Department of Medical Physics, School of Medicine, University of Patras, Rion, GR 26504, Greece.
Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografou, GR 15784, Greece.
Phys Med. 2020 Mar;71:39-52. doi: 10.1016/j.ejmp.2020.02.011. Epub 2020 Feb 20.
The purpose of this study is to employ magnetic fluid hyperthermia simulations in the precise computation of Specific Absorption Rate functions -SAR(T)-, and in the evaluation of the predictive capacity of different SAR calculation methods.
Magnetic fluid hyperthermia experiments were carried out using magnetite-based nanofluids. The respective SAR values were estimated through four different calculation methods including the initial slope method, the Box-Lucas method, the corrected slope method and the incremental analysis method (INCAM). A novel numerical model combining the heat transfer equations and the Navier-Stokes equations was developed to reproduce the experimental heating process. To address variations in heating efficiency with temperature, the expression of the power dissipation as a Gaussian function of temperature was introduced and the Levenberg-Marquardt optimization algorithm was employed to compute the function parameters and determine the function's effective branch within each measurement's temperature range. The power dissipation function was then reduced to the respective SAR function.
The INCAM exhibited the lowest relative errors ranging between 0.62 and 15.03% with respect to the simulations. SAR(T) functions exhibited significant variations, up to 45%, within the MFH-relevant temperature range.
The examined calculation methods are not suitable to accurately quantify the heating efficiency of a magnetic fluid. Numerical models can be exploited to effectively compute SAR(T) and contribute to the development of robust hyperthermia treatment planning applications.
本研究旨在通过磁流体热疗模拟，精确计算比吸收率（SAR）函数，并评估不同 SAR 计算方法的预测能力。
使用基于磁铁矿的纳米流体进行磁流体热疗实验。通过包括初始斜率法、Box-Lucas 法、修正斜率法和增量分析方法（INCAM）在内的四种不同计算方法，分别估计各自的 SAR 值。开发了一种结合传热方程和纳维-斯托克斯方程的新数值模型，以再现实验加热过程。为了解决加热效率随温度变化的问题，引入了功率耗散随温度呈高斯函数的表达式，并采用 Levenberg-Marquardt 优化算法来计算函数参数，并确定每个测量温度范围内函数的有效分支。然后，将功率耗散函数简化为各自的 SAR 函数。
INCAM 的相对误差最低，在 0.62%至 15.03%之间，与模拟结果最为接近。SAR（T）函数在磁流体热疗相关温度范围内表现出显著的变化，最高可达 45%。
所检查的计算方法不适合准确量化磁流体的加热效率。数值模型可用于有效地计算 SAR（T），并有助于开发稳健的热疗治疗计划应用。
