HIGH ACCURACY 3-DIMENSIONAL INVERSE ESTIMATION OF TEMPERATURE DISTRIBUTION IN A HUMAN BODY FOR ESTABLISHMENT OF HYPERTHERMIA TREATMENT

在本研究项目中，提出了一种非侵入性的热疗下人体内温度分布的逆数值估计方法。在该方法中，根据受试者的多幅时间序列单光子发射计算机断层扫描(SPECT)图像来估计每个组织的血流速度。我们的研究成果总结如下：(1)提出了一种同时估计受试者各组织的血流速度及其温度依赖关系和通过受试者受热区域的温度分布的算法。利用开发的温度估算程序，利用四层肌肉-脂肪动态体模模型对算法进行了验证。结果表明，温度分布可以估计在±0.2℃以内。(3)将我们的方法应用于基于X-CT图像建模的人脑温度估计。这些结果表明，人体横截面积上的温度分布可以估计在±0.5℃以内。(4)该方法也被应用于恶性胶质瘤患者的治疗计划。针式敷贴器的最佳位置和敷贴器的数量在所有情况下都可以很容易地确定，从这些结果来看，所提出的方法适用于计划有效和安全的热疗，也可以用于检查加热后的治疗效果。

In this research project, an inverse numerical estimation method of temperature distribution in a human body non-invasively under the hyperthermia treatment is proposed. In this method, the blood flow rate of each tissue is evaluated from several time sequential single photon emission computed tomography(SPECT) images of a subject under the treatment.The results obtained in our project are summarized as follows :(1) An algorithm to estimate the blood flow rates of every tissues of the subject, its temperature dependence and temperature distribution through a heated region of the subject under the treatment simultaneously is proposed. A finite element method (FEM) was used to calculate the temperature distribution.(2) The algorithm was tested with the four-layered muscle-fat dynamic phantom model by the developed temperature estimation program. The results show that the temperature distribution can be estimated to within ± 0.2 ℃.(3) Our method was applied to the temperature estimation of a human brain which is modeled based on X-CT images. From these results, it is shown that the temperature distribution over a cross-sectional area of a human body can be estimated to within ± 0.5 ℃.(4) The method was also applied to a treatment planning for patients with malignant glioma. Optimal positions of needle type applicators and the number of applicators could easily be determined in all cases.From these results, it is confirmed that the proposed method is applicable to plan effective and safety hyperthermia treatment, and also to check the effectiveness of the treatment after heating.