影响治疗温度的变化,并最终影响磁性热疗过程中恶性组织的热损伤。在传热过程中,当弛豫时间满足特定条件时,可以将双相滞后方程转换为Pennes\'方程和简单相滞方程。此外,不同的血液灌注率可能导致治疗温度的振幅差异,但该参数不会改变治疗过程中热传播的特性。
    Magnetic hyperthermia regulates the therapeutic temperature within a specific range to damage malignant cells after exposing the magnetic nanoparticles inside tumor tissue to an alternating magnetic field. The therapeutic temperature of living tissues can be generally predicted using Pennes\' bio-heat equation after ignoring both the inhomogeneity of biological structure and the microstructural responses. Although various of the bio-heat transfer models proposed in literature fix these shortages, there is still a lack of a comprehensive report on investigating the discrepancy for different models when applied in the magnetic hyperthermia context. This study compares four different bio-heat equations in terms of the therapeutic temperature distribution and the heat-induced damage situation for a proposed geometric model, which is established based on computed tomography images of a tumor bearing mouse. The therapeutic temperature is also used as an index to evaluate the effect of two key relaxation times for the phase lag behavior on bio-heat transfer. Moreover, this work evaluates the effects of two blood perfusion rates on both the treatment temperature and the cumulative equivalent heating minutes at 43 °C. Numerical analysis results reveal that relaxation times for phase-lag behavior as well as the porosity for living tissues directly affect the therapeutic temperature variation and ultimately the thermal damage for the malignant tissue during magnetic hyperthermia. The dual-phase-lag equation can be converted into Pennes\' equation and simple-phase-lag equation when relaxation times meet specific conditions during the process of heat transfer. In addition, different blood perfusion rates can result in an amplitude discrepancy for treatment temperature, but this parameter does not change the characteristics of thermal propagation during therapy.
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  • 文章类型: Journal Article
    理解活体生物组织的热行为有助于当前热疗法的成功应用。目前的工作是探索热治疗过程中辐照组织的热传输特性,其中局部热非平衡效应以及温度相关特性来自复杂的解剖结构,被考虑。基于广义双相滞后(GDPL)模型,提出了具有可变热物理性质的组织温度的非线性控制方程。然后开发了在显式有限差分方案上构建的有效程序,以数值预测脉冲激光作为治疗热源所照射的热响应和热损伤。包括相位滞后时间在内的可变热物理参数的参数研究,导热性,已经进行了比热容和血液灌注率,以评估它们对时间和空间温度分布的影响。在此基础上,进一步分析了激光强度和曝光时间等不同激光变量对热损伤的影响。
    Comprehension of thermal behavior underlying the living biological tissues helps successful applications of current heat therapies. The present work is to explore the heat transport properties of irradiated tissue during tis thermal treatment, in which the local thermal non-equilibrium effect as well as temperature-dependent properties arose from complicated anatomical structure, is considered. Based on the generalized dual-phase lag (GDPL) model, a non-linear governing equation of tissue temperature with variable thermal physical properties is proposed. The effective procedure constructed on an explicit finite difference scheme is then developed to predict numerically the thermal response and thermal damage irradiated by a pulse laser as a therapeutic heat source. The parametric study on variable thermal physical parameters including the phase lag times, heat conductivity, specific heat capacity and blood perfusion rate has been performed to evaluate their influence on temperature distribution in time and space. On this basis, the thermal damage with different laser variables such as laser intensity and exposure time are further analyzed.
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  • 文章类型: Journal Article
    我们的核心体温由有效的内部体温调节系统保持在[公式:见正文]C左右。然而,在外部温度调节下,各种临床方案都有更有利的结果。治疗性低温,例如,由于其对脑缺血的保护作用,因此发现对复苏的心脏骤停患者的预后有益。尽管如此,实践表明,目标温度管理的结果因个体组织损伤水平和治疗策略和方案的差异而有很大差异.这里,我们通过计算建模来详细解决这些差异。我们开发了一个多段和多节点体温调节模型,该模型考虑了与特定心脏骤停后相关疾病相关的详细信息,如镇静和麻醉引起的热不平衡,炎症过程引起的代谢率增加,和各种外部冷却技术。在我们的模拟中,我们跟踪接受复苏后护理的患者体温的演变,特别强调通过食道传热装置进行温度调节,在检查用冰浆替代胃冷却时,以及麻醉和炎症反应水平如何影响热行为。我们的研究为心脏骤停后患者的传热过程和治疗提供了更好的理解。
    Our core body temperature is held around [Formula: see text]C by an effective internal thermoregulatory system. However, various clinical scenarios have a more favorable outcome under external temperature regulation. Therapeutic hypothermia, for example, was found beneficial for the outcome of resuscitated cardiac arrest patients due to its protection against cerebral ischemia. Nonetheless, practice shows that outcomes of targeted temperature management vary considerably in dependence on individual tissue damage levels and differences in therapeutic strategies and protocols. Here, we address these differences in detail by means of computational modeling. We develop a multi-segment and multi-node thermoregulatory model that takes into account details related to specific post-cardiac arrest-related conditions, such as thermal imbalances due to sedation and anesthesia, increased metabolic rates induced by inflammatory processes, and various external cooling techniques. In our simulations, we track the evolution of the body temperature in patients subjected to post-resuscitation care, with particular emphasis on temperature regulation via an esophageal heat transfer device, on the examination of the alternative gastric cooling with ice slurry, and on how anesthesia and the level of inflammatory response influence thermal behavior. Our research provides a better understanding of the heat transfer processes and therapies used in post-cardiac arrest patients.
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