Andreozzi Assunta, Brunese Luca, Iasiello Marcello, Tucci Claudio, Vanoli Giuseppe Peter
Dipartimento di Ingegneria Industriale, Università degli studi di Napoli Federico II, P.le Tecchio 80, 80125, Napoli, Italy.
Dipartimento di Medicina e Scienze della Salute "Vincenzo Tiberio", Università del Molise, Via Francesco De Sanctis 1, 86100, Campobasso, ITALY.
Comput Methods Programs Biomed. 2021 Mar;200:105887. doi: 10.1016/j.cmpb.2020.105887. Epub 2020 Nov 27.
Hyperthermia treatment is nowadays recognized as the fourth additional cancer therapy technique following surgery, chemotherapy, and radiation; it is a minimally or non-invasive technique which involves fewer complications, a shorter hospital stay, and fewer costs. In this paper, pulsating heat effects on heat transfer in a tumor tissue under hyperthermia are analyzed. The objective of the paper is to find and quantify the advantages of pulsatile heat protocols under different periodical heating schemes and for different tissue morphologies.
The tumor tissue is modeled as a porous sphere made up of a solid phase (tissue, interstitial space, etc.) and a fluid phase (blood). A Local Thermal Non-Equilibrium (LTNE) model is employed to consider the local temperature difference between the two phases. Governing equations with the appropriate boundary conditions are solved with the finite-element code COMSOL Multiphysics®. The pulsating effect is modeled with references to a cosine function with different frequencies, and such different heating protocols are compared at equal delivered energy, i. e. different heating times at equal maximum power.
Different tissue properties in terms of blood vessels sizes and blood volume fraction in tissue (porosity) are investigated. The results are shown in terms of tissue temperature and percentage of necrotic tissue obtained. The most powerful result achieved using a pulsating heat source instead of a constant one is the decreasing of maximum temperature in any considered case, even reaching about 30% lower maximum temperatures. Furthermore, the evaluation of tissue damage at the end of treatment shows that pulsating heat allows to necrotize the same tumoral tissue area of the non-pulsating heat source.
Modeling pulsating heat protocols in thermal ablation under different periodical heating schemes and considering different tissues morphologies in a tumor tissue highlights how the application of pulsating heat sources allows to avoid high temperature peaks, and simultaneously to ablate the same tumoral area obtained with a non-pulsating heat source. This is a powerful result to improve medical protocols and devices in thermal ablation of tumors.
如今，热疗被公认为继手术、化疗和放疗之后的第四种癌症辅助治疗技术；它是一种微创或无创技术，并发症较少、住院时间较短且成本较低。本文分析了热疗过程中脉动热对肿瘤组织热传递的影响。本文的目的是找出并量化不同周期性加热方案以及不同组织形态下脉动热方案的优势。
将肿瘤组织建模为一个由固相（组织、间质空间等）和液相（血液）组成的多孔球体。采用局部热非平衡（LTNE）模型来考虑两相之间的局部温差。使用有限元软件COMSOL Multiphysics®求解具有适当边界条件的控制方程。参照不同频率的余弦函数对脉动效应进行建模，并在相同输送能量（即相同最大功率下不同加热时间）的情况下比较不同的加热方案。
研究了组织血管大小和组织血容量分数（孔隙率）方面不同的组织特性。结果以组织温度和坏死组织百分比的形式呈现。使用脉动热源而非恒定热源所获得的最显著结果是，在任何考虑的情况下最高温度都有所降低，甚至最高温度可降低约30%。此外，治疗结束时对组织损伤的评估表明，脉动热能够使与非脉动热源相同的肿瘤组织区域发生坏死。
在不同周期性加热方案下对热消融中的脉动热方案进行建模，并考虑肿瘤组织中不同的组织形态，突出了脉动热源的应用如何能够避免高温峰值，同时消融与非脉动热源相同的肿瘤区域。这对于改进肿瘤热消融的医疗方案和设备是一个有力的成果。
