Biokinetic of ⁹⁰Y-DOTATOC in human body during treatment of neuroendocrine and medullary thyroid tumors is described in this work. For this purpose, the human body may be represented by 4 compartments: blood, kidneys, urinary bladder and tumor. System of differential equations was developed a whose solution is presented in this paper. The aim is the determination of transfer coefficients between individual compartments for a better estimation of the dose in the tumor and other organs of the human body. A computer program is written in standard Fortran90 programming language.

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