Transport lattice models of heat transport in skin with spatially heterogeneous, temperature-dependent perfusion.
Transport lattice models of heat transport in skin with spatially heterogeneous, temperature-dependent perfusion.
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DOI：
10.1186/1475-925x-3-42
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发表时间：
2004-11-17
影响因子：
3.9
通讯作者：
Weaver JC
中科院分区：
文献类型：
--
作者：
Gowrishankar TR;Stewart DA;Martin GT;Weaver JC
生物传热问题的研究需要评估温度的时间和空间分布。此类问题传统上是使用 Pennes 生物热方程来解决的。这里使用传输晶格方法对通过传导和温度依赖性、空间异质血液灌注进行的热传输进行建模。我们通过使用代表灌注组织中的 Pennes 生物热方程的晶格以及非灌注区域中的扩散来代表热传输过程。三层皮肤模型具有未灌注的可行表皮以及真皮和皮下组织的更深区域，灌注恒定或依赖于温度。考虑两种情况：（1）表面接触加热和（2）空间分布加热。该模型与皮肤内不同功率沉积方法的瞬态和稳态温升的预测相关。在活组织温度超过 42°C 的位置，使用阿伦尼乌斯型速率方程估算累积热损伤。还通过根据组织学图像创建的二维皮肤模型来说明空间温度分布的预测。通过与具有均匀热性能和端部保持恒定温度的空间分布均匀汇的板的解析解进行比较，验证了传输晶格方法。对于典型的经皮血气传感条件，即使皮肤长时间接触 45°C 表面，估计的损害也很小。皮肤热特性的空间异质性导致 10 GHz 电磁场暴露期间温度分布不均匀。真实的皮肤二维模型表明，当被热丝尖端加热时，组织异质性不会导致局部温度显着升高。通过利用局部热模型和局部电（电荷传输）模型之间的数学类比来求解蒙皮的热传输系统模型，从而允许强大的电路仿真软件获得系统模型的基尔霍夫定律的解。传输晶格允许系统地引入真实的几何形状和空间异质热传输机制。简单、被动功能和更复杂的局部模型的局部表示都可以轻松直观地包含到组织的系统模型中。
Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1) surface contact heating and (2) spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42°C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45°C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. The heat transport system model of the skin was solved by exploiting the mathematical analogy between local thermal models and local electrical (charge transport) models, thereby allowing robust, circuit simulation software to obtain solutions to Kirchhoff's laws for the system model. Transport lattices allow systematic introduction of realistic geometry and spatially heterogeneous heat transport mechanisms. Local representations for both simple, passive functions and more complex local models can be easily and intuitively included into the system model of a tissue.