Microvascular contributions in tissue heat transfer.
Microvascular contributions in tissue heat transfer.
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DOI：
10.1111/j.1749-6632.1980.tb50742.x
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发表时间：
1980-01-01
影响因子：
5.2
通讯作者：
Holmes, K R
中科院分区：
文献类型：
--
作者：
Chen, M M;Holmes, K R
生物组织中热传递的许多数学公式都是为了研究热调节、舒适性或其他现象，其中温度和热通量的显著局部（与全身或区域相对）变化几乎不受关注。然而，对热疗作为癌症治疗的强烈兴趣的出现以及与超声和微波辐射相关的安全性，以及对热成像测量的定量解释的尝试，使得非常期望具有对小规模温度变化也有效的制剂。活组织不同于非生物材料，主要是因为脉管系统的存在。血管的大量以及结构和尺寸的多样性显然使得考虑它们对组织中的热传递过程的单独贡献是不切实际的，当然，较大的动脉和静脉除外。在传热和流体流动领域，当人们遇到大量结构的问题时，这些结构的个体尺寸相对于所研究的宏观现象来说很小，通常的做法是采用所谓的连续描述。在本说明书中，仅以某种统计方式考虑小结构的集体行为。通常，小结构的影响最终以介质的连续性质表示，在我们的情况下，是组织的热导率、比热和血液灌注率。本报告的目的是探讨这些性质与血管结构和功能之间关系的理论基础。它将表明，由于脉管系统，和血液灌注率大，活的生物组织是从根本上不同于惰性材料。因此，熟悉的热性质不能再被假定为与温度场的参数无关。换句话说，这些性质可以根据应用的性质而变化。考虑到生物传热问题的现有公式已被发现或多或少令人满意的描述涉及大规模温度场的传热的事实，
Many mathematical formulations of the heat transfer in living tissues'-'have been for the purposes of studying thermal regulation, comfort, or other phenomenon where significant localized (as opposed to whole-body or regional) variations in temperature and heat flux were of little interest. The advent of intensified interest in hyperthermia as a cancer therapy and the safety associated with ultrasound and microwave radiation, as well as attempts at a quantitative interpretation of thermographic measurements, however, have made it highly desirable to have formulations that are valid also for small-scale temperature variations. Living tissues differ from nonbiological materials primarily because of the presence of the vasculature. The large number and the architectural and dimensional variety of blood vessels clearly make it impractical to account for their individual contribution to heat transfer processes in the tissue with the exception, of course, of the larger arteries and veins. In the fields of heat transfer and fluid flow, when one encounters problems with a large number of structures whose individual dimensions are small relative to the macroscopic phenomenon under study, a common practice is to adopt the so-called continuum description. In this description, only the collective behavior of the small structures is taken into consideration in a certain statistical manner. Usually the influence of the small structures are ultimately expressed in terms of continuum properties of the medium, in our case, the thermal conductivity, specific heat, and blood perfusion rate of the tissue. It is the purpose of this report to explore the theoretical basis for the relationship between these properties and the architecture and function of the vasculature. It will be shown that because of the vasculature, and the large rate of blood perfusion, living biological tissues are fundamentally different from inert materials. Consequently, the familiar thermal properties can no longer be assumed to be independent of the parameters of the temperature field. In other words, these properties may vary, depending on the nature of the application. In view of the fact that existing formulations of the bio-heat transfer problem have been found to be more or less satisfactory for the description of heat transfer involving large-scale tempera-