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

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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.